Kohler 7000 series locked up?

[Mr Mower Man]

I had a Kohler KT730 (Spec 3035) with about 75 hours on it lose a camshaft, so I was repairing it under Kohler's warranty. The black plastic gear shattered, and little pieces of it were everywhere.
So today I put in the improved style camshaft, 4 new push rods (they were all bent), a new oil seal, a new oil filter and fresh oil, and put it back on the mower (Country Clipper zero turn). When I started the engine, it made a horrible racket for about 5 seconds, but then quieted down and ran well. I noticed that whenever I accelerated the engine, it was noisy during the acceleration, and maybe a little at higher RPM's. But it sounded quieter at lower speeds. I figured out later that the muffler has a loose baffle, so that may have been the noise.

But the main problem (aside from the fuel pump leaking almost directly over the muffler ) was that, after maybe 90 seconds of total run time (I started and stopped the engine 3 or 4 times), I stopped the engine and tried to start it up again. The starter gear hit the flywheel, but it wouldn't turn over! Locked up! So I removed all loads to the engine to make sure it wasn't something on the equipment causing my problem. Problem is definitely in the engine. I put a wrench on the PTO bolt to try to turn it, and it wasn't going anywhere. So I pulled the engine back off, drained the oil (no, I didn't forget to put oil in it!), and took the crankcase cover back off, not having any idea what I'd see inside. Everything looked fine in the crankcase. No scored bearings, no heat discoloration, nothing broke...it all looked like it should. Then I took the rod caps loose, and they looked good. The connecting rod bearings and crank journal looked fine as well, and the pistons moved freely up and down the cylinder. I saw and felt as much of the cylinders as I could from the bottom end, and the pistons still in place, and there was no scoring that I could tell. But the crank still would not turn, so I figured it must've seized at the magneto bearing. So I removed the flywheel and tapped the crankshaft loose, and much to my surprise, the upper bearing looked just as pristine as everything else. So did the crankshaft at that spot. Why on earth did the engine lock up?

Of course, this happened late on a Friday afternoon when I have to wait till Monday to call Kohler for any support. I slid the crankshaft back in place and buttoned the crankcase cover back on with 2 bolts, to see what the end play was. None. I thought all engines needed crankshaft end play, so this may be a problem. I'll have to reference the service manual for that. There is no gasket for the cover, just an RTV sealant. Problem is, it's been running 75 hours without locking up, and I only changed the camshaft, so I have a hard time saying a lack of end play is what caused the engine to lock up this time. I'm really at a loss here. Any ideas?

[bgsengine]

while reading the last bits it occurs to me to think of the flywheel magnets - they ARE known on many kohler models to come loose and because they are magnets, it is not always obvious - have you taken a close look at the magnets (spacing of them) under the flywheel and see if any look to have come loose?

[Mr Mower Man]

I did notice that the flywheel magnets *seemed* OK. But I can make a more thorough inspection. Good idea. I did look to see if the alternator was damaged. Also, the starter turns freely as well, as I don't think I mentioned that before.

[Mr Mower Man]

OK, I wanted to correct something I said earlier. There IS crankshaft end play. I just wasn't pushing/pulling hard enough on it before.

[lee]

Here's my experience with a locked up engine. I opened up a Briggs vertical opposed twin to replace the top main bushing because I was tired of hearing the "chuckle" at idle as Walt calls it. Turned out the bushing had just a small amount of wear, it didn't look bad at all, but it was indeed the cause of the chuckle. I noticed the crank had what I thought was a good amount of end play with the standard .015 thick gasket. So I tried a .005 gasket because I didn't have a .015 gasket and also wanted to see if I could tighten her up a little. I snugged up the sump bolts and pulled and pushed on the crank and I still felt a little end play so I thought good to go. Put her back together, turned her over by hand, put her on the stand, filled her up with oil, hit the starter and she fired right up and ran.......Then she locked up! Son of a.....what did I do now! Now she's tight and I can barely get her to rotate. Drained the oil, pulled the sump, everything looks fine, no metal particles thank God, and she rotates fine. I didn't have a .015 sump gasket but I did have another .005. So I put two .005 gaskets on it and tried it again. It's been running and sounding great for a while now. No knocking or chuckle or leaks. Here's what I think happened. The crank had a few thou of end play with just the one .005 gasket, BUT THE CAM DID NOT. I had no way to measure the end play of the camshaft so I didn't know it didn't have enough. The crank probably put a little more wear on the bottom main bushing than the cam did on it's bottom bushing creating more end play for the crank vs the cam. So the one .005 gasket was enough to give the crank some end play but not the cam. I know your Kohler doesn't use gaskets to set end play but I'm thinking maybe somehow the cam doesn't have enough end play and is actually what is binding up your engine. Just another idea.

[KE4AVB]

Also something else. Once the crankcase cover is off the crank can till while the flywheel is still on and hang up on the magneto. or stator. I would have started checking the items first instead going in right away. Even when loosen or remove thing the crankcase needs back for the crank to aligned or it can bind up. With lower clearances it could have been the new camshaft binding but since it is out completely apart no way of finding except to re-assembly it and checking if it is binding again.

Just thinking...

[Mr Mower Man]

The only thing different in the engine is the camshaft, so perhaps the cam end play is causing me some trouble. I see there's a spec for cam end play. For what reason, I have no idea, since I can't measure it! But I'm thinking I jumped the gun by tearing into the engine this time. Actually, I don't think the cam was causing the problem, because the crank still wouldn't rotate with the cover off. Even with the rod caps loosened, it still wouldn't turn. The trouble had to be at the top somewhere, and I'm not at all certain that it's not something to do with the flywheel. But yes, I'll have to reassemble it to find out for sure. I probably created more work for myself by the way I went about it. I'm getting some parts in today to reassemble it (head gasket kit and piston ring set, because I accidentally pulled one piston out the bottom of the cylinder), with a new muffler (it had a loose baffle creating noise), and run it again to see how it does. Funny thing is that it didn't lock up while it was running, just when I tried to start it back up! Never seen anything like it. I'll keep you updated.

[bgsengine]

Funny thing is that it didn't lock up while it was running, just when I tried to start it back up! Never seen anything like it. I'll keep you updated.

Close inspection of the starter gear and flywheel ring gear is in order, as well. Also make sure battery is fully charged, and also check a full rotation worth of the flywheel with the starter gear engaged (by hand, easiest is to turn engine backwards) and look for any clearance of binding issues. Not familiar with the 7000 series kohler but I have had a couple where the starter mounting bent just a little bit causing a lot of gear lash and when the engine hit compression, the starter or shaft would sometimes flex out just enough that the gear teeth slipped out and jammed (tooth on tooth) loosening starter bolts and re-meshing gears got t hem back in place until next time it happened - final solution was a new starter , which when we compared to the old one, found the "bend" in the starter mounting.

[38racing]

Here's my experience with a locked up engine. I opened up a Briggs vertical opposed twin to replace the top main bushing because I was tired of hearing the "chuckle" at idle as Walt calls it. Turned out the bushing had just a small amount of wear, it didn't look bad at all, but it was indeed the cause of the chuckle. I noticed the crank had what I thought was a good amount of end play with the standard .015 thick gasket. So I tried a .005 gasket because I didn't have a .015 gasket and also wanted to see if I could tighten her up a little. I snugged up the sump bolts and pulled and pushed on the crank and I still felt a little end play so I thought good to go. Put her back together, turned her over by hand, put her on the stand, filled her up with oil, hit the starter and she fired right up and ran.......Then she locked up! Son of a.....what did I do now! Now she's tight and I can barely get her to rotate. Drained the oil, pulled the sump, everything looks fine, no metal particles thank God, and she rotates fine. I didn't have a .015 sump gasket but I did have another .005. So I put two .005 gaskets on it and tried it again. It's been running and sounding great for a while now. No knocking or chuckle or leaks. Here's what I think happened. The crank had a few thou of end play with just the one .005 gasket, BUT THE CAM DID NOT. I had no way to measure the end play of the camshaft so I didn't know it didn't have enough. The crank probably put a little more wear on the bottom main bushing than the cam did on it's bottom bushing creating more end play for the crank vs the cam. So the one .005 gasket was enough to give the crank some end play but not the cam. I know your Kohler doesn't use gaskets to set end play but I'm thinking maybe somehow the cam doesn't have enough end play and is actually what is binding up your engine. Just another idea.

Which I assume is why Briggs says always use at least the .015 gasket. Increase endplay by adding gaskets but reduce by adding a thrust washer on the crankshaft.

[lee]

You can't go wrong using the .015 standard gasket on a Briggs. That said if Walt were here he'd tell us by the time he opens up an engine it has enough wear on it he uses the .009 gasket. He orders them in bulk and has never had a problem with too little end play. He has helped me on several occasions over the years and I take what he says as gospel. I'm betting the new cam on the 7000 series Kohler is just a tad too long leaving no end play.