John Deere LT155

[lefty]

Yes. The I can see the piston going up and down. And I can hear the air sounds of the piston through the carb, exhaust and spark plug hole as I actuate it by hand.

A question if I could:
I've been into the galley on a few Briggs but this is my first Kohler. I have the valve cover off now and notice a hole next to one of the pushrods. My guess is this is the port in which oil finds it's way into the galley. My leak down test was done when the valve cover was on. With the cover off, when I turn the flywheel by hand, at certain points, air whooshes out of this hole.

Using my limited knowledge and logic, I'm guessing that would happen during one or both of the downward cycles of the piston when crankcase pressure rises.

Am I correct?...If the head gasket is bad between the cylinder and the galley, would I be able to test this with the valve cover off by charging the cylinder at TDC with the valve cover off and checking for air shooting out of that hole? Or am I off base here.

[KE4AVB]

Sound you might looking at the reed valve area which could be missing the reed valve. Any way it just vents the crankcase area of blow-by gases of normal combustion so it sounds you have cylinder, piston. or rings damage. Here is a label part location diagram of he CV non adjustable head. If it was a blow head gasket then it would leaking around the push rod areas or out around the outer head area where the gasket is.

What I mean by blow-by gases it is the gases the normally make it way pass the rings into the crankcase. If not vented it would blow oil seals and gaskets. When there is a normal with the sealing the cylinder there would be excess pressure and it just finds the easiest way out during the leak down test.

By cycling the cylinder you just found the secondary use of the leak down tester that is not describe most leak down tester manuals. What you doing is checking not only the upper cylinder sealing but it at different levels. Most times it done with the push rods removed so valves are not opening and closing. And yes I had cylinders that marginally pass upper leak down tests but fail mid and lower levels due either a tapering or ovaling, sometimes both. This only works on cylinders that are not ported as in 2 cycles. Personally I have not seen any ported cylinders in 4 cycles.

[hanz63]

This could also be candidate for an exhaust valve seat that has come loose and is out of position.

[KE4AVB]

I can see the piston going up and down. And I can hear the air sounds of the piston through the carb, exhaust and spark plug hole as I actuate it by hand.

I just seen this as I just skim over the the post earlier. My question if using a leak down tester "How can air be coming out the spark hole?" since most of uses hose attached to the spark hole to pressurize the cylinder.

[lefty]

I can see the piston going up and down. And I can hear the air sounds of the piston through the carb, exhaust and spark plug hole as I actuate it by hand.

I just seen this as I just skim over the the post earlier. My question if using a leak down tester "How can air be coming out the spark hole?" since most of uses hose attached to the spark hole to pressurize the cylinder.

Sorry for the confusion KE4. I was just referring to how I knew the piston was moving. While setting it up at top dead center, I made those observations. During the leakdown test, I had my tester threaded into the spark plug hole.

[KE4AVB]

Tnx for clarification.

[lefty]

Thanks to everyone for all the info. I'm going to try that handheld impact tool and get in there for a gander. I'll check the valves, seats, and cylinder while I'm in there and report back with my observations.

[lefty]

This could also be candidate for an exhaust valve seat that has come loose and is out of position.

Bingo. Got the head off and sure enough, on of the seats has slipped out at an angle and the valve is not seating. (No broken bolts...yay!) There is a significant gap I can see light through-see photo.

So what are my options here? Can that be pounded back in? Does it need a new seat? Is it something a machine shop has to do? And most importantly, should a new head be put on given the condition of this head, deterioration of cooling fins and such (see last photo I posted).

I inspected the cylinder and it is in really good shape. No scratches and I can see cross-hatching in places. Feels smooth as glass.

[KE4AVB]

The seat is not available as a separate item. Now I have heard these seat being pressed back into place and a ring center punch indents place around the seat to hold it in place.

Looking at your image I can see where the head gasket was also blown. So you should check it to see if warpage has occurred from the overheating caused by the leakage.

Now the replacement head doesn't come with the valves or rockers; unlike Briggs. Kawasaki does the same thing I which recently that their complete head is just the head with the valve guides and seats installed. I seeing this around $ 149 with shipping.

[lefty]

When you say "pressed", do you mean pressed in a precision sort of way with a special tool or just kind of gently tapped gently with like a plastic hammer or something similar?

Also, given the condition of the head with the deterioration this one has, do you think that there would be a chance of success with this engine? Keeping in mind that this has turned more into a pet project/experiment.