S54 Dry Sumped engine oil pressure problems

[said]

https://youtube.com/shorts/uuMmvseWgME?feature=share

https://youtube.com/shorts/-iabgqg4DCE?feature=share

[sapote]

i think I might have found the problem, Intake cam has 0.5 mm of axial clearance, I will now measure the round clearance there, might be big and oil is coming out like a Faucett

0.5mm axial plays is bad, but I don't think too much axial plays is the cause of too much oil leak.
I watch the video; why the intake cam bearings leaking so much as compared to the exhaust? Could be bearing caps are not matched to the head - they were bored with the head and so not interchange able.

But this doesn't explain why the pump sucking air after 3 days engine off.

[said]

0.5mm axial plays is bad, but I don't think too much axial plays is the cause of too much oil leak.
I watch the video; why the intake cam bearings leaking so much as compared to the exhaust? Could be bearing caps are not matched to the head - they were bored with the head and so not interchange able.

But this doesn't explain why the pump sucking air after 3 days engine off.

Will check the running clearance too

maybe it’s super loose and that’s making oil leak!

Oil is not holding after 3 days, it’s leaking and when I start the car, pump is without oil after pressure stage, so needs to travel all the way into the filter, cooler, and then reach the engine.

other engine doesn’t loose that remaining oil, so when I start it, primes right away!

[bigjae46]

Will check the running clearance too

maybe it’s super loose and that’s making oil leak!

Oil is not holding after 3 days, it’s leaking and when I start the car, pump is without oil after pressure stage, so needs to travel all the way into the filter, cooler, and then reach the engine.

other engine doesn’t loose that remaining oil, so when I start it, primes right away!

Just thinking through this...

Its a positive displacement gear lobe pump so it is self-priming and has a pressure relief. The pressure relief is what regulates the pump pressure. So if you're getting 0psi at start up and then can build up pressure then its an issue on the suction side.

Pump have a pump curve and a lift specification. So if the pump is too high from the fluid then it won't readily fill the suction and create discharge pressure. You also have to consider head pressure - the pressure exerted by a fluid on a container. You do need some head pressure so fluid flows into the pump and then doesn't backflow as soon as the pump stops turning.

If you have to prime both pumps to get pressure, you might back some backflow of the fluid in the system between the reservoir and the pump.

But if your pump discharge pressure never reaches the desired spec then I'd check the pump relief/pressure regulator...should be the same thing.

So you could have two issues - backflow on the suction and a faulty pump.

Just an idea.

[said]

Just thinking through this...

Its a positive displacement gear lobe pump so it is self-priming and has a pressure relief. The pressure relief is what regulates the pump pressure. So if you're getting 0psi at start up and then can build up pressure then its an issue on the suction side.

Pump have a pump curve and a lift specification. So if the pump is too high from the fluid then it won't readily fill the suction and create discharge pressure. You also have to consider head pressure - the pressure exerted by a fluid on a container. You do need some head pressure so fluid flows into the pump and then doesn't backflow as soon as the pump stops turning.

If you have to prime both pumps to get pressure, you might back some backflow of the fluid in the system between the reservoir and the pump.

But if your pump discharge pressure never reaches the desired spec then I'd check the pump relief/pressure regulator...should be the same thing.

So you could have two issues - backflow on the suction and a faulty pump.

Just an idea.

Correct

BUT, pressure relief valve and reservoir is shared by the 2 engines, that whole thing stays in the car. Also, i have tried OEM engine pump into Race engine and viceversa, same problem, so its definately not the pump, or the dry sump system components. Pump sits lower than the reservoir, so its getting oil, but because of the reservoir oil pressure, its still being pushed, and because there is a leak in the engine, it flows into the oil pan. Then, i believe when turning the engine on, oil has to travel throught the scavenge into the reservoir. just ideas...

NEEDS to be the engine for sure

[sapote]

"Pump sits lower than the reservoir, so its getting oil, but because of the reservoir oil pressure, its still being pushed, and because there is a leak in the engine, it flows into the oil pan."
I don't understand this. If pump is lower than the reservoir then why you need to prime the pump after 3 days engine off, as the pump should always filled with oil.

The low oil pressure: I would check why the intake cam bearings leak so much oil.

[said]

The whole post is to find out why ! hahaha

with this engine, i have to prime the pump in order to have pressure, with the other engine, i dont. Even with the racing engine pump on the OEM engine i dont have to do it, so thats why i say the problem MUST be the engine. Where? i dont know, but maybe its on the intake cam bearings, its a possibility right?

the lower part of the engine doesnt leak oil, it has some oil but of course, i am putting 3 bar of pressure with the crank not spinning, oil have to go out somewhere...

"Pump sits lower than the reservoir, so its getting oil, but because of the reservoir oil pressure, its still being pushed, and because there is a leak in the engine, it flows into the oil pan."
I don't understand this. If pump is lower than the reservoir then why you need to prime the pump after 3 days engine off, as the pump should always filled with oil.

The low oil pressure: I would check why the intake cam bearings leak so much oil.

[sapote]

so thats why i say the problem MUST be the engine. Where? i dont know, but maybe its on the intake cam bearings, its a possibility right?

with the pump filled with oil once, and located lower than the tank oil level, the pump is outside the engine and so even if pump output hose not connected to engine (take engine out of the equation), the pump should be able to dump out oil when engine cranked, every time regardless engine was sitting 3 days or weeks. Connecting the pump output hose to engine or not makes no difference. Can you verify this?

What exactly you do to prime the pump after engine off for 3 or more days?

[said]

yes, true

But you cannot take engine out of the equation, because that is what holds the pressure.

I already mentioned both pumps work OK in stock engine, so this means both pumps are delivering oil immediately, but because 1 engine has leaks, it won’t hold the pressure and oil just leaks away, makes sense?

im checking camshaft radial clearance, that is my last suspicious.

To prune the pump, you take the belt off and drive the pump with a drill

with the pump filled with oil once, and located lower than the tank oil level, the pump is outside the engine and so even if pump output hose not connected to engine (take engine out of the equation), the pump should be able to dump out oil when engine cranked, every time regardless engine was sitting 3 days or weeks. Connecting the pump output hose to engine or not makes no difference. Can you verify this?

What exactly you do to prime the pump after engine off for 3 or more days?

[sapote]

yes, true

1, But you cannot take engine out of the equation, because that is what holds the pressure.

I already mentioned both pumps work OK in stock engine, so this means both pumps are delivering oil immediately, but because 1 engine has leaks, it won’t hold the pressure and oil just leaks away, makes sense?

im checking camshaft radial clearance, that is my last suspicious.

2. To prune the pump, you take the belt off and drive the pump with a drill
3. im checking camshaft radial clearance, that is my last suspicious.

I thought there are two issues: pump running dry, and pump not create enough oil pressure in the engine.
1. I thought the pump having issue of running dry after 3 days, but as you said in (2), ...
2. So the issue is not about pump cannot suck oil after 3 days, but it takes longer to fill the system because the oil in the engine was drain off after 3 days, and it needs to crank a long time to fill up. This is not priming the pump, but to fill the void in the engine system. I mentioned before, the system must have a check valve to prevent oil draining back to the pan (the stock setup has the check valve in the OFH for this). Even the loose tolerance cam bearings cannot cause the drain back issue (but it can cause low oil pressure issue).
Where is the check valve in this dry sump system?

3. Fixing the loose cam bearings will not fix the oil draining back problem.

Could you post a sketch showing the components, hoses, oil flow?

[said]

I think that fixing the clearances will fix the issue..

like i said, same dry sump system, without check valve, is working on the stock engine.
Same race engine pump, is working OK in the stock engine.

what is the only difference thing here? the engine.
what problems does this engine have? i found out .56 mm of axial play, and both camshaft caps, intake and exhaust at .76 mm radial clearance, while spec is .56 MAX.

i do believe solving this issues will hold back pressure and have same results as stock engine, it needs to, like is said, there is no other difference.

the OFH have a check valve, yes, but i dont think a Dry Sump system really needs a check valve, the pump just generates the required pressure always, but if there is no holding pressure at the other end, pump will not build up required pressure.

BTW, pump never runs dry, i have 4 gallons of oil there, and its always delivering,

I thought there are two issues: pump running dry, and pump not create enough oil pressure in the engine.
1. I thought the pump having issue of running dry after 3 days, but as you said in (2), ...
2. So the issue is not about pump cannot suck oil after 3 days, but it takes longer to fill the system because the oil in the engine was drain off after 3 days, and it needs to crank a long time to fill up. This is not priming the pump, but to fill the void in the engine system. I mentioned before, the system must have a check valve to prevent oil draining back to the pan (the stock setup has the check valve in the OFH for this). Even the loose tolerance cam bearings cannot cause the drain back issue (but it can cause low oil pressure issue).
Where is the check valve in this dry sump system?

3. Fixing the loose cam bearings will not fix the oil draining back problem.

Could you post a sketch showing the components, hoses, oil flow?

[sapote]

I think that fixing the clearances will fix the issue..

like i said, same dry sump system, without check valve, is working on the stock engine.

Why the system doesn't have a simple check valve? Air can be pulled in via the cam bearing gaps regardless the clearance. Air going in and oil going down the tank, same problem after a few days.

[said]

Havent seen any Dry Sump systems with check valves, and i have seen quite a few, even on planes and helis.

i believe the rotor design from the pump doesnt need one. Dont really have the answer to that.

Maybe Anri ???

Why the system doesn't have a simple check valve? Air can be pulled in via the cam bearing gaps regardless the clearance. Air going in and oil going down the tank, same problem after a few days.

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My understanding is, that because there is 3 stage scavenge system, and vacuum is generated inside the engine, having a check valve on the feed line might not open completely because of the vacuum, of course this will cavitate the oil pump and there will be no oil on the engine .

[sapote]

The head is way higher than the pump, so without a check valve oil will drain back. This is why the stock OFH has the check valve. It's cheap and simple so I don't understand why you say it has none.