7 year old Craftsman 21 hp riding mower hard to turnover & start, High compression stroke. Model 331877 2371 G5, YT3000

[ILENGINE]

I have the same problem with the 270000 model. How hard is it to fix the compression release? If I take off the oil fill cap it shoots oil a foot high. I was going to replace the head (valve last was properly adjusted at some point the sleeve came loose and the prior owner pinned it back in place, so that sounded like the culprit) but it sounds like the compression release is the more logical source of the problem. Everything else on the mower is perfect so I’d hate to scrap it.

i think you made a mistake on your model number. I think you mean 280000 series which the 21xxxx, 28xxxx, 31xxxx, 33xxxx all use the same 84005207 camshaft. And if the engine is running and you remove the dipstick they all will shoot oil all over the place. The piston going up and down will act like a large air pump pulling in air on the up stroke and then will try to purge that air on the down stroke. You have to run it and then shutoff the engine prior to removing the dipstick to check for the blown head gasket smoke.

 

[Ronni]

I bought a used craftsman riding mower for a few hundred dollars thinking that I could fix it. I was told it sat over winter and they couldn’t get it started this year. They said they didn’t know much about fixing it so they bought a new one. I figured it sounded like maybe a easy fix. Guessed wrong so far. They replaced the battery but with low torque I noticed. When I got it the battery was dead. Charged the battery, adjusted the Values to 005, both intake and exhaust. I tried to start the engine, a few times the engine didn’t want to turn over more then an inch. I rotate the engine by hand over the high compression and I tried starting the engine. The engine started right up and ran really good. Cool I thought!
, that I have fixed it. Wrong. When I tried to re started the engine, the same thing again. I replaced the started thinking it was bad or going bad. I replaced my starter. I still had the same trouble starting the engine, not turning over enough to start and now I broke two starter gears.

Q, I am not if the started is installed correctly, Is there supposed to be a shim/washer under the rear starter bolt Between the engine and the starter? When I was removing the starter a washer fell and not sure was it behind the starter or not? Currently there isn’t one and I have broke two gears now. Maybe that is my answer. Or is the high compression breaking my starter gears?

Q, I can’t tell if the crank/cam compression release lobe is releasing on my mower looking at the valves. The little bump what I have read and seen on the you tube videos. I have read an old 2014 forum had a similar problem but they replaced the starter and they were good. Or so good for me. I may have to take it down to the repair store if I can’t figure this one out.

Any help would be great

Stan

To answer your question about the washer; find an illustrated parts breakdown and find that washer on it and you will have your answer. Regarding the broken gear; that will have to be replaced or nothing will work properly. Regarding the hard starting; two things. First, make sure your battery has the required cold cranking amperes for the engine; that will be in the owner's manual. Secondly, if the starter is undamaged and new, you might want to replace the starter solenoid because they do go bad and that will cause your problem.

 

[MowerNick]

you need a camshaft. very common problem. in my shop we change a couple of those a week. the cam has a built in decompression valve that breaks off the cam. you also shouldnt keep running it like that because if one of the broken pieces gets jammed somewhere it shouldnt it could completely ruin the engine.

 

[PNWguy]

you need a camshaft. very common problem. in my shop we change a couple of those a week. the cam has a built in decompression valve that breaks off the cam. you also shouldnt keep running it like that because if one of the broken pieces gets jammed somewhere it shouldnt it could completely ruin the engine.

Thanks, I wish that I knew that beforehand. I removed my mower Engine today and opened it up. Sure enough, the cam decompression release valve is totaly destroyed. Broken in several piece. I am trying to find all of the small pieces. I think that I got most of them but think there may be some more unless they were in the oil when I drained it. One large piece came out when draining the oil. I just ordered the new parts. I have a new question, I removed both long push rods and they are different looking, does it matter which position they go in. There both the same length.

 

[PNWguy]

hmmm, thats a big tradeoff

I decided to do it my self, I found the problem, bad cam release. It was broken in man pieces. it will cost about $120 to replace the items and starter gears again lol, a lot better then $350. I can’t wait to put it all back together in a few days.

 

[PNWguy]

its really not that hard to replace the cam, its just right there after you take the oil pan off...

I like your video, yep, that’s my problem. I just bought a new cam online, so I should be good. Thanks for sharing.

 

[PNWguy]

Needs a Cam. been there, done that.

Yep, you are correct!

 

[PNWguy]

couple of points.
1. bertsmobile has really good advice...he is particularly reliable with his experienced suggestions.
2. just because you have a new battery does not mean you have GOOD WIRING AND CONNECTIONS. test and inspect every single red and black cable (heavy) wire and connection...Pay attention to the starter solenoid (red) and the flywheel solenoid starter (also red), and also the black heavy wire going to chassis ground. It might be just be a loose or corroded connection or a bad ground. If you have a clamp meter, you can measure the current across the heavy red cable connected between the starter solenoid and the flywheel solenoid starter. If the amps are low, you know you have a wiring issue a bad connection somewhere or the flywheel solenoid starter is bad. This assumes the battery you installed it GOOD AND FULLY CHARGED - not RUN DOWN from repeatedly trying to start the mower with it.!! yes?

and finally but certainly not this....this is one of those universal size fits all shade tree mechanics methods to check and engine isn't borked...it will not tell you what the problem is, but it helps you eliminate many other things

remove all spark plugs...rotate flywheel BY HAND. Engine should rotate easily with no resistance. If it doesn't, you know you have something related to engine (valves, auto compression release, bent valves, valves stepped out or damaged, borked crank, seized or broken piston/piston rings, failed or borked PTO (is belt under tension all the time?, even power off?)

hopes this helps....start with the simple things and work up to the harder things...in most cases, especially if mower is old, it's going to be a simple thing...like wiring that has corroded or a starter solenoid that

Thanks for the good advice! All of my connections are clean and tight. And you can rotate engine by hand. I removed the engine today and found a bad cam release mechanism. Broken into several pieces. I just order new parts that should fix it. Thanks everyone for helping me out. Hopefully everything will go back together and it fixes my problem.

 

[TobyU]

Also make sure you are adjusting valves correctly.
Your first post says. 005. That is incorrect for a 31xxxxx series.
They set at intake: .003-.005
Exhaust: .005- .007
You want intake to be in the tighter side since that is the one that does the compression bump.
Exhaust is best on the looser side since it is more likely to burn and valves cool when closed.
They both get more clearance when they wear unlike cars.

ALSO you need to set piston at 1/2 inch past TDC of compression stroke to set and not at TDC like many think.

Regardless, if you saw no bump, then the ACR is prob busted.

Problem is the aftermarket cheap ones are a crapshoot!
I used 3-4 with no problems they I know of BUT the last one bit me.

It was a friend's mower and it only lasted 10 mows!!

The lobes spun on the shaft.

I don't trust Briggs OEM ones much but I trust them a little more than Amazon/eBay ones.
The Briggs one is almost through it's second season now.

Make sure you pull the oil pump flat cover and gear before you put the sump back on or you risk jamming up the pump gear and having no oil pressure and that will blow engine in about 90 seconds.

 

[BobHog]

Most likely valve clearances. The compression release can break, but I would definitely check the valves first. If it is the compression release, make sure you get a new cam seal - they are a booger to get to seal again!