MTD lawn tractor turns over sluggishly, usually

[ Save This Page ] [ Follow Ups ] [ Post Followup ] [ Lawn Tractor / Garden Tractor Discussion Forum ] [ FAQ ]

SSB Farm Tractor Parts, Manuals & Antique TractorsAftermarket Farm & Old Antique Tractor PartsTractor Service, Repair & Owners Operators Manual ShopTractor ImplementsTractor SeatsTractor Front End LoadersPedal Toy Tractors Farm Tractors For Sale ClassifiedsAntique Tractors For Sale ClassifiedsTractors Forum - Help & AdviceTractor, Gardening, Mowers & Outdoor Equipment BooksTractor ProductsContact Us
How much is your farm tractor worth? Find resale prices for tractors built from 1939 through today, with complete specifications and serial numbers. Save 15% on our Official Tractor Blue Book sale!

Search This Message Board:

MTD lawn tractor turns over sluggishly, usually

MikeT I need some help with a hard-starting MTD lawn tractor, one with a 2 cyl B&S 18 hp engine.

Typically, when the key is turned, the engine turns over sluggishly and won't start. But sometimes (rarely) it turns over energetically and starts fine. The state of charge of the battery doesn't seem to make much difference, although if I jump it with a car battery, it typically turns over well, or at least better.

At this point the battery is brand new and fully charged. Terminals are clean and tight. Leads seem fine, but I haven't followed them to the starter or relay or wherever they go -- I don't have a manual and I've never disassembled this puppy; I bought it two years ago, used.

Can a starter motor get "weak"? Or can it be misaligned with the flywheel (or whatever) and bind? Is there a relay in the circuit and can it malfunction and not send full cranking juice to the starter?

I'm willing to dive into this thing, but I'd appreciate some troubleshooting tips.

Thanks. --Mike

bontai Joe Follow the negative battery lead to the other end where it connects to the frame and make sure that connection is free of paint, and tight. If not properly grounded, it might be causing the problem.
daviddude i seen this lots of times on briggs twins when the starter seems to hang up a bit as engine spins past compression....1st thing, check wires make sure connections are clean and tight. if this does not solve problem, then its time for new brushes in starter motor. and, yes the bendix gear on some will jump past flywheel gear. if this happens, turn key off and place your hands flat on engine flywheel screen and rotate engine backwards to dislodge bendix gear. good luck.
MikeT Thanks for both suggestions. I'll do a more thorough check of connections. Starter motor and solenoid are supposedly two years old.

I'm thinking I should use jumpers to apply juice directly to the starter terminals, bypassing the wiring, etc., and see how the engine responds. Film at eleven...

BTW: Do you know if this engine(18 hp B&S twin, 422707) has an automatic compression release?

And: What is an "LPG regulator"?

Thanks. --MikeT

daviddude no. that engine has no compression release. lpg regulator is a liquid propane gas regulator.
MikeT That's good to know; it reduces the possibilities.

Last night I tried starting the engine by bypassing the solenoid (relay), by applying current directly to the starter terminal from a known good battery. Same response: too-sluggish rotation. (So I don't think the solenoid or the wiring between the battery and the starter motor is the problem.)

Per another post, I confirmed the starter is disengaging cleanly from the flywheel.

All connections, both positive and negative (ground) seem tight and clean over the entire circuit.

But...during one of start attempt, the engine starting cranking well, at "full speed. (!)" But it didn't start as neither the throttle nor choke was set for a cold start, but I was encouraged.

So I set the two controls and turned the key again -- and it cranked sluggishly for a compression or two and then stopped, as it has been doing.

Can the starter motor itself be the cause? In other words, can a starter motor like this one generate less-than-normal torque even if it's getting ample current?

I thought an electric motor would either turn or it wouldn't, and if it did spin, then it's output torque would be the same regardless of the condition of its brushes or whatever.

Can someone elaborate on that?

Thanks. --MikeT

chris are you running a snowblower on this??? using in cold weather?? what weight oil in unit??? if you are still running 30w from summer this might be an issue if its cold out.
MikeT Thanks, but the lawn tractor and I are in Florida. Yes, I'm running SAW 30 in it, but temps these days are in the 70-80F range. Oil level is at the top of the recommended level (not overfilled).

No snowblower or other attachments, either.

Also, the drive belt fully disengages as it should when the PTO lever is all the way back for starting, so there's no drag from the blades or pulleys.

If I turn the engine over by hand, by using my hands pressed to the top of the screen (over the fan), the engine turns freely both ways, with the exception of the expected compression resistance. No funny noises, either.

In other words, I can't find anything that's dragging or binding.

I can't figure out why, for a few glorious seconds last night, the engine cranked at full speed, right in the middle of my troubleshooting. I probably cranked it 10 times over the course of two hours. The first five times it was way sluggish -- then one burst of being right -- then immediately (5 seconds later) back to being sluggish for the next four times. Battery charge was *not* a factor.

It seems to me the motor itself has some sort of intermittent problem, but I'm guessing. I think I've eliminated the battery, the solenoid, and the rest of the circuit, as I posted before.

Now I'm at the point where I want to solve the mystery for the challenge of it (in addition to cutting my grass).

Suggestions still welcome.


bontai Joe I'm looking forward to reading the solution to this mystery as well, it's got me stumped.
MikeT Does anyone know if a starter motor such as this one can exhibit low torque even if it's getting sufficient amps and has a good ground?

Also: Is there a way the motor and flywheel can bind? Again, the starting system used to work fine, but I wonder if the motor has shifted out of alignment. The engine rotates freely when I turn it over by hand. I have nothing to think any binding is occuring, but I'm trying to think of every possibility.

I may buy a starter motor and the swap the old one out...

This problem -- sluggish cranking even with a good battery -- seems relatively common with these tractors, based on the posts I see here. But I didn't see any real solutions. -- MikeT

daviddude the brushes and commutator in starter are stuck and dirty or, one of the field magnets inside starter is broke loose i had several with broke magnets and actually one with a out of round armutare which was rubbing againt magnets when turning.
chris have your battery "load tested" to make sure its actually putting out enough amps
MikeT Thanks for the load-testing suggestion. I'm familiar.

The starter motor behaves the same regardless of what I use for a battery; I've tried several, including a brand-new one that I filled and then charged overnight with a Battery Tender, etc.

The last time I got the engine started, I jumped the tractor battery with the battery in my car, with the car's engine running.

A few minutes ago I tried starting the tractor using its battery that had been on the Battery Tender for two days. It turned well for a revolution or two then got sluggish.

And when I felt the positive cables from the battery, both at the solenoid and at the starter motor, they were pretty hot. Not *that* hot, but almost too hot to be comfortable to touch -- beyond warm.

Can a motor fail in a way that causes it to drawn a lot of amps?


chris take your starter off. remove pinion gear. make sure there is no drag on the commutor. spin freely?? like said before the magnets can break. is the bendix straight? how do the bearings feel in the starter motor??? when you jumped tractor from car battery hoe did you hook up cables?? battery to battery. here we go. you need some jumper WIRES not cables. hook on jumper wire from ground on battery to ground on solenoid. the other cable from positive on battery to pos on solenoid. if problem goes away. there is issues with key switch or high resistance in pos side wiring from battery to switch to solenoid. more to come
c hicks Did it ever backfire when you shut off the engine? Did you hit something with the blades when you were mowing? I fouhgt this very same problem with a very similar tractor, and the fix was easy and very cheap. It sheared the flywheel key, and that puts the motor out of time. That also cause's hard turnning over just like you describe. Take off cooling shrouds remove flywheel and you will see if the key is broke. If it is broke install new one. Good luck.
MikeT Interesting possibility, but one I doubt. I don't see how improper timing would result in the engine turning over sluggishly from the gitgo, since the cylinders aren't firing (no ignition events).

But I'll keep it in mind. I'm going to first do some more troubleshooting based on other suggestions and then I'll start disassembling the damn thing to get to the starter motor. Removing the flywheel at that point should be relatively easy.

I'll report back what I learn.


MikeT I took off most of the sheet metal from the engine, the plastic fan, and removed the plugs. Engine turns briskly with the starter; no compression of course. Sounds like it should, too.

Every thing looks good about the starter and the flywheel.

But how does one remove the starter? (B&S 18 hp twin). It looks like the flywheel must be removed first to access all the bolts of the starter. If so, how does one hold the flywheel stationary while applying torque to the big nut? I couldn't find a notch or similar; I don't want to use the flywheel teeth.

I've got a parts manual but not a shop manual for this engine.

During reassembly, any special torque for the flywheel's big nut or the bolts for the starter?



P.S. While waiting for a reply, I'm going to disconnect, clean and reconnect the connections on the solenoid, etc.

MikeT P.S. Ground cable(wire) from battery goes to tractor frame, not to the solenoid.

Positive cable goes from battery to the terminal on one side of the solenoid. It then continues from the terminal on the other side to the terminal on the side of the starter.

I thought the key switch simply energized the solenoid, closing its relay and thus the starter circuit, sending juice to the starter.

Solenoid is relatively new; I replaced it last year when it melted; I don't recall the circumstances.

MikeT Thanks. I'm going to check the key once I figure out how to remove the flywheel.

I may need a special tool for that. (I don't see a way to hold the flywheel while I untorque the big nut. And I'm not sure if I'll need a special puller to pop the flywheel off.)

I'm waiting to receive comments from this list.


MikeT Does anyone know if replacing the starter on the B&S 18 hp engine on an MTD lawn requires requires that the fly wheel be removed? (It looks like it.)

If so, are special tools req'd to remove the sucker?

Thnx. --MikeT

Jim Mike, I just went through the same thing. No, you don't have to remove the flywheel. Just alot of patience is needed. You can get a wrench on the bolt and turn it out little by little. A helpful poster on this site helped me, now I'll pass it on. Good Luck.
MikeT Thanks.

You say get a wrench on "the bolt." But it looks like four bolts hold the starter assy to the case. There at the top of the starter, pretty close to the flywheel. IIRC, two of the bolts are easily accessible and two look pretty difficult.

Are we talking about the same engine?


Jim Sorry Mike. I guess we are'nt talking about the same engine. Mine is the 18 horse opposed twin. Only two bolts fasten the starter. One easily accessible, the other up underneath the flywheel. Sorry again for the confusion.

daviddude the starter is held in with 2 bolts i usually remove the near bolt 1st then when you un-do the 2nd bolt you will not be able to lift bolt out of the starter mount cos it will hit bottom of flywheel. just loosen 2nd bolt all the way, then lift starter up and out from under the flywheel with bolt still dangling in the starter mounting flange. then during reassembly put bolt back in flange hole slide starter back in. its eaiser than it sounds here. good luck.
MikeT Thanks for this, David.

Your email made sense to me until it said "lift the starter up."

To confirm: The starter on my engine is mounted vertically, with the bendix at the top. So it looks like loosening the correct screws would result in the starter *dropping down*.

I just want to be sure we're talking about basically the same engine. --MikeT

daviddude hi mike..i assume we are talking about the opposed twin briggs 18 horse engine. i believe the starter mounting flange and bolts are under flywheel. but, mabye i should have said, after loosening rear bolt, slide starter out a bit and drop down. the reason i said lift starter is so bolt threads clear the metal shroud under the flywheel but, mabye you diddnt have to do that. sorry about that. btw...did you get it out?
MikeT Thanks. I haven't yet tried to remove the starter.

Last night I again started the mower by connecting a car battery to the mower's new and fully charged battery. Zoom! I still don't understand where the trouble lies; I *think* I've eliminated poor wiring, connections, the solenoid, ignition switch.

It's like the starter requires a higher-than-normal amount of amps to generate enough torque to turnover the engine at an adequate. I don't know if starter motors can behave that way.

Someone has to know how to solve this problem.

I may replace the starter just to eliminate its condition as a possibility.


ec Well, Mike, I had exactly the same problem (same MTD, same symptoms) and I've solved it. Here's what I did. At the end of last season, it got so bad that the engine wouldn't turn over at all. I was reminded of two prior similar experiences: a '73 Dodge Dart 318 whose starter died (brushes wore down) and Navy shipboard electric motors always needing to have brushes and brush rigging replaced. So I assumed it was the brushes in the starter, and last fall, since I'm not an electrician, I ordered a new starter over the Internet from for $59.95. We live in Virginia, and it got below comfortable outside, so I didn't even open the box until today. But before I turned a wrench, I thought I'd check the Internet and see what I could find about replacing a starter. I found your dialogue, noted the same symptoms, and the good advice you had been given: a) the brushes probably being worn and b) how to deal with the 2nd bolt under the flyheel. Long story short, I did the replacement today while the battery charged, and about an hour ago the engine started and ran like a charm. I might open the old motor and look at the brushes to see if I want to replace them, but now that's pretty low priority. My advice: install a new motor. BTW, it takes approximately 25 1/4 turns to get the 2nd bolt out or in: a small wrench fits ok under the flywheel. Good luck.
MikeT That's good news; thanks.
I ordered a new starter late last week from Outdoor Distributors...for $190. I considered just getting brushes, but I need to get the problem fixed.
Does your MTD mower have the same engine (B&S 18 hp twin, model 422707)? If so, want to sell your starter? Contact me offline if you do.
In any case, I'll post how (if!) I ever solve this problem.
And thanks for the R&R tips. -- MikeT

JackB I have had the same problem with my 18 hp B&S engine. Very sluggish turn over. After checking all the electrical connections, battery etc., a I was advised to "clean" the starter. I removed the starter motor disassembled, and cleaned all the inside surfaces,polished the commutator and cleaned the brushs. I put it back together and it started the engine great. During the summer it started dragging again, so, I am in the process of replacing the starter motor.
MikeT After all this, replacing the starter solved the problem. The engine now cranks and starts great.

I disassembled the old starter (a Stens) and found two of its brushes badly broken.

So . . . slow cranking *might* not be a weak battery, corroded connections, bad relay or switch, etc.

Thanks for all the help. --MikeT

P.S. And, yes, replacing the starter on this engine is a simple task that does not require removing the flywheel.

MikeT You're exactly right. I replaced the starter last week and the engine cranks and starts great.

I took the old starter apart and found two of its four brushes to be broken into pieces. (A Stens aftermarket starter, BTW.) That explains the high resistance, as you pointed out. proved to be a good source for the replacment stater. Beware Outdoor Distributors, IMHO. --MikeT

John G Mike T what model is your engine?
mikeT Engine 422707.

(FYI: Replacing the starter solved the problem. Found that two of the brushes in the old starter were broken. It was an aftermarket starter; Stens. Replaced it with another because it was less than one-third the cost of OEM. From Jack's Small Engines.)


John G I have the same engine. What was the starter model number that you baught? Was it hard to replace yourslef becuase i am having the same problem.

MikeT Before buying a new starter, become certain it's the cause of the starting problem. Check the battery (or try another), check the connections for tightness and cleanliness, etc.

I got a Stens STE 435407 starter from Jack's Small Engines, $60 + $9 S&H. This is an aftermarket starter. The OEM starter costs $180+. (I would avoid doing business with Outdoor Distributors, based on my own recent experience with that supplier.)

Installing the starter was a straight-forward task requiring no special tools or tricks. Remove the tractor's body sheet metal to get to the engine itself. Remove the (red) shroud around the flywheel to expose the starter. Loosen the two bolts at the top of the starter -- one isn't easy to reach but is doable with a little patience. R&R the starter and reassemble.

Stens says the OEM brush assembly will work on that starter, should you want to refurb the old starter to have a spare. I'm not sure it's worth the money and effort.

HTH. --MikeT

Mike R No. There are two bolts holding the starter onto the block down through the starter frame from the top. One of them is under the flywheel but can be removed using an open end wrench without removing the flywheel. There is enough clearance up under the flywheel to get the bolt loose. Just had to do this on my 18 a few weeks ago.
MikeT You're exactly correct; I replaced the starter a few weeks ago the same way.

BTW, the brushes of the old starter were bad; two were cracked. I replaced the entire brush assy (the plastic fitting that holds the four brushes) and the starter now works like a champ.

Finally, the B&S brush assy perfectly fits the aftermarket starter. It costs about $13 new.



Dan Dang our MTD signature 2000 elitle have 18 hp twin power with starter we found that brush and 2 magnet was broken and have crack on it so where cheap new or used starter for lower price. I am very sad because it my favorite tractor. I don't like waste 100 dollars for starter so I heard it cost 60 dollars where I can get it? You maybe need replace all starter since my is so hard roll since bush is tight on shaft which slow roll and burn motor already.
FRED I just replaced the starter motor on my 18.5 twin. The Flywheel was impossible to remove without a special tool which I did not have. I managed to change the starter by reaching under the flywheel with an open end wrench for the inner bolt, The outter one is easy to get to. It went back on MUCH easier than it came off ! My son had been tapping on the starter with a hammer to get it to start and shattered the magnets which crumbled into the windings. DONT tap on the starter!
MikeT I got my aftermarket replacement starter from Jack's Small Engines for $60 + shpg. It's made by Stens, PN 435407. The B&S starter is $190.

The B&S brush assy works in the Stens starter; $13 from Outdoor Distributors.


MikeT The brushes will crack during normal use, it seems. At least that's what mine did. (I never rapped the starter.)

The lesson I learned from all this:

If the engine begins turning over sluggishly, and if you know the battery is up to snuff, immediately check the brushes of the starter.

In fact, it makes sense to have a spare brush assy on hand. $13 and easy to install.

Remove the starter, disassemble it, use compressed air to blow out the carbon dust, clean up the commutator with some 1200 grit, check the bearings, install the brush assy, and you're good to go again. --MikeT

Steve I have same 18 horse B&S engine on an MTD, with the same symptoms as everyone else. Slow, intermittent cranking performance. Thought I would share my findings...

1st, the starter is a piece of crap. It probably needs replacing.

2nd, these MTDs have horrible corrosion problems on everything. I would definitely check the back side of the key switch, all the connections on the starter relay, the relay function itself, battery terminal corrosion, etc.

I found problems with all the above on my mower over the last 2 years. I also was thrown for a loop by the starter signal wire (small wire going to the relay from the key switch). The terminal end of the wire was loose at the relay connector. Pinching the terminal tighter, and cleaning the relay's terminal blade cured the problem. No matter how much I went thru this thing, I still had horrible cranking performance. Voltage at the battery was 12.8. At the relay, it was 12.6. At the starter, it was 12.6 (disconnected). Hit the key, and the battery would drop to 9.8v. At the starter, it dropped to 5.6v!! The starter was drawing way too much power, heating up the cables quickly! Bottom line is the starter is bad.

I also noticed the starter's plastic gear was still engaged to the flywheels ring gear, and that some teeth didn't look very good. Stupid design, plastic! Also, the starter shaft was wobbly about 1/8", so it's shot. Theory: The plastic gear strips easily, causing it to stick in an engaged position. That causes the starter to run at the speed the motor runs, quickly burning up the starter motor and bearings. Fact: The starters suck.

Their symptoms closely resemble a battery or cable or wiring problem, which I have been troubleshooting for 2 years on and off. The whole time, it was the starter.

Don I have an MTD 12.5 hp w/Tecumseh engine. It will now start and I have checked the battery, replaced the starter, tested the key switch, the brake switch, and the solenoid. When I attempt to start I hear a faint noise but the starter never engages. Is there a system of troubleshooting I can try to isolate my problem and resolve this issue. Can I bypass all the switches and go directly to the starter? Please help me...I really need to cut my grass.
Don Sorry...I meant it will not start. Can someone help me?
Vince For what it's worth, I have similar tractor with a similar problem which I use now only in fall to pick up leaves because it has a catcher. By removing one spark plug, the starter-motor would actually turn sufficiently to start the motor on one cylinder. After running it for a while to warm up, I stopped the motor and re-intalled the spark plug and the starting was then usually possible - sometimes I would have to use the flats of my hands on the fan-cover to help spin the motor up to speed and over the first few compressions while cranking.
TDW Just replaced the starter motor on my briggs&stratton 14.5 on an MTD. Use it for snow thrower attachment in winter. Has always been slow to turn over. Found the brushes were binding in the plastic end cap on the old starter. Would hardly budge before the plastic warmed up. If the brushes are not making solid contact with the spindle you won't get full power. I think this is a common problem with winter use because I've had to put a heat lamp on it to get it to started in years past.
wade I went through three starters in three years on a 6 or 7 year old MTD with these symtoms before scrapping it.
Dick Kalinowski Great info! However, I type in Jacks small engines, and Network Solutions keeps popping up, instead, so i can't even locate that $60 starter...! Wazzup?!
Mr. Ed Have a Murray 18hp with the same problem. checked all cables, wires, and battery. I also checked the starter brush assy. Everything was good but dragging continued. I bought a new starter and although better it still drags at times. I was told by starter manufacture that my starter(693551) has a 14 teeth gear which makes for a bad starter gear to flywheel ratio(hard to turn bad design)and is common on 14 teeth starter. Can anyone tell me if there is any truth to this?
Chris Collins I have the B&S 422707 on a "Powr Kraft" (they can't even spell, never mind make mowers) same hard starting problem. New starter had the same problem. I put big battery cables in the mower to reduce the voltage drop and all has been fine this summer. I take good care of my stuff so I always open the hood and idle for a few minutes before killing the engine. Today as it idled I lost spark for no apparent reason. Does anyone know what the three leads should read normally? IS the yellow a ground to kill wire? I can only asume the red and white are for charging???? I am at a loss. Please help ecause I will not be able to sleep tonight if I cannot get it to run!!
Bryn Shuter I've had this problem ever since mine died about 3 months ago. Tractor is about 20 years old and had original starter. I brought a new one, I think from same place you mentioned (via e-bay). It lasted about 6 weeks and then had all these symptoms. The magnet was broken off and it had jammed and burned out. Now, my second replacement has all the same symptoms. A shame I threw the old one out, new bushes would have probably done the job (the originals were non-existent) but I figured a new one would be better :( I hope I can salvage something from the 2 new ones I have. I'd recommend trying to refurbish your originals, because the new ones seem to be very poorly made. Good luck.
Ryan Connor I had the same problem. I took my starter apart and found the brushes and magnets in good shape. I cleaned off the internals and put it all back together and had the same issue. It must be the internal windings failing or something. I purchased a new starter for my MTD tractor from jacks small engines and it turns over great now with no issues. The posts on this site were very helpful in working this issue out.
Louie For an illustrated diagram of all parts on your MTD lawn tractor, go to:
Then choose "Launch Illustrated Parts Look-up Tool"
Enter your model # 136L660F062 and click "search"

Kdeezy I have the same problem with my tractor, it's a Mtd w/ 21hp Twin B&S (whatever that means...). At first it was sluggish, especially in colder temps. I then figure out a temp solution by turning my flywheel to the peak of where there's most tension, then engaged the starter. That worked fine for a while, and now my starter is completely out. From reading the forum, I'm guessing I'll need a new starter or at least some brush replacements?...This tractor was purchased *brand new* is only 3 yrs old. Kind of a disappointment that this occurred after only the second season of usage, and not very often. I guess you get what you pay for, right?!
ron I have a 12 year old craftsman riding mower with a 18 hp kohler eng. It wouldn't start, so I replaced the battery. Still nothing. No click, nada. Then I replaced the starter and solenoid. Now, even with the key in the off position, as soon as I connect the battery, the bendix jumps and tries to engage the flywheel. But it won't catch the teeth properly and looks like it pushes the bendix too high, into the rubber bushing at the bottom of the gear teeth. Any ideas?
Jerry McClurg How much torque should be on the bolt that holds the fly wheel on and 318 John Deere?
1froggy1 I had the same broplem with my 17.5 hp ohv mtd. after checking everthing out and at a loss, I ask alocal retired small engines mechanic. He ststed the valves clearance needed to be reset.. I set up the clearances and it starts beautifully...
Derek I have a briggs 14.5 OHV engine and struggled with sluggish starting for years. I'm on my third starter on this 11 year old tractor. I was about to replace the current starter when I fished around a bit and saw posts on adjusting the valves. Never did this, did it today and it starts like a charm. All this time and my problem was not starters but valve adjustments. The extra compression was killing my starters over time. If you wonder how to fix this, check out this youtube clip. Very easy fix.

PJ I have a '97 Scotts with 17.5 Briggs ohv with sluggish starting since new. most recently not turning over. replaced battery, then solenoid but still no help. Just replaced starter (693551), still slow turnover then stops at a high compression point.
I found this site and thought the valves must be out of adjustment. I followed the instructions given by smalleng (youtube). No change in the apparent high resistance during the compression cycle.
Should I redo the valve adjustment?
Any suggestions will be appreciated.

Rol Try going to a john deer dealer and ask them for a relay kit. Should do the trick. For some reason the problem of clicking is widespread on most of the late model tractors. This relay kit cost about 40 dollars new from John Deere. That purple wire at the solenoid builds resistance on these tractors over time. I've thrown alot of money at this problem and the solution is a simple black relay with 4 wire and instruction on how to install comes with the kit.

Edward A. Stannard I have had the same problem with my MTD tractor for a year now. Most times it would get to the compression stroke and it would barely turn over. Sometimes it would turn over fine. I bought a new battery which only helped for a week or two. I eventually was jumping directly to the starter to try and fix it. Then I brought it to a small engine repair shop and the gentleman said it needed a tune-up. So he did a tune-up and I still had the same problem.

Well today, I finally figured it out! I went to start it this morning and the same thing (turns over until it gets to the compression stroke). Tried to jump directly to the starter and got the same thing. Then as I was sitting there trying to figure out what to do next, I noticed something. It sounded like liquid squirting inside the cylinder.

So I took the spark plug out and turned it over.


I put the spark plug back in and it turned over like crazy and immediately started up! That was the problem all along. You see, you cannot compress a liquid. So when the piston got to the point were it was encountering the gasoline on the compression stroke, it could not physically go any further. Anyway, problem solved. My solution will probably be to put an inline gas shutoff on the gas line and let the mower go dry when I finish using it each time so there is no chance of any more gas getting into the cylinder when it's sitting around.

Jim if you want to remove the starter, you can just use a wrench to get to the bolt under the flywheel. I undeerstand this can be hard so if you can't manage it, do what I did! Simply stuff rope into the cylinder (the spark-plug hole) not both, you only need to do this to one. Then you can turn the wrench to get the bolt off. (I used vise grips for this) and you dont need that special tool, you know the flywheel puller, to get the flywheel off, just take out all of the bolts for the plastic fins that cool the engine, and shove a pro-bar under the flywheel and pull up as you hit the side of the it and the shaft in the middle, and it should pop up! (sometimes this takes a while, especially on the bigger ones)
Rick G. could a bad spark plug cause it to start sluggish? I would think it would just not start, any thoughts?
Gary i have had the same trouble with mine.bought a new battery. took starter out cleaned it and inspected. re-installed starter.worked better than before but not for long. always works better when car battery is jumped to it.this is a yard machine 1998 17.5 hp. great machine when u grt it started. what cold cranking power should u use on these b&s engine's.
R.Russell I have the same mower and engine and have had the same problem for years. Checked and cleaned all connections. Removed starter and disassembled. Everything checked out OK...Cleaned up epoxy on rotor where It looked like it might be dragging and cleaned commutator. Reassembled and it started ok. Next day, same problem. Bought a new battery, although the old one checked ok. Same problem. This evening I had a brainstorm. I mounted the "OLD" battery on the left running board and ran a couple of heavy jumpers to connect the two in SERIES (Neg. to Pos) and left the solenoid actuating wire connected to the original battery so that I am using 12 v. to energize the solenoid, but 24 volts to the starter. Starter turns over about twice as fast and starting is immediate. I'll have to be careful not to ever grind very long, but since it starts immediately, I don't think that will be a problem. Bear in mind I just did this tonight, so I don't know if there will be any long-term negative effects, but my old mower isn't worth investing a lot in and this seem to be a good solution. last year I ran two batteries wired in paralell and it helped a lot, but starting was still sometimes a problem. I can't see why setting the valve clearance would have any bearing, since both valves would be closed at the beginning of the compression stroke and stay closed until the bottom of the power stroke. I strongly suspect the starter on this engine may have been barely strong enough at the beginning and it's permanent magnets may loose a little magnetism over time. This trick is sometimes used on old farm tractors that had six volt systems and I haven't heard of anyone burning up a starter.
river_ranger Valve adjustment did it for me, struggling with battery/starter all day, found this video and it works perfect now

HK Smith I imagine this thread is pretty old, but I watched the valve adjustment video Derek posted, did what the guy demonstrated on the video and whammo, problem solved-thing starts like a new tractor. EASY FIX!!Gone through 4 batteries, 1 solenoid and one starter rebuild over the last 4-5 yrs. This was my problem all along. Another related symptom other than not being able to start was when I shut the engine off after decreasing the engine speed back down to idle, the thing would backfire like a shotgun.
Mike Valve adjustment did it for me too. Thanks for the great video.
Herbflerb Great thread, lots of ideas and input. I have an 18 HP B-S on a MTD ... just like a lot of you... thanks to the comments above i pulled the starter and yup - this has to be the trouble. The armature was spinning out of round (probably due to a bad bearing) and rubbing against the permanent magnet, cracking it, and wearing it down thinner. that can't be good LOL. Wellsir, off to order a new starter! Thanks guys!!
Marco A I had the same issue with the starter malfunctioning. New starter at Amazon set me back $31.00 + $13.00 for 2nd day air shipment. Way cheaper than the $200 price at Lowe's!
larry i put a in line fuel shut off on my tractor and when im done mowing i shut off fuel and let mower run out of fuel its starts up fine the next time so i think fuel is leaking past carb into cylinder causing hydro locking

Eugene I to have this problem with my B$S Engine 18.5 H. I do believe I have a compression problem. The viedo on Youtube is in reference to a one spark plug valve adjustment, does any one know the procedure for a two spark plug B&S engine valve adjustment
EugeneR I need help locating the valve cover for a MTD Briggs and Srattion 18.5 engine. I am having trouble
starting because of compression not releasing. I am sure I have the same problem as everyone else is.
Please provide the actual location of the HOV cover and the procedure for adjusting the valves setting.

[ Save This Page ] [ Follow Ups ] [ Post Followup ] [ Lawn Tractor / Garden Tractor Discussion Forum ] [ FAQ ]
Post a Followup




Email Notification: If you check this box, email will be sent to you whenever someone replies to your message. You must include your email address above to receive this notification.

[ Save This Page ] [ Follow Ups ] [ Post Followup ] [ Lawn Tractor / Garden Tractor Discussion Forum ] [ FAQ ]


Sign Up For Our Monthly Special Sales!