Drysump

[Jim Cowden]

I have noticed an oil leak under my car and put it down to a loose or poor fitting around the scavenge manifold.
When I made the manifold I pressure tested it and I am reasonably confident.
But nothing is for certain so I started to pull it off to get at one fitting that is hard to get at.
This is when I realized that the sump had filled up with about 5lt of oil.

History
I cranked oil pressure about 4-6weeks ago.
About 2 weeks ago I removed the oil cooler off the side pontoon and replaced it with a water cooled Modine unit that fits to the oil filter housing as I needed the space.
After this work is when the oil leak started on the scavenge side after about a week or 2 and increasing as time goes by.
It did cross my mind that undoing the oil cooler lines had caused oil to drain to the sump but that cant happen.

I want to run it buy you just in case I am missing something as this is my first drysump.
Layout.
Modular 4.6
Original oil pump is supplying the engine (crank nose driven in front case).
The base of the tank is about at the base of the sump.
-16 supply hose this is the same size as the original pick up pipe(strainer).
2 stage scavenge pump to a manifold with 3 pickups from sump.

My immediate thought was the pipe passing through the side of the sump to the oil pump housing has a leak.
The method I used to make it was as follows.
Sump pan rails and sides (original sump) I cut the floor out and manufactured the pipe assembly with the sump bolted to the engine.
This assured me that the alignment was good.
The floor was then assembled, the pick up bolts are accessed through 2 o'ringed plugs that are removed.

If this was leaking I would expect an oil pressure problem.
It had 100psi cold because I put 15w40 in it.
I drained that and put 5w30 as per ford manual just to prove a point.
It dropped to 80psi.
Ford say about 55-60 hot so I think it will come in on this.
It had no problem getting oil pressure so I assumed my pick up was all good.

I am wondering if it is passing through the pump but it would have to pass out through the bearings and I find that not to be likely as that would indicate with a low oil pressure problem.

So I would happily pull the sump to check myself but is there something else I should look at first.
Obviously I still have to fix the oil leak on the scavenge side.

Jim

 

[Jac Mac]

Jim, Oil will drain back from your tank thru the scavenge pump to the pan over time.
Not sure I understand your system though. You say you have three pickups from the sump/pan, but only two scavenge stages via a manifold. Usually the manifold attaches to the outlet side of the scavenge pump sections to simplify the tank return to one large line. If you have the three pickups from the pan onto a manifold the scavenge will pull air in preference to oil if any one pickup is uncovered. Do you have any swivel fittings on the scavenge side- if these are under any misalignment tension etc they may leak oil while sitting.

 

[roaldin]

Be fastidious is all I can say.
After spending a small fortune on the dry sump engine in my car it needs a complete rebuild because somehow somewhere it seems that the engine ran without oil pressure. 4000k old... Investigations continue...

Wish I'd put that FJ20 in there now. (Just kidding Ron)


Tim.

 

[Jim Cowden]

Jac mac
I will check what fittings I used (been a while).
I will dump the manifold and make it 2 in 2 out.
I made the manifold to pull oil from the front as the motors on RF are a slight down hill at the front.
The chain generates a lot of oil so I was trying to get rid of it through the 3rd fitting.

The scavenge can drain back only what is in the pump and lines and they are only about 2-3' total.
The scavenge return to the tank is above the oil.
That is why I keep thinking it is from the supply side.
A window in the sump would be nice about now.

Jim

 

[Jac Mac]

You probably had around two liters in the motor on the pressure side, especially up around the top end, also when you swapped the filter/cooler unit any anti drainback systems would have been released. I have never actually measured the drainback factor versus time, but I know the TVR ( two scavenge stage peterson ) can have a couple of liters in the pan after sitting overnite after a raceday, dont know if there is a larger amount after an extended time. Will check levels if I remember in December/ January when we take it out of mothballs .
Dont try to remove oil from chain area, they need all the lube they can get, especially in a dry sump setup.

 

[Jim Cowden]

OK

I will rehash a few things and monitor it.

Jim

 

[Trevor Booth]

Jim,
with the 3 in 2 out scavenge manifold you would not be returning all of the oil to tank (as jacmac mentioned) so that would account for some of it being left in the sump. If the oil level in the tank is above the pressure pump it will drain back over time. The same applies for the oil cooler, it will drain back thru whichever pump circuit it is connected. I note that you are using the original internal pump. Have you checked the flow capacity of the scavenge pump that it pumps more oil than teh pressure pump.
Is the sump V bottomed with a trough to collect the oil
did you actually start the engine or just crank it.

 

[Jim Cowden]

Trevor
manifold has been removed.
The scavenge and HP pump is about 1/2 way into the tank height.
What you say makes sense as it will drain to approx that level.
The sump is flatter at the front and has a trough in the rear half.(crossmember in the way to go full length.).
I did not know the flow on the EHP pump but scavenge supplier gave me some recommendations and it seems to have worked out.
I started the engine yesterday for the first time and it seems to be evacuating the sump fine.
After I ran the engine I pulled the sump plug and the amount of oil was negligible.
I will check it on the dyno to check if it evacuates at higher RPM.
Oil pressure is spot on.

Jim