Oil leak source help. Rocker arms? And how to stop the leak?
01-29-2006, 04:09 PM
#1
Oil leak source help. Rocker arms? And how to stop the leak?
My car is a 1978 911SC with 52,000 miles. I've owned it for 1.5 years, and I have no service records.
Two weeks ago in order to try to find the oil leak source, I cleaned the lower edge of the lower valve cover and cam tower, and I cleaned the oil return tubes. This is on the left side (US driver's side) of the engine. I drove the car and then parked it. One week later, no leak. Now at two weeks there has been significant leakage. It is all dripping from the forward end of the cylinder head/cam tower interface on the left cylinder bank, but there is fresh oil all along the bottom of the cam tower. No sign of oil on the underside of the oil return tubes so I think the tube seals are OK. And there is some seepage from the valve cover and a couple valve cover nuts, but not enough to account for the amount of oil on the floor now. I can see that there is old oil leakage gunk accumulated on the backside of the cam tower and on the first three or so cylinder head fins closest to the cam tower. From looking at the Bentley manual and 101 projects, it looks like the leakage is probably from the rocker arm shafts. This appears the only opportunity for leakage from between the cylinder heads and cam towers.
Couple of pics.
Cylinder #3 area where the oil is dripping from and visible fresh leaking oil.
Cylinder #1 area showing oil junk on backside of camshaft tower.
My questions are: Am I likely right about the oil leak source? And can one stop the leak by tightening the rocker arm shaft bolts a little or is it best to replace the rocker arm expansion sleeves and expansion nuts with new ones? What about the O-ring seals mentioned in 101 projects? Can I just slide out the rocker arm shafts and put in the O-rings and reinstall without any additional disassembly?
Thanks for any help,
Brett
Two weeks ago in order to try to find the oil leak source, I cleaned the lower edge of the lower valve cover and cam tower, and I cleaned the oil return tubes. This is on the left side (US driver's side) of the engine. I drove the car and then parked it. One week later, no leak. Now at two weeks there has been significant leakage. It is all dripping from the forward end of the cylinder head/cam tower interface on the left cylinder bank, but there is fresh oil all along the bottom of the cam tower. No sign of oil on the underside of the oil return tubes so I think the tube seals are OK. And there is some seepage from the valve cover and a couple valve cover nuts, but not enough to account for the amount of oil on the floor now. I can see that there is old oil leakage gunk accumulated on the backside of the cam tower and on the first three or so cylinder head fins closest to the cam tower. From looking at the Bentley manual and 101 projects, it looks like the leakage is probably from the rocker arm shafts. This appears the only opportunity for leakage from between the cylinder heads and cam towers.
Couple of pics.
Cylinder #3 area where the oil is dripping from and visible fresh leaking oil.
Cylinder #1 area showing oil junk on backside of camshaft tower.
My questions are: Am I likely right about the oil leak source? And can one stop the leak by tightening the rocker arm shaft bolts a little or is it best to replace the rocker arm expansion sleeves and expansion nuts with new ones? What about the O-ring seals mentioned in 101 projects? Can I just slide out the rocker arm shafts and put in the O-rings and reinstall without any additional disassembly?
Thanks for any help,
Brett
Last edited by Brett San Diego; 01-29-2006 at 04:25 PM.
01-29-2006, 06:01 PM
#2
Rennlist Member
Hi Brett: Leakage from rocker shafts occurs during use, leakage from oil return tubes occurs when the car sits. I'm sure that if you take a flashlight and mirror and sight along the oil tubes toward their outboard ends you will see a puddle of oil that's formed inside each oil tube recess. Rocker shaft seepage on a virgin (52K mile) engine is almost unheard of, so get under the car and check those tubes more closely. Remember, it doesn't take much oil to produce a drip, and the tubes rarely leak from the inboard, crankcase, end. Let me know what you find!
Pete
Pete
01-30-2006, 12:43 AM
#3
Pete,
For what it's worth, I can see that the tubes on this cylinder bank have been changed. They are the 2-piece tubes, but the ones on the other side look to be 1-piece. I suppose I'll replace the O-rings on the tubes first and see what happens. Better to start cheaper anyway.
Thanks for the response.
Brett
For what it's worth, I can see that the tubes on this cylinder bank have been changed. They are the 2-piece tubes, but the ones on the other side look to be 1-piece. I suppose I'll replace the O-rings on the tubes first and see what happens. Better to start cheaper anyway.
Thanks for the response.
Brett
