Compression test results.

Gtin · Post by **Gtin** » 20 Feb 2019, 19:05

Hey guys. So I recently bought a 98 v70 xc on the word of it needed a radiator. Got the radiator in and found out it has a few other problems. Namely it overheats, smokes white when warmed up and has a lot of blowby. So i was doing a compression test today and the results are as follows. Im counting cylinders left to right i dont know if that's how they really go.

Cyl 1: 180
Cyl 2: 165
Cyl 3: 140
Cyl4: 180
Cyl 5: 185

Obviously 2 and 3 have issues. But I'm not understanding what the deal is. I put a little oil in cyl 3 and it jumped up. So bad rings. But then I did another dry test on cyl 2 and it had jumped up as well. Ran the car to clear the oil and cyl 2 read good after that still for one test, then dropped back down to like 150. So cyl 3 definately bad rings. Cyl 2 is psychotic, check. But the coolant system is also pressurizing really quick. Like I can take the cap off the overflow to clear it and after testing just one cylinder with like 7 turns it's pressurized again. Is that normal? What are the odds of a bad head gasket AND bad rings? Im a little lost here honestly.

WhatAmIDoing · Post by **WhatAmIDoing** » 20 Feb 2019, 19:15

Bad head gasket 100%. Hope you didn't pay too much. I'd swap the engine with a 'good' used one, based on what you described. Cheaper than rebuilding this mess.

Gtin · Post by **Gtin** » 20 Feb 2019, 19:19

Payed 650 for it. Plus 150 for a radiator... I was going to try some blue devil to limp it along for a while until I had some of the other projects my girlfriend is on me about out of the way. But the blowby and the compression jumping up on a wet test is stopping me. Those aren't normal signs of head gasket problems are they? And blue Devil won't fix rings.

Guy said he never drove it hot when I asked him

I think he meant he would road trip it with no coolant and disconnect the fan just to be sure.

Any chance he also damaged the turbo? How would I check that before dropping $$ on an engine? Poor girl only reads something like 150k on the dash. Thought I had found a deal

Post by **RickHaleParker** » 20 Feb 2019, 19:25

It may just be carbon sticking the rings on #3. Seafoam eats carbon.

Pour some Seafoam down the cylinders and let it soak for a long time. Stuff some rags in the spark plug wells. Turn the engine over to push out the Seafoam. Install plugs and coil pack. Start engine let it run until the black smoke stops. Retest the compression.

Keep an eye on #3 make sure the it does not go dry during the Seafoam soak.

Post by **ZionXIX** » 20 Feb 2019, 19:30

RickHaleParker wrote: ↑20 Feb 2019, 19:25 It may just be carbon sticking the rings on #3. Seafoam eats carbon.

Pour some Seafoam down the cylinders and let it soak for a long time. Stuff some rags in the spark plug wells. Turn the engine over to push out the Seafoam. Install plugs and coil pack. Start engine let it run until the black smoke stops. Retest the compression.

Keep you eyes on #3 make sure the it does not go dry during the Seafoam soak.

Is an oil change recommended afterwards?

Post by **RickHaleParker** » 20 Feb 2019, 19:37

Seafoam in Oil does no harm. Seafoam is added to Oil intently for crankcase cleaning.
Just keep an eye on the Oil. If it becomes dirty do a Oil change.

Gtin · Post by **Gtin** » 20 Feb 2019, 19:50

I'll definately give that a go. I remember a long time ago a buddy of mine suggested marvels mystery oil for the same thing, is seafoam better or does it not matter much?

Post by **RickHaleParker** » 20 Feb 2019, 20:13

For carbon removal, Seafoam is better. Seafoam was designed as a cleaning product. Marvel mystery oil was invented as a upper cylinder lubrication. However one cannot say Marvel mystery oil won't unstick a carboned up up ring. Both are good products.

Gtin · Post by **Gtin** » 26 Feb 2019, 00:52

Did the seafoam and got the compression up a bit to around 165 in cyl 2. Not perfect but I'll take it. Also ran some blue devil in it and I have noticed less smoke but the coolant system is still pressurizing, maybe not as much but it's hard to tell, I'm writing the blue devil off as a failure. Tried to test drive it today and had multiple misfires holding it down, didn't get time to check the spark or fuel, but the compression shouldn't be causing the misfire correct? 165 should be more than enough to allow combustion.

Post by **erikv11** » 26 Feb 2019, 10:00

First thing should have been to test for combustion gases in the coolant. Still worth doing.