Interesting oil pressure issue

[Keith Park]

This is a 2056, GA case, running with a baffle but enlarged return holes in it, Tuna can sump.
When pulling a big hill, with throttle near full consistently for more than a minute or so, the rock-steady oil pressure
Starts to back off, from 53psi to around 40, or a wee bit lower, this happens quickly and recovers quickly at the top of the hill when
The throttle is backed off, speed is consistent, road is straight.

First thought is of course, frothing… and this happened with the engines last build, and that had AA cylinders and KB pistons so I thought maybe blow-by,
But this build is OEM bored cylinders fitted properly to the KB’s, and Im having the same issues. This past weekend I made the hill run with about a half quart or so extra oil, same issue… it acts as if its sucking air but with the tuna can on there, brazed inlet tube, and extra oil it seems unlikely that its running that low in the sump, BUT… why ONLY under full throttle or near full throttle? Consistent RPM… 3400 on the highway.

Pickup tube was tight in the case when I last had it apart, but again, suppose it sucked a bit of air there… still, why only under heavy throttle?
Could it somehow be PVC related? I cant wrap my head around that one but this is a custom setup for use in a Type 3 and the crankcase breather
Has the restrictor in it but otherwise its just breather to the intake.

Stumped! Otherwise engine is running great.

Keith

[evanfrucht]

I think you may be correct about the oil getting whipped up or foaming up. With the engine tilted as you go up a hill the oil level essentially becomes higher than normal at the rear most part of the case.

Either that of you are dealing with cavitation which could be fairly normal. I would check to make sure your breather is not restricted or clogged I'm some way. Or maybe the hole is too small. The inner diameter of the breather fitting hole and hose should be atleast 1/2" inch. AN fittings can cause problems here as they are often have a small hole size compared to hose size.

Or the cavitation could be happening because the load of going up hill causes your oil temp to climb. That's more likely an agrevating factor if anything but who knows.
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1967 Bug ( the daily rod )
1964 Fury Wagon ( the pavement shredder )

[Keith Park]

well the hill isnt THAT steep, im doing 70mph up it so the car is still basically level. Oil temps dont climb more than 2-3 degree's during this, and are 195 - 215 on recent trips depending on outside temp.

The breather restrictor may be too small, thats possible... but how would too much crankcase pressure cause the oil to cavitate or foam? thats what Im not sure about...

[Wreck]

Check your battery is well earthed to the trans/engine . I had intermittent fluctuating oil pressure on the VDO gauge . Engine started fine so I didn't look at the earth first . changed the oil and filter with no change , pulled and cleaned the pressure relief , no change . Ran a temporary jumper cable . problem fixed . So I replaced the main earth cable .

[raygreenwood]

[Keith Park]

on a 65 degree day oil runs about 195, more if its warmer, it rises about 3 degree's over the 3-4 minute climb. Yea, never dives, just wanders down quickly from the rock steady 53 or so to 10 or 15 lbs less. Factory windage tray is in there with the drain holes hogged out a bit.

Stock 2L 914 heads, the vents run up to the little factory Y piece, I think its the flame arrester, then to the intake. Yes, it has the 3mm restrictor that you
recommended years ago.

One other insight, which may or may not have anything to do with it BUT...
idle speed is where it should be but just barely, cant adjust it any faster, and the cold idle is really not what it should be, even with the aux air regulator fully open when cold. would like to increase these a bit.

yes, the vacuum retard is working and I just checked the points and timing, all is good.

Keith

[raygreenwood]

[Keith Park]

NEver down a hill, always up under heavy throttle. Its a decent hill, long, 3miles or so but I can maintain 70mph up it, just barely with a stock engine and without issue with the 2056 so its not TOO steep, for those in the Northeast, its the hill on the northway going north heading out of lake George.

Ive got a mechanical gauge on it, never found an electronic one that I could rely on or whose sender would last more than a year. its Tee'd off the port for the stock warning light sensor.

[Keith Park]

Ran the hill again over the weekend, some sweeping turns at the top did not make anything worse as it crested the hill, so I don't think its sucking air either... still not sure whats going on.

Checked the breather, goes out of breather, thru 3mm reducer, into the intake manif box. Head breathers go thru Y and into the air cleaner manifold, ahead of the throttle valve, That OK? Dcell valve checked OK, still cant quite get the idle speed up to where it should be... another thing that bug's me...

Keith

[evanfrucht]

3mm reducer seems too small but then again I dont know what you mean or where the reducer is.

The breather hose should not be restricted or reduced at any point. It needs to have a 1/2" ID hole/hose size throughout, minimum.
_________________
1967 Bug ( the daily rod )
1964 Fury Wagon ( the pavement shredder )

[Keith Park]

The reducer is in the hose right out of the breather box, its Ray's suggestion, that then loops back into the intake air distributor. The heads breathers are not restricted and Y back into the air cleaner ahead of the throttle valve, I THINK thats where they are supposed to go.

Keith

[raygreenwood]

[Ohio Tom]

sounds like foaming oil.

Try a different brand of oil.

I found some oils foam worse than others.

[raygreenwood]

[Ohio Tom]

I can say this for sure..
I drag race. My motors don't get much warmup before running WOT to redline.

I used to run Mobil1 synth oil
I found it foamed really bad when cold.
So much so, that the dip stick would read 1/2qt over full after a pass. Wait 10min and its back to normal. ( could see the foamy oil on the dipstick.

It killed rod bearings.

I run PennGrade oil today because it does not foam no matter what.
I have no other experience.
I just know that chaining oil brands solved my problem ..

[raygreenwood]

[Keith Park]

Yes, Squareback.
Mechanical oil pressure gauge, copper line all the way up to it, been very reliable and rock steady for the past 30 years, only wavers on the top of the big hills on the highway. came down about 15 lbs on the last run, generally sits at about 50-53PSI on the highway otherwise. New motor, only a couple thousand miles on it.

Running Joe Gibbs DT50, Jake Raby's recommendation (Its his old 2056 kit)

2056 GA case with 2L heads and runners, matched to a Bus IAD and 42mm throttle body (that I got from you Ray, Thanks) Breather comes from the box, thru the restrictor and into the IAD.

Heads breath thru the Y connector into the intake before the throttle body, air cleaner side.

Yes, the D jet, Ive got it tuned pretty well now with a couple minor issues Ill post in the PhD post when I get time.

Ill try blocking off the head vents next run I make to the camp, see if it changes anything.

Thanks

Keith

[Keith Park]

Well I ran the same hill, same speed, same weather, but with the head vents plugged where they went into the air cleaner,
And Walla! NO loss in oil pressure!

Ok, this tells us something, but should I try a restrictor in that hose or something else??

[evanfrucht]

[oprn]

My experiance with foaming is with raw crude oil and I can tell you with total confidence that the thicker the crude oil is the harder it is and longer it takes to control foam. The difference is HUGE! Also, the thicker it is the longer it takes to run back from the heads to the sump. As Ohio Tom says temperature plays a big part too. Keep that oil temp up and the foam will go down.

Try dumping that tar you are using and put in regular 10W30. Report back please.

Hint: In the patch we use an anti-foam chemical which consists of, for the most part - diesel. It is amazing how little diesel it takes to do the job! 20 liters of diesel will take the bellyache out of a 60,000 liter vessel in just a few minutes if the oil is warm enough.
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