Oil Leak

[66StangFastback]

Hey guys.

I've got an oil leak and can't tell where it's coming from. It's the original 289, C4 combo. Engine was rebuilt recently and maybe has 2 miles on it since the rebuild, if that. It pours smoke from underneath the car, which we have determined is from an oil leak dripping onto the headers. When the car is off, sitting in the driveway, It doesn't leak, but it DOES leak when it is idling in the driveway. There is oil on the sides of the bell hoursing, as well as on the headers. It IS on both headers, so we couldn't really track it down to a certain side. We can't tell where the leak is coming from and was wondering if you guys knew of any places that might be seceptible to oil leaks, or any ideas you guys might have for tracking it down.

Thanks,
66

 

[66stangbluework]

I would check your valve cover gaskets, if its leakin onto the headers.

 

[66StangFastback]

We checked the valve covers and they seem to be clean around them. We think the head gasket could be pinched or loose or something, possibly allowing oil to be squirted through a small gap and it ending up all over the bellhousing and headers. Does this sound plausible to anyone, or has anyone had a problem similar to this?

 

[shotsy]

What about the oil preasure sending fitting on the back of the block? Dunnow how it would get to the headers but the belhousing I'd check there, Could be leaking from multiple places, My Cheap PCV valve (chrome autozone waste of cash) was dripping down onto the valve cover and then to the headers while it was running, and it took me a week of playing with the valve cover gaskets till I saw a dripp fall off the darn thing

 

[iskwezm]

What about the oil preasure sending fitting on the back of the block?

on a 289???? its on the front near the filter

 

[66StangFastback]

on a 289???? its on the front near the filter

Lol, that's exactly what I was thinking. We still haven't tracked down the leak so let the ideas fly.

 

[1966conv]

Most auto parts stores sell a dye kit and blacklight to find leaks as such. Put the dye in, run it a while, and flash it with the blacklight.
They also sell the dye for antifreeze. Same light will work. It works better in a darker area than bright sunlight.

You're sure it's oil and not tranny fluid? I had my converter loose and sent tranny fluid everywhere.

 

[69 302/351c]

I would suspect the valve covers....are they warped or been overtightned? Are they flat near the bolt holes? Since it only leaks when running, it sounds like something on the top end. The oil pressure sender is on the back of the block on a 351C. On a 289, it's on the lower left front.

 

[jcode68]

What part of the headers is it leaking on? Is it the lower part near the 4-into-1 section or up higher near the valve covers? Did you check the back of the intake for a leak onto the bell housing? Maybe you have a couple/few leaks and it's not all from the same.

 

[65notch]

i had the same problem, i found my leak because my car died on me at a stoplight. oil was leaking out of the valve cover gasket down onto the sparkplug and go inside and shorted it out, causing a dead cylinder. i couldnt see the leak except for on the sparkplug wire. i would replace the valve cover gaskets and possibly the valvecovers. if they are steel they bend real easily when tightened down. and then go from there.

 

[2nd Mustang]

As many have posted, sounds like valve cover gaskets, maybe someone forgot to tighten them? Use a nut driver. A ratchet will put too much torque on the nut/bolt and bend the cover's lip. Do you have breathers and or pcv valves on the valve covers?

 

[66StangFastback]

We have breathers on the valve covers and felpro gaskets. The covers are finger tightened down then snugged with a wrench. When running it there is no oil coming out of the valve covers, but underneath looking atthe heads there is moisture around where they sit in the block. The oil is closer on the 4 into one part, though i think it initially gets on further up, then runs down. It's also in a splash pattern on the bell housing. We were thinking it could be from not putting sealer on the bolts into the fly wheel? But...it's all over the bellhousing so theres no way if that's where it was coming from, it could get where it is. It's not a very steady leak. Sometimes it'll drip pretty fast, and other times it will completely stop. The car doesnt even have to be in gear, it does it at idle. The car runs fine, though the idle is a little fast because we haven't fully adjusted it. Our oil pressure looks good and we still have plenty of oil in it. It's not pinkish fluid so it's not tranny fluid. I might think about the dye kit. It's kinda one of those leaks that isn't leaking fast enough to throw anything off, but it'd be nice to solve it so there wasn't a burning oil smell and a little bit of smoke coming out, as well as we don't want to have the grease build-up that comes from leaks.

 

[2nd Mustang]

Maybe the rear gasket on the intake manifold? Did you use the gasket or a bead of silicone?

 

[Max Power]

Maybe the rear gasket on the intake manifold? Did you use the gasket or a bead of silicone?

Beat me to it. Also maybe a rear main.

 

[wild70stang]

Dude, the gasket on the bell housing is probably screwed up somehow. u said that when you are parked it doesnt leak, but the faster you go the more vibration the engine creates and thus it will leak. Its also near the exhaust tubes and underneath the car so if you put 2 and 2 together you get the answer.

 

[66StangFastback]

u said that when you are parked it doesnt leak, but the faster you go the more vibration the engine creates and thus it will leak.

But is DOES leak when we're parked, if it's idling. We have a bead of silicone to seal the intake. It seems like after a few good drives it's starting to slow down. It doesn't leak very much at all anymore. We've checked the oil and oil pressure and all is well, so I don't think it will cause us too much trouble. Possibly fixing itself? Maybe it's kinda gummed up the leak enough to get it to stop.

Thanks guys, I think it'll be alright, but if you just HAVE to throw more ideas around, go ahead, lol

66

 

[2nd Mustang]

Okay, only one more I can think of. Are you using synthetic oil? It is very thin and can get by the most minute cracks/imperfections.

 

[66StangFastback]

No, we're using regular oil. My uncle who built the engine said we shouldn't really ever need to use synthetic, so we probably won't.