drhess06259

Ok so I did a compression test and got 160 195 190 200. So I also did a leakdown and got 45% 5% 8% 4%. So i know cylinder 1 is off way off. I could hear the air commong out of the exhaust and nothing out of the intake on cyl 1. So I checked the valve clearences and they were ok except 3 which is why I was a little higher then the other and it fixed that one but cyl 1 was on so does that mean I have a bent valve or could it be something else like retainer? I had the head checked and milled and cleaned about 30k miles ago.

I know some of you are going to say my compression is low but it's a stroked motor with lower compression ratio.

crank

coul be a cracked retainer , bent valve is possible, (piston rings as well...... any oil burning?) check your retainers first

drhess06259

Pistions have about 300 miles on them and I checked them with another test they are good I know it's the valves just don't know how to check without taking the head off again can u change retainers without taking the head off?

crank

ya, you can change the retainers and cotters that hold them, but not the actual valve, the head must be removed for that. In order to change the retainers you need to pressureize the combustion chamber with compressed air to hold the valve up...and im assuming while you do this if one of the valves falls in the combustion chamber, while under pressure you obviously have a bent valve, but it could be bent in such a slight way it still may hold its self up.....just my 2 cents, good luck

R1_Pilot

Usually these are the steps that I take:

Compression test. If numbers are good then go do something else. Otherwise pour a very small amount of oil in that cylinder, if the numbers go up, then you have a ring problem.

Leakdown test. Once you determine that there is a cylinder that is leaking too much, try to hear for a hissing/air leaking noise:

- Intake off … if you hear it through here then you have an intake valve problem
- exhaust manifold off … here you would hear an exhaust valve leak
- oil pan off … you would hear piston rings leaking.

The last two are somewhat more difficult, but still easier than removing the cylinder head.

J

RedY2KS2k

There's also a possibility that that exhaust valve and/or its seat is burned. 30k miles would certainly be enough for that to happen, especially if the valves were adjusted too tight.

You mentioned a low-compression stroker build; does this engine have boost?

drhess06259

Yes it is boosted and an ap1 head so I know the retainers are my most likely suspect as the valve seals were replaced 30k ago

RedY2KS2k

Valve seals affect oil consumption; they have nothing to do with compression or leakdown. I still vote burned exhaust valve.

crank

when a valve gets "burned" what exactly happens?(does the heat warp it?) no thread hijack

R1_Pilot

Correct, I am not sure what I was thinking when I typed !

J