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Kohler Command Hydraulic lifters


Brettw

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Hey guys, could use a little help here.  I am not familiar with hydraulic lifters and exactly how they operate.  However, in repairing a Kohler CH18, the camshaft had missing teeth and the end of the shaft fractured off.  In addition to this, there were 3 bent pushrods.  So I have obtained a replacement camshaft and new push rods.  No bent valves or issues in that, however, in carefully testing everything, the hydraulic lifters appear to be stuck in their full extension and this causes too much lift and the complete compression of the valve springs and keeps the camshaft from turning any further.  1) What is the cause / solution to this?  2) Are the lifters bad and could this have been the cause of the original failure?  3) This issue is on 2 of the 4 lifters.  4) Engine was the most gunked up clogged up mess of grease, oil amn dirt/chaff I have witnessed and still not complete junk.  So it obviously was running hot as the cooling fins were buried in gunk.

I think I know how to "release" the apparent hydraulic lock on the lifters, but should I just replace them?  What causes them to pump up more than they should in the first place?

 

Any insight from those in the know would be much appreciated.

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4 hours ago, Brettw said:

Engine was the most gunked up clogged up mess of grease, oil amn dirt/chaff I have witnessed

I think this is the answer.  

This is my understanding of how a hydraulic lifter works - the oil pump pressure fills the hydraulic lifter and it expands; there's a check valve on the lower inlet end and a small hole on the upper end which lets oil pass to the end of the push rod.  The oil is constantly replenished.  If the oil exit hole becomes plugged, no oil can escape to allow for expansion as the engine heats up.  In effect you have a solid lifter with no clearance.  

If my understanding is incorrect, someone please enlighten me.  

Maybe you can take apart the lifter to see if it's plugged up?  Maybe a cleaning is all it needs?  

Just found this Kohler video that may "fix" your problem:

 

Edited by PhanDad
Added video
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Thanks, Bill.  I did see this and am going to bleed the lifters, but does anyone know what may have caused them to fill in the first place, and whether they may be prone to refilling again?

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I'm thinking if the outside of the engine was in such bad shape, then the oil was probably the same.  So the lifter bleed hole is plugged with crap and not only needs bleeding, but flushing all the gunk out.  Or lack of lube has caused metal to metal binding and the lifter needs to be replaced.   

Looking at the video it looks like there's a retaining clip of some short holding the internal piston in.  I'd try to remove it and take the lifter apart to see the internal condition of the parts.  

 

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Enjoying my daily afternoon 🍺 sitting on my shaded porch enjoying the cool non-humid breeze I’m thinking of your issue. 
The hydraulic lifter I’ve seen was from a car. Does the Kohler lifter have an oil hole where the push rod sits?  
Based on the time it takes to bleed the lifter in the video, I’m guessing not. 
If no hole then the bleed path would be through the annular clearance and if so, that could clog up more easily. 
I need an answer to your issue. 

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Kohler Command lifters are Small Block Chevy lifters. Yes, there is a hole in the lifter piston and push rod. This is how oil gets to the valve stems to lubricate. I would strongly suggest all new lifters and cam moly lube on the cam lobes and base of lifters.

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4 hours ago, Bill725 said:

I would strongly suggest all new lifters and cam moly lube on the cam lobes and base of lifters.

New lifters ordered.  I actually bled, disassembled the lifters and cleaned and freed everything up.  Except..........in the process of disassembly, one of the spring clips launched past my ear to somewhere in the general vicinity of the neighborhood. That, or it may still be in orbit for all I know, it was not to be found.  Sooooo, that drove the decision to say the heck with it, new lifters on order as I would have needed one anyway, and I'm not going through this and have the same failure again.  They were rather bronze in color, I believe due to the heat and the oil conditions.  The oil bleeding out of them was a bit heavy it seemed.  I am thinking the PO was using some type of heavier oil / STP to try to stem the leaking at the front seal.  His attempt to help the engine, I believe actually killed it.

Thanks to all for all of your help.

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12 hours ago, Brettw said:

New lifters ordered.  I actually bled, disassembled the lifters and cleaned and freed everything up.  Except..........in the process of disassembly, one of the spring clips launched past my ear to somewhere in the general vicinity of the neighborhood. That, or it may still be in orbit for all I know, it was not to be found.  Sooooo, that drove the decision to say the heck with it, new lifters on order as I would have needed one anyway, and I'm not going through this and have the same failure again.  They were rather bronze in color, I believe due to the heat and the oil conditions.  The oil bleeding out of them was a bit heavy it seemed.  I am thinking the PO was using some type of heavier oil / STP to try to stem the leaking at the front seal.  His attempt to help the engine, I believe actually killed it.

Thanks to all for all of your help.

Good idea Brett. Lifters were bright/shiny in the Command I finished this spring. You don’t want a do-over. 

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  • 4 weeks later...

Still working on it, Ron.  I haven't had time lately as we have been out of town on a few trips.  I believe the engine overheated to the point of letting the valve guides rise a bit, and that is the probable cause of the bent push rods.  I need to verify clearances and condition of the valve train.  Otherwise, it would be ready to fire up.  More to come..........

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  • 2 months later...

Update!  Runs like a top. Thanks to all for their input and help, Bill, your help and support, and the general info that always comes with open arms when questions are asked.  

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  • 2 weeks later...

Just a follow up.  The tractor is running excellent.  I am somewhat surprised, as it seems to run smoother and better than any previous Command. And after its all done and said for, and after a few hours of work cutting grass and working, it seems solid as they come.  Surprisingly, it does not smoke... at all.... not on running or on start up, or at any time.  Musta been a really good engine to start with with a leaking crank seal.  And, overall working through the tractor, it seems it was likely well taken care of until the PO used it as a worker, and let it sit outside between use.  So,  this one might be a real keeper and I got the rest of the resto started.  Seat pan still being cleaned up, a bit of light welding, and paint to come.

command1.jpg

command2.jpg

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