Operational oil pressure?

[Nevadan]

So, after doing my re-ring job I installed a new (used) instrument cluster with a repaired odometer and better working gauges. Much to my surprise the new cluster had a good working oil pressure warning light. I had never checked the oil pressure and did so once I saw the light! Below is the data with a good hot engine:

Location - At Idle - At 2000 RPM - At 3000 RPM

Head - 6psi - 20 psi - 20 psi

Filter - 10 psi - 22 psi - 23 psi

I've put 20,000 miles on this car and never considered the oil pressure was low, although I've wondered why it runs hot. Maybe this is it. There's no telling how many miles are on the car since the odometer wasn't working when I got it 2 years ago, but the odometer shows 163,000 now and had 143,000 when I got it. PO said he had the car for 7 years. I'm guessing there's 200,000 miles on it.

Any thoughts on putting in a new oil pump to get the PSI up to a minimum of 29 per the Bentley manual?

I don't want to pull the engine for a rebuild since I will start working on my replacement engine in May. I just need it to run good on my long distance trips for three more months.

I don't know which oil pump is in it (early -vs- late/larger) even though I just had the pan off to do the rings.

Should I just keep running it as is? I don't mind spending the $50 for the new pump if that would bring the pressure up to 29PSI.

[Nevadan]

The flashing red warning light and buzzer sound is distracting me from my new accurately working speedometer and nicely backlit instrument cluster (new bulbs). I can see the fuel and temp gauges on the right side of the cluster at night now!

[Quantum-man]

The low oil pressures aren't neccessarily a bad thing; unless there is a single bad bearing robbing the rest, the generally higher flowrates of oil will keep the bearings from seizing.
Nothing worse than a 'perfectly' fitting bearing that starves itself despite of it's associated high oil pressure upstream... Well that's my take on it

Just be sure that it's not low oil because of the oil pump needing a skim. Having said that, filter does seem low....

As far as I know, my current engine has never had a filter pressure sensor, as the housing is blank so that could be 28 years with just head monitoring

[Nevadan]

So, an update from today's work to resolve the oil pressure problem, with one question.

I pulled the oil pan to install a new larger flow pump and the existing pump screen was plugged with all the chewed up plastic pump pickup splash shield. Somehow I didn't get it clipped on right when I did the ring job!!!!

I installed the new pump after cleaning all the chunks and fine pieces out of the pan and other places. One of the piston nozzles had been knocked off by the chunks flying around so I replaced that also. There were also pieces at the pump gear on the intermediate shaft which had locked the shaft. It was a little spooky when it happened.

I'm very lucky I didn't destroy the engine!!!

I now have 40 and higher psi at 3000 to 4000 rpm but still not enough pressure between 2000 and 3000 rpm to keep the oil light and buzzer from going off.

Is there a different pressure sensor that has a little lower switch point for the sensor located at the oil filter? Or is there some electrical component I place in-line to reduce the signal? (I'm no electrician.) I don't want to unplug the thing.

I will be installing a MK I gauge cluster so I can see water temp, oil pressure and voltage.

The engine ran at a much better temperature today so even though it doesn't have "factory" oil pressure I'm confident it will be o.k. I'm pretty sure the piston oil squirters don't open until there's 20 pounds of pressure so at least I have oil cooling them off now.

I'm anxious to see my MPG following the ring job so now I can run a tank through it and find out!!!!

[air-cooled or diesel]

running 5w-30 syn ive got about 15 psi at idle at head,
i couldnt get filter flange sensor out to see that reading, but is higher than head reading (more like around 25psi at idle). sensors are seperate and in shop manual. 15w-40 reading will be higher.
lucky you caught that

[Nevadan]

I put a new high volume oil pump on and it helped a little. Another major problem caused by the ground up plastic splash guard attached to the oil pick-up tube was that no oil went to the KKK turbo and it ruined the seals, basically destroying the turbo. It was blowing oil out the exhaust creating a huge blue cloud behind the car. (Now I get to practice rebuilding a turbo!!) I had a spare Garret turbo and put that on this weekend. I now have decent pressure at idle and above 3000 rpm's. When the engine is hot there's 5 psi at idle and 40+psi above 3000 rpm's. The warning light and buzzer still come on between 2000 and 3000 rpm because the pressure is below 29psi.

Is there an oil pressure sender that switches on between 20 and 29psii? This will be for the sender at the oil filter. I could put a lower switched sender in and keep an eye on my MK I pressure gauge.

Bottom line is the engine probably needs new bearings all around but I'm confident it will run o.k. until I can get my other engine refurbished. I've certainly learned a lot getting the engine back to operational condition and the mistakes I made on this one will not be made on the other!!!!

[joat]

engines need 7 PSI for every 1000 RPM to keep adequate oil on the bearings... less than that and you run them dry and spin a bearing ....

[Nevadan]

Thanks Joat. That's the answer I was looking for.

I know the piston oil squirters open at 20 psi and I have 20 psi at around 2600rpm so it's in the safe zone. It's surprising how thin the oil gets at operating temperature. I'm running Shell Rotella 15 40 with a little less than a quart of Lucas.

I've got all my gauges installed so I can monitor actual water temp, oil temp at the head (I don't trust the reading I'm getting on this gauge since it only reads 80 - 90C), oil pressure at the filter bracket, voltage and boost.

I'm still considering putting a turbo Volvo oil cooler on to keep the oil temp lower. I'm going to a machinist on Monday to see how much it costs to make a longer SAE 3/4 - 16 (it's also 1/2 inch compression fitting thread) center bolt/pipe so I can keep the oil/coolant heat exchanger, add the Volvo remote oil filter sandwich plate, then the remote oil filter adapter. I don't want to remove the heat exchanger and there's not enough room for a filter if I keep it in place.

I'm also considering using some Shell (AeroShell) W15 - W50 aircraft oil to keep the viscosity higher.

After all the above changes I got 45 mpg on a 100 mile, 75 mph, flat freeway run last week. I also averaged 38 mpg on a full tank of around town driving.