Rear Main vs Oil Pan

[99Venom]

For a while now I've been collecting fresh oil on the oil pan bolts, bottom of the oil pan, engine backing plate, and bottom of the bellhousing. The front half of the oil pan does not have much fresh oil on it, it only shows up on the back half near the tranny. Just estimating I think I lose about half a quart every 2000 miles, so the leak is not very bad. I've checked the oil pan bolts and inspected the gasket area as best I can. I've also tried to check between the engine and tranny for the rear main but can't see anything definitive. I just wanted to see if anyone had a better guess than I do of where this leak is coming from? Or some suggestion on how to narrow it down possibly?

My initial thought would be going down the road the oil leak would only travel backwards, from the rear main backwards for example. But I'm sure the airflow underneath the car could be quite turbulent so there may be no way to tell which direction it's coming from.


The oil pan bolts between tranny and engine, backing plate is on bottom of pic

Same area on the passenger side, starter is on the left

Drivers side, clutch cable is on the upper left, motor mount lower right

 

[jeason15]

Clean everything really well, and let it sit for a few days and check your pan bolts again. If you're leaking, its more than likely your pan gasket. If not, run it and check again. Rear main seals tend to leak while running. Pan gaskets tend to leak static. Also, verify its not coming from higher up (ie valve covers). Good rule, follow the oil as high as you can, where it stops, whatever is above that is your leak. If you get really stuck you could always pull the transmission, clutch, flywheel and k member and replace both...

 

[01yellercobra]

The oil line is below the pan gasket. So sitting there it probably won't leak. If I had to guess it would be where the rear main cover meets the block and oil pan rails. That area needs RTV and some people forget to put RTV there.

 

[99Venom]

Clean everything really well, and let it sit for a few days and check your pan bolts again. If you're leaking, its more than likely your pan gasket. If not, run it and check again. Rear main seals tend to leak while running. Pan gaskets tend to leak static. Also, verify its not coming from higher up (ie valve covers). Good rule, follow the oil as high as you can, where it stops, whatever is above that is your leak. If you get really stuck you could always pull the transmission, clutch, flywheel and k member and replace both...

The leak only happens when running. I did verify the leak is not coming from anywhere above the bottom of the block. Where is the oil level in regards to the pan in these motors when they are not running? The oil level would have to be above the gasket to cause a static leak.

I think I will have to pull the tranny this winter anyways for a separate issue, so the rear main would easy to fix. It would suck if I have to pull the k-member too.

 

[BoostedByV]

Any updates ?

 

[01yellercobra]

Where is the oil level in regards to the pan in these motors when they are not running? The oil level would have to be above the gasket to cause a static leak.

The oil line is below the pan gasket. So sitting there it probably won't leak. If I had to guess it would be where the rear main cover meets the block and oil pan rails. That area needs RTV and some people forget to put RTV there.

You don't have to drop the pan to replace the rear main seal. I was able to unbolt the motor mounts and raise it enough to get the pan out.

 

[99Venom]

Any updates ?

No updates yet, the leak is still very slow so I'm just riding it out until I take it off the road for the winter, then I'll dig into it. I've got a bigger issue of a noisy TOB now so that will probably take priority.

 

[OldSVTGuy]

There is a tool to replace the rear main seal if that is your problem. It's an OTC item and somewhat costly - I paid $115f from Amazon. What it does, though, is make the rear main installation SO much easier. It has a thin lip that fits under the seal so it properly installs to the proper depth and keeps the seal lip properly oriented. It can be done without it but it is HARD to get the rear main seal evenly lined up and perfectly square to the crank without it. Just my .02. Good luck.

If you need it I can lend it to you if you agree to pay postage both ways - it ain't that heavy. I might could fit it into the one price priority mail box. Just let me know - willing to help out a fellow Cobra owner.

 

[BoostedByV]

No updates yet, the leak is still very slow so I'm just riding it out until I take it off the road for the winter, then I'll dig into it. I've got a bigger issue of a noisy TOB now so that will probably take priority.

I have the same leak and can't find where it's coming from
I guess it's gonna be the pan gasket
It started leaking after I went with breather set up

 

[99Venom]

I have a serious issue now with the TOB, so this winter I will definitely be removing the tranny and doing a clutch job. When I get the flywheel off I'll be able to tell if it's the rear main. I hope it is, because then I can kill 2 birds with one stone.

There is a tool to replace the rear main seal if that is your problem. It's an OTC item and somewhat costly - I paid $115f from Amazon. What it does, though, is make the rear main installation SO much easier. It has a thin lip that fits under the seal so it properly installs to the proper depth and keeps the seal lip properly oriented. It can be done without it but it is HARD to get the rear main seal evenly lined up and perfectly square to the crank without it. Just my .02. Good luck.

If you need it I can lend it to you if you agree to pay postage both ways - it ain't that heavy. I might could fit it into the one price priority mail box. Just let me know - willing to help out a fellow Cobra owner.

Thanks buddy, I might take you up on that if that is the case.

I have the same leak and can't find where it's coming from
I guess it's gonna be the pan gasket
It started leaking after I went with breather set up

When I get the tranny out I will report back. "When" is a big question mark because I've been wrenching on that car so much lately I'm just not looking forward to the effort. Maybe next month before it gets super cold.

 

[BoostedByV]

Jacked up the car , cleaned the oil pan gasket and around the bolts with brake cleaner. With the car still jacked up I turned on the car
Within three mins the gasket starts seeping between two bolts towards the rear under the started
I tighten the bolts and I'll see where it goes from here . Talk to friends and was told its oils gonna get worse.
From the beginning it looked a lot worse then it just seeping out one corner

 

[99Venom]

***UPDATE***

So finally got my lazy ass in the garage and fixed my clutch. Low and behold when I took the flywheel off the rear main seal was bone dry. There was no indication of oil whatsoever from anywhere above the oil pan. It especially seems to be leaking at the rear of the pan. Who knows what I'll do about that or when, but looks like the pan needs to come out.

 

[01yellercobra]

Check your dipstick tube. There's an o-ring where it slides into the block. If that o-ring is bad or missing or can cause a good amount of oil in the area you're talking about. Ask me how I know......

 

[NastyNate420]

Im kinda in the same boat as you. I had oil in the same area as you after a fresh build. It doesnt seem like the rear main as it only on the backside of the trans dust sheild. After further inspection i noticed a small leak from the backside of the valve cover. Im not sure if that my only leak but im gonna start there. the dipstick o-ring does sound like another possible culprit ill have to look at too!

 

[99Venom]

Check your dipstick tube. There's an o-ring where it slides into the block. If that o-ring is bad or missing or can cause a good amount of oil in the area you're talking about. Ask me how I know......

Oh I will definitely check that out, I would love for it to not be the oil pan. So please, tell me more about your adventure oke:

 

[01yellercobra]

Oh I will definitely check that out, I would love for it to not be the oil pan. So please, tell me more about your adventure oke:

My last set was known for "leaving it's mark" wherever I parked. I had a leaky oil cooler, leaky spark plug grommets, and a missing dipstick o-ring. After I fixed the valve cover and oil cooler I still had a leak. Everything below the oil pan rail on the driver side was wet. It went all the way back to the bellhousing. I actually pulled the trans to check the rear main. It was dry, but I replaced it anyway since I was there. I even swapped pans with one I knew didn't leak in case the rail was cracked. I had friends look at it and not be able to tell where it was coming from. Finally as a last ditch effort I pulled up the dipstick tube. There was no o-ring on it. So I gooped it up with RTV and the leak stopped. For a while anyway. I guess the RTV didn't like being that close to headers. After redoing the RTV a couple times I decided to replace the o-ring. Then I discovered I couldn't get the tube out without loosening the motor mount. And due to the way my headers ran I couldn't get the motor mount loose. I ended up getting pissed and cutting the tube. I picked up a Lokar flexible dipstick. It worked fine, but I didn't like how it looked. But that didn't matter as that project ended up falling apart and I moved on from it.

 

[99Venom]

My last set was known for "leaving it's mark" wherever I parked. I had a leaky oil cooler, leaky spark plug grommets, and a missing dipstick o-ring. After I fixed the valve cover and oil cooler I still had a leak. Everything below the oil pan rail on the driver side was wet. It went all the way back to the bellhousing. I actually pulled the trans to check the rear main. It was dry, but I replaced it anyway since I was there. I even swapped pans with one I knew didn't leak in case the rail was cracked. I had friends look at it and not be able to tell where it was coming from. Finally as a last ditch effort I pulled up the dipstick tube. There was no o-ring on it. So I gooped it up with RTV and the leak stopped. For a while anyway. I guess the RTV didn't like being that close to headers. After redoing the RTV a couple times I decided to replace the o-ring. Then I discovered I couldn't get the tube out without loosening the motor mount. And due to the way my headers ran I couldn't get the motor mount loose. I ended up getting pissed and cutting the tube. I picked up a Lokar flexible dipstick. It worked fine, but I didn't like how it looked. But that didn't matter as that project ended up falling apart and I moved on from it.

Good times, and it sounds like you went through quite a lot to remedy it. Question: Does it make sense oil leaking from the dipstick tube could be a static leak? When I was driving the car it would leak afterwards, but even after I stopped driving it a while it still kept leaking on the floor. I'm curious as to how there would be enough fluid pressure there to force the oil out (albeit very slowly) even with the engine off?

 

[Franco]

I'm gonna go with oil pan leak. Same issues as you.
Didn't wanna tackle it myself so took it to my buddies shop. Looks good now.

 

[01yellercobra]

Good times, and it sounds like you went through quite a lot to remedy it. Question: Does it make sense oil leaking from the dipstick tube could be a static leak? When I was driving the car it would leak afterwards, but even after I stopped driving it a while it still kept leaking on the floor. I'm curious as to how there would be enough fluid pressure there to force the oil out (albeit very slowly) even with the engine off?

It's not really a static leak. It's blowing out while you're driving, then when you park it drips. That's exactly what mine did.