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Old 03-03-2014, 04:56 PM   #11
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No, the oil doesn't help. When you do a dry test, your getting a base of readings for the wet test. When you do the wet test, it tests the rings in the piston. If the numbers go up during the wet test, then you have bad rings. If they stay the same, then head gaskets or valves are suspect.
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Old 03-03-2014, 05:00 PM   #12
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Yeah, and you need also intake manifold gaskets, valve covers etc.

Rockauto has 75 gasket set, 15 for head bolts + shipping costs. Lifters maybe smart to swtich same.



It hink that you need allways machining. Cold blooded man only buts old head back without it. Especially when head gasket fails its pretty sure that head takes minimal damage at least.


Maybe 100-150 for machining.


And if valves are at least little bit worn, its smart to replace these too. Money talks...
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Old 03-03-2014, 05:05 PM   #13
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Quote:
Originally Posted by Mike1995 View Post
No, the oil doesn't help. When you do a dry test, your getting a base of readings for the wet test. When you do the wet test, it tests the rings in the piston. If the numbers go up during the wet test, then you have bad rings. If they stay the same, then head gaskets or valves are suspect.
What i tried to say:
I wonder and local guru too that 140psi is good reading.

So even there is 30psi different for best reading, 140psi isnt still bad.


So if problem is piston ring wear or little valve wear thats not bad at my mind because reading is not low.


But if oil test helps to rise 140psi result then i can sleep my night well.


If not, then that head gasket.



One guy says too that valve'* cant be bad with that compression.
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Old 03-04-2014, 07:18 AM   #14
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again depends, if there were a bit of carbon build up to were only part of the valve was sealing it would.

as far as reusing the head, the 3800 is a pretty strong engine and if it wasent over heated i would just check it all over for warping with a strait edge and if not run it. the car is at the point were you dont want to spend a ton on it unless you have some sentimental value with the car
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Old 03-04-2014, 10:35 AM   #15
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Quote:
Originally Posted by jwfirebird View Post
again depends, if there were a bit of carbon build up to were only part of the valve was sealing it would.


as far as reusing the head, the 3800 is a pretty strong engine and if it wasent over heated i would just check it all over for warping with a strait edge and if not run it. the car is at the point were you dont want to spend a ton on it unless you have some sentimental value with the car
I dont understand all again...

Check it for warping but what not run it?

If car overheats you can still machine head in good shape i know?



Carbon buildup seals valve which gives false readings? Or 160-170psi numbers are carbon buildup increasing results and 140psi is more to real life?
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Old 03-04-2014, 11:12 AM   #16
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Rare for these engines to develop head gasket problems.......since the difference is really not that great(did you try a repeat test?), I'm not sure if a leak down test would help.....but like the guys suggested, do the wet test to see if pressure increases.....

Now for the big question, why in the world are you doing a compression test in the first place? There has to be some problem.....
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Old 03-04-2014, 01:02 PM   #17
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if you check the head and its strait i would just use it. without the machining. if its warped it has to be machined and thats up to you if the cost is worth it
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Old 03-04-2014, 06:26 PM   #18
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Big question answer:

I have compression test gauge and its cheap way to see something about engine condition.

Why i tested?

Because car has gived that steam on exhaust -> i wanted to check how about head gasket.

And because car is been very **** like i said. If compressions were bad at all then car selling is maybe good thing.


But now im just confused. I know that driving will also give problem or there is no bad problem at all but car is pretty often used and many kilometers per month.


And if example head gasket will blown bad, it will soon harm cylinder because oil will swept of because coolant etc etc...




Yeah and now i get what jwfirebird says.


Only thing which could occur rare? gasket problem for this car is 10 years stalling on carage?

But still, 7 years driven after that..
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Old 03-04-2014, 06:48 PM   #19
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Just curious, but when you are testing compression, are you letting it crank until you notice pressure stops raising, or are you just cranking a set number of cranks?
I would charge your battery up to be sure it is full of charge, and then test each one, stop cranking when you see pressure stops rising.

Also, note that the lowest reading cylinder should not be less than 70% of the highest and no cylinder reading should be less than 689 kPa (100 psi)
That is what my AllData manual says for specifications.
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Old 03-04-2014, 07:13 PM   #20
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Quote:
Originally Posted by WilliamE View Post
Just curious, but when you are testing compression, are you letting it crank until you notice pressure stops raising, or are you just cranking a set number of cranks?
I would charge your battery up to be sure it is full of charge, and then test each one, stop cranking when you see pressure stops rising.

Also, note that the lowest reading cylinder should not be less than 70% of the highest and no cylinder reading should be less than 689 kPa (100 psi)
That is what my AllData manual says for specifications.
I did it myself so i cranked first time about 2-3 times but then i confused and started again with 8 cranks. Battery is good condition and engine cranks well all the time.

Yeah ive noticed same numbers and that will go great with them. 119psi is 70% of my best so 140psi will great go there.



But first time i noticed that 2-3 cranks rised first two cylinders pressure at 140 because i confused when third was goin on. So pressure raises well too i think.



Still that adjacent cylinder readings worry me. Mechanic school handbook example for head issue was about half of normal compression ratio on worn cylinders. So about 70-80psi on this case.
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