I got the "No oil pressure - stop immediately" message. The light comes on when the car seems to warm up -maybe 3 miles of driving.
Oil changes have been long but regular, run regular 10 - 30 oil. About 80k miles, a lot of short drives 5 miles to work.
I have the local tire place do my oil changes because I grew up with the owner. They're not Volvo techs, but I trust them to not make a mistake.
On the previous oil change, maybe 200 miles ago, there was a lot of sludge in the oil filter. Looked liked fine coffee grounds.
So after the message popped up, I changed the oil myself this time. Some dirt came out with the oil, but not enough to worry about. the "No oil pressure" message persisted - no change.
Then I took to the local mechanic ( because I didn't want to drive more then 2 blocks). He dropped the pan, replaced the sump and oil cooler, did a nice job cleaning up the pan and bottom end. It was pretty caked with sludge. He was convinced the pickup was clogged enough to reduce oil pressure.
He test drove the car about 3 miles - OK. I paid my $900 ( ouch) and drove the car 2 blocks home. The "no oil pressure" message popped up. I waited a bit, then drove less than a mile and the message returned.
Anyone know a solution to this problem?
I've read some older posts about O rings. They were OK and replaced. Also saw posts about pressure relief valves, etc but no details. I assume the pressure sensor is Ok because the message shows itself only after warming up.

 

I wouldn't assume the oil pressure sender was working right at this point - I'd certainly say it would be a worthwhile effort to hook a manual gauge up in its place and see what it tells you.

The fact you're dealing with multiple instances of lots of sludge doesn't sound right at all. My V70 has 208,000 miles on it and the oil looks - well, like oil. I can't claim the insides of the motor look factory fresh, but there is NO "sludge" that I've seen anywhere.

In your case, there's one of several things happening...

1) The oil pump is shot and not producing pressure (always possible, though I can't say how frequently that happens to a Volvo motor).
2) There are clogged oil galleys in the block that are preventing oil flowing through to the sensor (and no doubt other places). I suppose there are things you could try short of a complete overhaul (like running Seafoam through your motor with the oil to clean it out... but that's kind of a last gasp approach, IMHO).
3) Your oil pressure sensor is bad. Happens all the time, though I would hope that the mechanic you took the car to would have checked that... (OTOH, I have lost faith in a lot of mechanics because of what they didn't do). A related possibility is that there could be a loose or intermittent connection to the oil pressure sender (which could explain why it changes when the engine warms up, though this could be the case with any of the other possibilities as well).

Also, it might be helpful if you'd define the "sludge" you've been seeing. To me, "sludge" is a dark, nearly black, thick, viscous material that borders on non-liquid. If yours is milky or a strange color, you might be dealing with something else like a blown head gasket. But again, any mechanic worth is weight in beans would have spotted that instantly.

 

Thanks for the reply.
The sludge was "normal" oil build up - caked black solids that look like oil if all the volatiles evaporated. Just a lot of it.
Today I'm putting a double dose of the oil flush in the oil. I've drained a couple quarts of oil out and added in the 2 quarts of flush. It smells like kerosene, and I suspect is mostly kerosene. Before you yell "Don't do it!" - I spoke to an old mechanic in which I have a lot of faith. He told me before there were oil filters, a regular oil change involved draining the oil and running straight kerosene in the oil pan for 5 minutes or so. Just don't rev the engine. I realize the tolerances are different now a days, but I still think low rpms don't need the lubrication that high speed requires.

Beside, I have not much choice to get the engine clean, and I believe little downside. The mechanic suggested pulling the valve cover and pouring a cleaner down through the engine. I would think this method is better. plus I don't want to pay him $50 an hour to troubleshoot.

When I drained the oil this morning, the fresh oil just installed with less than 5 miles on it was surprisingly dirty. the dipstick looked so clean I had a hard time seeing the level. But the oil that drained into the pan was not clear. It was not totally black, but not as clear as I expected. And in the bottom of the pan were some black particles, maybe ten of them the size of grains of sand.

 

I think you're on the right track. Obviously the oil should have looked pretty pristine after so little time in the motor. If I were you, I'd be tempted to put a couple quarts of new (cheap!) oil and some more flush (maybe Seafoam) into the system and idle it for 5-10 minutes and change it again, and repeat the process until it starts looking more like oil and less like dirt.

Even if the oil pressure problem is really a sender or loose connection, this will still be a good thing, since a clean motor is a happy motor.

 

So the double flush seems to have worked.
I ran the engine for 5 mins, 3 times with 1/2 hour in between each.
changed the oil. After 10 miles or so the problem seems to have been solved. So I'm not sure why so much sludge formed in the first place. maybe my short trips to work over 10 years.
I may switch to synthetic the next oil change.

 

I'm a big fan of synthetic oils. I had the valve cover off my Mk1 GTI back in the 80's with about 120,000 miles on it, and the cam and valve train looked like they'd been driven around the block a few times... I've never had a lube-related failure on any vehicle since I started using only synthetic oil. My understanding is that synthetic oil won't break down until a much higher temperature, so the sludge build-up should stop or at least slow down a lot. My guess is that once some of the passageways were blocked, your motor started heating up some of the oil to very high temperatures locally, making more sludge, blocking more passageways, creating more high temps and more sludge, ad infinitum. Sounds like you got it fixed - I love it when a plan comes together!

 

Wharf1999- I am having the same issues as you described... What kind or brand of engine cleaner did you use? Did you replace the oil filter each time, or did you used the same one and after completing 3 cycles you installed a new one?


Thank you!

 

I was having the same issue where the low oil pressure alarm would come on when my car was heated up and sitting at idle. I fixed my problem by just getting an aftermarket oil cap seal from ipd.

 

I don't remember the exact brand of oil flush, but there are two brands in the same gray quart plastic container available at AutoZone. ( and other autoparts) Gunk is one brand and I think "Motor something". The directions instruct to add the flush to your oil, run 5 minutes at idle. Then change the oil.
As I said, to remedy the lack of oil pressure, I thought I needed more cleaning, especially after the mechanic cleaned the oil pan and replaced the pickup screen/tube. So I drained about 2 quarts of oil out, then put in 2 quarts of the flush. I ran through 3 cycles of 5 minute running, and did not change the filter until after the 5 minute runs.
I did notice after the flush, the instructions did NOT recommend this for an oil feed turbocharger, which I have. But about 200 miles later things seem to be fine. And I have used the flush a couple times in previous oil changes, but only as directed.

 

Wow you guys were lucky in getting it cleaned up. I had the same issue after getting into sludge in the sump saga, on a XC70 2001, and posted a thread on that board, (intermitent low oil pressure?) same engine thou 2.4 Turbo. If you have sludge in the engine, you will have sludge and carbon in the Turbo oil feed pipe. With flushing and clean up oils, it can remove and clean the flakes and carbon from the engine and into the turbo oil feed pipe and block up the oil supply to the turbo bearing.(which happened to me) So it would be best to remove and clean the pipe and the oil feed to the turbo sooner rather than later.

Snippet from the Intermittent Low oil pressure. see XC 70 board.

The oil circuit is relatively simple. A sump for the oil storage, an oil pick up, a pump, a filter , an oil pressure switch and then to the oil way and pipes which feed the bearings, and journals etc.
It is always best to start at the beginning, (or do the easy stuff first) so I of course dropped the oil filter to check the condition of the filter. It was a little dirty with the black carbon flakes still being flushed out of the engine. But not enough to cause that low oil pressure.
I then dropped the sump; the sump was relatively clean with a few flakes of black carbon at the bottom.
Looking up at the bottom end of the engine, the oil pick up pipe tube screen looked clean.
BUT! Taking my pinkey (This is the smallest finger on the hand opposite the thumb) and running it around the inside of the oil pick up there was a good deal of carbon flakes.
I removed the oil pick up pipe from the engine and when turned upside down all these back carbon flake dropped off the trough of the oil pickup head and covered the mesh screen.
The mesh screen was also dished up into the oil pipe. It was flat when I removed it from the last sump clean out during the turbo-repair, the mesh material had also started to tear at one section.
I have elected to remove the mesh screen to prevent the mesh being sucked into the oil pump at some blockage of the mesh screen. This seems the lesser of a number of evils.
The mesh on the pickup tube is to prevent lumps of metal going through the oil pump. These lumps being larger than 1mm the size of the oil pick up suction mesh. Some of these carbon flakes seem to be ideally sized to block off the mesh and thus prevent oil flow. About ½ a teaspoon full was inside the oil pick up trough, which was enough to cover the mesh screen. There was about another ½ teaspoon full in the sump once I cleaned it out and less than ½ a teaspoonful in the oil I drained out. I can expect more as the engine gradually cleans its self of the consequences of the sludge.
Since the mesh screen was dished inside the oil pipe once the mesh is blocked you will have no/little oil pressure. Hence on the stopping of the engine, the back flow of oil will flush the contents of the mesh screen off and give you normal oil pressure on start up. Until the screen blocks up again.
I toyed with the idea of drilled holes in the dished oil pick up trough to allow the carbon flakes to drop back into the sump, but rejected the idea.
i.The mesh was dished and had started to fail.
ii. Does the pickup trough have some self cleaning design for the mesh screen, as the oil is sucked through it?

iii. The flakes will continue to circulate around in the sump until the next oil change.
So the solution Synopsis the removal of the pickup suction screen:
The debris that is causing my problem is carbon flakes from the sludge issue I had. These are products of combustion, carbon and oil baked onto the hot surfaces of the engine. These will slowly come away from internal surfaces of the engine with clean fresh oil and the mechanical abrasion of the oil splashing around inside the engine. They are relatively soft, and can be broken down by rubbing between the fingers. So these going through the oil pump should not be an issue. The oil filter will then catch and remove these partials. Regular inspection of the oil filter, and change as required will help to clean up and remove the carbon flakes from the engine.


Bydand

 

Thank you all for all the advice/feedback...

Reporting back...

I did what Wharf1999 suggested and that was running seafoam through the oil. I poured half the bottle or 8 ounces into the engine oil. I instead ran the seafoam for 20 minutes. I drained the oil, but i still used the original oil filter. There was some chucks of sludge in the oil after draining. I then refilled the oil and ran the car without seafoam for 20 minutes to see if the low oil pressure would come on... AND NOTHING... I have driven 150 miles and NO signs of low oil pressure. After, driving 150 miles I also bought a oil cap gasket for extra measure. I bought the oil cap rubber gasket at Volvo. When I pulled my original oil cap gasket it was very dried out and thin cmpared to the new gasket. It has been over 250 miles and no signs of the low oil pressure... Thanks guys!

 

I have had exact same problem on my 2002 Volvo V70 XC 2.4L T engine. No oil pressure light was coming on while Idling also it would of flash when going over bumps or sharp turns. Problem with this car is oil filter housing unit. Most mechanic shops never clean the bottom of housing unit and dirt and sludge gets on bottom which can block your oil pressure . I flushed the engine oil using motor flush that you can find in autozone . I flushed the old oil from the car and cleaned the oil filter housing with brake cleaner, changed the oil filter with new one also I used 5quarts of 5w-30 oil and bottle of Lucas oil stabilizator. (This Volvo takes 6 quarts of oil) I drove the car for hour and light went off and haven’t been back ever since. Make sure to clean oil housing until. Black plastic cap that goes on top of the oil filter and you will see the difference.