A bit of background.
My engine (short block) was assembled wrong by a "professional" about 23 years ago before I got it. When I got it I finished assembling the rest of the motor and found the cam timing was wrong. After several posts and help from Jake Raby we found the cam gear had been installed backwards and a new hole drilled to make it fit. At that point Jake had me split the case, mic the cam and crank and get the numbers off the bearings. All that checked out. I rereassembled the engine and everything went well. Now 23 years later I have the engine in the car and it runs pretty well. (using Brad Penn 30wt break in oil) Except the oil pressure idiot light comes on at idle after the engine warms up. Maybe 10 min of driving. Now based on the threads I have read and the books I have there are no components that affect the oil pressure once the oil is warm? The check valves are for cold oil correct? Hot oil should just bypass the oil pressure bypass valves?
So I will change the oil for 20w50 VR1, but really am I just grasping at straws? What can actually cause this other than bearing wear? An out of spec oil pump? Anything else?

Thanks for the help

Peter

Are you feeding the idiot light from the stock/oem sender?
Can I assume no other gauges monitoring pressure?

if you're using a two-pole, non-oem sender they can trip at a higher level (8psi) vs. where a normal hot idle is probably anywhere from 1.5-7psi. If you use a VDO 2-Pole Sending Unit, the idiot light is triggered at 8psi, and you will be constantly freaking out at hot idle wondering "what's wrong".

good info here - hoping it's just a case of a sender/gauge issue.

https://vwparts.aircooled.net/VDO-80psi-Oil...m-p/v360006.htm

Thanks for the reply. I think it is the stock switch, but I will be trying to asses the actual values. Even 8 psi seems low, what is the acceptable warm idle psi?
the link indicates 1.5 - 7 psi at hot idle, that seems insanely low. IS that really the standard?

Here's what they say at that link: (but I'm sure the big brains here will weigh in)

We don't feel that the VDO 80psi Oil Pressure, 10 X 1mm, Dual Pole Sending Unit is the "right" sender to use for aircooled VW Engines because the oil light comes on at too high a pressure. Stock is 2psi, this comes on at 7-8psi.
Aircooled VW Engines usually have a hot idle anywhere from 1.5-7psi when properly built (Proper sized pump), and using the correct viscosity oil (10psi/1k RPM hot cruise). More pressure than this at cruise causes the stock oil cooler to be bypassed, and oil temps skyrocket. When you size the pump and oil viscosity properly, you should see hot idle between 1.5-7psi.

If you use a VDO 2-Pole Sending Unit, the idiot light is triggered at 8psi, and you will be constantly freaking out at hot idle wondering "what's wrong".

The solution is to use a VDO 1-Pole Sender with the STOCK Oil Light Switch, to get the use of your Oil Pressure Gauge, with the correct operation of the stock oil pressure switch activating your Warning Light.

Regardless, we are offering this for you enthusiasts that want a high warning light pressure instead of the 2psi stocker.

Yeah, I didn't understand that. So basically they are setting this up to come on when the pressure is too high not too low right? At 8psi the light would be on all the time on the low end. And on all the time when the engine is cold on the high end. Clearly I don't understand something.

No just when below 8 psi. You should get an oil pressure gauge in there to see what is up. It is still not clear which you have, 2 pole or original?

Stock comes on lower - two-pole idiot light sender comes on higher. So...if you use a two-pole, you'll see the light more often.

But - since you're using an OEM - AND, IF it IS a sender issue - yours might be bad. I'm just trying to go down this path because it's the easiest/cheapest fix first.

I'd swap that sender.

Perhaps the oil pressure regulator is worn or the spring is tired. You could try installing a Tangerine Racing oil pressure relief valve -- https://tangerineracing.com/shop/ols/produc...re-relief-valve

This can be installed with the engine still in the car.

Ditch the running in oil to start with ,your choice of oil is great as long as full zinc which I think it is.
Buy or borrow a mechanical oil pressure gauge and fit that for a proper reading off your oil switch with extension hose , ideally you should achieve 75psi cold and around minimal 10psi hot, I don't remember what I got on my last build when hot but 10psi/1000rpm is good.
If these numbers aren't their time to investigate further ,good luck ,cheers.

In my car (new to me) the light would often come on with a quick stop when the engine was hot. When I enquired about this, it was suggested to make sure the oil was filled to the upper mark on the dipstick, not the lower which is where it was. This made the difference and the light no longer comes on when the engine is running.

My car has the idiot light and the Factory console VDO pressure gauge, and it was showing 5-8 PSI when the light was on. The light would stay on for a few seconds only.

Since you already know the bearings are good/not worn out

It could be a wrong sensor
But could also be a few other things

If the oil relief piston was sticking open due to scoring and dirty bore that’s possible

The other possibility is too much case sealant not torqued quickly enough
Causing the case to have too wide of a gap at mounting surfaces. Causing the loss of pressure at the bearings from wide tolerances where the case halves come together

Never forget about the POS undersized T1 oil pumps if you’re using one of those

Thanks all!
I ordered Tangerine Racing oil bypass thing. Will change the oil and check the pressure with a tester. I guess at some point I will change the oil pump as well. What is the current recommended oil pump?

Im not sure there is a “good” T1 pump. The excess clearances of the T1 aftermarket pumps is a well documented, known issue.

Here’s what you can do short of switching to an O-ring T1 pump which would require splitting the case which would not be fun at this point.

1) remove it and measure it. If it is an easy slip fit in & out that’s a very bad sign. Measure the pump OD. It should be 2.757” which is basically a light (0.001”) press fit into the 70mm (2.756”) case bore that requires some light hammer tapping. This is the way the OEM T4 pump was set up with respect to clearances. If your pump is loose, shop around, measure pumps and find one that is a better fit.

2) while you have the pump out, make sure you have the gear end clearance set to 0.003”. Excess gear clearance really diminishes idle oil pressure. There are a number of pump cover gaskets out there that are way too thick. Basically the pump should be surfaced so the housing is zero clearance to the gears and then you would be using a 0.003” thick gasket.

If you have both #1 and #2 working against you I wouldn’t be the least bit surprised to have low pressure at idle and a flickering idiot light.

How about option 3?

If the type 1 oil pump has excessive clearance, maybe consider refurbishing a type iv pump. Seems much more the way to go compared to splitting the case. Of course if you're building a motor, a Gene Berg o-ring pump has merit (just buy and install versus rebuilding a 50+ year old pump).

There is at least one post here that covers refurbishing a type iv pump.

I like the idea of buying something new just because I can rule out the dumb mistakes I will make fixing up an old one. I would like to maybe build another motor that I can swap this one out for, so I will be looking for a short block 2l. I have some heads and pistons/cylinders. With that in mind what oil pump? GB26 mm or 30mm? or other ideas?

have you confirmed the low oil pressure with a known good gauge? I would connect a T fitting and run a mechanical (tube) gauge into the cabin. I use this setup on all my older machines, several Porsches, Alfas, Dodge. for me its cheap insurance

I haven't yet. Just got a gauge last night.

30 mm pump is out of the question unless you’re running external cooler and long plumbing runs.

Bigger isn’t better. 30mm will lead to oil cooler bypassing and running hotter than a 24mm (stock) pump.

Update: Removed the old switch and installed a test gauge. Cold idle was 25 psi but only 33 psi at 3000 rpm. Unfortunately I didn't get to warm it up because the engine fell on its face and died, crank for a bit and it starts runs for a bit and dies........

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

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

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

Excellent. Now maybe a new idiot light sender?

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

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

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?

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.

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.

yes!

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

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.

Not an in car job
Motor pull

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

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.

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!!

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

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

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.Click to view attachment

This is what came out of mine.Click to view attachment

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!

Good work sticking with it - congrats.

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



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

Scary mistake
Could cause motor loss
Glad that didn’t happen

Yeah, back in 2003 when I bought the car the PO said he had the lower end built by a "professional". When I got it home I built it out and found that the cam gear was on backwards and modified to work that way.... valve timing was totally insane. Tore it down and mic'd the bearing and got all that right, fixed the cam gear, but didn't have an M14 triple square so I left it. I guess that's on me..... I have no idea who it was; someone in PA.