I just did a compression test and I want you guys to take a look at the results and give me your opinions.

 

The turbo side head has a crack between the exhaust port and the water jacket, so I plan to replace the heads. The reason I did a compression test was to see how worn the piston rings were. I want to know if I should replace the whole engine or just the heads. BTW, the engine should have no more than 70,000 miles on it because it was a used Japan engine gurranteed to have no more than 50,000 miles and I think I put about 15,000-20,000 miles on it.

 

Here are the results:

BTW, I cranked the engine about 5 times for each reading.

 

Cylinder 1

Reading 1: 125 psi

Reading 2: 125 psi

 

Cylinder 2

Reading 1: 130 psi

Reading 2: 137-140 psi

 

Cylinder 3

Reading 1: 138-140 psi

Reading 2: 137 psi

 

Cylinder 4

Reading 1: 127-130 psi

Reading 2: 133

 

After I did this test, I decided to do it again but this time I squirted some oil into the cylinders.

 

Cylinder 1

Reading 1: 175 psi

Reading 2: 170-175 psi

 

Cylinder 2

Reading 1: 165 psi

Reading 2: 163 psi

 

Cylinder 3

Reading 1: 155 psi

Reading 2: 155-160 psi

 

Cylinder 4

Reading 1: 155 psi

Reading 2: 155

 

I am concerned about how much the pressures raised after I squirted oil into the cylinders. Although I admit that trying to get the oil to go into the cylinders was a pain in the butt and I think I got carried away and put too much oil into each cylinder.

 

Are these readings normal? Is it normal for the pressures to raise this much after oil is squirted into the cylinders? Are my piston rings worn?

What type of oil was it? I usaly use MMO for that type of thing. If it was heavy oil(like 10W-30 or better) then, YES, the compresion will sky-rocket. The heavy oil will "hydralic" your gauge and it's not a true compression reading, espicaly if U got 2 much in there. Now if U used lighter oil,(MMO, WD40, 3-n-1, ect.) then I would start looking @ the rings.

There's an awfully big difference between Cyls 1-2 and 3-4. No two cylnders should be more than 10 PSI apart with that kind of mileage. I'd redo the heads first, then send it in for rings if that didn't solve the problem. (And I'd find another source for JDM engines. I think you got taken on the mileage.)

Wagon, I think the difference is 10% not 10 PSI, but even at that dry there was more the 10% on the second reading, but it actually exceeded #2 when oil was added.

I think a leakdown check would be more accurate in this case.

the pre-oil numbers are right around the 10% variable range.. I wouldn't worry too much unless the engine is runningcrappy

Well, I squirted into the cylinders the same type of oil that I was running in the crankcase, Mobil 1 10W-30. Also it was hard to tell if the oil made it into the spark plug holes, so some cylinders may have gotten more oil than others. I guess that explains why the compression skyrocketed after oil was added. I guess that means I can discard those readings. Should I do the compression test over again with something like MMO or WD-40?

 

BTW, The compression rose quickly after the first and second strokes on each cylinder.

 

I ran the car down the high way before the compression test and the engine runs great, even with the crack in the turbo side head and the large exhaust leak in the crossover pipe .

 

Whats a leak down check?

Leak down test is where you create the pressure and then test how long the motor can hold it. I've never done it but it test how well the rings are sealing. If it doesn't hold the pressure very long when the piston is at TDC then your rings are shot.

 

Keith