1998 V70 Low compression

pappatho · Post by **pappatho** » 04 Oct 2015, 17:24

Long story short I bought a 1998 V70 for the manual transmission for a potential swap into my 850R. I was told it had a bad head gasket. The owner was surprised it started up the day I got it to load on the trailer. It has been sitting in my yard for months and I was thinking about fixing it and using it this winter. It is a non-turbo with about 225,000 miles. I have run it a few times just to keep everything operational and it always started fine.

The check engine light is on so I pulled codes and got.
------ ECU 7A has 4 DTCs: 0E 0C 1B 7B
------ ECU 7A DTC #1: 0E -> EFI-522 -- Rear HO2S, preheating.
------ ECU 7A DTC #2: 0C -> EFI-153 -- HO2S sensor signal, rear.
------ ECU 7A DTC #3: 1B -> EFI-232 -- Long term fuel trim, idling.
------ ECU 7A DTC #4: 7B -> EFI-123 -- Engine Coolant Temperature (ECT) sensor.

I figured I should try and verify the head gasket was bad before sinking money into it. I tested compression and got:
#1 200psi
#2 157psi
#3 196psi
#4 202psi
#5 189psi

I didn't think to try pouring oil in #2 to see if that brought the number up.

I then hooked about 90psi air into cylinder #2 thinking I would hear it hissing out the coolant reservoir or somewhere else obvious. I could hear a slight noise coming from the engine area, but couldn't figure out where it was coming from. The coolant reservior didn't seem to pressurize, I couldn't hear anything at the tailpipe, I tried the dipstick and oil filler and didn't hear or feel anything there either. Maybe it was the intake.

Any suggestions on how to proceed to figure out why the cylinder is low? Should I just put the car on the road and drive it and see what happens? I have no service records and there is a sticker saying the timing belt was changed at 103,000.

Post by **E Showell** » 04 Oct 2015, 17:33

If you're going to just put it on the road, you better change the timing belt and associated components or we'll be talking about much lower compression, like zero.

greenman86 · Post by **greenman86** » 04 Oct 2015, 18:45

Piston rings on cylinder #2 could be more worn then the other cylinders. I had a 98 v70 where I had one dead cylinder so ended up junking the car(didn't have a work space then). Depending on when the last timing belt was done, you may get away with just replacing the timing belt if your trying to save money.

Post by **rspi** » 05 Oct 2015, 13:35

I wouldn't worry about that compression number.

If the gasket is bad, it may still give good numbers.

pappatho · Post by **pappatho** » 05 Oct 2015, 16:10

My original plan was to look for bubbles in the coolant with the engine running. Once I saw how the hose went into the reservoir I figured that wouldn't be possible. I did notice that the level did rise significantly as the engine warmed up. If I revved the engine when it was warm coolant would spray out the hose that leads into the top of the reservoir. Is that normal, or does that indicate head gasket failure?