Oil leaks, but only while driving

chax · Post by **chax** » 12 Jan 2012, 17:00

My '94 850 turbo wagon w/143k miles has an oil leak that's bad enough that the front of the gas tank gets oily! After driving, I'll put it up on ramps and crawl under: there's always several drops of oil hanging down from the rear of the oil pan. I wipe them off, then wait for them to start forming again...but they don't. What might be the source (because they look wet, even after wiping them off) are both the seam between the oil pan and the lower half of the block, and the seam between the lower and upper havles of the block. Is there a reason either of these would leak only while the car is being driven? I recently replaced the "right" (front) engine mount, which involved jacking up the engine via the oil pan: I'm wondering if this could have compromised the oil pan gasket (or is it just sealant?)

If it's coming from the upper/lower block seal (or gasket), is there some kind of sealing coating that might be spread over it, to stop the leak?

Thanks for your input!

Post by **jblackburn** » 12 Jan 2012, 17:07

Oil leaks can be very hard to track down, as it looks like it comes from just about anywhere.

By this amount of oil, though, I think you've got blown seals (led to by a clogged PCV system desperately in need of help).

Check out this one first. Is there oil in the vicinity of that metal plate or on the hoses below it? If you remove it, does the cam seal fall right out into your hand?

There's a weep hole in between the engine and transmission - IS oil dripping directly from there? If so, you've got a leaky RMS, and may need to decide just how much you like your car and want to keep it. A RMS repair can run upwards of $900 as the transmission and engine have to be separated.

Post by **rspi** » 12 Jan 2012, 17:22

I had all kinds of oil coming from the back of the S70 motor and found a small access panel leaking. Oil was blowing everywhere. The kit cost about $8 from the stealer, maybe less at yours. Easy fix but hard to find.

Post by **rspi** » 12 Jan 2012, 17:24

About a month later I did blow a couple of cam seals. One of them fell off in my hand.

http://www.atthetipwebs.com/technologyi ... s70glt.htm

chax · Post by **chax** » 12 Jan 2012, 18:31

Thanks, guys!

jblackburn: the seals should be good: I replaced the PCV in fall of ’10, and there’s currently no signs of failure, and did extensive work on the head this past summer: reconditioned, replaced t-belt, etc, including replacing all cam seals. I’ll check there, though, as well as the weep hole: ya never know.

rspi: I saw your post in another thread, while researching this. What I’m planning to do is clean off the back of the engine with my “Steam Buggy” to see if the source of the leak becomes more evident. You’d think it’d pretty straight-forward, ya know? And what are those plates on the back of the engine for, anyway? Connecting rod and/or crank inspection?

I’ll post again, after further investigation.

Post by **rspi** » 12 Jan 2012, 18:44

I have no idea what the ports are for. I had to wipe my motor down several times and put it on ramps. I don't think I seen the leak until the car was running and on ramps. I seen the oil seeping out. I may have even had my wife reving the motor a little.

Our cam seals went about 17 months after I replaced the PCV system. I believe they were after market seals. It happened right after I switched to full synthetic on the car. I think the plugged PCV system stressed them to their near death and the synthetic finished them off. I have heard people complain about after market cam seals failing within months of installing them. Some as soon as 5 months.

DAK · Post by **DAK** » 12 Jan 2012, 19:05

I recently had a similar problem with my 98 V70XC...but solved with a valuable hint, I found that there was a tear in the 90deg hose from the PCV Oil Trap to the Block. It would drip down the front of the block only after driving - looking like a leak at the seam in the block, or the Oil Pressure Sensor, or Oil Pan...but it was the hose. Don't know if your car has a similar set up, but GL.

volvo850black · Post by **volvo850black** » 12 Jan 2012, 20:44

Check out the oil return tube, it's at the back of the block and runs from the turbo. Look up the tutorial on this site. I had a similar issue and had lots of oil all over the bottom of the car and it was only while driving. The o-ring where it goes into the block is a common failure
P.s. I may be calling it by the wrong name.

SimLyons · Post by **SimLyons** » 12 Jan 2012, 22:59

I know almost all you guys know this, but maybe have had bad experience with it? I had very good experience using a dye that you put in the oil (it's a very small amount) and (clean the engine off first) then run or drive the engine/car for a short period. Use a black light (I just have a trouble light with that bulb in it) and it will help find the source in a short time. Just running the engine is usually better so you don't blow the oil all over the bottom of the car.

chax · Post by **chax** » 03 Feb 2012, 17:56

Thanks for all the input. I cleaned off the back of the engine with my "Steam Buggy" (remember those?), then took it for a spin: upon returning, it was clear that the oil was leaking out from where the oil return tube enters the block. I sealed it with silicone, and went on my way. It started leaking again, though, despite all the silicone. Note that although I recently changed the CHRA, which involves removal and reinstalltion of the oil return tube, and I thought I had installed a new seal, but now that I think about it, the seal may have been for the dipstick tube. In any case, I'm going to take a look at it, particularly the hole into which the oil return tube fits, to see if it's blocked at all. Will keep you posted.