[JLMounce]

If you have a smoke machine coming, I'd wait to remove anything from the engine yet and run several smoke tests. That should help you determine the actual location of the leak. What would suck is to assume it's the RMS or rear pan gasket, only to replace those items and the leak be somewhere else.

As an example a front main leak can present at the back of the car because the oil runs down the pan rails to the rear.

Also for the record, those recommending an NOS rope seal, may be on to something. My engine had a 2 piece rope seal in it before I rebuilt it last year and it was bone dry. That engine was a about 25 years old and sat for a good 10 years. The cork pan gasket leaked from drying out though.

[Dragncar]

Originally Posted by gtorich

Hey, Dragncar, missed this while typing , i got cork gasket from butler, will have to measure it, if not a 1/4 inch i will get what you did...........what did you use for the rest of the pan.

Rich

No gasket on main part of pan. Ultra Grey , thats it. I put a layer of the Grey on both the block and the pan. I think it seals better that way.

[Dragncar]

You might have a little drip coming from under the reap cap. I put a little Aviation sealer on the very rear of that bolt pad and torqued it down.

[NeighborsComplaint]

Originally Posted by gtorich

Think i got some pics mixed up, check out post 20, thats a little more than the two small drops i had posted.......this was driving the car never going over 3 grand on shifts, if i got into the high 5 grand, it was worse, got the motor out now and hoping to find out what is going on with this thing.

Rich

Yeah, that’s an RMS leak, traveling right down the pan rails. I used the BOP one piece oil pan gasket but not their RMS. I tried a 2 piece and it was a leaker despite putting serrations in the seal groove, filling the anti-rotation holes and setting the block -half first followed by the cap-half, trimming for an interference fit, etc. leaked after 15 minutes of running. The BOP gasket was installed just like the multi piece with silicone sealant at the corners and under the rear pan seal. Trick is to degrease the gasket from whatever they use as a mold release so the silicone sticks.

[steve25]

Thumbs up to the above!

Removing the mold release agent from these seals is the first step in using them.
Wax and grease remover from a automotive paint supply source is what I always have on hand.

[HWYSTR455]

When the rope seals sit over a period of time without engine running, they can dry up some and leak. After a couple times driving, that slight leak would go away.

During assembly, I never removed/wiped down the seal, but I would apply a coating of engine oil with my finger prior to installing the cap.



.

[performerrpm]

ive never had any problems getting the rope seal included in felpros kits to seal. last one was 2021ish tho, i have a few up on the shelf thats 5 years old or older but new. i decided to try the best rear main seal on a 455 last night because this thread.

instructions said to drill for a roll pin into the main cap but that areas kinda thin so i used the sealer method to lock it in instead. clearly says do not use sealer on ends of rope seal but do use it on surface of cap to block. i did a light coat kinda around the back outter surface to keep oil from passing through but seams like it would still get through the ends of the rope seal.


i know on the older style u would ultra black the ends.

[64speed]

Mine leaks. About a half dollar size every night. Y’all know how many times I’ve had this engine out. I just put down a drip pan in the garage and roll out. Wash the bottom of the engine occasionally. I just can’t pull it out again over that. Maybe one day.

[Hesster1977]

It seems the Pontiac 400 engines are sensitive to CC Pressure, and a good PCV system is a must. It only get's worse with Engine Mods and more HP. No pretty little Breather Caps will work either. I got tired of the drip mess so I replaced the rope seal with a Viton one, and installed a Butler Evac Pump. That's damn expensive, but any leaks are gone forever.

[gtorich]

Got the smoker running today, hope these vids come out, tried to put them on you tube and copy the links, me and the puter do not play well together...........see if any of you guys can tell where the smoke i comming from.

https://youtube.com/shorts/QUGGFKIaJ6w?feature=share

If this dont work, have a few more vids, just have to figure out how to send, i have the links in a email

[gtorich]

another one i hope

https://youtube.com/shorts/y9ckZ-jLivM

[gtorich]

Im hoping this is working............better than going out to the movies

https://youtube.com/shorts/D4cR5ryb0Fc?feature=share

[gtorich]

https://youtu.be/OkDLG1e00ho

Hard to tell where its coming from

[zippy]

I would say its coming from the seal to crank. Does your crank have the serrations at the seal location? Could be through those.

[gtorich]

The zip, no idea if i have serrations on the crank or not, never saw it, been to 3 different shops, you would think someone might have noticed that. lol................here is a pic a little after messing around with the smoke machine, oil was drained a week or so ago.....I can try to get some better vids, having a hard time with the u tube deal,

Im thinking that last vid might be the best one

[zippy]

Looks exactly like my 455 leak. I have a 2pc BOP seal that was used on my last eagle crank for like 500mi before cam lobes went and messed that crank up beyond repair.
Have a SCAT forged in now, but re used the BOP. It leaked with the Eagle too. Contemplating pulling in spring and going rope seal. Just a PITA in 2nd gen F body with headers.

[lust4speed]

Haven't seen this posted, but I look for a starburst pattern of oil on the crank flange. If it is the main seal there will be oil streaks from the center of the crank down the flange. If it is from the pan or other areas the flexplate/flywheel will be coated and streaked but the crank flange will be surprisingly clean. Usually works for me but your mileage may vary...

[Dragncar]

Originally Posted by Hesster1977

It seems the Pontiac 400 engines are sensitive to CC Pressure, and a good PCV system is a must. It only get's worse with Engine Mods and more HP. No pretty little Breather Caps will work either. I got tired of the drip mess so I replaced the rope seal with a Viton one, and installed a Butler Evac Pump. That's damn expensive, but any leaks are gone forever.

I got tired of leaks too, BOP one piece and Moroso 3 vane.
Nice car, ditch that air cleaner. The most HP killing air cleaner I know of.

[gtorich]

This might be a better vid, my mech aka, my wife explaining

https://youtube.com/shorts/dTfx_RLFUKE

[gtorich]

Originally Posted by lust4speed

Haven't seen this posted, but I look for a starburst pattern of oil on the crank flange. If it is the main seal there will be oil streaks from the center of the crank down the flange. If it is from the pan or other areas the flexplate/flywheel will be coated and streaked but the crank flange will be surprisingly clean. Usually works for me but your mileage may vary...

Thanks Mick, will have to check my pics but the crank flange looked pretty clean, the flywheel bellhousing was coated with oil, oil on starter, oil on headers, oil on trans, oil flying back to the mufflers, some oil even on rear bumper.

Not sure what im gonna do with this motor, this will be the 4th try with the rms, i had other stuff done also but always put a different seal in.

Have way too much crankcase pressure the way it is, and i just had it re-ringed a few yrs ago, im worried fix this again, and im looking at the same results.

Thinking of trying a different motor, i see Paul Kippen has a 428 short block for sale, maybe throwing my kre heads on that and hope for the best.

Rich