Oiling problem, excessive pressure. Type 1

[JoeE13]

I have read through Jimmy111thread and its links https://www.thesamba.com/vw/forum/viewtopic.php?t=280293. I have a 78.8 x 94 high compression motor with 26 mm pump and full flow oiling system. My oil is VR-1 10/30 conventional. This motor is powering my 1000lb Autocross formula car.
I have a remote oil filter mounted to a recently added bypass to bleed off pressure. At startup my oil pressure with out bypass was 100+, needle buried on both old mechanical and new Autometer electronic gauges. It is about right bc I have had oil filter gaskets blow out, that makes quite a mess. Now with the bypass startup is 75/80 psi but I lose pressure when real hot 220+. I have inserted a ¼” spacer on the bypass spring to bring up hot oil pressure but, now I am back to 100 psi at start up.

At last race this is what is going on; startup 100 psi once then gets to 150-170 the pressure starts to come down but if I rev it to 3 to 4k it goes right up to 85ish. It is not until 200+ oil temp that the pressure stabilizes at 10 psi per 1000 rpms. Then after 2 runs on either 40 second or 75 sec course oil temp over 220 pressure barely hanging on at 20 to 30 psi regardless of rpms.

My 1st attempt to see what was going on I changed the oil to Mobile 1 5/20 synthetic just to start it and low rpm to see if pressure was better. No change, I never let it get real hot only to about 160 and still pressure too high.
My other fix is just bypass the filter etc by coupling the oil lines to and from motor remove oil filter from system. I am concerned that this is still too much pressure in the motor. I am at a loss and looking for suggestions to further my research, an answer would be good as well. Thanks

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09 Banshee Formula Autocross car
https://www.thesamba.com/vw/forum/album_search.php?search_author=JoeE13
08 to 18 Factory Five Cobra
http://s207.photobucket.com/user/JoeE13/library/FFR%20Cobra?sort=3&page=1

[mikedjames]

Typically this is the oil pressure relief piston hanging up goving high cold oil pressure.
The low hot pressure is wear.

On my engine that did this, the relief piston had worn a shelf in its bore , it was so locked in it took a lot of effort to remove it. Then I improved it a little with a half round file up in the bore.

But the engine took that behaviour to its grave, when a conrod poked its bolt out of the top of the case in a separate incident.

Near its final days it would start cold at 100 psi and once up ro 250 degrees the pressure was about 3 psi at idle.
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Ancient vehicles and vessels

1974 VW T2 : Devon Eurovette camper with 1641 DP T1 engine, Progressive carb, full flow oil cooler, EDIS crank timed ignition.
Engine 1: 40k miles (rocker shaft clip fell off), Engine 2: 30k miles (rebuild, dropped valve). Engine 3: a JK Preservation Parts "new" engine, aluminium case: 26k miles: new top end.
Gearbox rebuild 2021 by Bears.

1979 Westerly GK24 24 foot racer/cruiser yacht Forethought of Gosport.
1973 wooden Pacer sailing dinghy

[JoeE13]

Not good the motor was just built last fall and maybe 15 to 20 hrs on it. I will look into condition of oil pressure relief piston.

[modok]

the oil relief valve is not working, find out why.
-wrong spring?
-Stuck?
-Oil passage and vent passage plugged or not drilled?

spring specs
Free length 1.210"
Wire size .055-.056"
coils 6.75

[JoeE13]

Thanks will pull it and check. Just so I am sure the relief valve is located under block towards oil pump and crank pulley, the front side in my first pic, right?

[modok]

With a "dual relief" case, the valve by flywheel is the oil pressure relief valve.
The valve more toward the oil pump is the oil cooler bypass valve.

A single relief case has only one valve, which performs both functions.

[rayjay]

Put the oil cooler back on and maybe the low oil pressure when hot goes away.

I can tell you from experience that a System 1 oil filter will tolerate oil pressure high enough to wreck an oil pressure gauge !! Plus you get to look at the screen for junk.

I would also get rid of the sharp 90* fitting on the oil pump cover and use a tube end.

[mark tucker]

there are many things that can cause this...restriction, filter plumbed rong, stuck valve,blob of something somewhere... spun bearing...oil pump cover,oil pump,cooler,cooler bypas addaptor, cooler seals, cooler gasket, fittyings, hoses etc. eye wood knot run it till it was figured out I dont see a sharp 90.....looks like tube to me. butt eye could bee rong.

[rayjay]

I looked at his gallery photos and there is a hdwe store brass 90 on the oil pump cover's outlet [ which of course is another square 90. The oil pressure is of course measured after this but 90s are known oil pressure killers.

Also in his gallery pics there is a pretty nice oil cooler. That being said, if your motor ever expires and puts a lot of metal in the oil it's best to replace the cooler.

[mark tucker]

I was looking at the pics in this thread... they look to be tubes.of coarse that may also be too small or restrictive. or another fitting somewhere may be restricting... where is he taking the pressure reading from, if its' the std case location than all that's a moot point for the most part.

[rayjay]

Restrictive fittings before the oil pressure gauge tap will definiitely cause low oil pressure when hot. He has multiple problems going on.

I won't bring up the excess wheelbase . I wonder why the builder did this ??

[JoeE13]

I think it is standard location. If you zoom in 1st pic you can see the original plastic tube from mech gauge going into the block between exhaust pipe and crank pulley.

[JoeE13]

I have eliminated the potential oiling plumbing problems by running a -12AN 2 foot hose from pump back the return fitting just a smooth 90 degree path 6" diamenter bend. As soon as it started pressure buried to 100+. Looks like I will be checking the relief valves this winter. My temporary fix is the remote oil filter mount with a bypass set on 75 psi. The engine operates fine from 180 to 220, temp hasn't gone higher than that. Once hot it runs fron 20 psi up to 60's at 6500 rpm. Thanks again for the comments.
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09 Banshee Formula Autocross car
https://www.thesamba.com/vw/forum/album_search.php?search_author=JoeE13
08 to 18 Factory Five Cobra
http://s207.photobucket.com/user/JoeE13/library/FFR%20Cobra?sort=3&page=1

[rayjay]

So you are saying that eliminating some of the restrictive plumbing got you the hot oil pressure that you need ?

[JoeE13]

[Onceler]

Seems wore out all over. Re-cond. case?
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1972 Karmann Ghia

[JoeE13]

[Onceler]

Missed the part where you fixed the hot pressure issue. Good deal. Looks like fun!
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1972 Karmann Ghia