no oil pressure at startup...possible synthetic oil?

[jetfiremuck]

Im finding no oil pressure upon startup after sitting for a few days. itll run for 2 minutes before the light goes out. Im running 15-40w full synthetic. I did a mechanical oil pressure test and its reading 60psi cold. The engine has just had new mains and big ends installed and has over 70 miles done since refresh.

1. Is it possible that the slipperyiness of the synthetic oil is causing drainback thru the pickup tube into the oil pan.
2. Ive removed the oil press relief valve and spring and checked all good there.

3. Ive run the engine since refresh using synthetic oil.

Crank wasnt removed for bearing changeout. Oil pump was reinstalled and primed .

Obviously this cant go on without bearing damage. If i idle up the engine to 1400rpm for a few seconds or so light goes out. Shut off and restart all ok until left overnight.

Any ideas.

[ngoma]

This is a somewhat common problem; we used to think the oil pickup tube seal would fail and allow oil drainback after some time, with subsequent delayed prime. Do you notice it happening worse if the car is parked facing uphill?
Dr. Dan suggested to me to a) try heavier weight oil, b) overfill crankcase by approx. 1 qt. I like running the lightweight (0w-30 I think) full synthetic so overfilling the crankcase seems to help. Good that you have a mechanical oil pressure gauge hooked up. Important Q for science: ---What is the mechanical oil pressure at startup when the low oil press light is lit?--- That will help us ascertain whether it is actually causing a problem or not.

Originally Posted by jetfiremuck

1. Is it possible that the slipperyiness of the synthetic oil is causing drainback thru the pickup tube into the oil pan.

Probably not that it is synthetic. If anything, probably more related to the viscosity value of the oil.

Originally Posted by jetfiremuck

2. Ive removed the oil press relief valve and spring and checked all good there.

No scuffing? Current thought is that the scuffing is what allows loss of prime, esp. long period, esp. when parked facing uphill (long oil pickup tube, oil pickup a long way from the oil pump).

Originally Posted by jetfiremuck

3. Ive run the engine since refresh using synthetic oil.

Good for you! Full syn oil highly recommended for these.

Originally Posted by jetfiremuck

Obviously this cant go on without bearing damage. If i idle up the engine to 1400rpm for a few seconds or so light goes out. Shut off and restart all ok until left overnight.

Your mechanical oil press gauge will tell us what is really happening upon startup rather than relying on the dummy light.

[v8volvo]

Originally Posted by ngoma

Dr. Dan suggested to me to a) try heavier weight oil,

I think that is backwards, maybe he misspoke. True that heavier weight oil would raise the pressure *after* the system already primed and running, but it would have a negative impact on length of time to get oil circulating and build initial pressure. Lighter weight oil would help with that and heavier would hurt. 15W40 is too heavy for sure especially in cooler months.

0W30, 0W40, 5W40 (all synthetic) seem to be what works best. Overfilling or at least keeping the sump at the full mark does seem to help too.

Tom Bryant's favorite is 5W30 Mobil 1. YMMV, but the important part seems to be the cold number. 0W or 5W best.

Originally Posted by ngoma

Important Q for science: ---What is the mechanical oil pressure at startup when the low oil press light is lit?--- That will help us ascertain whether it is actually causing a problem or not.
...
Your mechanical oil press gauge will tell us what is really happening upon startup rather than relying on the dummy light.

Do I remember right that others have talked about something happening to the oil pressure switch (for the idiot light) that can delay its turning the light off even after pressure builds? Something about the diaphragm inside the switch leaking so that oil moves to the backside of it, then it obstructs the switch from opening.

As you said, the mechanical gauge's reading will show that if there's something wrong with the switch.



One more question: is this something you are noticing only now after doing the internal engine refreshing, and was not a problem before that work was done? Or has this engine always done this while you have had it?

[jetfiremuck]

The oil pressure sender unit is a beck and arnley correct for the engine (with light rather than a gauge). I can tell by sound that the engine has no oil pressure as when the light goes out the engine tone changes. The sender and light are working and verified with a mechanical pressure gauge. Im satisfied that the issue is oil pressure.

Im running Sinopec brand 15/40w full synthetic oil with a motorcraft brand FL1A oil filter. I find the oil feels like a teflon type slippery feeling between my fingers, in comparison with dino oil. (subjective)

I was using rotella 15/40 regular diesel oil with same filter type before the refresh.

I did a timing belt, water pump when I reringed and replaced main and big end bearings. Packed oil pump using vaseline and flushed and checked oil pump pickup tube all ok there. Oil pan was scrubbed and cleaned as new.


So what are my options.

How much oil on the dipstick max level can I go safely. As it is now it reads 1/4" above the hatched mark on the dipstick .

Only other option is to drain and refill with non synthetic and try that. Its bizzare that if the engine is anything other than flat that this problem can manifest itself. I m aware of the long run to the oil pump from the pickup.

Would a new oil pump with tighter clearances help?

Engine is parked and started on a flat surface .



Thanks for all the suggestions.

[ngoma]

Originally Posted by jetfiremuck

... a motorcraft brand FL1A oil filter.

That FL1A does not appear to cross to the correct D24 oil filter. While the threads may fit, and the o-ring fit, there may be differences important in this case, in regards to filter bypass valve and more importantly, anti-drainback valve. That would be less wasteful to try first, replace the filter with the correct one, rather than drain all the (fresh good synthetic) oil.

Originally Posted by jetfiremuck

So what are my options.

How much oil on the dipstick max level can I go safely. As it is now it reads 1/4" above the hatched mark on the dipstick .

Usually the hatched area indicates 1 qt. top to bottom. It's a pretty large oil pan, so you could probably run 2-2.5 qt. overfill w/o problem, maybe a little more.

Originally Posted by jetfiremuck

Would a new oil pump with tighter clearances help?

IDK, I think it's more related to the pressure relief valve condition. Your inspection showed pristine surfaces, piston and bore, correct?

Originally Posted by jetfiremuck

Engine is parked and started on a flat surface .

What if you tried parking it nose down as a test? That may tell us something.

[jetfiremuck]

Thanks for the info. Id rather add 1-2 qts extra and see if this helps and eliminate the oil feed issue. This would be going from 7qts with filter change to 9...... if i add 2 more. Im still in the safe zone is that correct?

I am concerned about risking runaway. ill report back on this. Ill do this first and see what the results.

Pressure relief valve spool was fine. Found no scratches.

ill try jacking the discovery from the back check.

If after adding the oil the oil pressure issues go, I will pull the oil pan and check the bearings. Im not sure how long the synthetic oil would protect the bearings without oil pressure.

Jerry






The FLIA oil filter ive been using consistently in all my cars 3x 03 discoverys, aerosatar 98jetta tdi for over 20 years and can attest to its quality.

[ngoma]

Originally Posted by jetfiremuck

The FLIA oil filter ive been using consistently in all my cars 3x 03 discoverys, aerosatar 98jetta tdi for over 20 years and can attest to its quality.

Nobody is doubting the quality. Even the best quality built filter can be problematical if it does not meet the correct specs for a particular application.

The issue is that it may not have the correct anti-drainback or pressure bypass characteristics. Especially the anti-drainback valve behavior. For example, the FL1A filter appears to have between 3-4 times lower Bypass Valve Opening Pressure than correct spec. Mann W 940/4.

[jetfiremuck]

Ill order a few and see how they go. Thanks

[v8volvo]

Originally Posted by jetfiremuck

Only other option is to drain and refill with non synthetic and try that. Its bizzare that if the engine is anything other than flat that this problem can manifest itself. I m aware of the long run to the oil pump from the pickup.

Would a new oil pump with tighter clearances help?

I don't think synthetic oil vs non-synthetic would make any difference, all else equal. The viscosity of the oil is the real factor, I would guess.

What about switching to a lighter weight oil along with the correct spec type filter? A 5W30 or 5W40 oil is what I would expect to give the biggest difference in length of time to build pressure. Even in Florida, 15W40 oil is very thick first thing in the morning, synthetic or not.

15W40 is good for diesel pickups and semis, but I don't think it really has any place in our small high speed automotive diesels. One time I had a tired AHU TDI that I was trying to cheap out on the maintenance, and used some 15W40 dino oil I had in it. It developed a terrible rap and miss that would occur if I was trying to accelerate above about 3000 rpm before the engine was fully warmed up. I switched back to 0W40 and the problem went away. I suspect what happened was the hydraulic lifters were pumping up too much (or couldn't bleed off pressure fast enough) with the too thick oil when cold, and they were holding some valves open when the revs got too high. Felt and sounded scary when it happened, like the engine was about to put a rod through the block, big popping noises in the intake manifold. That taught me that these lightweight engines really don't like heavy truck oil!

[jetfiremuck]

I added 2qts extra to the engine. It hadent been started for 3 days prior. Left the oil drain down into the engine for 30 mins before starting. Cold start and oil pressure light went out quickly. Strange and still doesn't explain the drain back. This while using fl1a oil filter.

Man filter arrived.....a big canister of a filter with a hex head. Started engine until oil press light went out then installed Mann filter. Restarted and oil light went out. I'll report back.

Does the Volvo engine produce a marbles in a can sound when running?