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crank shaft oil seal
Posted: Tue Aug 23, 2022 1:10 pm
by WYO311
rear crank shaft seal : when I sent the block to the machine shop I neglected to take note the rear seal placement . i see two grooves outboard of the bearing , which is the correct one for the seal?
Re: crank shaft oil seal
Posted: Tue Aug 23, 2022 2:33 pm
by Bwk2000
WYO311 wrote: Tue Aug 23, 2022 1:10 pm
rear crank shaft seal : when I sent the block to the machine shop I neglected to take note the rear seal placement . i see two grooves outboard of the bearing , which is the correct one for the seal?
Hi. You posted this in the “Forum Problems†category, which is primarily used for technical online issues and forum software update notifications - It doesn’t get many views. If you place your question(s) in the “General Discussion†or “The Quick/ Small/ Stupid Questions†category, it will get MANY more views that can help you out.
That being said, it’s the outside one.
* Also remember to leave about 1/8†of the seal above the mating surface when you trim it down so it will seal the ends properly.
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Re: crank shaft oil seal
Posted: Tue Aug 23, 2022 7:07 pm
by notoptoy
I moved the topic to tech discussions.
Re: crank shaft oil seal
Posted: Tue Aug 23, 2022 8:07 pm
by Gregs672000
Take your time and do this right (follow directions, which includes soaking it in oil for some time). I've done at least 4, and this is the first one I've had leak, didn't soak it first. Don't know if it's a myth but the leak sucks and there's no easy fix without pulling the crank.
Re: crank shaft oil seal
Posted: Tue Aug 23, 2022 10:09 pm
by Nissanman
I also forgot to pre-soak the rope seal.
Fortunately, the rest of the car was no where near ready so I filled the sump with oil and sat the engine on its' backside for a month or three.
I know that may not be viable for some folks but it worked!
I have recently had the transmission and engine back plate off and there is not a trace of an oil leak

Re: crank shaft oil seal
Posted: Wed Aug 24, 2022 10:01 am
by Gregs672000
Ya, mine leaks a fair amount... pisses me off. To make it worse, I'd have to remove the crank scraper I put in with special sealant etc just to get started. I'd try some "engine leak" pour in stuff but I don't have a lot of hope, and I don't know what it might do to the newer gaskets throughout the engine... grrrrrr.
Re: crank shaft oil seal
Posted: Wed Aug 24, 2022 10:35 am
by Habitat.pat
Slightly off topic, but when I replaced my rear seal I referred to the tech wiki & read the instructions there. Haven’t finished my engine rebuild yet, so I can’t say if I was successful.
One thing I would like to have found was a photo of correctly installed seal. Mine bulged out some against the crank but I don’t know if it’s too much. It would be much easier to take the time to replace the seal now rather than having to pull the engine again.
As an associated question, how tight should the crank be with a new seal? I assume I should be able to turn the crank by hand on the counterweights. If someone who does these seals often could put a torque wrench on the crank & post a reading it would be quite helpful.
Peace,
Pat
Re: crank shaft oil seal
Posted: Wed Aug 24, 2022 12:20 pm
by spl310
Gregs672000 wrote: Wed Aug 24, 2022 10:01 am
Ya, mine leaks a fair amount... pisses me off. To make it worse, I'd have to remove the crank scraper I put in with special sealant etc just to get started. I'd try some "engine leak" pour in stuff but I don't have a lot of hope, and I don't know what it might do to the newer gaskets throughout the engine... grrrrrr.
Have you noticed any improvement with the scraper?
Re: crank shaft oil seal
Posted: Wed Aug 24, 2022 12:26 pm
by nismou20
Hey Greg, there is a 50/50 chance that the leak could be from the bottom half. I took the chance and got lucky. Just a pan removal, rear bearing block and new pan gasket. I was shoving rags into the void between trans /engine as a diaper until the fix.
Re: crank shaft oil seal
Posted: Wed Aug 24, 2022 12:42 pm
by Bwk2000
Gregs672000 wrote: Wed Aug 24, 2022 10:01 am
Ya, mine leaks a fair amount... pisses me off. To make it worse, I'd have to remove the crank scraper I put in with special sealant etc just to get started. I'd try some "engine leak" pour in stuff but I don't have a lot of hope, and I don't know what it might do to the newer gaskets throughout the engine... grrrrrr.
Greg.
If you go the route of trying a leak sealer, I recommend ‘Blue Devil Rear Main Sealer’.
Haven’t used it myself, but I personally know three people who have. Within 2-3 weeks, two of the three leaks stopped completely and the remaining one was reduced to a manageable few drips. Those were over a year ago and the seals are still holding - I know, I was surprised too. Guess it’s not just snake oil anymore

Re: crank shaft oil seal
Posted: Wed Aug 24, 2022 6:18 pm
by cbez
Bwk2000 wrote: Wed Aug 24, 2022 12:42 pm
Gregs672000 wrote: Wed Aug 24, 2022 10:01 am
Ya, mine leaks a fair amount... pisses me off. To make it worse, I'd have to remove the crank scraper I put in with special sealant etc just to get started. I'd try some "engine leak" pour in stuff but I don't have a lot of hope, and I don't know what it might do to the newer gaskets throughout the engine... grrrrrr.
Greg.
If you go the route of trying a leak sealer, I recommend ‘Blue Devil Rear Main Sealer’.
Haven’t used it myself, but I personally know three people who have. Within 2-3 weeks, two of the three leaks stopped completely and the remaining one was reduced to a manageable few drips. Those were over a year ago and the seals are still holding - I know, I was surprised too. Guess it’s not just snake oil anymore
Not for our rope seals tho
Re: crank shaft oil seal
Posted: Wed Aug 24, 2022 6:42 pm
by Bwk2000
cbez wrote: Wed Aug 24, 2022 6:18 pm
Not for our rope seals tho
Well … Sh!t

Re: crank shaft oil seal
Posted: Thu Aug 25, 2022 10:14 am
by Gregs672000
spl310 wrote: Wed Aug 24, 2022 12:20 pm
Gregs672000 wrote: Wed Aug 24, 2022 10:01 am
Ya, mine leaks a fair amount... pisses me off. To make it worse, I'd have to remove the crank scraper I put in with special sealant etc just to get started. I'd try some "engine leak" pour in stuff but I don't have a lot of hope, and I don't know what it might do to the newer gaskets throughout the engine... grrrrrr.
[/quote
Have you noticed any improvement with the scraper?
Well, it's really hard to know since so many other variables changed at near the same time. Overall I would not recommend it due to fitment issues (A LOT of clearance work). I've been hearing a very disconcerting rattle at certain rpms, but was relieved to find its my oil dip stick vibrating against the plate. Subjectively, my engine is running noticeable cooler, but I think most if not all of that is due to the fuel injection and ignition control I have. I have no objective data to support installing one. If I do the rear main seal again, I would probably elect to keep it out.
Thanks all on the sealer info... I hate having to take things apart yet again, but that seems to be my only real option.