Trouble With type 4 engine oil pressure.

[joosep]

What could cause low oil pressure on freshly built type 4 engine.
2+ years ago I started building that engine for my friend but I had some accidents and I wasn´t able to finish sooner than now.
Engine case was put together in 2-3 steps 2 years ago and I´m not sure I didn´t make any misteke on that.
Today was the first start and braking in the new cam but pressure didn´t come up normally, it too 4-5 times 10-20sec starts before pressure started rising from 3psi to 10 psi at 1500rpm. later it had a bit better pressure but when oil was 90c it was low again.
with 5w50 100c oil it was
0.4bar @ 1000rpm ,
1.3bar @ 2000
2bar @ 3000
3bar over 4000rpm.

I drained it and its totally black with little shine. No flakes. Yes it had too rich mixture and assembly grease in.

What could be out of the case checks I could make? The plugs under the case cant be somehow fault? upside down, missing or smtng? I use external oil radiator, pipes taken from original holes. I use stock oil filter housing, just added a thread and AN4 for turbo oiling. Oil filter is without internal valves.

[Piledriver]

Looks great!

Those are perfectly normal oil pressure readings for a hot aircooled engine if the oil pump is a reasonable size, and clearances are a touch loose, as they probably should be on a boosted engine. If it's a Schadeck or CB (or Melling) pump the body OD will be loose in the case, leaking pressure and sucking air from the case, it's supposed to be an interference fit of ~.003"-005", someone decided to make them easy to install... A lot of folks o-ring their pumps. I have, but it must be installed with the case apart unless one has done a lot of case prep to allow insertion with the o-rings on. Have heard of using Molykote spray or other coatings to build up the pump OD as well. Im currently running a Melling 28mm pump with dual orings, one to prevent leaks to the case and one to prevent external leaks, as the iron pump does not expand with the aluminum case.

As to the initial pressure rise issue, a good shot of oil pumped through the oil pressure sensor hole to make sure the system is prefilled with oil is a Very Good Idea. Your lines and cooler probably take ~2 quart, maybe 3 or more if it's a front mount cooler.

If you were running rich on startup, you may have fuel dilution, I usually dump the startup oil after cam breakin or maybe a hundred miles.

[joosep]

Thats bad, that I didn´t notice your answer because I opened the engine but didn´t work with the oil pump O rings. Had ever heard about that and seen it.
What I did was that I changed the bearings and installed new 26mm oil pump. I quess It came from beetle because it was built like that not like type4 pump but maybe the aftermarket type 4 pumps just look like beetle pumps.

We are at the same problem, lack of pressure.
As I read my Log from computer it has quite same pressure as last time but this time I know the real temp and dont quess its 100c

with cold oil its good but goes down when it warms up at 1150rpm idle
1.4bar @ 35c
1.1bar @ 44c
0.8bar @ 51c
0.7bar @ 61c
0.6bar @ 70c
0.5bar @ 80c
same readings with mineral 20w50 and with synthetic 10w60 oil, same readings last time and now with new pump and bearings,

Now it all goes worse. This pressure is measured from filter passage not stock measuring point because I took turbo oiling from there. Added 1.5mm restrictor today for turbo and when it idles its 0.2bar difference measured from correct place or from filter housing. I quess its OK because it bleeds to turbo some of the pressure.

But it goes worse

When I rise tha RPM the difference goes bigger from measuring points.
when at 1150 idle the difference is 0.2bar like 0.5 vs 0.3 then with 2000rpm its 1.3 vs 1bar and with 3000rpm its like 1.7 vs 1.2
So it seems like its coming off again. Like a bad dream and I´m really pissed off. is it 1.2 or 1.7 it will be dead when boost hits it on 3k rpm.
What I noticed was that original pump never came out of the case without splitting it, it was just too deam tight. Now that aftermarket 26mm pump slips in like its nothing. I quess that is the problem why performance pump didnt´t make any improvement and when measured from same space the readings are 100% same.

[Piledriver]

There is also a pressure drop across the filter. This is inherent.
Try a bigger filter. PH8 fits IIRC, but is a bit long.

Most aftermarket ACVW pumps leak oil and suck air internally. You can oring them (you can buy them oringed sometimes) but they do not work properly, and the oringed versions cannot be installed without splitting the case.
The stock pump is a far better unit unless completely worn out-- rebuild it and reinstall.
They are a bit tricky to pull but that is how they are supposed to fit, even on a T1.

[joosep]

At the moment I removed pump and ported it to match without edge. (it was like 4mm offset on suction side and 3mm on pressure side. Then I cleaned it 100% and put some silicone on both parts (case and pump) pushed pump in and removed excess silicone from ports with swab on stick.
It may not hold for that pressure but atleast should work on suction side. If thats not big enogh difference I quess I have to take it apart and measure crank. Last time I didn´t Just checked its smooth and without worn marks.
Filter is a bit smaller than original becaude I use turbo exhaust. I start looking new filter without valve, this one has flowback valve but this car doesn't need it when its not upside down (Like my 944 needs)
If I´m not mistaken all oil goes frew cooler all the time (No thermostat on these engines) I quess AN10 and totally 2.5m hoses cant make that effect. I beleve it can make a little lag but not more. This case has only one oil valve with spring, I guess thats only for maximum pressure and cant make any difference at the moment.

[Piledriver]

There is a thermostat but it is pressure based, just like a T1.
I assume you have the stock bypass pistons/springs in place.

The pressure control/oil cooler logic bore at the pulley end works ~exactly like a T1 setup, flow goes only to mains above ~42 PSI, switches to flow through cooler under that. When pressure is too high, piston goes further down bore and bypasses to sump, or back to pump inlet on later cases. Same late cases also have no secondary relief on passenger side of case, this primarily gives a bit better pressure limiter, may also serve as an air escape on startup as it is at the very end of the circuit.

You can get "high pressure" bypass pistons and springs for T4s but it only shifts the oil cooler and bypass pressures higher, it will not help a low pressure issue. They MAY help your long, restrictive oil cooler setup, as well as high pressures at cruise RPM bypassing the oil cooler. Really thick oil/big oil pumps can cause high oil temps due to this.

The ~ideal setup would be to block the bypass in the filter housing, (US dime is right size) use a filter with built in bypass (most) put a thermostatic sandwich adapter on it, and run THAT to the cooler and external filter, returning to the case ideall at the pulley end of the mai oil gallery, or at the cooler adapter. (latter easier but more restrictive)

Having said all that, you still have a stock size pump (26mm), and 7 PSI at hot idle is absolutely normal on a stock engine.

[joosep]

I just write it up what have been happened in last few weeks.
Engine came down and to parts again because I really wasn´t pleased with that pressure ans sloppy pump fitment. It just made clocking noise when you heat the oil to 90c and let it idle, when it was near 1000 or lower rpm. It blinked betweeb 0.3-0.4 bar (near 5psi)
I regrinded the crank and ordered new bearings. Also replaced all gaskets. Made oil pump to tight fit.
Result is strange. Little improvement on low RPMs but insane peak on 4k (starts at 3.5k already)
compared to last time it was like that:

difference:
5 -> 7 PSI@ 1000
17 -> 19 PSI @ 2000
29 -> 33 PSI @ 3000
43 -> 68 PSI @ 4000

oil was same mobil 5w50 and oil temp was same (near 90c)
As you can see there is massive change on 4k somehow. When it was not warm yet it act not normal also it was 3 vs 1 bar @ 1000rpm in same minute, it floated. Seems like this valve is still making some problems. All I can quess is that valve can make that change on 4k also. Smtng like it sends it all to cooler until that point and somehow my cooler lowers the pressure. Its really big 12 row cooler with electric fan (controlled by ecu) Maybe I can somehow manipulate that spring or coil? I was thinking about making it softer. If I´m not mistaken it moves then more far and it opens ports like it doesnt need cooling and goes it directly to crank. I quess it lowers maximum pressure too because it lets it back to pump suction side more easy. Maybe it can still cool it down somehow. Another option is to switch cooling fan really early to keep it quite cold. On idle it can keep it under 70c if needed, it ads some PSI, not sure how low I can keep on the road. I´m still wondering how I can see such increasment on 4k rpm, what could cause that.
I´m afraid of the pressure on 2 and 3k, on 3.5 its alreadi good (45PSI)
I quess I have to put it together and start tuning it on my dyno. At the moment we have winter temps here and I can give you final result after 6 months.

I´m a bit thinking about removing original oil filter mount and close cooler lines to make it all new with external thermostat.

Here you can see RPM vs pressure (engine temp is oil temp in C)
https://www.youtube.com/shorts/2nv3c618Hrc

[Piledriver]

You had to press the pump in, right? should be .003"-.005" interference fit.
Also having the passages match up is critical.
Drive shaft may need pressed in a tad to reach cam notch properly, I give at least 1mm clearance for the cam end play to wear.

I once did a test by swapping over to a good 5w30 synthetic from 20W50 Castrol GTX (back when it was usable).
My hot oil pressure improved. Noticeably. Even a little bit better at idle.
Oil temp at cruise dropped ~50F.
(this on an old, bone stock 1700cc T4 in my 914)

Why? The oil was now going through the oil cooler at cruise RPM as soon as it got hot.
...otherwise it would get hotter and hotter until pressure dropped enough to go through cooler, rather than bypass.
Unless you are driving in Oman in midsummer you don't need 50-60 grade oil, and probably not even then.
Certainly not with ~stock pump size and bearing clearances.

I run Rotella 5w40 in most everything, but on a fresh T4 a good 5 or 10w30 might be in order.
Maybe even a straight 30.

I'd prefer to use an actual oil thermostat and bypass the factory bits for the oil cooler, even if I use the factory cooler/location externally plumbed. (wondering if a Corvair cooler would fit)

[Bruce.m]

I use synth 5W30. It’s particularly better when the engine is cold & it doesn’t hit excess psi. However it will creep past a tiny leak point unlike a thicker oil.

If you have an oil filter canister, id suggest synth oil since it keeps the dirt in suspension & carries it to the filter. Dino oil lets the dirt settle in the sump plate where it gets cleaned out at every 3K oil change (when you only have the T1 tea strainer).

[joosep]

Pump is now so tight it cant be pulled out installed it when closed the engine case. oil lines have ported to match. I use new 26mm Type1 pump. I resurfaced cover plate for better stright than original. and made it all really nice and tight. Also changed a little that part what goes into cam and let it some endplay there.
At the moment I´m not worried about temp issues because we have winter here and my cooler is many times more efficent than stock one. If I want, I can keep it on 66c (150F) on idle with my cooler and fan on it. Im worried about that something hold back the pressure under 4k. on 4kRPM it adds 22PSi momentally from somewhere, when I rise only 100-200rpm.

On different oils I look only 100c viscosity at the moment when the problem is only in the pressure. I´ve looked that number on tens of different oils (I used to work in oil shop) At the moment I use only with maximum visosity and between 22 and 44 units.

[Piledriver]

What brand is the pump?
I will swear off Schadeks and all other poor fitting pumps forevermore if someone is actually making pumps that fit.
(other than Revmaster, which fit but are 38mm gears and you have to set up the engine to use all that oil... or modify it to be a scavenge stage)

The pressure burp is possibly initial flow of colder oil out of the cooler?

[Bruce.m]

When you say its a type1 pump, im assuming its been modified for a type4 use? The tooth length differs for type4 vs type1 (how far it projects to engage with the cam gear)

According to previous posts from Ray, the pressure relief valve doesn’t seal particularly well so pressure at idle is 7psi or so. Thats the bolt on the side of the case underneath the cylinders (certain engine codes only)

[Piledriver]

If we are talking about the little one under #1 on early blocks , Jake suggested he replaced the spring with a spacer. IIRC there is also a tiny drilling in the piston on one of mine (ea block) I assumed was to allow air to escape.
AFAICT it was an OG bottom end, std std everything Kolbenshmidt elephants on mains and all.(still is)

If its really/truly not needed a setscrew (with slightly jacked threads as a locking measure) might be a better plan.

You can press a T1 pump shaft out a touch to reach the t4 cam drive notch
(i shoot for 1mm end play, i test with play-doh or little wad of foil)

[Bruce.m]

Agreed (shaft / gear modification).

I measured up a good stock T4 pump, T1 early & T1 late and took notes so i can mix ‘n’ match. For example i use a late model T1 mexican pump with a 3 bolt camshaft, after clearancing & tooth adjustment.

Ray suggested a ballbearing may seal better than the sloppy piston. Ill be looking at that carefully on my next T4 build

[Piledriver]

I'm still wondering what brands of pumps fit properly, Schadecks certainly do not, Mellings require orings as they are loose and also do not expand... etc. Do CB pumps fit now? Febi-Bilstein? I haven't had much like except with very old NOS.

The CB dry sump pumps don't fit the case any better (Schadeck) but that can be dealt with on T4s by converting them to straight throughs, with the scavenge stage feeding the original filter port and a bit of external plumbing. pressure stage with a iron cover with an outlet or the GB relief cover (also using as outlet) Plugging the internal interstage passages is trivial.
Does take a bit of work to fit it between 914 engine mounts. Have oringed them works well.

Fits under fan housing with a slight massage as well.