My sister has a S80 T6 that i do the repairs onfor her. The oil light came on and the read out says: NO OIL PRESSURE, TURN OFF ENGINE WHEN SAFE. It stays on most of the time but turns off sometimes. I know that there is at least some oil pressure because she has driven it 2000 miles with the light on.

The pressure sendor is very hard to get at. I pulled it out and tested it (seamed ok. was N/C. w/pressure applied it had open circuit or resistants). I ohmed out the wire harness to it, again, ok. The light stayed off for a day after I messed with it but is back on.

If I could get a test gauge on it does anyone know what the pressure should be? What is the required psi for the sendor?(to keep the oil light off). Has anyone hear of this problem? Could I have a weak oil pump?

Any help will be appreciated before I pull it all apart again to (I guess) replace the sender.

Thanks

 

I don't know thet pressure off hand, but I'll tell you I've diagnosed and repaired tens of these and it's almost always the oil pan seals!

There are o-rings in the pan that seal oil passageways from the oil pump to the engine, and from the pick-up tube to the pump. The seals go bad. There is a kit from the dealer that should be fairly inexpensive, that has all the (updated) seals you'll need.

You will need the special gasket material, which probably isn't cheap. It's an anerobic sealant (cures in the absence of air).

If you do it, let me know and I can give you some tips on how to do it.

 

So, the seals leaking will drop the oil pressure and cause the light to come on?

Yes, I will do the job. Tips would be helpful, Thanks.
I work for ZF. The marine division. We us Loctite 518 to seal gear cases. It dries in the absents of air. Do you think it would work? Is it needed to seal the oil pan?
Thanks for the help.

 

So, the seals leaking will drop the oil pressure and cause the light to come on?
Yes, the seals leak and suck air into the pump, lowering the pressure, causing the light to come on, and ticking from the lifters.. When the light is on, pull the dipstick and you'll probably see air bubbles on the stick.


Yes, I will do the job. Tips would be helpful, Thanks.
The subframe needs to be dropped down a bit on the passenger side to get the pan out. You generally have to support the engine from the top when you do this. I'm not sure how I would do it without it. You need alot of room on the bottom of the engine to get the pan out.
The pan doesn't drop straight down, so you need to move the subframe and I thing the oil cooler lines near the front of the engine.
When you put the o-rings in the passageway recesses, I use a little krazy glue to keep them from going anywhere.
When I get the pan off, I try to let the engine drain for as long as poosible, because oil will continue to run down onto the gasket mating surface, and possible cause a leak.

I work for ZF. The marine division. We us Loctite 518 to seal gear cases. It dries in the absents of air. Do you think it would work? Is it needed to seal the oil pan?

ZF used to be a bad word around Volvo, back when they had them in the 740s'! I would bet that the loctite would work, but I've never used it. The Volvo stuff is applied very thinly with a small paint roller, you don't need very much. Is that similar to the Loctite 518?

B
.

 

Ok. I did all the oil pan seals. There hard and needed to be done but it didn't fix the problem. I put a test gauge on where the sendor is. I had 38psi when it was cold but as it warmed up the pressure dropped. After about 5 minutes it had only 2.5 psi at idle and raised to 6 psi when the rpms are raised. I also noted that after @ 1500 rpms and higher the pressure starts decressing again.
Someone told me to check the crank vent box. I did remove, clean, and reseal the vent box 30k ago. I don't understand how the vent box could cause this low psi.

Could it be the oil pump or soming else?
Also, how could I get a manual that shows the lubrication system?

Thanks

 

Wow! I find it hard to believe that the problem is not fixed. I don't think I've ever seen one of these pumps go out.

Did you find any seals that were distorted or popped out?

Are the symptoms exactly the same as before?

Did you replace the seals for the pick up tube also?

How was the condition of the pan, was there alot of sludge buildup?

B

 

I did replace all the seals: two on the pan, one on the sump pipe, two on the pipe that I removed from the pan. The smaller one at the pan-to-block was popped in at one spot. The o-rings were very hard.
I didn't see any slug in the oil pan or the suction pipe.

Symptoms are exactly the same. No change. However I didn't check the pressure prior to resealing the pan.

Those o-rings are under pressure, right?
Do they easily push in and leak when replaced. I work on ZF marine transmissions and we use this type of sealant and o-rings on alot of our gears. Do you think I should recheck the oil pan seals before pulling the pump?

The guy at my volvo dealer asked if I had changed the vent box yet. How does that effect oil pressure?

Thanks again for all your help.
Happy T-day

 

It sounds like you replaced all the seals.

The o-rings can get knocked when trying install the pan, that's why I recommended using a little krazy glue on the o-rings that seal the pan to the block. However, do you remove the pan again or replace the seals? That's a tough one.

Does the light come on when you start the car cold? Or does it come on after it warms up?

Are there air bubbles on the dipstick when the light is on?

How much oil are you putting in the engine and what kind?

B

 

The oil light is on when the oil is warm. I have checked many times and never find air bubbles in the oil.

I put 7.5 qts of Castrol 10w30 full synthetic in it.

 

So you have 2-6 psi of oil pressure? That is so low!

I don't see how the vent box can affect oil pressure, only crankcase pressure.

Since you found the o-ring on the pan had popped out, I would say that is the cause of the problem. I've seen it 10-20 times on these engines. That o-ring seals the passageway from the pump to the engine, so it is crucial that it is installed correctly.

How confident are you that it didn't move? Because you either need to pull the pan again, or replace the oil pump. I wish I could make that decision for you.

Hopefully someone can offer some other advice that may help.

Good Luck,

B

 

The engine may be so sludged that cleaning the oil pan broke alot of junk loose then it is clogging up the pick up tube.

 

I found no sludge in the pan or in the pick up tube when I re-sealed the oil pan.

 

Was the bottom of the engine all sludge?
I had a S70 that I had to remove the oil pan 8 times to get the engine cleaned out all the way.
If you drain the oil soon try to look through the drain plug hole and check out the screen and see if it is clogged.