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Discussion Starter · #1 ·
So, by now, you guys know I'm a moron. Thats okay, its out in the open now, I can deal with that.

So... I ran a compression test, and I'll give you the short of it before I go into the long.

All of this was done engine hot, fuel pump unplugged, throttle fully open, andseven pumps. All as I read in my manual.

Cylinder #1 - 175psi.
Cylinder #2 - 175psi.
Cylinder #3 - 170psi.
Cylinder #4 - 165psi.

It took two to three pumps to level out, which the manual says points to the rings. They also seem to very slowly loose psi. I mean, at the rate of about 1psi every 5-10 seconds. It was hard to see on the gauge and I had to watch it for about a minute to believe it.

So then. I do what the manual says, and pour some oil in the cylinders. In the first cylinders, I used two cap-fulls of oil as the manual says 1-2 squirts. I didn't have an oil can, so I just guessed.

Cylinder #4 - 240psi. (Two cap-fulls of oil)

I said, holy crud. Apparently two caps is too many. Cylinder #3 gets one cap.

Cylinder #3 - 200psi. (One cap of oil)

I'm still sure thats not right. So, cylinder #2 gets half a cap.

Cylinder #2 - 180psi. (Half a cap)

Then, I never did Cylinder #1 because of all the time I was taking, and the fact that I left part of the compression tester in there... its just a long story. So it stayed at 175psi.

During the tests with oil in the cylinders, it took two pumps or so to get to peak pressure.

Now, I'm pleased as punch with 175psi, thats within a few % of the rated 180, after 17 years, that isn't too shabby.

I'm going to take the head off this weekend, but I'm really debating if I need to do the rings. The head is getting professionally cleaned and re-sealed, so I know it'll be done 100% right, and I'll I'll have to do is change the bolts out and the gaskets.

But since the compression isn't terrible, what are my chances of needing to redo the rings? The oil test seems to point in that direction. More money, more work, and less driving, especially since I'm learning as I go. I can't find anyone around here to reliably help.

Anyway, post your thoughts.

Side notes as to what went wrong:
1) Took me like 15 minutes to find the freaking fuel pump, because the manual wasn't very clear on how to disable it.
2) Removed the spark plug boots, by hand, and destroyed one. Again. I'm not the Hulk, but it keeps happening to me.
3) After all that, I had to fly to sears as fast as my Oldsmobile would take me to get an extension. I swear I had one, but I couldn't find it. I needed it to take the spark plugs out.

*sigh*
 

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Redoing the head will lead to bottom end problems for sure. Seems like pulling the crank out and putting in new rings and bearing is a safe bet for years of trouble free service. I freshened my head then threw a rod through the block a few month later.
 

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Could you please update us as to why exactly you did the compression test, and why you think anything is wrong? Also, what motor is this on?

Sorry, i'm unfamiliar with your past issues, but your test sounds normal to me... #4 seems a touch low in comparison to the rest of them, but its not TOO out of the ordinary.

By the way, the cranking was done with the throttle in the wide-open position, correct?

Oh, also what compression gauge are you using to see the leakdown? A compression gauge in working order should not allow you to "watch" the pressure drop over time after the test is done, unless it is leaky itself...
 

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Discussion Starter · #5 ·
Yes the throttle was blocked open.

The reason I've done this test is because I'm burning oil, at first it was a lot, then I replaced the valve stem seals, and now it only burns it after I rev the engine or in any way put it under a load. You can idle it for 30minutes with no trace of smoke, at all.

As soon as you touch the gas, smoke. Then, when you let off the gas, it dies down, and will eventually go away or diminish to almost nothing.

The motor is a D16A6, stock.

I'm using the compression tester thing from Sears. I imagine it ain't the greatest.
 

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A working compression gauge should hold the reading you get. You should be able to take it from the engine, put it on your bench and go eat lunch, it shouldn't drop.

Sounds like the valve in the comp gauge maybe damaged. They usually screw out like a valve core from a tire, though they are not the same part. I'd advise replacing the valve.
 

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I think stock spec is only 175-185 psi. Your compression rings seem fine to me. If anything you have worn oil rings.

Are you under the impression that the gauge leaking 1 psi every 5-10 seconds means the engine is not holding pressure? That leakage is in your gauge just so you know.

Next time, you don't have to unplug the fuel pump, just pull the ecu fuse.
 

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Discussion Starter · #8 ·
dohcrxl said:
Next time, you don't have to unplug the fuel pump, just pull the ecu fuse.
Son of a gun.

dohcrxl said:
Are you under the impression that the gauge leaking 1 psi every 5-10 seconds means the engine is not holding pressure? That leakage is in your gauge just so you know.
Yea, I get that now.

dohcrxl said:
If anything you have worn oil rings.
Thats what I was afraid of. :cry:
 
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