Using lots of oil, PCV symptoms (but I already replaced it?)

[SkyVolvo]

I'm trying to work out some issues with my '94 850 Turbo wagon. It's got about 245k, and it's been drinking oil like crazy. I finally decided to check the actual rate I was losing oil, and it looks like about one quart every 500 miles.

None of this is ending up in the parking lot. I've never found a puddle underneath the car.

Places it does seem to be going:

1) I'm pretty sure I'm burning up some of it, maybe in the turbo. My understanding is that oil that is actually burnt gives off blue smoke, but oil that is spilled on a hot surface gives off white smoke. I get a fair amount of white smoke while driving around town. No, I don't think it's coolant - my oil looks pretty dirty, but not milk-shakey.

2) There was, and has for a long while, a huge, gross amount of caked crud all over the turbo around where the intercooler hose connects. Just a big slimy mess. I finally got back there with some degreaser and uncovered that area. It's shiny for the moment, but whatever is below that top part of the turbo is still caked over.

3) Some of it is pooling up beneath the engine cover. I removed the cover today to do a compression test and found it pooled up in several of the pockets in there. I don't think it's the oil cap seal, because I've replaced that recently. It crossed my mind that as much oil as I have to add to this car, I may have spilled some, but not that much.

Okay. So the first assumption is that it is, at the very least, a PCV thing. I do have little puffs coming from the dipstick. This bothers and confuses me, because I did the whole PCV system maybe 20-25k miles ago, give or take. And it has shown these symptoms for awhile (although the oil consumption has gotten much worse in the last several months). Do I need to tear this thing apart and do the PCV again? I don't really plan to own this car for more than another year - two at the most.

I'll tell you what the compression test read, but I don't trust the numbers I got or the gauge I borrowed from O'Reilly. It was my first compression test, so while I warmed the engine I didn't actually get it up to full operating temperature (my bad). My dry test numbers were between 60-70 on all cylinders, but honestly, the car starts and runs just fine, so I don't buy that. Wet numbers were about 90. This old wagon still has a lot more fire than those numbers would indicate, so I plan to borrow a different tool and do the test right tomorrow.

So...I guess my question is what I should be looking at next. Should I dig back into the PCV system? On the '94, underneath the spark plug cover there's a metal vacuum line that I've read can clog the system: http://volvospeed.com/vs_forum/topic/13 ... placement/
Since I replaced the rest of the PCV system, there's a small, hopeful part of me that wants to think bypassing that metal line is the key to some of my problems. How would I go about bypassing that?

Have I blown any other seals by now? How would I know if it was the RMS? A quart every 500 miles is a lot. I've heard that one of the o-rings on the turbo is another frequent culprit.

Anyway, as you can see I'm all questions. Thanks for reading through such a long post.

[abscate]

RMS and cam seals would leave puddles of oil like BP.

White vs blue smoke isn't relevant, the apparent colour is a result of the particle size scattering light differently (try putting a bit of milk into water to see this home...wear safety glasses and give it to the cat when done )

You oil is probably going out the tailpipe. It does sound like you need to do PCV again, though.

[rspi]

Compression test numbers, hmmmm. I find it hard to believe that the numbers are that low as well. My thoughts are, numbers that low would cause misfires. So, lets assume that the numbers are low, looking at the wet numbers, wow, those are 50% higher. So, that being the case, I think the car does have worn rings. I could see them being maybe 10 to 20% higher, but 50???

I'd say it has worn pistons and you are getting a lot of blow by because of it. Just keep adding oil and get rid of it soon.

[jblackburn]

30 psi between compression test numbers isn't significant.

Check out the PTC connection at the turbo intake hose before redoing the job completely. After that, maybe the port at the oil pan is clogged.

I think it's dumping oil out the exhaust as well. If your intercooler hoses/throttle body are super oily, it's burning it. If not, it's just dumping it on the exhaust side of the turbo.

Another thing to look for: leaky (not blown) cam seals can seep a lot of oil at the bottom of the timing belt cover or down to the transmission pan without ever showing signs on the ground.

[mikealder]

Did you try attaching a 5/8" hose to the lower port in the block that the PCV tank connects to (the oil return port) and blow through the hose, if you can blow through it and hear bubbles the port isn't blocked, if you can't blow through it is still blocked and can need the sump off to clear out, have a look at where it blocks in this picture:



The oil from the PCV enters the square channel cast in the sump where the upper red arrow is, it then flows in to the sump where the lower red arrow is pointing - Note this picture was taken after I had cleared the port out and removed the baffle plates in the sump to make it easier to see.

Repeat the compression tests but this time try to get a compression tester with a metal pipe that you can secure in to the spark plug thread, it is very difficult to get enough of a seal with the rubber pipe compression testers due to the depth the plugs are seated at.

Do you get a large amount of smoke from the exhaust if you let the car idle for five minutes then apply the throttle, also do you get large plumes of smoke when re-applying the throttle after a long hill decent? - Mike

[obayha]

Might as well throw in bad valve stemseals while we're looking for oil loss.
That is where most of mine is going.
Just change the filter every once in awhile. The oil is self changing.

[SkyVolvo]

Update on the compression:

Hot/dry test:
130 - 132 - 131 - 125 (I tested this cylinder a couple times - the other readings were 115 and 120, but I wasn't confident about the seal) - 133

I do realize these are pretty low, but then, the engine is also pretty old and I'm at least glad the numbers are fairly consistent.

I'd tell you the wet numbers...but when I went to test the first cylinder, the hose on the gauge burst. I added about an ounce of oil to the cylinder - is it likely that I did anything wrong? Also, is it worth trying a third auto parts store just to do the wet compression test?

When I did the PCV back around 220k, I did clean all the ports and the PTC and everything (I haven't had the courage yet to take any of that out again). I don't remember how thoroughly I checked the lower connection from the oil trap (that's the one you're talking about, right Mike? The lower one in this photo?). I would have cleaned out the visible part but may have missed the bend.



If I wanted to clean that out...would I have to take the whole thing apart again? Is there some sly way I could get to it underneath?

FWIW, the metal vacuum line beneath the spark plug cover was clear. I did give it a new hose to the PTC because the old one was so loose I doubt it was very effective at all.

[jblackburn]

Unfortunately it would all have to come apart again. Good news - it's much easier the 2nd time.

Look at the PTC connection first. Most easily accessible and could be a source of the clog (it's a pain in the ass but at least you don't have to take out the manifold).

[SkyVolvo]

If it's not the PTC, I'll see if I can borrow a friend's garage space some weekend soon (the apartment is less than ideal for this kind of job).

While I'm digging in there, it seems like replacing that PCV hose with 5/8" heater hose is a good plan, as discussed here: https://www.matthewsvolvosite.com/forums ... =1&t=53448

And on the '94, there's no vacuum nipple on the left side of the manifold. The line from the PTC goes up to the top of the engine, through a metal line under the spark plug cover, and then back to the vacuum tree. I figure I may as well go straight from the vacuum tree to the PTC, unless there's a good reason not to.

Should I get parts to replace everything, or should I expect the hoses and oil trap to be useable since they're only 3-4 years old? It seems like it should be a blockage somewhere else, like the oil return port. It'd be nice if I could just get the heater hose and call it good.

Last, it seems like that oil return port can be a bear. In another post, mikealder talks about having to do this:

I replaced the PCV parts only yesterday, spent ages clearing out the return port back to the sump as it was blocked with sludge/ carbon, in the end I resorted to a couple of cans of carb cleaner and rodded the inlet to the sump out with some clear plastic pipe. This resulted in carb cleaner in the oil so that was dropped followed by a gallon of flushing oil before dropping that out and filling with decent quality oil.

If I have that kind of buildup, should I expect to have to drop the oil pan to get it done right?

I know you MVS moderators can't predict the future, but you all constantly impress me with your expertise.

[mikealder]

If it is the return port that is blocked you can try a few things as detailed below but you might end up with no option but to drop the sump which isn't too bad. Some of the bolts are of different lengths so a sheet of card to stick the bolts through as you take them out is handy to ensure the right bolt goes back in each hole - Just pop the bolts through the card in the pattern of the sump pan.

If you do end up dropping the sump pan get a set of replacement O rings for the oil pump feeds as it would be silly not to change them while you are in there.

The 5/8" hose is a good modification worth trying on your engine, you can use the same length of 5/8" hose to check the lower port isn't blocked and then put it to good use as part of the PCV system.

For rodding out the oil return port I used about 3 meters of 1/4" clear plastic tube, feed the tube down the port all the way down to the base of the sump before pulling the pipe out, the crud will now be inside the plastic pipe so cut the filled section off and repeat until clear. If at this point you still can't blow through the port it will be the bit you can't really get to without dropping the sump pan that will be blocked, spraying a can of carb cleaner down the port then send the 1/4" clear pipe down to the bottom of the return port (so it sits in the carb cleaner) then blow through the pipe to agitate the cleaner fluid, if after a while this works and clears the port you will need to change the oil as carb cleaner in the oil isn't good.

The first time I took the PCV to bits took about 5 hours to strip and rebuild (including time to clear out the port), the next time I did it took 30 minutes to strip it down so you should find the whole job much easier this time - Mike