Oil Lines

[English179]

Good morning,

Having completed my racing season (2nd with this car, 97VD) I am pulling the engine out for a rebuild. During this process I have examined the oil line routing closely for the first time.

It draws out of the bottom of the bell housing to the inlet side of the pump. ON the outlet side, the first two outputs go back to the swirl pot, with the 3rd going to the oil cooler and from the oil cooler up to the engine near the oil filter.

Is this a 'normal' type plumbing? Why do the first 2 outlet return oil back to the bell housing?

At the last race meeting (very hot 35 - 38 degrees C) I was having oil cooling issues for the first time hence my increased interest in the plumbing of the oil system.

Any advice/comments are appreciated.

Regards,

John

[Fred Michael]

The two lines going back to the tank are from the scavenge stages of the pump. The line going to the cooler is the pressure stage.
Pretty normal setup, although personally I like to cool my oil on the way back to the tank.

How hot was the oil and where are you measuring temp.

[S Lathrop]

I would recommend that you add a in-line screen to the pickup from the tank and an inline screen on the return lines to the swirl pot.

The oil cooler is most efficient as it is now. But I prefer that the oil cooler be on the return to the tank. The cooler does a very good job of separating oil and air from the scavenge lines.

For year I have opted for an oil/water heat exchanger where your cooler currently is. The advantage of the heat exchanger is that it heats the oil at the start of a race and cools the oil once every thing is up to temperature. I have found that the oil will generally run 30 F hotter than the water, which if just right.

[English179]

The oil got to 128 C and the sensor is in the bell housing. It is an old PI system and I have been having some sensor problems, mainly related to not reading temps (I have been having intermittent sensor drop out, if that makes sense).

John

[Fred Michael]

That is higher than I would like to see in my engine for sure. Hot day but not excessively.
I would verify your temp sensor is functioning properly and look into a better cooling solution. Larger cooler, different ducting, etc.

[S Lathrop]

The oil got to 128 C and the sensor is in the bell housing. It is an old PI system and I have been having some sensor problems, mainly related to not reading temps (I have been having intermittent sensor drop out, if that makes sense).

John

100 C would be great. But you don't know what the oil temp is after the cooler. It may be just fine.

[English179]

It was my last meeting on that engine, thank God. I was prepared to lunch the engine if that happened as the meeting was interstate (Sydney) and I just wanted to be on the track.

I have previously had the occasional high water temp alarm on hot days but I have never previously had a high oil temp alarm.

What methodology would you use to check the sensor?

John

[S Lathrop]

What methodology would you use to check the sensor?

John

Place them in boiling water. You know that is 100C and that is in the range you are running.

[Modo]

Quickie -- 2 scavange lines, one in front collects oil under braking, one in back under acceleration, fyi

[a. pettipas]

I would recommend that you add a in-line screen to the pickup from the tank and an inline screen on the return lines to the swirl pot.

Slight thread drift but I think you want in-line bullet filters on the scavenge lines coming out of the sump to trap any debris headed towards the pump and protect the scavenge stages... I could see installing one in the pick-up line from the tank to the pressure stage, as you say, but I don't think I have personally seen that placement... but I have seen the poppet/spring assembly on the pressure side stick because of trash getting in there...

[S Lathrop]

Slight thread drift but I think you want in-line bullet filters on the scavenge lines coming out of the sump to trap any debris headed towards the pump and protect the scavenge stages... I could see installing one in the pick-up line from the tank to the pressure stage, as you say, but I don't think I have personally seen that placement... but I have seen the poppet/spring assembly on the pressure side stick because of trash getting in there...

If you just have lines from the scavenge pump to the tank, you are returning foamy oil to the tank. The screen filters do a very good job of separating the oil and the air. If the engine starts to shed metal, the screens will help trap some of the bigger particles and possibly reduce the damage to the engine or the oil pump by recirculating the metal.

The screens also help cooling the oil by separating the air and oil. What gets to the tank is oil and air not a mixture of both.

[a. pettipas]

All makes sense but filters on the scavenge output back to the tank obviously don't do anything to immediately protect the pump scavenge stages from engine trash that is sucked out of the sump, but output side filters - besides the seperation/cooling benefits - would help get any trash that made it through the pump before it's pulled back into the pressure stage via the tank... does anyone plumb bullet filters into both scavenge input and output lines?

[Fred Michael]

Many pans have screens in the scavenge tubes.
Gets the big stuff but may or may not save the pump.