Please help I am at a loss, rear main seal

TEMP67 · 11-05-2012, 04:03 PM

Hi guys Owen from Australia here I have just joined the forum as i require some help with the following rear main problem which is causing me a major headache and i am now at a loss as to why.

I own a 67 Tempest, which I have been restoring over the last few years, everything is going fine apart for my recently rebuilt 400, i brought the engine from the USA back in 2010 as it was almost impossible to source a 400 here. The guy i bought the engine off said it had been recently rebuilt, once it arrived i stripped it down and all checked out fine with a lot of goodies used

(I'm a qualified engine re-builder but have been out of the game for 10yrs).

Before putting the engine back together I the purchased a viton seal from BOP and installed it as per any other 2 piece seal i had previously. Engine goes in car seal leaks.

I then removed the engine and stripped it down again I then did some research to find that there were specific instructions for the seal installation which did not come with the seal. I then assembled the engine once again installing seal as per the instructions. Engine goes in again seal leaks.

Engine removed again, stripped down and thoroughly inspected, I didnt like the look of the bearings so sent the engine to a local re-builder who blue printed the crank, rods and block. He found front main tunnel out of alignment and clearances miles out so re-ground crank 20/20 re-sized rods.

I then put the engine back together this time using a rope seal as i had lost confidence in the BOP Viton seal. Engine went back in yesterday and guess what? Seal leaks.

I have rebuild 1000+ engines in my time and never had a seal leak like this. Does anyone have any ideas i am lost.

jetstang · 11-05-2012, 05:26 PM

I used the best graph seal and it worked great. There is a sticky on the thread, but am sure you know how. They say the rope seals dont' have the same ingredients as back in the day, asbestos. Viton seal is also hit or miss. My seal hasn't leaked a drop.
Here's a link to the company:
Vintage Automotive Gaskets - Head Gaskets and Rear Main Seal Gaskets - Best Gasket

TEMP67 · 11-05-2012, 05:52 PM

Jetstang

Thanks for your reply, I actually looked at these 6months ago but struggled to find someone who would ship to Australia. I buy most of my parts through Summit but they do not stock the best Gasket Seals.

As I mentioned previously I have installed 1000's of seals in all different types of engines but have never had problems like this, and I am really dreading pulling this engine out again for the 4th time

jetstang · 11-05-2012, 08:59 PM

Falcon sells them on ebay here. Maybe you can search our ebay and find someone that ships international.

TEMP67 · 11-06-2012, 12:34 AM

Jetstang

Just checked Falcon out cheers for that, only issue with them is shipping cost to Australia, $20 for seal & $38 for shipping. WHAT !!!!!!!!

By the way a lot of useful info in the sticky thread thanks.

TEMP67 · 11-06-2012, 01:34 AM

Another quick question guys how much oil should a 400 take with filter change?
I am starting to think the engine may have come with the incorrect dip stick and i have overfilled the crankcase.

FlambeauHO · 11-06-2012, 07:33 AM

5 quarts is a good starting point, depends on your pan. 38 for shipping sucks but it beats the hell out of pulling the engine again.

jetstang · 11-06-2012, 08:12 AM

He'll have to pull the engine, and drop the crank out to install the seal. I would inspect the seal area on the crank for wear or damage that may be eating the seal. I don't know why shipping is so much, or if one of us could throw it in a mailer pouch and ship it cheaper to you. Of course, there would still be $10 shipping to us. Good luck, hope it works out for you. I have a spare 350 and 400 if you have any future needs.
I thought Pontiacs take 6 quarts. If you put 5 quarts in and it's overfull, then you have the wrong dipstick. I'd fill it with 6 and remark the dipstick.

geeteeohguy · 11-06-2012, 12:15 PM

My 1967 400 takes 7 quarts of oil. Says so in the owners manual, and, with filter, it does. TEMP67, what's changed since you were in the business is the removal of asbestos from the old rope seals. The new ones, except for the Best Gasket Graph-tite, are prone to leakage. I have had personal good results from 3 Viton seals used on different Pontiacs recently. No leakage at all in thousands of miles. But, a Viton seal needs a perfect crank journal and perfect cap alignment. I would suspect your rear main cap area is a bit imperfect, which is much more common on the big journal engines like the 428 and 455. A Graph-tite seal should work for you. Follow the instructions, though...you don't "roll it in" really hard like a conventional rope seal. Good luck, and, G'Day.

TEMP67 · 11-06-2012, 12:56 PM

Guys thanks for all your feedback and advice.

The first thing I will be doing to night when i get home from work is drop the oil and measure. I am starting to believe now that this is the main reason why I am having my rear seal woes as think I may have put 9 qts in to get it reading on dipstick which is obviously way to munch with a stock pan, I cant believe I didnt think about this earlier.

Geeteehoguy - tunnels caps and surfaces are all perfect I have inspected everything thoroughly numerous times time looking for the exact cause, but if I am correct there may have never been an sealing issue more a crankcase capacity issue which as caused the oil to blow out at the weakest point the rear main.