Kohler cam timing

[thebuggyman1]

IMG_1164.jpgIMG_1161.jpgI have a real tough one for the engine guru's out there.
I finally got the Kohler 40 horse for my bigfoot project rebuilt and back together.
I tried to start it and it wouldn't build compression or pump air. Sooooo, out comes the motor, and the side cover comes back off to make sure I wasn't a tooth off on the cam to crank allignment. To try and keep this short I'll spare the details of how many hours I spent today trying to figure this out. Basicly, with the marks aligned, The intake valve stays open too long. I tried shifting the cam gear off the mark and the piston will hit valve. And yes it has good compression with the rocker arms removed.
The model# is ch1000, and the history on it is: at about 120 hours of use the p.o. let it overheat. Thats when I got it. The cylinders were worn and it needed to be bored to .020" over and new pistons. Everything else looked good. The current working theory is the gear on the crank slipped when it was overheated....the timing mark doesn't line up with anything....neither cyl TDC or BDC, or the rod journal (thats where I'd guess it should be). Any Ideas?

[msafi65]

Is the crank gear keyed or pressed on ? Does it have a compression relief on the back side of the cam gear? Don't have any great ideas but some questions. I'm not with my manuals for two weeks. Good luck

[fmints]

Try returning everything back to the orginal position (mark to mark on the crank and cam) and set the valve lash( valve clearance ). Tampering with the cam is suicide for the engine. I beleive that your problem is with the valve clearance or in your heads. Maybe there are two different lengths of pushrods, one length for the intake and another for the exhaust. I will try these first, especially the valve clearance If not it would not hurt anything, and wouldn't cost a thing to check. The clearance specs should be in the manual if you have one, if not you can google and find a downloadable pdf. I hope this helps!!

[wfo]

agree....alighn all marks together...crank at 12:00 and cam at 6:00
that is your starting point

[LarryW]

I know its not the same exact engine but looks like it can happen and does look like yours is spun. The dot should line up with a line in the casting. Here is the thread I found talking about it.

http://www.lawnsite.com/showthread.php?t=350124

[thebuggyman1]

Is the crank gear keyed or pressed on ? Does it have a compression relief on the back side of the cam gear? Don't have any great ideas but some questions. I'm not with my manuals for two weeks. Good luck

Crank gear is pressed on.....no key, that would be too easy. No compression relief on cam, and I have the manual. It doesnt give pictures or any info other than to line the marks up.

Try returning everything back to the orginal position (mark to mark on the crank and cam) and set the valve lash( valve clearance ). Tampering with the cam is suicide for the engine. I beleive that your problem is with the valve clearance or in your heads. Maybe there are two different lengths of pushrods, one length for the intake and another for the exhaust. I will try these first, especially the valve clearance If not it would not hurt anything, and wouldn't cost a thing to check. The clearance specs should be in the manual if you have one, if not you can google and find a downloadable pdf. I hope this helps!!

No valve lash on this one, it has hydraulic lifters, simply torque to 130 in-lbs. All 4 lifters are identical, same with the push rods, and rocker arms.

agree....alighn all marks together...crank at 12:00 and cam at 6:00
that is your starting point

At this point, it has no valve interference (hitting piston), but does not build compression. It is leaving the intake valve open.

I know its not the same exact engine but looks like it can happen and does look like yours is spun. The dot should line up with a line in the casting. Here is the thread I found talking about it.

http://www.lawnsite.com/showthread.php?t=350124

The pictures there help Larry. This is what we were thinking....why wouldnt the timing mark line up with anything, it makes no sense. The service manual has no pictures of the allignment, but it does have a drawing of the crank that shows the dot by the counter weight.
With any luck I will find out today if the crank and gear will have to be replaced.

[fmints]

I know its not the same exact engine but looks like it can happen and does look like yours is spun. The dot should line up with a line in the casting. Here is the thread I found talking about it.

http://www.lawnsite.com/showthread.php?t=350124

I agree with LarryW. I just looked at a kohler crank that I had laying around and the dot lines up with the weld on the crank. thats your problem. Good looking LarryW.

[fmints]

I agree with LarryW. I just looked at a kohler crank that I had laying around and the dot lines up with the weld on the crank. thats your problem. Good looking LarryW.

Here is a pic to back up my statement!
2012-06-04072232 picture by fmints - Photobucket

[msafi65]

I see from parts book the sprocket isn't sold seperatly. It was probably installed in a jig at the factory. Is the a chance in h. that Kohler would install one if the crank is sent to them? Good luck

[thebuggyman1]

After thinking about this all day, I came home and lined the cam up with the casting line on the counter weight. Thinking that this should be a standard thing on all Kohler cranks.
I spun the crank over...no interference with the valves......spun it over a little faster (spinning by hand), and it makes compression and pumps air like it should.
Hopefully I will hear from a Kohler rep tommorrow to verify this is correct and I'll just change the gear to the right position.
Kohler wants to sell a $300 crank, not a $20 gear so there is no way they would fix mine.

[LarryW]

I thought you could probably just line it up like you said and run it but then there is a chance that the gear would move again. Is that a "non-interference" motor?

I mean if you know where it should be dont worry about the dot. It may not be 100% right though unless you are lucky enough to have it spin in an increments of exactly one tooth, lol.

[thebuggyman1]

One tooth is 10 degrees (alot). And near as I can tell it is a half tooth off from doing just that. Tomorrow I will talk to my machinist, maybe he will just cut a keyway in this one, or put a spot of tig weld on it.

[fmints]

One tooth is 10 degrees (alot). And near as I can tell it is a half tooth off from doing just that. Tomorrow I will talk to my machinist, maybe he will just cut a keyway in this one, or put a spot of tig weld on it.

Yeah i was thinking that Tigging it should be good!!

[Tomo]

hi
place no1 piston TDC
camshaft lobes pointing away from tdc [this sets the cam for compression stroke ]
assemble crank and cam as per above

NB small block kohlers use no key way and have a pressed sprocket that do slip and crack
The customer service at kohler can tell u how the teeth of the gear align to the casting marks on crank
cranks cannot be repaired ,parts were unavailable last time i enquired

tomo

[thebuggyman1]

The Kohler lives

I pulled the timing gear off and repositioned it, alligning it with the crank casting mark on the counterweight. It's up and running! With a little more info this makes sense.
When the motor overheated the main bearings moved out of their normal position and put pressure on the timing gear making it even hotter.

Now my problem is the rubber isolation mounts are not stout enough hold back the 40 horse....the motor moves alot, and I'm afraid they are going to break loose. I may have to replace them with a solid mount, but I'm hoping to figure out a different solution.