Rear main seal??

S

sport05

New member
Had valve cover gaskets replaced a few months ago. Substantially stopped oil leaking. Noticed a new, small leak. Leaking where Bell casing butts up to rear of oil pan. Dripping down to bottom of casing. Also noticed a little (motor) oil on steering rack. Could just be from road bounce.

Does this sound like rear main? I did notice a little fresh oil on passanger rear corner of valve gasket cover. Tightened bolt a little and no more leak, for now.
 
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I have a similar leak. I think its the rear main but its such a tiny leak im not to worried about it. I clean up down there when I change my oil every 4000 miles but yeah its a small leak.
 
If it is leaking enough, clean off the area well so it is dry, the put it on ramps (safely!!) and let it run to operating temp. If it is the rear main, the drip should come out of the drain hole of the bell housing that butts up to the engine oil pan.
 
Forgot to mention, I have recently been able to smell burning oil when I get out of the vehicle (sometimes). Is a rear main leak too low to smell burning?
 
Could also be the mechanic did not properly re-seal the half moon knock outs while doing the valve cover gasket. This happened to me. I also thought it was rear main but it wasn't. Dealership said it is common with mechanics not familiar with our engines.
 
If it is the half moona you should be able to take a paper towel (when engine is cold!) And wipe around the back side of valve covers....if the towel comes back with wet oil....you found your culprit. Or at least one of them.
 
My $0.02:

When I did valve covers the first time on a '97, I didn't replace and reseal the cam plugs (on the back side). Sure enough, after sealing everything up and driving around a few months, those started leaking too. So I had to redo it all and include cam plugs the second time. Still had a very small mystery leak after that, but I was dang sure it wasn't valve cover related at that point. I used a little telescope mirror to check the back of the engine at intervals to make sure the leak was no longer from valve cover.

Edit: I resealed the half moons both times though.
 
sport05 said:
Forgot to mention, I have recently been able to smell burning oil when I get out of the vehicle (sometimes). Is a rear main leak too low to smell burning?
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that is most likely the vc leaking onto the pipe, snug it up till repaired, often they bolts are so loose they turn by hand. :Cowboy:
 
If you are wondering whether or not you're still leaking on the back side of your heads from either the half moons or cam plugs, get yourself one of those telescoping mirrors with a light. I bought one from Sears and it works great to see in areas you don't have a direct line of sight to.

Heres' a link to the one I bought at Sears:

Sears.com

Also, here's the video [MENTION=102606]infamousRNR[/MENTION] and I did for the valve cover gasket job if you find you need to go back in and either reseal the rear half moons or replace the cam plugs.

<iframe width="560" height="315" src="https://www.youtube.com/embed/N5fAXAuGozI" frameborder="0" allowfullscreen></iframe>
 
Update: had valve cover gaskets redone. Cam plugs. Cam seals. Spark plug grommets. New pcv valve/grommet. Pretty much had every seal and grommet replaced that can be done, except the rear main seal.

I went to a better shop and they said the last ones didn't do any clean up around valve cover gaskets and didn't silicon half moons. I still have a tiny tiny drip where I've drawn the arrow. It so minimal it doesn't drip on the driveway. Is this where you would expect a rear main seal to leak? I'm wondering if it could still be residual. It's been about 3 weeks since the work was done.
 

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I'd say that in the general area of the rear main but could also be the oil pan? If you have minimal rust and it looks like you do, you could check and tighten the oil pan bolts to spec...

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sport05 said:
Update: had valve cover gaskets redone. Cam plugs. Cam seals. Spark plug grommets. New pcv valve/grommet. Pretty much had every seal and grommet replaced that can be done, except the rear main seal.

I went to a better shop and they said the last ones didn't do any clean up around valve cover gaskets and didn't silicon half moons. I still have a tiny tiny drip where I've drawn the arrow. It so minimal it doesn't drip on the driveway. Is this where you would expect a test main seal to leak? I'm wondering if it could still be residual. It's been about 3 weeks since the work was done.
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Well hopefully they put FIPG or the like in ALL the required places. Hopefully they used OEM parts.

It sounds like it's slowed down to almost a stop since the repair. Could be residue even 3 weeks later. Not sure what the leak rate was before the repair. I would get some engine degreaser and saturate the back and bottom of the motor and pressure wash the areas really well then keep a close eye on it. As a matter of fact, right after cleaning it up, take it for a good drive and then crawl under there a see if it's coming from the seam. If it is, then it very well could be the rear main seal.
 
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ThorInc said:
I'd say that in the general area of the rear main but could also be the oil pan? If you have minimal rust and it looks like you do, you could check and tighten the oil pan bolts to spec...

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Good look getting at those bolts! I had a rust issue on my oil pan, pinhole leak caused oil spills and it was a pain in the ass. Be sure to pop off those skid plates and take a look at the pan!

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Thanks for the speedy responses! Yes we used all OEM parts and made sure FIPG was used in all necessary places. Also proper torque on everything. I bought some cleaner yesterday and am going to spray everything down and power wash this weekend. The leaking was considerably worse before. It was leaking on both sides of the bell housing and middle. I reached up there yesterday on the flat side of the casing where it butts up to the pan and had a little fresh oil on the rag. I drove about 10 miles this morning and there is a tiny bit of oil where I drew the arrow on the picture above. Frustrating
 
So I got under and did some looking today. Sprayed break cleaner over everything and washed real good last night. Wonder if the hole on the front side of the bell casing in the picture below is a closed hole or open? Pretty sure this is where the oil is coming from if open. Everything above looked very clean. I noticed the back of the oil pan kind of sets back in the bell housing.
 

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It's a drainage hole and if it is leaking from there (through the hole) it's the rear main........if you let the vehicle warm up you should see it leak right through that very hole while it's running.
 
ThorInc said:
It's a drainage hole and if it is leaking from there (through the hole) it's the rear main........if you let the vehicle warm up you should see it leak right through that very hole while it's running.
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Boom! That's gotta be it. Guess I'll live with it for a while. I'm out of funds chasing these oil leaks.
 
sport05 said:
So I got under and did some looking today. Sprayed break cleaner over everything and washed real good last night. Wonder if the hole on the front side of the bell casing in the picture below is a closed hole or open? Pretty sure this is where the oil is coming from if open. Everything above looked very clean. I noticed the back of the oil pan kind of sets back in the bell housing.
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Get a small stiff wire and poke the drain hole a couple times to clear the passage. Be advised oil may come out.
 
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