CV461S Stopped running.

[joea99]

Was running and shut off. Would not restart. When cranking, seemed to "over speed" and would "backfire" occasionally.

There is spark and starting ether would not fire it.

Did a compression check, which was near zero, but reading the engine manual, there is an auto compression release, so that is useless. Trying to hunt up a leakdown tester now.

Anyway, figured to check valve lash and adjust, so pulled the valve cover and plug and find the exhaust valve clearance is "a lot" and the intake is "nothing". Went through several engine rotations and the rockers move normally.

Looked for a way to adjust lash. Found none. Reading the manual, again, (what a concept), seems these engines have hydraulic lifters and there is no adjustment.

So now I am not sure what to think. is the Zero intake clearance part of the compression release, or does it indicate a problem?

How to proceed?

 

[Mower King]

Was running and shut off. Would not restart. When cranking, seemed to "over speed" and would "backfire" occasionally.

There is spark and starting ether would not fire it.

Did a compression check, which was near zero, but reading the engine manual, there is an auto compression release, so that is useless. Trying to hunt up a leakdown tester now.

Anyway, figured to check valve lash and adjust, so pulled the valve cover and plug and find the exhaust valve clearance is "a lot" and the intake is "nothing". Went through several engine rotations and the rockers move normally.

Looked for a way to adjust lash. Found none. Reading the manual, again, (what a concept), seems these engines have hydraulic lifters and there is no adjustment.

So now I am not sure what to think. is the Zero intake clearance part of the compression release, or does it indicate a problem?

How to proceed?

The compression release, ACR, on most all mowers are on the Ex valve

 

[ILENGINE]

With a hydraulic lifter type system you shouldn't have noticeable valve clearance because the oil in the lifters will keep the clearance to nothing. I would be looking at the exhaust valve to make sure it has closed all the way and the seat hasn't came out and holding the valve open..

 

[joea99]

With a hydraulic lifter type system you shouldn't have noticeable valve clearance because the oil in the lifters will keep the clearance to nothing. I would be looking at the exhaust valve to make sure it has closed all the way and the seat hasn't came out and holding the valve open..

I suppose the only way to know is to pull the head? I have a cheap "bore scope" but can't really see anything.

 

[joea99]

The compression release, ACR, on most all mowers are on the Ex valve

Might that cause the apparent excess exhaust valve lash? I've no idea how the ACR works.

 

[Fish]

Can you put up some pics?
Like a pic of the rocker arms?

 

[Fish]

But would guess a loose valve seat.

 

[joea99]

I could post some pictures if I know what you wanted to see. Top view, side, open, closed?

Rather than pull the head, HF has a leak down test kit, pretty cheap. That could tell the tale.

 

[Fish]

I could post some pictures if I know what you wanted to see. Top view, side, open, closed?

Rather than pull the head, HF has a leak down test kit, pretty cheap. That could tell the tale.

Just take a few, especially at tdc.

 

[Mower King]

I could post some pictures if I know what you wanted to see. Top view, side, open, closed?

Rather than pull the head, HF has a leak down test kit, pretty cheap. That could tell the tale.

You don't need a "leak down" tester just to find if compression is leaking from a valve, just make sure both valves are closed or looks closed....remove rockers just to be sure, and put air in the spark plug hole....if a valve is stuck open, you will hear the air coming out, THEN you must pull the head to see why!