Rear Main Seal Stop Leak

[Bittenagain]

I've got a 2006 build 482 Keith Craft Robert Pond Aluminum block motor in my Cobra. I get a few drips from the main seal whenever I drive it. Looked inside bell housing with scope to see if it was pan or seal, and it looks to be originating at the seal. I was recommended by a local engine builder to try Blue Devil Rear Main Seal Stop Leak, which he had had good results with on a couple of his older builds. Have not called KC for their opinion yet.

In general, I'm not big on snake oil, but the guy who recommended it is a solid, knowledgeable engine builder and tech. He said it didn't cause any problems and worked well.

Anyone had any luck with this product or have concerns about damaging internals? If no harm, might just try it. Will post outcome if I do, but would like to hear any thoughts from others. Thanks!

[blykins]

Does your engine have a PCV valve?

[Gaz64]

And how is the engine ventilated, by breathers to atmosphere, remote breather tank, or back to carb airbox etc?

[Bittenagain]

I believe it vents through the oil fill tube cap and also a PCV valve at the rear of the intake manifold.

[Bittenagain]

Also, motor has about 10K miles on it also. Been running Valvoline 10-30 conventional race oil. Doesn't see hard use or high rpms and is changed regularly...

[Hall1836]

Used blue devil on my 351/427, rear main seal with positive results.

[undy]

Same problem with my similar KC 482" build. I finally just gave up and now consider it a progressive oil change device.

[Bittenagain]

I hear you on the progressive oil change device...but would like to eliminate mess it makes on garage floor and on car underside. If crankcase pressure is part of the problem, maybe needs more venting, but I don't think that is it (although, may be contributing?). Still undecided and gathering information.

[blykins]

How long has it been doing it?

Aluminum blocks pose issues that cast iron blocks don't have because the aluminum moves around so much.

[olddog]

Some people seal the engine up with a PCV installed. This keeps the entire engine close to the same pressure, as manifold vacuum. Some newer EFI setups do this to eliminate the constant leak of unmeasured air flow into the engine. A long subject that does not apply here.

I have concerns with this idea:

1) Sucking the oil pan in. I have no idea what the high capacity oil pans can withstand.

2) At wide open throttle, is the blow by gasses more than a single PCV can take away?

Pros:
1) The higher the vacuum, the less air is in the engine, thus less energy is lost spinning air and oil droplets.

2) The engine cannot leak oil out, when it is under vacuum.

I suppose you could install more than one PCV. Alternatively, put a check valve to a vent, so that air cannot be sucked into the engine, but excess blow by can be vented out.

I know this is done many ways around racing. I have heard of exhaust venturies used to evacuate the crankcase, and vacuum pumps. Also dry sump systems typically run under vacuum.

[blykins]

You will never suck an oil pan in, especially with just a PCV valve. I have dry sump engines that pull around 15 inches of vacuum on the entire engine.

The PCV valve is simply just a check valved vent. At WOT, it does nothing. You normally complement the PCV with a valve cover breather or another source of venting.

I don't use PCV valves. I hate them. They have caused more issues than they help, especially on a higher end engine. Guys don't pay attention to them, the valves fail, or are not sized correctly, and then the engine starts smoking...

[patrickt]

But if you are going to use one, get one that is adjustable, so you can measure it, tweak it, and play with it. And, you might as well fab in an oil separator as well. Remember, working on these cars is almost as much fun as driving them.

[Tom Wells]

Bob,

If you decide to pursue a PCV installation, do a search for it on the First Coast web site. There is some info there you might make use of...

Tom

[PaulProe]

Originally Posted by Tom Wells

. . . PCV installation, do a search for it on the First Coast web site. There is some info there you might make use of...

Tom

Tom
Could you give a little more info on the link/site you refer to. Searching Google "first coast pcv installation" reveals a lot of pages, none of which seem to address the problem.

Who/where is 'first coast'

Thanks

Paul

[Tom Wells]

Paul,

My apologies!

BittenAgain is local to me - didn't think about anyone else being confused by the reference.

Here's the link: FirstCoastCobraClub - Index page

Put PCV in the search box in the upper right corner and you'll find the info I was referring to. It does reference one of patrickt's posts about the PCV from this (ClubCobra) web site. I have put recommended the PCV on my Zephyr (the one with the 557) and have one for the Cobra as soon as I getta round tuit ;-)

The Zephyr still leaks, but I'm not sure where the oil comes from. I have plenty of absorbent mat that my son provided, so the urgency of finding it hasn't been great enough. I'd rather be driving it.

Tom

[Bittenagain]

Tom, thank you for your comments concerning the PCV info at the First Coast Club site.

I'm not convinced that crankcase pressure is my issue, as I don't have other symptoms like oil blowing through breather cap or dipstick. But not saying it couldn't be contributing to the rear seal leak. One has to choose which rabbit holes one wants to go down...

Will look at PCV valve and see if maybe it needs to be cleaned (duh!). Was mostly inquiring about the Blue Devil product to see if others might have had experience with it. Just would like to eliminate the rear seal leak mess, if possible...

[olddog]

I was never a fan of additives to seal an oil leak. Is it was a rope type seal it might help it. I doubt KC would have used rope on an aluminum block.

Rubber seals, I doubt. If the additive can make a rubber seal swell, then it is likely to harm the rubber. So it might help for a while and then make matters worse. Don't forget about valve stem seals and all the other places that rubber may fail.

BTW - FE have a plug in the back of the block, and the rear main cap seals to the oil pan by sliding a nail into the seal to expand it. I recall many threads where the owner had to pull the flywheel before they could see exactly where the oil was coming from. Although FE have a bad reputation for the rear main seal leaking, that is mainly do to the cast iron blocks sloppy grove depth cut into them. Ford was using a rope seal and it didn't matter. Modern seals do matter. New blocks are machined better, at least I would expect that.

[PaulProe]

I ran this issue by a senior FelPro engineer at a PRI show a couple years ago. He was familiar with the FE oil seal, having worked on it early in his carrier.

He blamed the issue on a number of things:

• On the original models, it was an issue of machining and assembly tolerances. The big three were not know for high quality in the 60's
• Crankshafts: The original crankshaft has a spiral knurl in the general area of the rope seal. Its purpose was to channel any oil back to the pan. Some replica crankshafts had not included it in their design or had mis-manufactured it.
• Most importantly: The original seal was designed around the use of compressed asbestos to withstand the heat and forces of the seal. When asbestos was outlawed, the alternative materials do not perform to the level of the asbestos and do not properly meet the specs of the original design. The best you can hope for is one that only leaks 'a little bit'

His solution: Use the highest quality seal you can buy (guess which brand he felt that was ) and make sure the installation procedure was 'perfect' or the leak is guaranteed. If you've ever studied the process, you can't just slap it together and hope it will work. It takes a certain amount of experience and skill.

I run a Wagner PCV on my FE and found once it is set properly and my crankcase pressure is controlled, my leaks become tolerable.

Can they ever be stopped? I was informed by a fellow owner; "I was a salesman for Ford vehicles back in the day. Not saying FE's leaked, but we used to put a drip pan under the literature rack in the showroom" Remember, we're playing with 60's technology, expecting 2020 results.

Paul

[blykins]

The original FE's had rope seals and were not aluminum.

You can pretty much expect a leak from an aluminum FE block. It's just the nature of it.

I haven't had (knock on wood) a cast iron block rear main seal leak in forever. Seriously, I can't remember the last time.

I don't use the side seals and nails. I use silicone. Works perfectly, doesn't take forever to shape the nails, and you don't have to worry about the varying side seal cavity sizes on different blocks.

[joyridin']

I have used this a few times. It works great. I have used their trans stop leak and many other products with great results. The stuff is a bit hard to find, but I see it on Amazon now. If you look up their dealers, you will find one near you. Usually an automotive repair facility. I would not use it for a long term fix, but until next Winter? Sure.

https://justicebrothers.com/products...ine-stop-leak/