Installing rubber dowels (Advice Needed)

1941 - 1945, MB, GPW Technical questions and discussions, regarding anything related to the WWII jeep.
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semberae
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Installing rubber dowels (Advice Needed)

Post by semberae » Wed Sep 15, 2021 12:10 pm

I need to change the rubber dowels on my rear main. I am getting oil seepage in this area. Last time I replaced oil pan gasket the dowels had a loose fit. Engine is in place in Jeep, so I will be doing this from underneath. Any advice on removing old dowels, cleaning holes, installing new ones, sealants used, tricks to install, etc. would be greatly appreciated.
Thanks in advance.


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dpcd67
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Re: Installing rubber dowels (Advice Needed)

Post by dpcd67 » Wed Sep 15, 2021 12:28 pm

I use permatex on them, and make sure they protrude 1/4 inch. Not much else to it. Many do not use sealant. But also put it on the cap surface. Are you sure that is where it is leaking from?
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Wolfman
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Re: Installing rubber dowels (Advice Needed)

Post by Wolfman » Wed Sep 15, 2021 12:33 pm

The dowels are loose in the holes ??
Sounds like they were not installed correctly .
Sounds like you are just going to remove the old dowels and install new ones. Not remove the rear main bearing cap.
The old dowels should just pull out. Needle nose pliers or a sharp O-ring pick to snag them and pull them out should do the job.
The dowel holes are 3/8" diameter. A 3/8 drill bit will clean the holes out. I also use a 3/8 drill bit in the dowel holes when I install the rear main cap for alignment fore and aft.
Spray carb. cleaner into the holes and blow the holes out with air.
The new rubber dowels will or should slide in the holes easily. A loose fit.
The dowels will also be too long. Do not cut them off !! Suppose to be this way.
When you are ready to install the oil pan, put a drop of Ultra Black gasket sealer on the end that goes into the hole.
Put a light coat of oil goes on the outside of the dowel and insert both dowels into the holes and install the oil pan. The gasket sealer will seal the bottom of the hole and hold the dowels in place.
As the pan is tightened up, the pan will push the dowel into the hole, causing the dowel to swell up in the hole and form a tight seal. Oiling the dowel aides the swelling and sealing process.
This is also why you don't trim the dowel flush with the pan gasket surface of the block so the swelling up will happen.
Add oil and go have some fun !
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dpcd67
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Re: Installing rubber dowels (Advice Needed)

Post by dpcd67 » Wed Sep 15, 2021 4:10 pm

If you trimmed off the dowels flush then you created the leak; they squash and fill the holes. Although I had one engine with dowels made from RTV and it didn't leak, but don't do that.
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Re: Installing rubber dowels (Advice Needed)

Post by Bruce W » Wed Sep 15, 2021 5:37 pm

dpcd67 wrote:
Wed Sep 15, 2021 4:10 pm
I had one engine with dowels made from RTV and it didn't leak, but don't do that.
:x That’s what the Vega used :lol:
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Re: Installing rubber dowels (Advice Needed)

Post by Wolfman » Thu Sep 16, 2021 7:19 am

VEGA :twisted:
My former mother-in-law had one of those and I got stuck with working on it. :evil:
Hated that car !!
GM used RTV to seal the front and rear of the intake manifold to the engine block on later small block V-8s. Never was too fond of the idea.
I have heard of using RTV instead of the rubber dowels. ???
Not big fan of the idea.
Use the rubber dowels and do as TJ & I suggested. You will be lot happier.
Mike Wolford
CJ-2A
VEP GPW
Comm./Inst. SEL
AOPA ( 47 yrs)
EAA ( 47 yrs)
4th Inf. Div. - 5th Inf. Div. - 2nd Armor Div. - CIB


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