Mystery Leak ???

[freeheelbillie]

So as with many of the others in here I have been on a mission this summer to track down leaks of all kinds. I have found the majority of them rather easily…until now. I started from the top and have been working my down the engine. I replaced the valve cover and distributer gaskets and finished the oil pan gasket this weekend. It was a mess down there with 40 years of blow-back and grime. I painted the pan while I had it out so I know it’s not leaking.
But a drip of fresh clean oil has reappeared from what I assume is the transmission bell. It leaks enough to leave a spot about the size of a half dollar in about 4 hours then seems to stop dripping all together. I spoted what looks like a hole but I am not sure if it’s supposed to be there. See Photo. Is my rear main leaking?

Any ideas?

1970 Bronco Sport
302 V8
3 on the floor
70,000 miles

 

[Justafordguy]

Is it motor oil or gear oil? If it's coming from there and is motor oil it's probably rear main. Check real close up top at the rear of the intake also. They are bad about leaking there and it will drip off the bottom right where you show it the pic.

 

[freeheelbillie]

Is it motor oil or gear oil? If it's coming from there and is motor oil it's probably rear main. Check real close up top at the rear of the intake also. They are bad about leaking there and it will drip off the bottom right where you show it the pic.

The flat part of the bell that faces the oil pan is clean and free of oil so unless its leaking down the inside of that plate it can be coming from there...I ran my finger up there and its clean.

It looks and feels like motor oil, is that hole supposed to be there?

 

[Justafordguy]

If it's the back of the intake it usually runs around the side and drips off the bottom. If it's coming from inside the hole/bellhousing it is the rear main.

That hole is supposed to be there.

 

[freeheelbillie]

If it's the back of the intake it usually runs around the side and drips off the bottom. If it's coming from inside the hole/bellhousing it is the rear main.

That hole is supposed to be there.

Well I cleaned off the bell housing plate and there is oil slowly dripping down it. So I guess its the rear intake...maybe the new gasket didnt seat properly? I used a single piece, non crushable, silicone gasket. I guess it wont be too bad taking the pan back off and trying to get it to seat better?

what a pain in the a$$

 

[302fix]

I'm thinking. not the pan the intake manifold.

Try just torqueing your intake manifold down to about 22 ft lbs in a criss cross pattern.

 

[Justafordguy]

X2, Also try cleaning off the back of the intake and then looking for fresh oil.

 

[freeheelbillie]

Thanks again for all your advise. Turns out the rear intake wasn't seated properly. I ended up draining it, removing the pan again and reinstalling it. This time I paid more attention to the front and rear intakes and now I can actually see the gasket gently squeezed all the way around the pan's edge. %)

It was a pain but nothing an ice cold PBR can't wash away and I know its done right.

May the war on leaks continue!

 

[MattW]

?:?

Did you pull the oil pan off or the intake manifold?

 

[markperry]

Are we talking rear pan gasket or intake gasket?

 

[freeheelbillie]

Are we talking rear pan gasket or intake gasket?

rear pan gasket...sorry about that

 

[freeheelbillie]

?:?

Did you pull the oil pan off or the intake manifold?

Well it didn't leak all night after removing the pan and reinstalling the gasket but after the drive in this morning the leak is back, although not as bad...

Could it be the rear intake? It seems to me if it were the rear of the oil pan gasket it would be dripping off the oil pan itself. But it's running down the face plate of the transmission bell. Does anyone have a diagram of the rear intake?

Should I just wave the white flag in mar war on leaks?

HELL-p!

 

[MattW]

Sounds like it could very well be your intake manifold. Climb back there and look at the manifold towards the the firewall. Probably need a flashlight to see it.

It's a fairly easy gasket to replace. Drain your coolant down, take off your carb and other stuff that's on top of or in the way of removing the manifold. The hardest part may be to actually get the manifold off, it can be stuck on there pretty good. Remove the old gasket material from the manifold and heads. Put the new one back on and reverse the steps.

I would start with the intake manifold and hopefully that is your problem. If not the next step would be the rear main.

 

[markperry]

It's a matter of preference but I would highly recommend NOT using those flimsy gaskets they give you for the front and rear of the manifold!

They are easy too tighten too much and squeezing out! I used the right stuff gasket sealer, and haven't had a leak in over a year! I actually didn't even use a pan gasket on mine, just the right stuff!

 

[freeheelbillie]

It's a matter of preference but I would highly recommend NOT using those flimsy gaskets they give you for the front and rear of the manifold!

They are easy too tighten too much and squeezing out! I used the right stuff gasket sealer, and haven't had a leak in over a year! I actually didn't even use a pan gasket on mine, just the right stuff!

I am starting to think that you're right (in the case of the oil pan anyway) I typically like the silicon/non-crushable/no sealer needed gaskets. This was a FelPro one piece...I have always had great performance out of em'

I'll take a closer look at the rear intake, if its the rear main shes gonna have to leak I guess %)