Volvo 850 T5-R Oil leak at high RPM

[Ram]

Hello MVS,

First of all, merry Christmas!
This site has helped me numerous times through the great write-ups you guys have posted. However, now I need your help to track down a rather irritating oil leak.
I own a Volvo 850 2.3 T5-R with 190k on the clock. I have had many problems with oil in the intake system, which I thought was due to a leaky turbo. I then installed a 16T from ARD with angeld flange, new downpipe and a Do88 "BigPack" intercooler kit with RIP - afterwards had it tuned to 273 bhp and 440Nm.
I then drove to my parents for the holiday, 140 miles, with 90 mph on the motorway (I live in Denmark ) and 3500 RPM for approx. 2 hours. When I pulled the pin, I could see I had used about 1 quart on the trip... Further investigation shows that the oil ended up in the engine cover, in the bottom. I jacked the car up, removed the engine cover and tried to track the source. There was a small "string" from the silicone hose on top of the turbo turbine housing to the intercooler pipe - not where a quart has run through, I will return to this. Furthermore, the center bolts from the oil pan on the exhaust side had drips on them, and I could not trace the source higher than were the oil pan meets the engine block. This morning I noticed a spray on the bottom right wheel well, but couldn't investigate as I don't have the tools right now. However, I did confirm that the PCV leads oil to the intake (hence the string on the turbine housing) - I did the rubberglove test and it inflated - crankcase pressure, but the exhaust doesn't smell like burning oil nor smoke. I changed the PCV 2 years ago, where I cleaned the PTC nipple thoroughly but the ports on the block looked clear, so I didn't scrape them.
Now it gets very interesting; I then drove to my sisters, 100 miles with 70 mph at some 2000 RPM for 1h 20m - NO OIL LEAK! Pulled the pin, was the exact same as when I left.
My theory is that somewhere there is a weak link (duh), but the pressure is only high enough at 3500 rpm to leak.

- Can the oil pan sealant go bad?
- Is it possible that the PCV ports is plugged all the way though the oil pan?
- Since the leak is RPM determined, can it then be the oil cooler lines?

I hope you guys can help me track down the source. Sorry for not adding pictures, I can do this on request when I get home on the 27th.

Kind regards,
Ras

[oragex]

Which brand was the PCV box?

Just an idea, some of the PCV hose clamps to the block may got loose a bit, may leak oil. A small mirror and a flash light may help looking under the intake if the leak appears at the front of the engine.

While there, I thought the glove should be sucked it, when the PCV is working properly?

[Ram]

The PCV kit is from a German company called "Skandix", which produces some quality items equivalent to OEM.

I will jack the car up when I get home, but the leak is coming from the back of the engine, not where the PCV box is located.
I suspect the lower PCV port on the engine block to be completely plugged and clogged with sludge, which causes pressure in the crankcase, and oil in the PTC nipple. I will also take a closer look on the oil cooler lines, which are prone to failure at the milage of my car...

You are correct, but since mine is being inflated, something is surely wrong.

What baffles me is still the RPM determined oil leak.

[tryingbe]

Did the car need boost to maintain 90mph?

[Ram]

As far as I recall, no. I have no loss of engine power, quite the contrary. The engine only burn a little bit of oil during startup, most likely valve stem seals. But other than that, none - the exhaust smells clean after all the journeys.

[FLXC90]

Classic symptoms of PCV, even if your port is not clogged, the hoses may be, or they may have leaks, preventing proper scavenging. See the ultimate pcv write-up in the repair database. The faster the engine turns, the more pressure develops in the crankcase. If your motor cannot scavenge the oil vapor and air mixture, it will find the path of least resistance. Oil cap seal, the hose on the cam cover, rear cam seals (under the distributor and cam sensor are all the common sites for pressure leaks. Eventually front cam seals and rear main seals.

If you need to, pull the pin up a little, allowing it to act as a breather, wrap loosely with a rag to prevent oil spray under the hood until you can repair it.


https://www.amazon.com/AT-205-ATP-Re-Se ... B017C5YWNQ

try this to reduce impact of valve stem seal leak.

Also, a decarbon of the top-end with seafoam or the like will clean off the mess the valve seal leak leaves.

[rspi]

I feel your pain. Oil loss sucks and I to experienced higher oil consumption at high speeds. Half of a quart in 140 miles is way to much. Even at high speeds, you should be driving (cruising) in vacuum, not boost.

First you should do a compression test, just to check the health of the piston rings. If you have any lower than 140 psi, you have wear issues. Before you do the warm test, with the car running, pull the fuel pump fuse or relay to cause the fuel to drop off before you do a compression test. You don't want fuel washing down a piston and giving you a low reading. I doubt this is your issue but you should check. Shouldn't have blow by unless you have readings below 125 psi. Do a wet test to make sure the gauge is good, should read over 185 psi wet.

After compression is verified good, fix the PCV system, with the engine warm, the glove should suck in, even at higher RPM's. Check for leaks first, cracked vacuum lines, disconnect at the manifold end, etc.. I'm shocked as to how quick some of the after market lines break, deteriorate, etc.. If you can't see any broken, you may want to have it smoked before tearing it apart. If no leaks are found, tear it apart and clean out the posts real good, all the way down into the oil pan. I have seen some blocked in the oil pan area. You have to jam something down the holes to make sure it's clear. The one I pulled apart the other day was blocked pretty bad. As mentioned, a plugged or damaged PCV will cause leaks, especially if the engine is under pressure.

If all that checks out, I'd consider pulling the head and having a valve job done. 22 year old seals are going to leak and you may not see the smoke from inside the car, but someone following close behind may see it. I was using about 1 quart of oil every 2000 miles at 75- mph and a quart every 800 miles above 80 mph. So I think speed/engine RPM can effect leakage, consumption. My PCV was/is good but my valve stem seals were original at 362,000 miles. My plan was to pull the head and do a valve job at 350,000 as a maintenance item to clean the valve seats, valves, and replace the old seals to reduce oil consumption and reduce the chance of burning a valve. Guess what, burnt a valve at the 362,000 so off the head went. Now oil consumption is way down, like 1 quart per 3500 miles.

[rspi]

What oil weight are you running and what is the ambient temp in Denmark?

[Ram]

I will do a compression test sometime tomorrow, or the day after. But just to be sure, a compression test doesn't tell me where the problem in the cylinder is, just that there is a leak. Don't I want to do a leak down test, to figure out whether it's valves, rings or gasket?

As for the PCV system, I have a plan to drop the oil pan to verify whether ports are clogged or not, and to change various seals and the entire PCV system - maybe even the oil cooler hoses, according to how it looks under the car.

I also want to have the cylinder head completely refurbished at a machine shop, but not before the compression/leak down test.

It is some 50F in Denmark right now - great winter! And I'm running Catrol Full-Synth 10w40.

[scot850]

Compression testing can tell you whether the leaking is in the piston rings or the valves. First test the cylinders warm and 'dry' for each cylinder. Then retest each cylinder with a small amount of oil added to each cylinder. The oil will help seal the piston rings if they are leaking and the cylinder pressures will increase if the pistons are worn/leaking. If the valves are the issue the cylinder pressure readings will not change.

Neil.