# Please help I am at a loss, rear main seal



## TEMP67 (Nov 5, 2012)

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.


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## jetstang (Nov 5, 2008)

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


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## TEMP67 (Nov 5, 2012)

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:shutme


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## jetstang (Nov 5, 2008)

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


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## TEMP67 (Nov 5, 2012)

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.


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## TEMP67 (Nov 5, 2012)

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.


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## FlambeauHO (Nov 24, 2011)

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.


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## jetstang (Nov 5, 2008)

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.


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## geeteeohguy (Feb 2, 2008)

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.


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## TEMP67 (Nov 5, 2012)

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.


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## ppurfield001 (Jan 21, 2008)

TEMP67 said:


> 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:shutme


I had the same issue with a very leaky rear main seal on my 1967 GTO. I used a Viton seal and literally jammed as much as possible in to ensure no leaks. Been three months, and no leaks so far. Good luck.


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## jetstang (Nov 5, 2008)

TEMP67 said:


> 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..


LOL at you, thats funny, 9 quarts? Yep, that will make it leak. Had a guy at the track running around the pits to borrow oil, because he had the oil fill on the valve cover out and couldn't see any oil, so he was trying to fill it up. He blew all the seals on the motor that race, and I bought the car broke for $100. I replaced the motor, but hindsite as it is, I should of drained the oil, refilled it and see if it leaked.
Hopefully overfill will fix/slow the leak.:cheers


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## TEMP67 (Nov 5, 2012)

Well don't I feel like a complete F%&#in tool, just dumped the oil and measured it Yep 9 bloody qts :shutme:shutme:shutme
Refilled with 5 qts but not a single drop on the dipstick :confused

Now for some root cause analysis guys
Could someone please help me out with the following info
1 - What is the length of a stock 400 dipstick, tip to seal cap?
2 - What is the length of a stock tube protruding from the engine block?


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## geeteeohguy (Feb 2, 2008)

Depends on the year of the engine and the year of the pan, stick, etc. As I said, my '67 400 holds 7 quarts with filter. My '65 389 holds 6 with filter. Later engines held as little as 5 quarts with filter. This is with a normal sized filter. I would run a total of 6 quarts if I were you, and get a different dipstick. Then, I would mark the "full" line on the 'stick and be done with it. What year is your actual engine?? I can measure my dipstick tonight and let you know the length....it's the original one.


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## ppurfield001 (Jan 21, 2008)

TEMP67 said:


> Well don't I feel like a complete F%&#in tool, just dumped the oil and measured it Yep 9 bloody qts :shutme:shutme:shutme
> Refilled with 5 qts but not a single drop on the dipstick :confused
> 
> Now for some root cause analysis guys
> ...


My engine guy had a problem with my dipstick on a 1967 400 engine. The bottom half fell into the crankcase! I had the engine out to replace the rear main seal (I know you relate to that) and he noticed this issue. He re-built the dipstick so that it read "full" when seven quarts of oil were added with a new oil filter. As said previously, no problems so far... Good luck and put some shrimp on the barbie for me. Regards.


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## TEMP67 (Nov 5, 2012)

Geeteeohguy how do i tell what year the block is? These are the numbers.
Numbers above water pump 373423 YC
Numbers down side 28P201865

I am really starting to think the tube is not right and believe it is approx 3-4inch longer than it should be, if this had have been any other engine such as a Holden 202, 253, 308, Ford 302, 351, Chev 327, 350 etc etc: i would have picked up that the tube was incorrect straight away.
I guess I will have to notch this up as a learning experience as this is the first Pontiac i have ever re-built.

How can i upload some video so you guys can see her running?


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## BearGFR (Aug 25, 2008)

Welcome to Pontiac 

The key to getting these things to seal is to slay a young goat and place the entrails in a circle around the car during the full moon....

Seriously, rear main problems just come with the territory. You can be meticulous in assembling these engines yet for some reason, some will seal and some won't.

I've got a Viton seal in mine that I know for certain I installed to the letter exactly according to direction, yet it leaks some. Had I known then what I know now, I would have gone with the graph-tite seal. Why? My engine has been align-honed - and the process (shaving the main caps and honing) results in a main seal passage that is now no longer perfectly round. The viton seal has a hard time dealing with that - the graph-tite seal tends to do better.

Since the motor has to come out to do the job right anyway, before putting it back into the car, fill it with the correct amount of oil and use your engine stand / engine hoist to tilt it back at a good angle and leave it overnight, then inspect for leaks. 

Bear


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## TEMP67 (Nov 5, 2012)

Bear 

Thanks for your feedback. 

Now that i have established the root-cause i could safely say that correct installation of any seal would have probably worked if I had have put the correct amount of oil in to begin with. Speaking of that is anyone able to help me confirm the correct dipstick tube length for my year block so I can work out the correct level for the dipstick?

Tomorrow will be D-Day tho, now that the oil is at the correct level I will take her for a run and see if the leak persists. If so then I guess I will pulling it out again for the 4th time and will be fitting a graph-tight seal, a task I am seriously dreading.

Actually I should re-phrase that, putting it back in is what I hate, the time and effort it takes to get those two center header bolts back in is a frickin nightmare :shutme last time it took 10mins to drop the engine in and 3 hrs laying on my back on the cold concrete just to get the header bolts


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## GTO JUDGE (May 14, 2005)

IMO regarding the dipstick issue: Knowing the correct amount of oil that goes in a 400 with filter change would be full: If the dipstick is showing over or under filled..... If it were me, rather than go through the hassle of finding another or pulling this or that.... I would mark the dipstick where it reads at the 6Qt spot then scribe the dipstick at that spot and create my own reliable fill point. At some point when engine is pulled etc then concentrate on a correct dipstick. Just my .02


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## 2drhdtp (Nov 15, 2010)

"G'Day" Temp67
Please consider when using liquid volumes, the difference between
Imperial Measure, US Measure, and Metric. My '66, 389/464cid takes, with new filter-
4 Imperial quarts, or 5 US quarts, or 5 litres.
I have installed a 3in, 2 piece viton seal,,,,,,no problems. 
Gremlins may originate from anywhere anytime.


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## TEMP67 (Nov 5, 2012)

GTO totally agree with your statement however with 6Qts of oil it isn't even reading on the dipstick at the moment, hence the reason I am hoping some one can assist with the correct tube length. 
It doesn't have to be 100% exact, whatever someone can tell me i will add an inch cut it down, then scribe dipstick. When the engine comes out I will set it up correctly as suggested. I just don't want to cut the tube to short to start with.

By the way thanks for every ones help you have made me feel very welcome on this site.


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## geeteeohguy (Feb 2, 2008)

Temp, the date code on the block is near the distributor hole. The casting number of the block can help date it, too. It's on the passenger side at the rear, near the belhousing. Post those numbers and we'll nail it down. The numbers you listed are the Engine Unit Number and the partial VIN number. No '67 and earlier blocks had a partial VIN on the front of the block or anywhere on the block, so yours is '68-up.


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## TEMP67 (Nov 5, 2012)

Hey guys here is a you-tube link showing first start.


http://www.youtube.com/watch?v=XL6b6EcRN0Q&feature=youtu.be


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## TEMP67 (Nov 5, 2012)

The Verdict

Fired her up today and drove around the block a few times, Yep rear main still leaks, Oh well to be expected. Time to order a graph-tight seal and pull engine again.

Geeteeohguy Casting # is 9790071 I found a decoder which lists this as a 68-69 block does that sound correct? 

Is anyone willing to help me out getting a couple of graph-tight seals and posting them to Australia so i don't have to give Falcon $38 for shipping for a seal worth $20, PM if you can?


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## BearGFR (Aug 25, 2008)

TEMP67 said:


> Hey guys here is a you-tube link showing first start.


Nice. I love me some Pontiac fire-ups. :cheers

Bear


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