318 rear main seal replacement

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MadMC63
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Re: 318 rear main seal replacement

Post by MadMC63 »

They are slightly bigger than the holes so it will seal, you pull them through with pliers.
1971 Dodge D100
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Re: 318 rear main seal replacement

Post by PwrWgnDrvr »

Yes, pull them thru, that locks them in and they stay put. The cork is good stuff. Prep the pan by spreading RTV on the pan, applying the cork gasket and let it set several hours until it is fairly well glued to the pan. After that, install the pan and the gasket will stay in place, well sealed to the pan. Add more RTV to the block side of the cork if you want it extremely well sealed.

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Re: 318 rear main seal replacement

Post by stumblinhorse »

R2D100 wrote:Well, after a bout of holidays and cold weather, i finally got around to doing some work on the rear main. I was able to get the rear main out and replaced, the new pump installed, all the old sealant scraped off and the pan nice and clean. Opened the box for the fel pro oil pan gasket then realized that its a 4 piece cork gasket thing. I just dont trust using that gasket with the way it overlaps where the cork gasket meets the seals. Not to mention, i couldnt get the tabs of the seals into the holes of the oil pan, even after hitting the seals with a heat gun. Anyone have a good recommendation for a solid one piece gasket? I hesitate to use this felpro garbage.
Glad you got the old seal out! Any tips? I will be doing this when it warms up around here is CO.
1969 D100 LWB 318 np435
2001 2500 SWB 5.9 Cummins nv5600
2016 3500 SWB 6.7 Cummins 68RFE

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Re: 318 rear main seal replacement

Post by R2D100 »

Got the pegs through the holes after heating up the seals in really hot water and then pulling the ends through with a pair of pliers. Much to my surprise, the rubber seals were pretty tough and stretched like crazy. Still dont like the four piece design on the 318 oil pan gaskets. No one piece gaskets to be found!

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Re: 318 rear main seal replacement

Post by R2D100 »

Glad you got the old seal out! Any tips? I will be doing this when it warms up around here is CO.[/quote]

Advice.. well, it was surprisingly easy to get the rear main seal out, in my case. I didnt have to push very hard and it started coming out on the other side of the crank. I would suggest getting a nice 1/2” breaker bar for the bolts on the crank bearing cap. Also, get a hex drive socket that fits in the oil pump driveshaft hole and spin it to make sure the pump isnt stuck. Mine was actually stuck and i had to return it to the parts store. Was fishy cause the first pump had a dingy box that was already torn. Mustve been a defect that was returned and somehow sold to me. Anddd you will have to lift up the front end of the truck to let the front axle drop enough to get the oil pan out. Its a fairly simple job if the rear main seal doesnt give any issues. Last job i did was replacing a clutch an a mini cooper. Thank god i dont have to deal with that nonsense

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RonHall76
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Re: 318 rear main seal replacement

Post by RonHall76 »

Have a 1971 318 (GM318R 34232545) that was dropped into a 67 W100. Do not want to remove the engine. Truck was already lifted and has hedders so oil pan is easy to get at. Already have starter off and engine oil filter off/oil drained. Currently in the process of replacing the expansion plugs (just started to weep on a couple) and engine mounts. Thinking I also should replace the rear main seal.

Based on this post/thread, it appears I can do it without removing the tranny, I just have to remove the oil pan. It also appears that the rope seal was replaced by a 2 piece rubber seal. Found an old Mopar part# online - (3549392). Cannot find a current cross reference.

!. Does anyone know the correct part and a source for the 2 piece seal?

2. Part of the reason I am doing this is a slight weep at the hole for the bell casing/flywheel cover. Have picked up all the parts to replace the clutch, and have a rebuilt 4 spd (same as existing) that I want to install. Wondering if it is easier to get at the seal when the clutch and tranny work is done ... or will we still have to remove the oil pan (no noticeable leaks)?

3. Part # for pan gasket? Will 360 gasket also work?

FYI - Reason for not yanking the engine. This is a runner that I use around the property (has push bumper with electric winch). Have a frame off/engine rebuild (318) restoration going on a 68 W200.

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Re: 318 rear main seal replacement

Post by PwrWgnDrvr »

You MUST remove the pan because the seal is under the #5 main bearing cap, which also has to be removed, along with the oil pump.

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RonHall76
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Re: 318 rear main seal replacement

Post by RonHall76 »

Makes sense ....

Noe I just need to find the proper replacement parts.

Since the pan needs to come off, makes me wonder about tackling the timing chain.

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Re: 318 rear main seal replacement

Post by Red383 »

Rockauto lists FEL-PRO BS40245
as a Rear Main Seal Set; Rubber; Two-piece

I need to do this on my Poly too.
1965 Dodge D200, 318 4-speed converted to 4x4 with NV4500 trans

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Re: 318 rear main seal replacement

Post by WarEagle »

Completed this same replacement last month on my '67 D100 318 per the process documented in this tread. Used these parts:
1. Fel-Pro BS4025 Rear Engine Main Seal Set
2. Fel-Pro OS6566C1 Oil Pan Gasket Set
3. Melling M72 Replacement Oil Pump

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