98 V70 glt compression test interpretation

Post by **henmill** » 25 Mar 2015, 17:11

Hello all,

This may be a long one, so bear with me please..

My car has about 230k miles, 100k of which I've happily done myself over the past ~6 years since I've owned it. I try to take good care of "the silver bullet" but I must admit it has been mostly neglected last year due to lacking funds.

I haven't been driving my wagon for a couple months now due to bad performance, and the last time I drove it I was seeing white smoke coming from behind the engine around where the turbo is located. Also have been losing coolant slowly for some time now, but I do have a cracked reservoir cap and even a crack in the plastic inlet to the radiator.

After reading online a bit...I think I may have jumped to conclusions but decided my head gasket could be going. So the past couple months I have been slowly buying up all sorts of parts to do the head gasket job as well as a general maintenance overhaul including timing w/ water pump etc and PCV system replacement, vacuum hoses oil and coolant gaskets galore etc etc. In addition to buying all sorts of things I need anyways I have been doing a lot of studying of the job, me being a confident novice.

I just performed a compression test..twice actually, one last week and one just about an hour ago. Last week my number two cylinder had significantly lower pressure than the rest, maxing out at around 120 psi after maybe ten cranks. The rest made it to around 190-210 psi in 5 or 6 cranks. I followed the advice of my haynes manual and added a bit of oil through #2 plug hole and that improved the number a bit, bringing it maybe to 170-180 range. Now this had me worried it could be ring wear, meaning the bottom end of my engine would need love too. So I mulled it over and decided to try again today, this time I added about a 1/4 - 1/2 quart oil before warming it up because it was on the low side of the dipstick. Anywho, run compression on all 5 and they all easily achieve the upper 100's psi range, without much variance. According to haynes, the reading should be 11-13 bar for my engine, and lo and behold all five were within spec today. o.O

What do you guys make of this? Should I forget the head gasket and just do a maintenance overhaul and keep an eye on compression readings? This thing has been SEEEPING oil for a long time now, so it needs a serious cleanup and lots of oil seals for sure. I also just got a leakdown tester but have not yet performed leakdown due to today's results.

Keep in mind I've never done a head gasket job, but the idea of a full on overhaul of the top half of my engine sounds really nice in my mind. Whenever I tackle a big job I like to go all the way if possible...however I don't see rebuilding the entire engine top to bottom as feasible for me right now. But I am willing to do whatever it takes to get my wagon running how it should again.

Thanks for any input folks

Post by **scot850** » 25 Mar 2015, 19:51

That's a puzzler! You could have a sticky valve or compression ring and using oil has somehow lubed it back into action.

First question - When was your PCV last changed, or do you know? If you have not done it or had it done in the last 100k miles, it is overdue on a high mileage engine. Read up on the rubber glove test and go from there.

Smoke at the back of the engine could be leaking oil from the top of the engine. Take the spark plug cover off and see if there is oil leaking down the back of the engine.

White 'smoke' at the back of the engine could also be one of the turbo cooler lines failing. Check NOW! They are a PITA to change but are not expensive.

Others may have different opinions, but I'd do the following:

1) Fix the water leaks AFTER having the cooling system checked for head gasket leaks. This can be done with a gas analyser attached to the filler cap. If this is good (no leak registered) then repair all the water leaks - radiator, header tank cap and turbo cooler hoses. Also check the radiator hoses as the lower one tends to go first, and if you use an aftermarket radiator, replace the upper hose to as they tend to leak at the radiator as they can't form to the plastic of the top radiator hose outlet when the rubber has aged.
2) Then if the PCV is showing signs of pressurising the crankcase, this is an ideal time to do the PCV system while the radiator is out as you will have plenty of access, and you may have to pull the thermostat housing to get to the inlet manifold nuts at that end. I can do it without removing, but it is tricky.

Once that is done you should give the car an oil change and make sure you use a Volvo/Mann oil filter and give the car a good run. Hopefully all is good.

The other reason that cylinder may have been down is a leaking injector washing down the bore. Using the engine and running it frequently may hid the issue, but allow the engine to regain it's compression with use.

Other inputs?

Neil.

Post by **henmill** » 25 Mar 2015, 20:50

Thanks for the reply Neil.

I did the PCV system I believe around 4 years ago..not sure the mileage interval that would be, but I've already picked up the parts to do another PCV refresher as I figured it could use it. Hasn't been 100,000 miles but like I said I'm looking to do a sort of overhaul here. Not familiar with the rubber glove test but will certainly look into it.

Also, I am now fairly certain the smoke was simply oil burning off the exhaust/turbo like you said. There was an immoral amount of oil pooling on the cam cover under the plastic spark plug cover and I think it was just draining off the back of the engine. I plan on inspecting the turbo and all associated hardware during this job and making sure it is not in need of a rebuild (another thing I have no experience with but intend to learn about).

My main concern here is whether I have piston ring wear...when you mentioned compression ring are we talking about the same thing?

I just know that this engine could definitely use de-carbonizing up top and a lot of TLC and I'm prepared for that, I just am really hoping that the bottom end doesn't need a complete overhaul also. But if so, then so be it I guess.

Thanks again for your input!

Henry

Post by **Ozark Lee** » 25 Mar 2015, 21:50

Mike has a neat trick to figure out compression problems that worked for me. I adapted a compression gauge to hook up to my air compressor and then pressurized the low compression cylinder (you will need to find TDC on that cylinder which I did with a wooden dowel).

From there you can tell typically hear where it is leaking. If you hear the air through the exhaust then you have a bad sealing surface on the exhaust valve, if you hear it at the intake, then it is an intake valve problem, if you hear or feel it through the oil cap or the dipstick then it is usually a ring or cylinder wall problem. If the coolant bubbles then you have a head gasket issue.

My compressor goes to 125 PSI but that is enough to tell.

...Lee

draser · Post by **draser** » 26 Mar 2015, 08:01

With symptoms described and factoring in mileage it's normal wear and tear. Nothing catastrophic just bore wear. I'd fix it up good, leaks and such, and keep on driving until she quits.

Post by **henmill** » 26 Mar 2015, 09:42

Ozark Lee: isn't what you described essentially a leak down test without seeing the % leakage? I think I will be doing that next to gain more insight into my problems. But I do have a question about finding TDC on this engine...I remember reading that because of the 4 stroke cycle, TDC is at the top of every other rotation of the crank and the engine should be on the compression stroke so that all valves are closed before filling with air. So how am I to know when my piston is actually at TDC? Forgive me I have never done this, just want to make sure I understand what I'm doing here.

off topic: are you in MO ozarks or AR?

draser: is bore wear really not a huge deal so long as I take good care of the rest of the engine? At first I feared this meant total engine rebuild, but it sounds like I should just fix 'er up and keep on truckin...

-Henry

Post by **FLXC90** » 26 Mar 2015, 14:35

Do a de-carbon using the solvent of your choice (seafoam, lubro-moly, lucas) then check compression again. Worn valve stem seals lead to the carbon build up that prevents valves seating fully, also causes burned exhaust valves, somewhat common to prevalent on these engines (depending on maintenance and drive style). Then fix your leaks, and re-evaluate where you are. You may find a happier outlook.

Post by **FLXC90** » 26 Mar 2015, 14:38

Oh yeah, NAPA sells block check kits, and some parts stores loan them out. Determines presence of exhaust gasses in coolant. I did not condemn my 230k mile car based on results of that test. I just need to change heater core and radiator for the same leaks you describe.

draser · Post by **draser** » 26 Mar 2015, 16:55

Bore wear becomes a problem when car's hard to start, uses oil other than leaks and you feel it low on power, everything else being okay. If you don't see any of these then you're good.
TDC occurs every rotation, ignition is every other due to the fact that a full engine cycle takes 2 crank rotations. So when you line up the notch on crank pulley to mark on cover you may be at either compression or exhaust stroke. If you remove the cam sproket cover you may see sprokets at 12 o'clock (compression) or 6 o'clock (exhaust).

Post by **henmill** » 26 Mar 2015, 19:32

Thanks for the advice everyone. I'll look into renting a gas analyzer/block check kit this weekend, and seafoam the heck out of it. I think I'll do a good wash on the outside of the engine too because it is seriously nasty and I can hopefully see some obvious leaks. Didn't get to work on it today after work because weather was not so great here. Will update after more work is done, till then more input is welcome!