Rear main seal 🤦🏽‍♂️ help please

spongbob

Greasemonkey
Oct 1, 2022
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Blue Devil engine seal and stop leak at auto zone does work .it will tak a week or about 60 miles maybe less with a few days to soak into your seals. I don't like additives or cheap fixes I beleave in the hard way but let me tell you that name blue devil will get your problem over in no time".... remember when you change oil to use it at least one more time "to get enough material to last ....then you might not even have to re apply .it's got a blue bottle it might even be at wal mart it's on ebay too aside from that gtx Castrol in the green bottle leaks" much less and can't be beat for a chevy or olds ect.period.. I will not say the same for penzoil or valvoline you heard it heer.!
 
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78Delta88

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May 23, 2022
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As an older GM guy, and having seen this before, the following: If you have a "mechanic" that is piece mealing it or chasing the problem, you don't need him/her.

Rear mains leak and they start many times with in the first 6 months of being new. You could raise the engine, pull the pan, pull rear cap and replace it, but it is not a do it yourself item when you are first starting to work on cars.

The first thing you learn is that you break more than you fix, and you are not nearly as good as you think you are, and most of the times you will be wrong. It takes time, busted knuckles, lost sockets down the manifold, burnt fingers, smack your head on an engine hoist as you crawl out from under something, pick up and launch your top box across 3 bays of the shop on a bad day. Plus much more way before you get to the point to where you start to think that you might know something.

You have a 40+ year old car, and restorations or even keeping one on the road, is expensive. So the trick is to do the "vital few" first and be frugal.

For anyone working on your car.... "Trust but Verify", and ask questions.

You don't want to have to take out a payday loan to replace your worn out muffler bearing.

So ok.... Old school here. Get a bottle of 5 min flush, put it in... Start engine, run until you hear change in pitch, run no more than 8 min if you don't hear it. Shut down let it cool, drain. Do a full oil change with new filter and new oil, just the cheap stuff. Drive 100 miles and do another oil change. Use high quality like a Wix filter from NAPA, and high quality 10/40W. I always used Quaker State. Add full bottle of Marvel Mystery Oil First, then fill remainder with the oil. Should be 5 quarts total. Don't do 5 quarts and then add MMO.

Put the Marvel in FIRST, and then the oil. This will help clear up the leaking main.

Edit: Forgot to add. After 2nd oil change drive 500 miles and change oil again.

As before..., use a good quality filter and 10/40W. After the 500 mile change, you are back on regular oil change schedule.

Now on the anti freeze leak.... Where is it? This is more important than the dripping oil and your mechanic should have told you this!

The 307 has a front plate that has a gasket to the block and then on the other side is where the water pump mounts to. This plate rusts, and around the holes it can and will erode. Under pressure the coolant will spray or seep out under the gasket.

If you are seeing anti freeze in this area, you run the risk of the coolant getting in the engine oil. From behind the front cover it will drip into the pan and mix with the oil and you can't see this. This will destroy your bearings with the rods being first, and then the mains. Antifreeze has viscosity similar to hot oil but it provides no cushioning effect. This will "wipe out" your bearings.

If the antifreeze (coolant) is from the outside like a tube or hose, or radiator leak, that's not so bad. But if it is collecting low on the block and you can't see where it is coming from, you need to get ready to "Remove and Replace" it is called an "R&R" of the water pump. This is way more important than a few drips over night. Antifreeze in the engine oil will destroy the engine.

The other item is the the freeze plugs, also called expansion plugs. The bad one is on the drivers side front and it is right behind the motor mount very hard to get to. Almost impossible to replace. But can be done.

Find someone that knows how to pressure wash the engine compartment without breaking things and or cracking the exhaust manifolds. The idea here is to start with something clean and then it's much easier to find leaks. Most AutoParts stores have the UV dye and the specialized light you need to use the UV. This is a big help in finding leaks.
 
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Oct 14, 2008
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Give it a try. It may swell the old rope seal and stop or reduce the leak. Also a thicker oil like a 20W50 will reduce the leak somewhat as well. Unless you plan on driving it in below freezing temperatures, 20W50 won't cause any issues.
 
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Clone TIE Pilot

Comic Book Super Hero
Aug 14, 2011
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Thicker oil will cause increased cold engine wear until it warms up. Another thing thing to keep in mind that 2 piece rear seals even in good shape will seep a little oil. That is why most manufacturers switched to 1 piece rear seals which actually seal better.
 
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78Delta88

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May 23, 2022
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I'm there with the 20/50, I've seen that help, but I would still keep with 10/40 for the first few oil changes.
 

1320chevy

Apprentice
Jun 23, 2023
51
39
18
I got down there an look at it myself guys, the leak it’s coming down and dropping from off my oil pan and some was on my pipe also. sh*t I even seen a little antifreeze leaking from the bottom of the motor also smh It’s not a lot of oil but I’m pretty sure it’s coming from that rear main. I even checked the valves and they were dry after the install and letting it run. I might as well prepaid myself to get ready to get a new motor faster then what I wanted 🤦🏽‍♂️
"Leak is coming down"??? Yup, happens every time you have gravity. Clean everything up, run it and look and see where the highest point you see oil coming out is. you can use a mirror or dye and black light to pinpoint the source. With a small leak, I'd try using Lucas stop leak. Out of all the chems I've tried over the years, it seems to be fairly good and does no damage to other internals. If it's leaking from an aged "dry" seal, it should help a lot. Give it some time though. It's not instant.
 
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57 Handyman

Master Mechanic
Feb 6, 2017
339
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ck80, I've been trying to locate this thread in order to respond to your questions about the inner structure. Honestly, I don't know what is inside so will let you decide by posting a few pictures. The first one was a test fit and has a few of the stock pieces installed--gauge pod, radio/AC bezel, and glove box. As you can see, the color matches very closely between the dash replacement and stock pieces. The second picture shows the back side--the stick was part of OPGI's shipping setup.

20230902_160226.jpg
20230902_162432.jpg

I haven't decided when I'll start the installation as I will need some assistance to pull the old dash out, remove the harness, and re-install the dash.
 
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57 Handyman

Master Mechanic
Feb 6, 2017
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My apologies!!! This got posted in the wrong place/site. Trying to multi-task/not paying attention.
 
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78Delta88

Royal Smart Person
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May 23, 2022
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No worries, I liked the pics. Dash looks good.

When I did my Delta 88 I couldn't find a decent dash and I reached out to the company in California and they were basically send it in and you get the invoice when done.
 
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pagrunt

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Sep 14, 2014
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ck80, I've been trying to locate this thread in order to respond to your questions about the inner structure. Honestly, I don't know what is inside so will let you decide by posting a few pictures. The first one was a test fit and has a few of the stock pieces installed--gauge pod, radio/AC bezel, and glove box. As you can see, the color matches very closely between the dash replacement and stock pieces. The second picture shows the back side--the stick was part of OPGI's shipping setup.

View attachment 229938 View attachment 229939
I haven't decided when I'll start the installation as I will need some assistance to pull the old dash out, remove the harness, and re-install the dash.
So this is what I'll be getting when ever they get mine in to ship my way (was originally to be here next week, the middle December, currently middle April, next ???).
Ordered in black cause they don't do dark maple.
 

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