So the first time I did compression test I quit after 3 cylinders and had assumed it was hopeless. I posed here and got advice to go further with test. I did the compression test with all plugs pulled about 3 weeks. I wrote the #s down. I bought a leak down tester from amazon so finally i had time to complete that today. The readings are in this order .1,3,5,7--2,4,6,8. compression (85-120-130-150) (150-140-90-120) The only one I did wet compression test on was # 2. It went from 85 to 90. I forgot to redo the rest wet. That being said, to me the numbers for the leak down test just don't seem right. 15,12,10,14--17,18,17,12.The compressor is set at 100psi. The gage varied between 20 psi down to 10 psi on the manifold when it was in the "set" position. I took multiple readings and picked the lowest readings because I figured this was the point where the valves were closed tightest.TDC After I did this I put my plugs back in then I realized I did not do wet compression test on all cylinders (air head) Anyway what is the opinion could these # be real or am I missing something. I still have freeze plug issue to deal with before my Truck moves though. Upper,back, drivers side. Is it easier to go from the bottom for that issue or the top? My truck sits really high and I have bad lower back and bending over the truck is rough. #7 plug had old rusty water residue on it. I repaired the plenum about 4 thousand miles ago and replaced the plugs then. What is the thought on my test results Do they seem legitimate? 98, 5.9 gas. I'd say around 170,000 miles

 

Time for a rebuild with those compression numbers. The highest and lowest must be within 15 percent.

For the leak down test, each cylinder must be set to TDC. If you did that, and you got that much pressure drop from 100 psi, then you have leaking somewhere. Did you not figure where the leak was for each cylinder? Intake manifold, valve cover, exhaust, Oil dip stick, etc.

I'd say you have cracked heads and possibly piston rings if these numbers were from correct testing.

Any oil in the coolant? Coolant taking on dark color?

 

The leak down test numbers are TDC and they are percentage #s I could not see nor hear any leaking .That's why I was wondering if they even seem legitimate to you guys. Seems to good to be true from my eyes. I'm thinking the tester may be junk. Especially because cylinder #2 has such little compression.

 

I don't think you understand the tests. There are tons of youtube vids for both.

By your Original post, your low cylinders are cyl1=85 and cyl6=90, otherwise don't understand what you're trying to say. Fact is that 85 is almost 50% of a high cyl at 150.


[QUOTE=ericluck;3342183]The readings are in this order .1,3,5,7--2,4,6,8. compression (85-120-130-150) (150-140-90-120) The only one I did wet compression test on was # 2.



For just comparison sake, I have 176K miles. Here are my compression numbers...dry and wet.




Cyl1 being the lowest and throwing misfire codes, leak down test showed leakage at 70 psi down from 90 psi.




All my heads were cracked at the valve seats.


Just trying to make sense of your readings and now you're doubting them. Are you throwing any CELs? I would think so if the compression is that low...