Front Main seal replacement

[Rich Johnson]

I need to replace the front main oil seal on the crank shaft pully. It gushes oil.
I have a new seal and gasket for the timing cover.

How do I get the crank nut off (is it right or left hand thread) and how do I get the pully off?

Yes dumb I know but I have asked a few folks and nobody seems to remember. I have been postponing this for about 4 or 5 years and want to get my truck running again.

 

[vtdeucedriver]

www.g741.org its the forum for the M-37. There is a thread there on all you want to know.

 

[Rich Johnson]

I thought this was the M37 forum.

 

[Mike_L]

The website mentioned is 100% M37. This is the M37 section of SteelSoldiers. Many of the M37 guys are over here occasionally but for the best audience on the M37, G741.org is the place.

I haven't searched for the G741.org thread mentioned but I did look in the manual and it isn't mentioned anywhere I could find.

 

[T. Highway]

Hi Rich,

The nut is right hand thread. (look at the direction of the hand crank drive tangs, this is an easy way to tell thread direction on older engines) The fanbelt pulley is held on by 6, 1/4" hex head fasteners.
Once you remove the large center nut you will need to use a harmonic balancer puller to remove the pulley hub from the crankshaft.

A couple of other details to save you grief later on.
If you are using seal #CR21820, Victor 49521 or equivalent you want to make sure that the oil slinger is in place behind the timing chain cover. If its MIA you will want to use a National 6636S seal, but never use the OEM oil slinger with this seal because of clearance issues.
Do yourself a favor and buy a Redi-Sleeve # 99218 then prep the pulley hub and apply a good sealant before installing the Redi-Sleeve. The new seal will last much longer.

Hope this helps and please stop over on the G741.Org site for more details about your M37.

Bert

 

[Bill W]

To ad to T's post
after installing the new seal and you go to remount the timing cover leave the timing cover bolts loose until after you reinstall the crankshaft pulley hub, this way the seal will align (center) itself better on the shaft, ( just don't forget to tightin cover bolts after your done)

 

[Rich Johnson]

Ok so I have the motor mount removed and the timing cover off.

The whole reason behind doing this job was I was puking oil while driving around and I figured it had to be the front main seal since I really could not see it behind the ox yoke motor mount.

I know the leak was not the oil pan seal because I had replaced that already.

I am wodering if it could posibly be leaking between the timing plate and the block (IE behind the gears) that could possibly be leaking out when the oil drains back down into the pan. The reason I think this is because there is no oily mess on the back of the harmonic crank pully. The truck has not been started in 4 years or more but I would think if the oil was leaking out of the seal it would have gotten the back of the pully a mess. But its not, its dry and rusy, fairly clean. The timing cover has some grunge on it but not excessive.


Oh and I have CR -5417 46-USA supplied by midwest military per request for the correct part.
Should I remove the large gear and chain and pull that plate loose and clean it all up and silicone it to the block?

 

[T. Highway]

Rich,

I would remove the gears and look for the leak behind the plate.
You did say that you replaced the oil pan gasket, but by you mentioning oil gushing from the front of the block. I would wonder if the front cork gasket isn't sealed correctly.

Did you use a liberal amount of oil resistant (Ultra Pro or Superflex) hi temp sealant around the mating corners of the aluminum pan sealing block and the cork gasket?
Did your pan gasket set come with the small rubber "whisker type" seals that go under that front aluminum part?
I would recommend against sealing the whole plate down with silicone, I have seen too much used and end up squeezing inside of the timing chain cover and then migrating into the oil pan, only to be sucked up into the oil sump screen and clogging it over a short time frame.
I use high tack spray on gasket sealers from Permatex for flat machined mating surfaces that have paper/fiber gaskets. To seal the timing chain cover I like using the Anaerobic 548 Orange type of sealant because it stays flexible to a point.

Was the OEM oil slinger in place when you removed the timing chain cover?

Hope this helps,

Bert

 

[Bill W]

T
Maybe I'm just getting senile but I don't remember there being a slinger, mine had a tiny nozzle that sprayed oil from the main oil galley onto the gears???

 

[Rich Johnson]

There is a ring around the crank that I think is the oil slinger.

I dont recall much about the oil pan gasket, I did it some 5 years ago or more. It was cork and I used liberal amounts of blue RTV to stick it on. I dont recall any aluminum parts. Just block, gasket and pan.

 

[T. Highway]

Bill,
The OEM oil slinger is on the crank, a flat washer with a keyway slot and slight bevel to keep oil from following the journal out the front of the chain cover. Your not loosing it, this is often overlooked by most. This was removed if a seal was installed with an intregal slinger such as the National 6636S seal.
Rich,
The seal under the aluminum block will weap small amounts oil but the amount of sealer around the corners of the pan to this aluminum block will gush oil if not sealed correctly.

Bert

 

[Rich Johnson]

Im not sure what you mean by aluminum block. Is that the half round block on the front that the crank bearing is in, right behind/below the timing gears? I did not realize that was aluminum.I am wondering if I should pull that plate off from behind the timing gears. I has one bolt in it backwards, meaning that the bolt is inside the block and I would have to jack up my engine some other way cause right now the oil pan is sitting on blocks from the axle.I remember checking on this leak many times and concluding that it had to be the front main seal since it appeard to be coming from in front of the oil pan. Also I had done the pan gasket with generous amounts of permatex 2 non hardening goo, not RTV as I originally said. I think I might jump over to the 741 forum and ask too for more input. Its been years since I was there and it kinda dwindled away back then.

 

[T. Highway]

Rich,

I replied to your question over on the G741 site.

Bert