# New engine question



## WhittP (Jun 19, 2013)

I just got my engine back from the shop yesterday. It sure runs well but I have a question before I get it put in. I read that you can check the rear main for leaks by tilting the front of the engine up and leaving it overnight.

I did this last night and....there were a couple of drops. The engine has couple of hours on it from the dyno runs so what do you think? Does it need a new seal?


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## geeteeohguy (Feb 2, 2008)

It may or may not leak when it's in the car. I would be tempted to install one of the new one piece seals in there, even though it's a lot of work. Nothing as depressing as installing a new engine, having it all buttoned up, and have it leak oil right from the start. BTDT.


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## WhittP (Jun 19, 2013)

The shop used a 2 piece Viton seal after they attempted to use the new one piece seal and had trouble with it. Not sure what the malfunction was but they said they've installed dozens of the 2 piece seals with no issues.

When the engine was on the dyno I inspected the area around the crank and oil pan (from what I could see) and I didn't see any evidence of a leak. Zero drips under the machine or engine. When it was removed was when I ran my finger under the lip of the oil pan under the rear main and it came back with a little oil on it.

That made me nervous enough to tilt the motor overnight. It produced 2 drops like I said so is that a for sure sign it will leak or, is the fact that it's now submerged in oil, a situation it will never be in again, causing a leak that would not occur once installed?


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## PontiacJim (Dec 29, 2012)

I used the BOP 2 pc seal in my last 400CI. Followed the instructions, and had no leakage. Yet, have heard others say it did not work for them and they liked the graphite rope seal. Bottom line, each to his own, but do we know it was the seal or the installer?

I have never heard of tilting the engine as a test. MY PERSONAL OPINION is that the rear main seal won't be immersed in oil like the test and the test may simply be overloading the job that the seal is designed to do. When things are spinning and pressure is developing in the engine block, I think you could imagine a different set of values now being placed on the seal and to me _that_ would be the true test.

If your machine shop is OK with it, then it should be good, because they will be the ones tearing it back down for free to reinstall another seal. Unfortunately, you have to pull the engine and transport it to them. 

Could the oil be seeping from the pan-to-block gasket? Did you install the metal corner tabs on the pan that go under the pan bolts to distribute the torque of these bolts evenly? They are often left out, myself included if they were not on the engine I purchased -even I miss a few things myself. Now I look for these things.

The bottom line is this. You have doubts. If you install the engine and it leaks, you'll kick yourself because it may have been easier to address the leak with the engine out. If it doesn't leak, then your happy and your doubts were unfounded. If you trust your machine shop, discuss your concerns again with them and make sure they will replace the seal at no cost to you if it leaks once you install the engine or ask if they feel that they should look at it now.


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## WhittP (Jun 19, 2013)

I got it to leak again and it looked like it's the rear of the oil pan and not the rear main. I took the pan off and put some gasket maker along the rear part of the seal. I let it set up overnight and I refilled it with oil and tilted it again this morning. Hopefully it's dry when I get home.


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## 666bbl (Apr 13, 2014)

A simple trick with any 2pc rubber rear main seal is to clock the joint a wee bit past the parting line of the cap/block. A 1/4in is more than enough and won't move when you assemble. I know you had yours done but anyone else looking at the infamous Pontiac rear main issue as a topic, try it. Works like a champ. Don't discount the effect that well designed PCV systems can offer in regard to oil leaks. Negative crankcase pressure keeps em clean and even helps with oil ring control. The basics are always your best friend. Mix it with logic? Winner every time...


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## WhittP (Jun 19, 2013)

Thanks for all the tips. I got the motor in yesterday and ran it for a bit. Everything is completely dry so far.


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## PontiacJim (Dec 29, 2012)

WhittP said:


> Thanks for all the tips. I got the motor in yesterday and ran it for a bit. Everything is completely dry so far.


Yay!!!!!!!!!!


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