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View Full Version : Kohler CH750 30HP Flywheel / Lifter Question


mdmccool
03-10-2012, 07:06 PM
Hi Guys-

I'm finally getting around to overhauling the CH750 on my Toro mower I bought used last season. The number 1 cylinder head had a burnt valve and after rebuilding the head the engine ran well, except I discovered that it used oil fairly quickly.

So, now, after complete tear-down / new rings / etc, while bleeding the lifters, I discovered one frozen lifter - frozen solid. After about an hour of soaking/squirting/working, etc I finally get it freed-up and working well. No bent pushrod/rocker - no other signs.

Question is: Although it has been freed-up should I use it or replace with new? If I replace it should I replace both lifters or just one.


Also, the ring gear on the flywheel is pretty chewed-up. Starter would grind occasionally so I want to replace the flywheel while I have everything apart. These are not too cheap new. Found some inexpensive used ones on ebay. Are these fairly interchangeable? I know these engines have a ton of variations, I've seen some sellers state that these flywheels the same for most V-Twins - not sure if this is the case.

Thanks for the help,

Matt

piston slapper
03-11-2012, 08:23 AM
Replace the lifters....don't want it to come back and fail again.
You need the correct flywheel. The ignition system is flywheel specific.
It should be easy to match up , as it looks different from all the rest.
Your flywheel should have slots molded into it and be fairly flat (DSAI ignition)
It is used on the 740 and 750 engines. Also make sure the magnets under the flywheel are not damaged.
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McDuff426
03-11-2012, 08:24 PM
Amusing things I see in shops time and time again, the technician using a magnet to pull a lifter or placing it in a magnetic parts tray.....Congratulations Sport! You have just successfully installed a number of "Chip Catchers" where it will do the most good, attracting abrasive goodies to Kohler's notoriously soft cam.

Pulling flywheels, not enough time to get the puller, "naw, we just loosen the fastener, stick a bar under the flywheel and smack it with a hammer till it pops" This makes the flywheel ring like a bell, who's flexing has just compromised the bond of the magnets to the flywheel.

Flywheel replacement, first is there a local machine shop they may be able to replace the ring gear, flywheels will be specific to application different stators have different magnet compliments. The sound of ceramic magnets and stator laminationís disagreeing on who got there first is an unforgettable expensive but brief sound effect.

Kohler consuming oil, first, 10W30/SE/SF? stuck oil pressure relief valve? valve stem seals? carb so rich it's washing the oil off the cylinder walls?

One more extra this mfr does not "key" align timing components, they depend on a
driving press fit gear for a cam drive which naturally can slip, altering the valve timing,
outward indications are low power, usually 1 cylinder's exhaust header will glow dull red, engine overheats
Good Hunting!

McDuff426
03-11-2012, 08:58 PM
This is what happens when you hit send by mistake....

More about lifters, the final polished surface of the cam lobes is achieved in service with a special break in lubricant, the lifter face and cam lobe become a matched set, lifters must go to their original position, failing to observe this is the leading cause of engines coming back in less than 100 hours missing lobes (a bump less bump stick )

It's just like tapered roller bearings, once it's been in service it should remain "married" to the components (races) they were run in with, but then I guess some folks enjoy rebuilding spindles
wheel & such.....

Kohler recommends servicing lifters and cam as a unit.

PS..bet the burned valve and locked lifter go together

mdmccool
03-11-2012, 09:38 PM
Thanks for the replies. The flywheel I was considering is on ebay, item number 200721734180. (just put 200721734180 into the search and it will bring the item up). At $60 with free shipping it's a pretty good deal...now not so sure it will fit my application.

When I first got the mower it had the original carb on it - someone filed down the mixture screw stops and had the #1 cylinder running too lean, #1 got too hot and the exhaust valve was burned bad. I read that these 30's had carb and ignition problems, installed a new carb and rebuilt the head w/new valves and it ran good and strong - only it would use oil slowly. Figured with cylinder 1 getting hot they probably wiped out the rings. I ran the mower for a season after rebuilding the head and only recently tore it down for a rebuild - it's been apart less than a week until I discovered the frozen lifter - strange as I don't see how it wouldn't have bent a pushrod or caused other problems...but I also doubt that it would freeze-up sitting on the bench.

I wouldn't mind putting a new set of lifters in but as McDuff said the cam and lifters should go as a set...another tear down, new gaskets again, etc to replace the cam.

Matt

piston slapper
03-12-2012, 05:36 AM
This is what happens when you hit send by mistake....

More about lifters, the final polished surface of the cam lobes is achieved in service with a special break in lubricant, the lifter face and cam lobe become a matched set, lifters must go to their original position, failing to observe this is the leading cause of engines coming back in less than 100 hours missing lobes (a bump less bump stick )

It's just like tapered roller bearings, once it's been in service it should remain "married" to the components (races) they were run in with, but then I guess some folks enjoy rebuilding spindles
wheel & such.....

Kohler recommends servicing lifters and cam as a unit.

PS..bet the burned valve and locked lifter go together

Jibberish......you should probably read a few books before you try to write one.

Replacing a single lifter is common.....never had any issues as long as you use the cam lube that comes with the lifter.
You can't replace the cam without replacing the Crankshaft ....would you have someone replace a gearset because he had a defective lifter?
The lifter probably locked up when the pushrod was removed .....it fully extended and was worn internally and jammed.
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mdmccool
03-12-2012, 08:30 AM
Thanks piston slapper, that makes quite a bit of sense. Will definitely replace the defective lifter.

Back to the flywheel - even though the ebay seller (auction number above) guaranteed that the flywheel will work with my engine, I think maybe it's worth buying a brand new one as there seems to be too many variations. Would hate to get this thing back together only to have ignition trouble because a slight difference in magnets/placement, etc.

Thanks again for the help,

Matt

piston slapper
03-12-2012, 08:58 AM
Just checked ebay......not the right flywheel.....keep on shopping...

mdmccool
03-12-2012, 06:46 PM
good to know - thanks for the help, much appreciated!

Matt

McDuff426
03-12-2012, 07:01 PM
Just trying to help, obviously 23 years as a Kohler service center and the accumulated literature, bulletins & tech seminars are of little value, my apologies for wasting your time.

The very best of fortune too you.

piston slapper
03-12-2012, 08:01 PM
McDuff.....we are all uncompensated helpers on this site.
I'll give you the benefit of the doubt.....one question.....
How could you EVER suggest a cam replacement without replacing the crank???
The only time wasted was your own........
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piston slapper
03-12-2012, 09:19 PM
Just trying to help, obviously 23 years as a Kohler service center and the accumulated literature, bulletins & tech seminars are of little value, my apologies for wasting your time.

The very best of fortune too you.

Didn't mean to call you on the porch....
Speed readed your reply.....came across the cam issue....drew my conclusions.
I still call them like I see them.....Al.......if you had stayed on the bench instead
Of the front counter ....you would have been one of the best.....and probably blue collar.....give me a call...
Slapper
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