Oil leak from fuel pump!???

[Topsterguy]

Okeedokee, I seem to have an oil leak comming from those two tiny  (vent?) holes in the side of the neck of the Holley mechanical fuel pump on my coupe! Doesn't seem to do it at lower RPM's but at higher ones there's oil going on to the header right there from "somewhere", and the only place I can see it comming from is there cuz there's oil all over the top of the pump. Is it possible for the diaphram in there to leak / crack / rupture and the oil to leak out those holes? I cleaned it off, took it for a run at normal RPM and it stayed clean, but when I took it up a long hill and popped the hood there was lots of oil sitting on top of the pump - right under those little holes! HELP!!!

[Topsterguy]

Okeedokee, I seem to have an oil leak comming from those two tiny  (vent?) holes in the side of the neck of the Holley mechanical fuel pump on my coupe! Doesn't seem to do it at lower RPM's but at higher ones there's oil going on to the header right there from "somewhere", and the only place I can see it comming from is there cuz there's oil all over the top of the pump. Is it possible for the diaphram in there to leak / crack / rupture and the oil to leak out those holes? I cleaned it off, took it for a run at normal RPM and it stayed clean, but when I took it up a long hill and popped the hood there was lots of oil sitting on top of the pump - right under those little holes! HELP!!!

If it makes any difference it's actually an Edelbrock pump!

[enjenjo]

Okeedokee, I seem to have an oil leak comming from those two tiny  (vent?) holes in the side of the neck of the Holley mechanical fuel pump on my coupe! Doesn't seem to do it at lower RPM's but at higher ones there's oil going on to the header right there from "somewhere", and the only place I can see it comming from is there cuz there's oil all over the top of the pump. Is it possible for the diaphram in there to leak / crack / rupture and the oil to leak out those holes? I cleaned it off, took it for a run at normal RPM and it stayed clean, but when I took it up a long hill and popped the hood there was lots of oil sitting on top of the pump - right under those little holes! HELP!!!

Yup, it's possible. Sounds like new pump time.

[Crosley.In.AZ]

yep , they can puke oil from the holes.  usually gasoline pukes out when a pupture happens, but oil is there too.

[Topsterguy]

Ahhhhhh, once again I knew I could get an answer from you guys!  So obviously the diaphram is ruptured, or whatever, so could that cause gas to go into the crank case? I checked the oil and it seems okay and not "increasing".

[Pep]

I've seen that happen on standard pumps as well. I found no way of fixing it. There is a seal somewhere inside that's worn. I replaced the pump and it fixed the problem.

[soldermonkey]

I have seen this problem also but the problem was a lack of proper venting of the crankcase. You stated that this only occurred at higher RPMs and that at idle there was no oil.
I do not know what engine you are running but assuming the SBC the oil in the small chamber behind the fuel pump is minimal at best and should drain back to the pan without any problem. I would check your PCV valve and hose and also the vent that allows fresh air to be drawn into the engine. A plugged PCV can also increase oil consumption as well.
The only external clue I have seen from a ruptured fuel pump diaphragm is raw gas squirting from the vent holes. I have also seen gas contamination of the engine oil from a ruptured fuel pump diaphragm. At higher RPMs and especially going up hill the combustion pressures are higher and will put increased loads on the rings and cause more blowby to reach the crank case and could overpower even a properly working PCV. One other point if you are only getting the oil control problem when you are at a relatively open throttle position and most likely low vacuum levels ("going up a long hill") the capacity of the PCV system to evacuate the crankcase will be diminished.
I saw this problem on a customers Ford with a 390 many years ago and the customer had fixed it the only way he knew to, he had put tooth picks in the holes and that had worked for him for over 30,000 miles, but his engine had very high miles.

My $.02

Good luck and keep us informed.

dave

[Topsterguy]

I have seen this problem also but the problem was a lack of proper venting of the crankcase. You stated that this only occurred at higher RPMs and that at idle there was no oil.
I do not know what engine you are running but assuming the SBC the oil in the small chamber behind the fuel pump is minimal at best and should drain back to the pan without any problem. I would check your PCV valve and hose and also the vent that allows fresh air to be drawn into the engine. A plugged PCV can also increase oil consumption as well.
The only external clue I have seen from a ruptured fuel pump diaphragm is raw gas squirting from the vent holes. I have also seen gas contamination of the engine oil from a ruptured fuel pump diaphragm. At higher RPMs and especially going up hill the combustion pressures are higher and will put increased loads on the rings and cause more blowby to reach the crank case and could overpower even a properly working PCV. One other point if you are only getting the oil control problem when you are at a relatively open throttle position and most likely low vacuum levels ("going up a long hill") the capacity of the PCV system to evacuate the crankcase will be diminished.
I saw this problem on a customers Ford with a 390 many years ago and the customer had fixed it the only way he knew to, he had put tooth picks in the holes and that had worked for him for over 30,000 miles, but his engine had very high miles.

My $.02

Good luck and keep us informed.


Thanks Dave - lots of good info! I'll check the PCV but it's all new and about 600 miles. It's a fresh 383 SBC and I've got a PCV on one side and a breather on the other. There doesn;t seem to be any indication of gas in the oil and the oil is really clean. I put on a new fuel pump tonite so I'll try it out tomorrow and see what happens, and I'll post the results!   Thanks again!   Larry

dave

[Topsterguy]

I have seen this problem also but the problem was a lack of proper venting of the crankcase. You stated that this only occurred at higher RPMs and that at idle there was no oil.
I do not know what engine you are running but assuming the SBC the oil in the small chamber behind the fuel pump is minimal at best and should drain back to the pan without any problem. I would check your PCV valve and hose and also the vent that allows fresh air to be drawn into the engine. A plugged PCV can also increase oil consumption as well.
The only external clue I have seen from a ruptured fuel pump diaphragm is raw gas squirting from the vent holes. I have also seen gas contamination of the engine oil from a ruptured fuel pump diaphragm. At higher RPMs and especially going up hill the combustion pressures are higher and will put increased loads on the rings and cause more blowby to reach the crank case and could overpower even a properly working PCV. One other point if you are only getting the oil control problem when you are at a relatively open throttle position and most likely low vacuum levels ("going up a long hill") the capacity of the PCV system to evacuate the crankcase will be diminished.
I saw this problem on a customers Ford with a 390 many years ago and the customer had fixed it the only way he knew to, he had put tooth picks in the holes and that had worked for him for over 30,000 miles, but his engine had very high miles.

My $.02

Good luck and keep us informed.


Thanks Dave - lots of good info! I'll check the PCV but it's all new and about 600 miles. It's a fresh 383 SBC and I've got a PCV on one side and a breather on the other. There doesn;t seem to be any indication of gas in the oil and the oil is really clean. I put on a new fuel pump tonite so I'll try it out tomorrow and see what happens, and I'll post the results!   Thanks again!   Larry

dave

Yup, that's what it was! Put a new pump on and evrything's fine! I did check everything else tho, Dave, and it was all fine! Thanks again!  Larry