To replace rear main seal, or not to replace rear main seal -

[AR67GTX]

That is the question.

Have some oil drips from the Hemi and as usual they are not easy to trace around the big thing. But this deals with the oil pan which is off and the rear main that isn’t. I suspected the pan but the pan and tray with black composition gaskets were thoroughly cemented down with what must have been two full tubes of black RTV - a bear to get off and clean up will be worse. In studying it I’m highly doubtful it was the pan although a drip or two may have worked their way through a couple of bolt holes. But in any case it’s going back with new gaskets.

So now I’m trying to focus on the rear main seal. It just seems too dry inside the BH to have a significant rear seal leak. There is a little oily residue on top of the ledge of the seal retainer and a little oily film by the starter and a few points but that oil could be coming down the BH/clutch cover gap, sucked in by the roating assembly and slung out. I’m usually finding a drop of oil hanging from the weep hole in the clutch cover and coating the gap between the clutch cover & BH. But for the most part the seal retainer looks dry As does the transmission side. The clutch cover is relatively clean on the outside but does show a oil film on the inside.

Following are pictures around the seal retaining area And one of the TO bearing area. The one with my dirty finger is what I wiped off of the ledge on the backside of the factory seal

The pan has been off a day so oil has run down on the gasket surfaces. So while I’m in here do I replace the rear seal or would that risk a bigger mess. I probably have a few seeps up above but right now I’m just dealing with the pan and rear main areas. I’ll get to the others

 

[Tony 69]

I would probably replace the rear main simply because you are already there pretty much. I need to do mine too I think. I get about 2-3 drops out of the same area after driving and then the car has to sit 30-45 minutes before it will leak. Definitely aggravating.

 

[zyzzyx]

I would have put a Fluorescent tracer in the oil to locate the leak before I tore it down, but
it's too late now. Just replace the seal because you're almost there. If it leaks on you and
you didn't replace the seal, I'll hear you scream all the way in Illinois!

 

[AR67GTX]

I feel you guys are right. Probably kick myself if later if I had to do it again. I think once I get this buttoned up I will add the dye. But I felt pretty certain at least some of my problem was in the pan/rear seal area so might as well eliminate it first.

Anyone have any comment on the Hughes Engines rear seal retainer - the one with two side seals? Seems like getting rid of the factory, less precise one is probably a good idea.

Thanks

 

[1969VAGTX]

Getting ready to tackle the same problem on my auto-Hemi. Have a pretty significant leak that is coming from behind the dust cover. I assume that it is likely the rear main. Hoping to get this replaced before Carlisle.

 

[AR67GTX]

Good luck - a tip just in case you don’t read the FSM like me until after you can’t get the pan off. The crank needs to be turned past top dead center about 15 - 20 deg to get the crank counterweight out of the way so the pan will slip out.

 

[Beekeeper]

I will throw this link up for a few pointers on the main seal replacement. I’m not an expert but hope it helps.

 

[AR67GTX]

I saw that video yesterday - may have found it from a older thread. Thanks

Todays questions after more exploration:

1. Measured my oil pickup and it is way off. Further it is tilted with the rear 1/2” higher than front. Including est 1/8” for two gaskets and a tray I have clearance of 1/2” to 1” off pan bottom. Way to much to tweak. My pan measures 5 1/8” flange to bottom on inside. My question is it looks like the intake might hit the cross member when I try to unscrew it. That isn’t the biggest problem as I can always cut it, but I should be able to thread a stock replacement in with the engine in the car - right? That would be a mess if it hits.

2. After looking at the seal retainer side seals with my insp camera I‘m fairly sure the side seal on at least one side is weeping oil although I suspect the crank seal has been doing it’s job. That would seem to go along with a smaller oil leak/drip vs a puddle under the car and that there isn’t a lot of oil slung around inside the bell housing

too. I will probably use Hughes seals but seeking opinion on if to stick with stock retainer or get the Hughes billet retainer?

3. I’m used to oil pans having a stamped in part number like my 440 pan. No numbers on this Hemi pan and it seems consistent with a six quart pan including filter. We’re Hemi pans not identified with a part or series number on them? Anyone know if 5 1/8“ sump is correct for a stock Hemi pickup?

Thanks for all help.

 

[1969VAGTX]

I will throw this link up for a few pointers on the main seal replacement. I’m not an expert but hope it helps.

I checked out that video earlier this week on YouTube specifically to get a better understanding of what is involved. Thanks.

 

[Beekeeper]

I saw that video yesterday - may have found it from a older thread. Thanks

Todays questions after more exploration:

1. Measured my oil pickup and it is way off. Further it is tilted with the rear 1/2” higher than front. Including est 1/8” for two gaskets and a tray I have clearance of 1/2” to 1” off pan bottom. Way to much to tweak. My pan measures 5 1/8” flange to bottom on inside. My question is it looks like the intake might hit the cross member when I try to unscrew it. That isn’t the biggest problem as I can always cut it, but I should be able to thread a stock replacement in with the engine in the car - right? That would be a mess if it hits.

2. After looking at the seal retainer side seals with my insp camera I‘m fairly sure the side seal on at least one side is weeping oil although I suspect the crank seal has been doing it’s job. That would seem to go along with a smaller oil leak/drip vs a puddle under the car and that there isn’t a lot of oil slung around inside the bell housing

too. I will probably use Hughes seals but seeking opinion on if to stick with stock retainer or get the Hughes billet retainer?

3. I’m used to oil pans having a stamped in part number like my 440 pan. No numbers on this Hemi pan and it seems consistent with a six quart pan including filter. We’re Hemi pans not identified with a part or series number on them? Anyone know if 5 1/8“ sump is correct for a stock Hemi pickup?View attachment 1306332

Thanks for all help.

That pan is correct for 70’-71’ hemi and six pack engines.

 

[Fran Blacker]

66 pan has an indent for idler arm. not mine.
NEW Mopar 1966-69 426 Hemi Oil Pan | eBay

 

[AR67GTX]

That’s good to find out. Looks like it’s easier to find a pickup for a later model engine. Interesting on the idler arm, mine seems to be clearing OK.

Thanks

Didn‘t get any feedback on the seal retainer so went ahead and ordered a Hughes seal retainer and seal kit. Now if I can get the screwed up existing oil pickup off.

 

[AR67GTX]

i realized my oil pan is lacking the front baffle - probably removed because the butchered up pickup wouldn’t clear. So looks like I’ll just get a new, reproduction oil pan.

Fran - that one you linked to on EBay I’ve seen listed for 66 to 69 Hemis but looks like a deeper sump. But I can’t find a depth on it on any of the listings. The 70/71 is 5 1/4” deep which gives good ground clearance and is probably the simplest choice - $99 at 440 Source. Some more research I guess.

 

[Fran Blacker]

66 is a 5qt pan I think 70/71 is a 6qt pan. You may find a better price, just used for picture.

 

[chtampa]

I am on the opposite side and say, "If it's not broke, don't fix it". One or two drops? Get a drip pan.

 

[AR67GTX]

well, it’s a little late for that and in my opinion with the high end of the pickup an inch off the bottom, it was near broke. The missing front pan baffle is probably not a big deal but if the Ma Mopar accountants bought the engineers argument that it was worth the 10 cents or whatever to install, guess I’ll go with them.

Look at this hatchet job on the pickup, sectioned and welded in two places. Must have been a pickup for a deep pan they shortened. And even with two cuts the screen was tilted left to right and front to back.

Looks like the rear seals were OE type with the fiber side seals. Then they filled behind them with RTV and it was pretty loose and oily so I think oil was coming past them. I think the crank seal was OK although they didn’t offset the seal to the retainer connection.

 

[Kern Dog]

If you believe Uncle Tony, synthetic oil is more likely to leak than Dino oil.
I’ve had equal amounts of leaks with both.
The guys that report that their engines don’t leak a drop must have made a deal with the Devil. I’ve had some amount of leak with every engine. I’ve tried different gaskets and sealants too.