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-   -   Compression Test results questions. (https://ecomodder.com/forum/showthread.php/compression-test-results-questions-13110.html)

Verdann 05-01-2010 06:42 PM

Compression Test results questions.
 
So I knew I had a dead cylinder from a previous dry test that I did. Today I finally got around to doing dry/wet tests to check if it was rings or valves. Looks like valves from what I understand, but I wanted to post and get a second opinion on my results.
Dry Wet
Cyl 1 170psi 215psi
Cyl 2 150psi 185psi
Cyl 3 0psi 0psi

With those results all I need is valves right? the psi should always go up with a wet test? or am I looking at needing a to do rings as well? If it's rings, then I'm gonna have to wait a while longer, cause I can afford to do valves, but not rings at the moment.

Johnny Mullet 05-01-2010 11:32 PM

Burnt valves is the most likely cause.

MadisonMPG 05-02-2010 09:36 AM

Do rings while you're there.

Christ 05-02-2010 12:21 PM

Unless you don't plan on pulling the engine, do the rings and a light hone anyway. If you're just going to pull the head, and don't want to touch the bottom end, then yes, it's either a burnt/cracked/bent valve, or it could also be a hole in a piston.

Most likely is the valves, unless you have a severely broken piston ring with a chunk missing, or another very obvious problem.

While you have the engine apart, it's probably also a good idea to diagnose and repair the almost 10% change in compression you have across the other two cylinders. More than likely, you have a valve seat issue on the 2nd cylinder, or gunk/carbon buildup that's preventing the valve from seating properly.

While you have the head apart, clean it thoroughly, and check/replace the valve stem seals, as well as the valve guides, if they're worn at all.

These are all things you won't want to have to do later, once you've already put it back together.

Verdann 05-03-2010 06:54 PM

I've got it all apart, found that part of the compression issue is that the number 3 cylinder has a cracked piston, but also that the exhaust valve was burnt. So looks like I'm doing the bottom end as well. :( How do I go about removing the valve guides? I plan on buying the head rebuild kit from 3tech and since it comes with new guides, might as well use them. Also any recommendations on where I can find new pistons that are inexpensive?

Christ 05-03-2010 06:55 PM

I can't tell you how to do valve guides... I do it the "wrong" way.

Verdann 05-03-2010 07:05 PM

I wasn't aware of a right or a wrong way. lemme guess the wrong way involves a hammer and something on the guide to push it through?

Christ 05-03-2010 07:07 PM

I use a bolt. Thread the guide with a machine thread, then thread the bolt in 20-30 turns and use a slide hammer to pull it.

I've been yelled at about 100 times for it, but it just never sinks in... :)

elhigh 05-03-2010 10:39 PM

Quote:

Originally Posted by Christ (Post 172917)
I've been yelled at about 100 times for it, but it just never sinks in... :)

Because it keeps working, yes?

Johnny Mullet 05-03-2010 10:57 PM

I have not had to do valve guides yet, but I would leave that to a machine shop. Get your pistons at partsdinosaur.com


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