Rear Main & Groove in Crankshaft

[squeak104]

So I just inherited a short block but have a problem. Where the rear main seal rides there is a groove cut in the crank. Below is a picture of the crank. I know they make redi-sleeves for harmonic dampners for other vehicles but I've never heard of one for the back of the crank.

So far I've come up with two options: (1) Double, possibly triple the gasket on the plate that holds the rear main and slot the bolts for the oil pan to move the seal away from the groove. (2) I've heard that Hapco Rebuilders here in Indiana can weld the crank then turn it back down to the original size eliminating the groove. But I'm not certain, I'll be calling them tomorrow to find out for sure.

Anyone else ever run into this problem?

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[turboglenn]

Man, that's pretty common honestly, I haven'taheard of any cures or fixes for it, but i can say the groove in my current crank looks similar to that (and so was my last one) and neither leaked

But what stumps me is that if these cranks are supposed to be nitrided and have to be re-nitride hardened after machining, then why the hell is the rear main seal part osft enough for a rubber seal to wear through?

As for your options... I like the first one, but wonder about room between the block and flywheel.. but i've got a spare to experiment on if i remember when i rbing the flywheel for it over here to have the engine complete before mounting it up on a stand where it can be ran.

The second one,, as a weldor I know this is possible, but i've heard so much talk about having to re-nitride the crank after any welding or machining that i'm not sure how feasible that becomes sincei dont' know what the cost of nitriding is.

 

[squeak104]

After speaking with Hapco Rebuilders he said they have quite a few crankshafts there with grooves in them that don't leak. He said I should be alright no leaks, as long as there aren't any nicks in the groove that can tear the seal. As long as I have the clearance between the plate and the flywheel I'm probably going to try to bring the seal outward just to be on the safe side.

 

[->PrOjEcTGS<-]

Just like Glen said. When I rebuilt my engine my crank had a similar groove. All is fine and there are no leaks. I wouldn't worry about it.

 

[AshTsi]

I had the same groove on my crank on a past rebuild as well.. put it all together and it was fine for me.

 

[Jeff99GS]

Yeah I had that groove too. My machinist told me to add a thicker gasket...but im not to worried about it.

But what stumps me is that if these cranks are supposed to be nitrided and have to be re-nitride hardened after machining, then why the hell is the rear main seal part soft enough for a rubber seal to wear through?

There is actually metal in the seal underneath the rubber...I found that out when I tried to cut one off with tin snips. NOT so easy to cut.

 

[squeak104]

Alright I'll let it ride then. Knowing my luck though it'll probably leak like crazy.

 

[turboglenn]

Yeah I had that groove too. My machinist told me to add a thicker gasket...but im not to worried about it.




There is actually metal in the seal underneath the rubber...I found that out when I tried to cut one off with tin snips. NOT so easy to cut.

Is the metal in the lip that provides the seal or are you just talking about the external diameter? I know there's some metal in the seal, but i didn't think there was any that could actually contact the crankshaft where the rubber part does.

 

[Jeff99GS]

I'm not sure about that. I know there is that metal spring behind the lip of the seal. I will go look at one and cut it in half then let you guys know what I find out.

 

[->PrOjEcTGS<-]

Yea there is a metal spring behind the rubber. It's to help keep the rubber in contact with the metal surface it's sealing. If anything it might actually seal better with the groove since it will have a place to bed into.

 

[Jeff99GS]

Okay I cut my old rear main seal in half. (my crank was scored from THIS EXACT SEAL)Sorry for the blurry pic. But it clearly shows NO metal should be in contact with the crank.

So that Kevlar type rubber must be cutting into the crank. I guess it's tough shit.

My Machinist seems to think that is Normal. And seeing as we all have the groove I guess it can't be too bad.

Do they sell and undersized rear main seals? So you could have the crank milled and polished to remove that groove?
Also, why doesn't the front seal make any grooves??