Low oil pressure when warm, Crushed. Finally get to drive the car and the idiot light comes on Options

[FlacaProductions]

Oooh - did you bump something during the messing around? 10psi per 1000rpm is the general rule of thumb so you’re in the range…

[trojanhorsepower]

Maybe, but nothing obvious I've seen yet.
The switch that was there is a Bosch .45bar switch.

[trojanhorsepower]

Sweet!
CHT was disconnected. Running better now. Didn't get it very hot, but ran a while and never went below 10 psi.

[FlacaProductions]

Excellent. Now maybe a new idiot light sender?

[brant]

This seems very concerning if it were me

Not below 10 you mention
But is it 70 at start up
Is it 40-50 psi on the highway at 75mph?


The 10 figure is the very bare minimum
Thought this was a fresh build
Sounds like your on the threshold of rebuild at 10 psi

I think you have a yet undiscovered issue

As stated earlier have you examined the bore of the relief piston?

I have been in your shoes on a fresh rebuild with low pressure
My motor came apart again for line bore when it happened to me

[emerygt350]

I assume you mean didn't drop below 10 at idle?

[trojanhorsepower]

Sorry, correct, not below 10 at idle (only a few minutes though). It never seemed to go over about 35, but I did not push the motor past about 4k rpm. Hopefully today I can change the oil and try again. Then I will add the CFR bypass setup when it arrives. Out of curiosity is reasonable to change the bypass setup with out draining the oil?

[emerygt350]

I am not sure. I put the tangerine bit in there when I rebuilt mine so no oil at the time. Also, what viscosity are you using in your oil? I use mobil1 0w40 euro and find it holds up to high heat better than some dinosaur oils. Lots of people use 50 weight in these but I think that's too thick for the reasons mentioned above. After I get off the highway when the oil is real beaten up and hot I will drop maybe to 8 but my light doesn't come on. After a couple minutes in town its back to 10+ at idle. I do have an aftermarket oil pump though. Hot and hot highway I am at a minimum of 35 at 3k cruising. If the temps outside are even slightly cool (in the 60s) it will be up around 40+ at 3k highway cruising.

I would also say that cruising at 60 doesn't result in that behavior. Only 70 mph interstate cruising. 60 through the country doesn't thin the oil like that for me.

[Geezer914]

2056 with CMP 26mm T1 pump. Tangerine oil pressure relief valve running Driven 15w/50 oil. 78psi. cold and 40psi. hot at 3400rpm. I have biral cylinders and my oil temp runs around 185-190 degrees. 10 psi. hot at idle, 1100rpm.

[ChrisFoley]

Out of curiosity is reasonable to change the bypass setup with out draining the oil?

yes!

[trojanhorsepower]

The latest:
reminder -fresh build 4 cyl 2056, tangerine oil bypass bit installed, 3 psi low oil pressure switch, VR1 20w-50 oil.

cold oil idle 65 psi, warmish is more like 10. Took the gauge off (a test setup) and drove it but never drove it long or hard. No light.

Drove it a lot this weekend. It runs pretty well. When driven until its fully heated up and idled down say when you pull up to park the low oil light comes on. If you blip the throttle it goes off, but would come back on if allowed. It seems fine while driving, nothing feels hot, but I don't like it.
So what are the odds its just the oil pump? Can the oil pump be replaced with out splitting the case?

Thanks

[emerygt350]

Do you have a pressure gauge? I would want to know what the pressure is while driving before I attacked the pump. I believe it is possible to replace it while in the car, it is accessible from below but I would want to make sure it was perfect, so that may be harder with the engine in the car.

[brant]

Not an in car job
Motor pull

It’s all about the surface leveling and thickness of plate gap

[trojanhorsepower]

I had a pressure gauge rigged up for testing and drove the car some. It seemed to follow the 10 psi per 1000 rpm at least up to the higher revs. I never took it over 4k rpm, but it seems like it never got to 40 psi either. Very subjective though, trying to drive, watch the tach and gauge. I have been thinking of adding a permanent gauge, but I afraid it will be too depressing......
It is at very low rpms (below 1000) that the pressure seems to drop out.

[Chad911sc]

I have been, and still going through the same thing. It’s very frustrating and patients is a virtue. I replaced my oil pump while still in the car the first time because it had a very steady drip coming from between the pump and case. It can be done safely, but it’s true the room to work is limited. I used the cast iron oil pump cover with a piece of 400 grit paper and WD 40 to fix the leak. Mine leak was due to an imperfection in the case, and it came out and it sealed nicely afterwards. I didn’t notice my low idle oil pressure until after that. I had noticed the leak after breaking the cam in on my 2056 as well. My oil pressure however, would follow the rpm’s up to 5500 no problem, but once it got to 220, my idle pressure was falling down to 4lbs. I bought the Tangerine oil valve in hopes that it was the problem as well, but the same thing happened after reaching temps. And I had a 30mm pump in it because I have external filter and cooler/fan combo.
So I finally bit the bullet and pulled it out of the car and disassembled the engine to find my middle bearing was wiped out. The other bearings looked perfect. I took my crankshaft to my best friends house who builds mud truck race engines and he put it in his V block set up and my crank was out of round .008 thousands. This crank had been sent to a recommended local machine shop to be checked out completely. The owner said everything was perfect with it and it only needed a polish. I was super happy and on my way to build the engine. Long story short, there is only a couple things from what I understand that can explain this problem. Oil pump clearance and bearing clearance.
I’m hoping yours is oil pump interference issue. Before pulling the engine and tearing it all down, you could try to put a CB 26mm pump in there. Thats what I had in mine initially, and it fit tightly. If it doesn’t work, it will only cost you your time and less than a hundred bucks. If you want to do it, send me a pm and I can send you details and pics of how I did it in the car.
Best of Luck!!

[VaccaRabite]

Do you know what your bearing clearances are? Low oil pressure can be caused by a lot of things, including excessive bearing clearance. Yeah, learned that one the hard way myself.

Someone here already mentioned milling the pump housing to decrease your tolerances there, and that will help too.

I don't recall what viscosity you are using, but if you are getting low numbers using a 20w50 oil, it may be time to pull the engine.

Zach

[trojanhorsepower]

20w50 oil.
Bearing to crank checked out right. Bearing to case unknown.

[trojanhorsepower]

RESOLUTION!

Boy when Jake says check everything that means everything!

I finally figures out (thanks 914world) where the oil pressure control valve is and what fastener it has.

Here are the parts from my 1.7l donor motor.

This is what came out of mine.

Notice the missing part?

I installed the spring from the 1.7l and cold idle went over 70psi up to 80 with a little throttle. After a long drive idle pressure is 15! So much better then 2.

When I put this motor together over 20 years ago the short block had been assembled by a "professional". We found many problems, but I did not know about the pressure control valve and didn't have an m14 triple square so I left it alone.
Looking forward to some more driving!

[FlacaProductions]

Good work sticking with it - congrats.

[930cabman]

Those German boys (and girls) didn't include many "extra parts", glad you got her fixed. The oil had been bleeding away without the spring in place

(IMG:style_emoticons/default/cheer.gif)

forgot to ask, engine builder was (is) a professional ????????