PDA

View Full Version : Oil spewing out dry sump tank


Jungle Boy
09-22-2002, 12:44 PM
Does anyone have a any idea why a friends dry sump is spewing oil out under full rpm. The engine is a 434 small block; Little M block with gear driven sump pump. The engine runs good on the dyno (635 HP), but when it's installed in the boat and has ran for 15 minutes or so, it starts to blow oil out the vent (breather) at full throttle. Leak downs have been done and the engine is good. It's been torn down twice and found nothing wrong. The engine builder has done many of these engines for sprint cars, cascars and river racing jetboats. He's stumped and is thinking that perhaps there is a flaw in the block. We have tried a different pump, hoses and taped off breathers in our effort to isolate problem. Any ideas??????? :mad:
Infomaniac
09-22-2002, 05:07 PM
Where is the vent?
On a small block we run a pipe between the valve covers in the front of the engine. Put 2 breathers there about 5" or so higher than the top of the valve covers. This is Sprint Car style.
Jungle Boy
09-22-2002, 05:11 PM
Infomaniac:
Where is the vent?
On a small block we run a pipe between the valve covers in the front of the engine. Put 2 breathers there about 5" or so higher than the top of the valve covers. This is Sprint Car style.I guess I forgot to explain that it's blowing out the dry sump tank vent breather, not the valve covers.
HighRoller
09-22-2002, 06:35 PM
Have you taken the cap off the tank while it's running to see what's happening?The oil should be swirling around the outside wall coming in,so maybe you have a broken baffle in the tank or something.Other than that maybe there's a blockage in the pressure side somewhere and the scavenge side is overfilling the tank.The oil in the tank shouldn't be anywhere near the top while running.
Infomaniac
09-22-2002, 06:48 PM
He should vent the tank back to the engine somewhere. Usually the lifter valley on injected engines with 3 piece intakes. In the oil pan will work also. The engine and tank will both have the same ambient pressure that way. Be sure wherever it is, it is well above the oil level in the pan.
Easy fix.
Make sure there is not too much oil in the tank also.
wink wink wink wink
[ September 22, 2002, 07:52 PM: Message edited by: Infomaniac ]