Compression test results mystery?

1164 Views 5 Replies 5 Participants Last post by DC5Sandbag, Nov 15, 2017

JByron

Discussion Starter · Nov 13, 2017

Hello all, I was hoping you could help me figure this one out:

Two weeks I ran a compression test because my car was bogging and there was smoke coming from the exhaust during startup

Cylinder 1: 151
Cylinder 2: 60
Cylinder 3: 151
Cylinder 4: 151

I left the car alone until today, I ran seafoam spray engine cleaner and lube (through the throttle body) thinking I might have a stuck valve or something. Results:

Cylinder 1: 120
Cylinder 2: 151
Cylinder 3: 151
Cylinder 4: 151

WTF

So I dropped some oil into cylinder #1, along with some seafoam, started the engine and revved til the smoke stopped

Cylinder 1: 151
Cylinder 2: 151
Cylinder 3: 151
Cylinder 4: 151

So, is my engine ok?
Why would the low psi cylinder move from #2 to #1 in two weeks/after seafoam?
I had some white smoke coming from the behind the valve cover during startup that went away?

What is my next step? Valve clearances? More seafoam spray? Lol?

Thanks!

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nats007

· #2 · Nov 13, 2017

Compression looks good now... Drive for a couple days and see how it feels. No clue why the results were above, but maybe the seafoam just had to run through the system.

Probably worth doing a complete oil change to get the old stuff out and fresh oil in

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Andymsr1

· #3 · Nov 14, 2017

I would assume the low reading was a mistake. There was probly never anything wrong? Just my thought on it.

I've been messing with cars for a while and I have adopted the theory that if the problem only happens once, its not a problem.

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JByron

Discussion Starter · #4 · Nov 14, 2017

nats007 said:
Compression looks good now... Drive for a couple days and see how it feels. No clue why the results were above, but maybe the seafoam just had to run through the system.

Probably worth doing a complete oil change to get the old stuff out and fresh oil in

Yeah, I'm going to daily the car next week and test throughout the week, maybe seafoam one more time, then if all is ok change the oil and spark plugs.

Andymsr1 said:
I would assume the low reading was a mistake. There was probly never anything wrong? Just my thought on it.

I've been messing with cars for a while and I have adopted the theory that if the problem only happens once, its not a problem.

Haha, I hope that is the case!

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Thewrai6th

· #5 · Nov 14, 2017

JByron said:
So I dropped some oil into cylinder #1, along with some seafoam, started the engine and revved til the smoke stopped

Cylinder 1: 151
Cylinder 2: 151
Cylinder 3: 151
Cylinder 4: 151

Usually you would be putting the oil in to determine if the piston rings are bad. The oil fills the piston to wall gap and causes the compression to go up.

Your numbers seem a bit odd though, exactly 151 across the board is unheard of, but possible. Do another compression check after a few trips and see what you get. Make sure you are getting 4-5 full compression strokes, or that the gauge is not going up any further. You may only have gotten half a stroke on the first two readings.

It's possible you had something stuck and the seafoam magically did something, like loosen up a stuck ring. I'm not a big fan of randomly dumping "seafoam" into the engine. Some people swear by it, but I have seen some disasters as well.

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DC5Sandbag

· #6 · Nov 15, 2017

I agree with Thewral6th on your compression test procedure/results. Also, Seafoam makes a good product but it’s not a cure all for all your engine's ailments.

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