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Username Post: Rear Main Seal Replacement        (Topic#348583)
rain_man_rich 
Contributor
Posts: 110

Loc: Grants Pass, OR
Reg: 02-09-14
12-06-17 09:33 PM - Post#2717151    












OK all you pros and shadetreer's here's the dealio: tonight when I got home from work I smelled major oil burning. I took a look at the dipstick and it was barely showing. I filled it up knowing I have a major leak going on. I grabbed a flashlight took a look under the truck and didn't see anything dripping, turned the truck on and sure enough, drip, drip, drip near the rear of the engine (one every 5 seconds or so at idle). It was pretty dark and cold so I went in to sulk for a while and make a plan of attack. Obviously I'm going to need to for sure determine the source of the leak when I better conditions (not wearing slacks would help).

Here's a couple of questions to get started with. First, what else can leak that fast back there? Second, I've never changed a rear main seal out before. A little homework has revealed it's a one-piece and a couple of videos later I notice that people are using some kind of tool to drive in the new seal. More research yeilds costs of these tools in the neighborhood of 75 to 200 bucks. There must be an old school tried and trued method that doesn't involve a one-time use of a tool that costs that much, right?

1994 K 1500 5.7 auto



 
Low priced Genuine GM Auto Parts
rain_man_rich 
Contributor
Posts: 110

Loc: Grants Pass, OR
Reg: 02-09-14
12-06-17 09:38 PM - Post#2717152    
    In response to rain_man_rich

oh! I forgot to ask for words of advice on what to look out for while I'm doing this job. Things like "might as well do oil pan gasket while you're in there" or "carefully look at the crank surface" type of thing..




 
Shepherd 
Contributor
Posts: 977

Loc: Lake George, NY
Reg: 11-11-15
12-07-17 04:57 AM - Post#2717158    
    In response to rain_man_rich

If you have the one piece seal the trans has to come out, plenty of how to's on the net, seal surface must be lightly oiled of course. Make sure it is not the back of the intake or a valve cover gasket.



Edited by Shepherd on 12-07-17 04:59 AM. Reason for edit: No reason given.

 
Chevytech 
Subject Matter Expert - Senior Member
Posts: 3694
Chevytech
Loc: Twin Cities, Minnesota, U...
Reg: 04-25-04
12-08-17 07:35 AM - Post#2717302    
    In response to rain_man_rich

The rear main seal is not a common problem on these engines.

Take a look at the oil sender by the distributor. The oil from it can run down to the flywheel cover.

For those of you that are wondering why you are not getting replies to your thread:

Did you give the model, year, engine, fuel system type, and transmission information?

If your vehicle has been altered from stock, let us know about that too.


 
rain_man_rich 
Contributor
Posts: 110

Loc: Grants Pass, OR
Reg: 02-09-14
12-08-17 04:52 PM - Post#2717344    
    In response to Chevytech

Good news! Its the seal at the filter adaptor!




 
rockfangd 
"4th Year" Gold Supporting Member
Posts: 2251

Age: 31
Loc: Utica ny
Reg: 04-13-10
12-08-17 06:12 PM - Post#2717353    
    In response to rain_man_rich

dont go dorman if you can help it.
Stick with Oem.
I would have said sender too

Old School GM fan FOREVER


 
bowtie44s 
Valued Contributor
Posts: 3758
bowtie44s
Age: 34
Loc: wv
Reg: 08-29-12
12-08-17 07:51 PM - Post#2717364    
    In response to rockfangd

  • rockfangd Said:
dont go dorman if you can help it.
Stick with Oem.



Agreed! Felpro are normally good gaskets. Not in this case. Felpro and Dorman both leak. Get the OEM and they will be cheaper than the aftermarket. I got mine at the dealer for $6 or $7.

Jeff

'88 Chevy K3500, aluminum head roller cam 511inĀ³ stroker 10.5:1 compression, 96 NV 4500, 94-98 grille, 305/70-16 (33x12) BF Goodrich KM2s, 91 cluster swap


 
rain_man_rich 
Contributor
Posts: 110

Loc: Grants Pass, OR
Reg: 02-09-14
12-08-17 08:34 PM - Post#2717367    
    In response to bowtie44s

already picked up the acdelco at the dealer $5.22. Christmas is back on again. Im going to to the oil cooler lines at the same time. One or both of them is making a mess up front.





 
454cid 
Frequent Contributor
Posts: 2442
454cid
Age: 44
Loc: West Michigan
Reg: 02-18-12
12-08-17 09:47 PM - Post#2717374    
    In response to rain_man_rich

  • rain_man_rich Said:
already picked up the acdelco at the dealer $5.22. Christmas is back on again. Im going to to the oil cooler lines at the same time. One or both of them is making a mess up front.





I tried replacing only one, and the other one only lasted another year or two. The Dorman replacement I used didn't last either. Check to see if Rockauto has OEM..... or some people cut the crimps off and get new hoses put on the hard lines by a hydraulic hose shop.


99 K3500 RCLB


 
rain_man_rich 
Contributor
Posts: 110

Loc: Grants Pass, OR
Reg: 02-09-14
12-10-17 09:10 PM - Post#2717534    
    In response to 454cid

Well that job sucked. It would have helped if my teeth weren't chattering from the freezing fog. The old gasket was really baked up in there. Scraped it out the best I could but wasn't real happy with it. Doesn't leak oil for now. I guess thats as best as it's going to be for a while. Noticed that oil was continuing to drip out of the drain hole in the flexplate cover so I think I still have some work to do. It's not real bad like one drop every 3 or 4 minutes. A rebuild/crate is in my future I'm afraid.





 
454cid 
Frequent Contributor
Posts: 2442
454cid
Age: 44
Loc: West Michigan
Reg: 02-18-12
12-11-17 09:36 AM - Post#2717579    
    In response to rain_man_rich

  • rain_man_rich Said:
Well that job sucked.



Yeah, I was having flashbacks after reading what you found the problems to be...... working overhead, limited access, oil everywhere.....and cold this time of year.

  • Quote:
It would have helped if my teeth weren't chattering from the freezing fog.



There's snow on the ground here.

  • Quote:
The old gasket was really baked up in there. Scraped it out the best I could but wasn't real happy with it.



Mine is just the o-ring. You have a paper gasket too, correct? When I did my water pump last winter, I used hand held grinders with wire wheels to remove all of the old gasket material. An old Dumore, and a modern cheapy from Harbor Freight. That allowed me to get the surface perfect in the limited access area.

Take it to the do it yourself car wash and clean up the engine compartment and as much of the underside as you can. That'll make it cleaner for next time, and get rid of much of the mess that might continue to drip now.


99 K3500 RCLB


 
rain_man_rich 
Contributor
Posts: 110

Loc: Grants Pass, OR
Reg: 02-09-14
12-11-17 02:23 PM - Post#2717599    
    In response to 454cid


  • Quote:
The old gasket was really baked up in there. Scraped it out the best I could but wasn't real happy with it.



Mine is just the o-ring. You have a paper gasket too, correct? When I did my water pump last winter, I used hand held grinders with wire wheels to remove all of the old gasket material. An old Dumore, and a modern cheapy from Harbor Freight. That allowed me to get the surface perfect in the limited access area.

Take it to the do it yourself car wash and clean up the engine compartment and as much of the underside as you can. That'll make it cleaner for next time, and get rid of much of the mess that might continue to drip now.




There are indeed an o-ring and a gasket. The gasket is a multi-layer composite of paper on the outside with some sort of metal sandwiched in between. This is when in new condition. 20ish years and a million gallons of oil pumped later the gasket was pretty much returned to its original state, carbon. Carbon fused to the block LOL.

I gave the ol' wire wheel approach some serious consideration but did not want to inadvertently send a piece of wire through the oiling system. It doesn't leak, or at least I didn't see any drops in about 10 minutes from that location so I may have accidentally fix it. Time will tell I suppose. And I'm with ya, it's going to the car wash soon, I just couldn't get in the rig right then. I was pretty grimy and the interior of my vehicles are not. Besides I was more interested in a hot shower and a hot buttered rum.

It was cold, snow or no, How cold was it rainman? It was so cold that I bungie-corded the screwdriver/scraper to my hands because I couldn't grip them.





 
rockfangd 
"4th Year" Gold Supporting Member
Posts: 2251

Age: 31
Loc: Utica ny
Reg: 04-13-10
12-11-17 07:24 PM - Post#2717634    
    In response to rain_man_rich

totally been there too many times.
Fingers work great when you cant feel them

Old School GM fan FOREVER


 
Low priced Genuine GM Auto Parts
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