Oil pressure loss on hills

[aksyta]

I've been driving my bug on some trips through mildly hilly areas and sometimes on uphills I'll lose up to 20 psi indicated by the VDO pressure gauge which usually reads around 40-50 psi on the freeway at about 55-65 mph. The dipstick reads as full right after shutting off the engine on flat ground.

I have a 1500 single port motor, with a large deep sump that brings total oil capacity up to about 6.5 quarts, a high flow pump, and a filter bracket attached to the pump.

I replaced the oil sump plate with a nice billet one since the one I had leaked. When I did this and got the old sump off, I noticed the pickup tube was extended with a piece of copper plumbing pipe which fell out when I pulled the sump off, and there is no strainer. The tube was cut at an angle on one end, I assume so it could rest on the sump plate and stay connected to the stock pickup tube. I did have to push it a little to make it stick on the stock pickup tube so I could fit the new sump on without it falling off. My concern with this is either I loosened the stock pickup tube somehow or the copper tube fell off, and either or both of these things is letting air get into the oil pickup when the oil moves around on uphills.

What I'm here to ask is are there any other causes for a sudden (takes about 5 seconds) drop in pressure on a mild hill, and how should I go about fixing this? I might eliminate the deep sump or get another, smaller compete deep sump kit with proper pickup extension, and either way get a strainer.

Also, if the stock pickup tube inside the engine is loose or broken, how would I go about fixing it?

[ROCKOROD71]

downshift dude
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1971 STD BEETLE- DD-1st car, 1st love. keepin' it stock! 1600DP, Solex 34-3 Mexi Bosch SVDA Dist NOW w/POINTS
1977 WESTY "KrustyKamper" 2L FI

[aksyta]

I'm not climbing mountains, these are maybe 20%/10 degree grades at most. The engine isn't shouldn't lose that much pressure that quickly from heat, especially with the amount of oil in it and how quickly it recovers pressure on flat ground.

[Max Welton]

Yeah, you're sucking air. Either from where the the tube extension is fit on the tube or where the stock pickup press-fits into the case up by the oil pump.

Max
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1967 Type-3 Fastback
Under the Knife https://shoptalkforums.com/viewtopic.php?f=24&t=151582
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[aksyta]

[Max Welton]

[Max Welton]

PS: Here is a pipe expander from the galley.

Max
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1967 Type-3 Fastback
Under the Knife https://shoptalkforums.com/viewtopic.php?f=24&t=151582
Home Stretch https://www.thesamba.com/vw/forum/viewtopic.php?t=767836

[airschooled]

If the pickup tube was loose in the case, it would be sucking oil on the downhills, not the uphills.

Gravity, dudes......
Robbie
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[Max Welton]

Education yo.

Max
_________________
1967 Type-3 Fastback
Under the Knife https://shoptalkforums.com/viewtopic.php?f=24&t=151582
Home Stretch https://www.thesamba.com/vw/forum/viewtopic.php?t=767836

[Danwvw]

Let me guess, it's got a big oil pump on it right? A 30mm or something? I went through some of this on a single port motor. I think it was an F case maybe H case?
I think the problem is the choice of parts.
I would start by removing the sump all together, What oil filter does it have? What oil weight?

Think about this: As the car goes uphill the oil runs to the back of the engine and I don't know but the scenario may be that through the longer pickup tube it is farther down to the oil level so the big pump is causing cavitation in the small original tube or even somewhere where it goes to the pump or in the pump.

Lighter weight oil should solve this problem too if this is what is happening.
Even just staying in a higher gear may solve the problem.
"aksyta"
One thing is for sure, It's real, you are running your engine without oil pressure when it happens.
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1960 Beetle And 1679cc DP W-100 & Dual Zeniths!

[Cusser]

Maybe just add an extra pint or quart of oil.
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1970 VW (owned since 1972) and 1971 VW Convertible (owned since 1976), second owner of each. The '71 now has the 1835 engine, swapped from the '70. Second owner of each. 1988 Mazda B2200 truck, 1998 Frontier, 2014 Yukon, 2004 Frontier King Cab. All manual transmission except for the Yukon. http://www.thesamba.com/vw/forum/album_page.php?pic_id=335294 http://www.thesamba.com/vw/forum/album_page.php?pic_id=335297

[Danwvw]

More oil would help if this is what is happening. The thing about these engines, I just looked at a case and there is more room for oil in the back of the case than in front. So the oil level would go lower going uphill.
I found even 10W40 will cavitate in a single port with a 30mm oil pump. I would try 5W30 or 0W40 and I would not drive it up a hill cold.

Check out "TheEZGZ" here at 13:45 in this video he has opened up and angled his oil pump on the intake. TheEZGZ video. On a 1500 single port case the intake holes at the pump are quite small the main thing is how well does your pump hole match? It may be the wrong pump for a later case so there is a big offset where the holes meet up. I would start if doing a full flow get a 26mm small hole pump and perhaps modify it to supply the 1st gear better the way "TheEZGZ" did.
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1960 Beetle And 1679cc DP W-100 & Dual Zeniths!

[mascrappo]

Depending on what part of Texas, you may try Valvoline Racing 20W50 oil? Works well for me in hot New Mexico. No controversy needed about my oil choice, just giving my suggestion.

[Danwvw]

Yes, If it is cavitation then 20W50 should make the problem of the oil light coming on much worse. Remember it matters how thick the oil is when it's cold too.
_________________
1960 Beetle And 1679cc DP W-100 & Dual Zeniths!

[mascrappo]

What works in beautiful Oregon may not work in Texas. I say it's only 2.5-3 quarts of oil, drop the plug and give both light/thick oil a whirl!

[aksyta]

I run valvoline vr1 racing 10w30, it works well enough but maybe 5w or 0w would be better since the engine takes a while to warm up the large quantity of oil, especially in the winters even though they just barely reach freezing here. This is a recent issue as far as I've noticed, and I've always used 10w30 so the oil is probably fine.

This doesn't trip the oil light even though I use a dual sender with the higher threshold warning light, just a drop in indicated pressure on the gauge.

[mascrappo]

I have discovered in my lifetime, try the simplest things first. If you barely freeze, you are well within VR1 20W50 range. VW's used to run straight 30W, so 20W cold is ok. What's it going to hurt? Try the thin Danwvw suggests, if still does it, try my suggestion. Oil changes are quick and inexpensive, engines are not. THEN, if you still have issues, more in-depth work is in order.

[aksyta]

I've tried 15w40 shell rotella before, the pressure just goes way up. With 10w30 I get down to about 10 psi/1k RPM only on the hottest days while driving on the freeway. Cold start idle pressure on a freezing day is around 50 psi. I've had a pressure gauge on the car for as long as I've had it, and switched from a mechanical sunpro to electrical VDO after I rolled it. The readings have been fairly consistent between both, though they may not be entirely accurate. Since it has a high flow pump and the engine has fairly low miles(therefore bearings and parts aren't as worn out and loose), the pressure would be senselessly high with 20w50.

[Danwvw]

It could just be the cold weather an all that oil has to warm up like you say. 10W30 seems reasonable to me. 20W50 would be ok in the summer in Texas on a stock single port engine, especially if it was a 6mm stud oil pump case. They had much smaller oil pumps?
Do you know what size of oil pump it has? Is it full flow? What filter do you use?
This loss of oil pressure problem for me was on a single port engine that I had put like a 32mm filter pump on it eventually lead to the engine seizing up a main bearing.
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1960 Beetle And 1679cc DP W-100 & Dual Zeniths!

[mascrappo]

Please let us know what you do and what remedies it.