MFI oil return to breather cover

[svandamme]

I replaced my breather cover, because it was .. well
DIY'ed by the PO , and couldn't replace the gasket below it :



i got a replacement, but the partnumber was superceded

the new one looks identical, except it doesn't have the pipe
that connects to the MFI pumps oil return hose.
there's a hole with thread in it though


my question :

can i just screw in a coper attachment for hose
it would then be at 90 degrees, so i would have to find a hose cut it pretty short and make the bend to the pump

or

is there a partnumber for a pipe that would screw in to the breather cover, so the original short (2.5 inch) hose fits directly


does anyone see a problem with the 90 degree bend?
i think it could work, it's an oil return and the oil supply to the mfi isn't a thick one, even if the throughput of the return is less than a straight hose, due to bending. it would still be more than the oil supply.

any thoughts or suggestions on this??

[svandamme]

bump : nobody?

[304065]

Why don't you do away with the MFI oil feed entirely?

Check the archives. No less an expert than Gus himself recommended filling the pump with clean oil and putting a plug in it.

[KevinG]

I had just that thought myself, mainly because I could not get the 'banjo'?? fitting at the case to stop leaking. Just a minor leak, but still a mess over time. My question is how do you fit the oil pressure switch that screws into the top of the fitting?

[svandamme]

kill the feed?

i'll certainly look into that. would cut down a number of potential oil leaks, any drawbacks?

Kevin, i think you can screw the oil pressure switch directly in the engine case, i think it's the same size thread, haven't tried yet.


what you can try with the Banjo , is use copper rings in between , the copper is softer than steel or aluminum and should work better when it comes to leaks..

[svandamme]

John, you wouldn't know the thread from the oil feed kill?

was it a thread Gus started?

tried Gus and mfi , came up with 95 hits... none of the subjects seemed directly related.

EDIT

got the thread

MFI with no oil return ?!?!?!?!

[Rot 911]

Stijn, I too remember that thread. It was not started by Gus and as I recalled had to do with an MFI pump needing a rebuild.

[svandamme]

well, another problem solved
another step closer to having the heart of the beast planted back into the beast !

might get it done this weekend... can't wait, little anxious... will the engine still run after i've messed around with it? will it be smooth? will it be dry??

thanks John for this tip, i'll try it, not a daily driver so i don't think it should pose a problem to not have the oil circulate through the pump...

[sundaypunch]

Originally posted by KevinG
I had just that thought myself, mainly because I could not get the 'banjo'?? fitting at the case to stop leaking.

For your information, that's not a banjo fitting, it's a "hollow screw". I was made aware of this when I tried to order one. I guess they don't have banjo's in Germany

[Tspringer]

The MFI post in question was posted by me. My 2.7RS engine was built by Supertec and the pump was built by Gus. It shares no oil with the engine. It was dumping fuel into the oil for some reason and I suspected an internal pump leak and thus fuel getting into the shared oil supply. When I noticed that the stock oil line and sharing mechanism was gone, I called Gus to inquire. Gus was quite nice and I spoke with him at length about my pump on two occasions.

Gus made it very clear the he felt there was no need at all for the MFI pump to share oil with the engine. He said he felt it could cause more problems than it fixed. The oil from the engine does not flow at full oil pressure to and from the pump. Its more of a slow sloshing type feed and trickels some oil to the pump and it runs back slowly. Gus said the pump will retain more oil and flow it better if it does not share with the engine. On my pump, he had plugged the return line and instructed me to fill the pump to just slightly above the top oil fill and then screw in the bolt as it was running out so it would be right at the full point. Then just change it every few years or so.

Take a look at photos of many old factory racers.... they dont share oil. Just remember to change it every couple of years and dont worry about it.


Terry

[vol96]

This tip sounds like an excellent solution to prevent fuel from the MFI pump getting into the shared oil supply.

However I have a couple of questions:

I had a 72E MFI which had the same symptions as most, runs rich, fuel gets into oil, and also had an oil leak from the rubber cap that covers the control rack (on the back just above the pulley).

If the pump oil is isolated from the engine:
Over time wouldnt the oil in the pump become mostly (or entirely)fuel?
IE- MFI pump leaks fuel into its now isolated oil supply. Oil level rises. Oil/fuel leaks out the control rack cover. Oil becomes more and more diluted with fuel.

In that 72, the engine oil level would rise due to fuel contamination form the pump. It would rise about 1/2 quart from one oil change to the next.....approx 3k miles. I dont know how much oil the MFI pump holds but I would guess no more than a quart. Thus, in about 6k miles the MFI pump would be full of fuel...not oil. Maybe dangerous, mabe not. But certainly lacking lubrication. ...If my scenario is true.

I would be interested to hear others experience with this mod. Hoping that my scenario is false and that it works fine and doesnt hurt anything.

[304065]

You are assuming that the fuel in your oil is coming from the MFI pump oil supply. While possible, the more likely scenario is that an excessively rich mixture is putting fuel in the oil through the injectors.

In any event, fuel contaimination of the oil is a problem that should be fixed before the MFI oil supply.

I have to admit I was EXTREMELY skeptical of this at first.

[vol96]

John,
Sounds like you have used this mod. On a race car or a street car?

How do you change the oil in the MFI pump? Do you have to remove the pump?

[svandamme]

yeah ,been staring at a parts diagram, bit confused too.

do i just put the pump on it's side, plug the intake hole
then fill it up with oil completely? or not?

wouldn't gear oil , like swepco 101 be a good oil for this sort of appliance? or is there no advantage over normal engine oil?

[svandamme]

i've gone ahead and screwed in a copper "nipple?" in the breahter cover, then recycled an oil line from a 924 or something wich already had a 90 degree bend in it, and tightened it up nicely

i guess it will hold, it's a return tube , so the pressure on the tube is not as high as it would be on a feed tube.



got one small question related to this pic :

on the back of the air filter housing , there's that thing, no idea what it does or why it's there, and kinda forgot the what was attached to it. i think it was a thick tube that goes to the oil tank.

but i kept all parts, and only have one tube left

which leaves me wondering about the breather cover:
what goes on that one, and where does that go to?

anybody has any hints?

[svandamme]

just noticed on my oil tank pic, that there's two hose attachements
one on the tank , one on the filler

so i guess the air intake thingie goes to one of those, and the breather cover to the other? but which one goes where? or doesn't it matter?

[brokke]

Stijn,

There are two breather hoses connected to the oil tank. One is connected to the air filter, the other to the engine. I think it is not a good thing to run the egine without a hose connected between the breather cover and the oli tank.

Peter
911 2.4S

[svandamme]

thx peter, i assume it doesn't matter which tube is connected to which attachment in the oil tank?

[Peterfrans]

I have the crankcase connected to the oiltank and the airfilterhousing to the filler neck.

[Peterfrans]