Wont Stay Running; Low Compression

[TalonJohn94]

Ok. Bought a small air compressor and did a leakdown test with 80psi.

Bad news, I think. I put it at TDC and tested it and heard some leakage. And then to really test it, I pulled out the rockers on cylinder 1.

Bad news ... immediately I heard a lot of air leaking out of the exhaust

I am SO FRUSTRATED, because I had the machinist (a poster on these forums) go through this head twice. And I have no more $$ to send to another machinist.

 

[bertrenolds]

Do the damn leak down test, I've been bothering my buddie to check my engine but it sounds to me like a valve problem. What's ripping apart your head and looking gonna take you, alot harder then doing a leak down test right? I did learn how to check for cylinder wear.

 

[TalonJohn94]

What are you talking about?
I just stated that I did a leakdown test. I started with the basics, by pulling the rocker arms and pumping the cylinder with about 80lbs of air. And then I heard it escape through the exhaust. Therefore, the valves aren't seating correctly and/or weren't lapped in correctly.

I didn't need to get percentages.

 

[TalonJohn94]

OK. Did a proper leakdown test on cylinder #1.

It shoots right to 40%.

Is it worth doing the rest?
Any advice on what to look for if/when I pull the head again?

 

[Spoolin4Ever]

OK. Did a proper leakdown test on cylinder #1.

It shoots right to 40%.

Is it worth doing the rest?
Any advice on what to look for if/when I pull the head again?

Might as well, you already bought the compressor, right? nd you want to know what's up, right?

 

[TalonJohn94]

OK, resolved after leaving the car alone through the winter. Turns out the valve job was garbage. The machinist (who will not be named, don't want to start trouble right now) left sunlight coming through on all the exhaust valves and a couple of the intake valves.

After what seemed like forever, I finally got them lapped in my hand put it all back together and now it runs great. Just pig rich, but thats another issue.

Moral of the story: If you want something done right do it yourself, or at least check someone else's work whenever possible.

 

[Backinajiffy12]

Moral of the story: If you want something done right do it yourself, or at least check someone else's work whenever possible.

^This!