Was going around a corner yesterday in my 2000 s70 non turbo and the oil light came on. I immediately turned it off, coasted to a spot then restarted it. The light was still on, but the engine is quiet as ever. I figure that it must just be then sending unit, and drive on my way. Couple days later I notice that I have a lot of valve noise, about as much as it did prior to me doing all the o-rings. I turn it off, turn it back on quiet as can be, light still on. Did a chem tool oil system flush, changed oil, filter, and sending unit, found that my sending unit was pretty sludgey, and replaced it. Started it up, no oil light, quiet as can be. drive it a bit to warm it up and light is back on, there is some valve noise, but not as bad as some cars like my rodeo. When I did the o-rings 5k miles ago, there was a considerable amount of sludge, i did have my pan dipped and scrapped out all the sludge i could find, made it look good as new before I put it back together. I'm thinking it could be the pump or a failing pressure relief valve in the pump. Any ideas? I have 156k miles and always ran synthetic oil.

 

What kind of oil filter are you using? Should always use Mann or Volvo oil filters. I've seen this low oil pressure before. Squealing turbo, valve noise, oil light on. Cheap filters are not liked by most Volvo's, especially Turbos... Also, make sure your oil cooler lines are not damaged, pinched or kinked... I know a Volvo man that said he couldn't remember the last time he had to do an oil pump on a Volvo. He's been working on them for over 30 years... That would be the last thing I would think it was.

 

probably lossened up some of the sludge and now it is clogging the pick up screen to the pump.

 

The engine may have damaged the rod bearings. I would drop the oil pan and check the rod bearings and the pick-up screen. If your engine has solid tappets a lack of valve train noise is not a very good indicator of oil pressure. I just went through this and ended up replacing the engine after finding a #5 rod bearing had spun and damaged the crank and block.

 

Anything i can do to disolve the remainibg sludge? Ive hear of some old timers letting it soak in diesel overnight to loosten sludge. I would really hae to take down the pan again, id rather do any other job. Lol. As far as rod bearings go, ive never seen any metal shavings in the oil all looked well when i did the o-rings. Any thing io can do to push and circulate some kind of solvent to clean out any and all sludge?

 

The problem that I noticed is the oil doesn't drain back from the head very well. If you look at it from the end it's t-shaped and the oil pools up under the cams and cooks when you shut the engine off.. When I took mine apart the further back from the oil pump the dirtier the valve train was. Also the passages that lube the cams are only about 1/8th to 3/16th in diameter. You might be able to flush some solvent through the plugs that you remove to check the valve clearance. I'm surprised the o-rings didn't fix your problem. That was the start of my problems but the dealer kept trying to flush the engine until it started knocking.Your going to hate removing the pan a lot worse if the crank gets damaged. I would take the sender out and hook up a manual gauge and see what you have for oil pressure. Have you cut the old filter oven to see if it has metal in it? I'm not convinced that synthetic oil is any better especially if you stretch out the change intervals.

 

Sludge, this is interesting... How long have you owned your car? How many miles did it have when you got it? When did you start using synthetic? What kind of synthetic oil do you use (brand)?

I have had cars with over 400,000 miles on them and have run one about 20,000 miles without an oil change and have never seen sludge in any of my motors. I have also put magnetic plugs in a car before to try to find metal deposits (just in case). My guess is that the oil filter would catch any metal shavings.

I assume the oil level has always been full

 

As far as the orings go, I did them because when it was hot, with the ac on, when you would come to a stop and the idle would dip low for a brief second, the oil light would flicker, as most do when the orings start to rear their ugly head. Prior to the orings being replaced, i did have very minor valve tick at idle, however i just assumed is normal for this type of lifter set up, I've run Isuzu cars with this set up 300-400k with no issues, noisy all the time. When I did replace ALL the orings, they were definetly hardened, cracked and what not. upon start up when i did them the engine was quieter than ever. As far as the filter goes, its a cartridge, so I'm not sure what you mean by cut it open, i can see the filter medium and not shavings, never seen any before either. As far as how long I've had the car, got it in 2007 with 50k miles and have always used Mobil one since then, changed between 3-6k miles. So when I took the pan down there was sludge all in the pan, pretty bad, hence why I had it dipped in a chemical tank. Up inside the block, the sludge was caked up in the consistency of mud, it looked like I had let the crank sling mud for a while. I did scrape that up as best I could and cleaned out the pickup. Honestly never seen so much sludge in my life, no even in a diesel engine, not sure why it was so bad, I never use any additives of any kind ever just straight up oil.

 

Very unusual for the non-turbo model. Are you sure that you did the oil changes timely?

 

Yes, oil changes done between 3-6k miles with Mobil one. I will be pulling down the pan in the next few days, anything I can do to circulate some kind of solvent really desludge this for good? I know a shop that I worked at we had a true flush machine that would circulate hot solvent through the system, but we never had any adapters for the canister style filter. As much as I hate to go, might my dealer have such a machine?

 

There is no "flush" for this that is any good. You have dead-end passages in the head and you start pushing stuff around, you'll end up with blockage somewhere. You'll fry a cam, lifters and other things.

I'd go back to Mobile and tell them what you have. If you've documented the changes and have that kind of a mess, see if they will warranty the product and results.

 

you can drain a couple of quarts of oil and put some auto tranny fluid in and run it some. it has a lot of detergents and will clean it up but may be too little too late. i replaced a motor before for this condition. was cheaper for the customer than disassembling and cleaning out everything. i also has a high milage (230k) one before that the customer was misinformed and was laxed in his oil changes anyway (a couple of 12k and 16 k intervals) and had to take the pan down, clean out as best as possible, remove the cam cover, set up a shop vac with a heater hose on the end, scrape away the sludge w/ a screwdriver and suck it out. car wasn't worth a motor and i believe it kept running. i left that dealer a couple of months later so don't know the long term outcome.