• Hello there guest and Welcome to The #1 Classic Mustang forum!
    To gain full access you must Register. Registration is free and it takes only a few moments to complete.
    Already a member? Login here then!

Rear Main seal leak or something else?

A

Anonymous

Guest
I have had a small leak that is dripping from the scatter shield since the car had been completed on the Blue Twin turbo car. I first thought it was the rear main seal so I replaced it but seen no improvement, its a 2 piece seal. Upon removal, the old seal (which was new) showed no nick or crack or scuff that would indicate a leak area and it was offset with silicone sealing the mating surfaces. Upon futher examination the front side of the flywheel is dry but there seems to be some oil on the clutch side. Also there is a puddle of oil in the bottom of the scatter shield. I was able to see the top of the intake and valve covers and they are dry and dusty and replaced the oil pan and gasket and it appears it's not there. All ideas welcome as this seems to be a weird one. Oh, the leak seems to be much worse under boost as I can smell oil burn where it is hitting the headers.
 
"70 StangMan" said:
A poodle of oil ?? :shrug
Click to expand...

My cornbread was about to burn and I'm the worlds worse speller. Fixed it.
 
Leaking from the tranny front seal?

I had a leak very similar to yours and replaced the rear main seal twice without fixing it completely. Swore it was nothing else. When I rebuilt the engine last winter, I added studs to mount the oil pan and used the cork seal recommended by Canton and the leak is now gone!
 
I changed the pan from the old style to a new Canton. Also used a new silicone gasket insted of the cork (which I tried a rubber gasket also). It appears its not from the oil pan gasket but actually is from the inside of the scattershield. Would it hurt to pressurize the internals to say about 2 or 3 lbs? You think maybe it will reveal itself?
 
It's a stab, but isn't it possible for oil to wick through the flywheel bolt threads?
 
I know I have to seal the flywheel bolts on my 289.


FYI, Canton suggests using Fel-Pro oil pan gasket; FPP-1809 to avoid leaks.
 
All indications would suggest that's the location its coming from. One other question, are they not oil galley plugs on the back of the engine? If it were one of these leaking, wouldn't the front of the flywheel be wet? Guess I'm in for pulling the tranny and clutch. Crap!
 
Isn't there a couple of allen head plugs in the back of the block? Could they leak oil?

Ya...those...you beat me to it.

Oil will flow in odd directions...
 
After removing the tranny and flywheel it seems that it is indeed the rear main seal, again. I blocked the PVC ports and applied about two pounds of air pressure to the dipstick tube. Around the rear seal there is about 60% of the area leaking air, almost like theres no seal in place at all. Never have I seen one do like this. I can only imagine how much oil is blowing out this area as it will not even hold a pound of pressure. Could I be using the wrong seal? Crap! All ideas appreciated.
 
Here are some photos of the rear main seal. Its chewed up pretty bad. I did find a few scratches on the crank where the lip of the seal contacts and polished them out but judging by the damage I'm not sure a scratch caused this, but then again the seal was replaced only a few months ago. Hopefully this will solve the problem and I can paint the exhaust one last time. The oil did "flow in odd directions" and was leaking at the front of the transmission at the bottom where it joins the bell housing. They were also spray pattens on the exhaust and surrounding area and I can only assume the spinning flywheel was slinging the oil like a spray everywhere. I will know tomorrow if its fixed.
 

Attachments

  • 001.JPG
    433.1 KB · Views: 69
  • 006.JPG
    424.9 KB · Views: 66
  • 007.JPG
    414.5 KB · Views: 73
Is the seal in backwards? I seem to recall putting the lip facing the other way on the 289 I just did.
 
"Sluggo" said:
Is the seal in backwards? I seem to recall putting the lip facing the other way on the 289 I just did.
Click to expand...

It does look backwards to me also and it should be offset by at least 3/16 on the ends.
 
You must log in or register to reply here.
Back
Top