Resealing the Cam Housing

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rmel
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Resealing the Cam Housing

Post by rmel » Wed Dec 30, 2020 2:19 pm

If you are observing oil leaking along the seam of the Cam Housing (Housing between the rear
of the motor and Bell housing), the housing seal may be failing.

Both my trucks were leaking a wee bit of oil along the Housing seam. I have removed and
resealed the Housing on both trucks now -- recently on the 712. I just got sick of applying
RTV along the seam. From what I have learned (and experienced), the most common place
a leak can occur is the seam directly along the base of the Starter motor as that is a stress
point. That is where I was leaking on the 710 and there is not enough gap in there to get a
good bead of RTV to stop it. On the 712 the leak was on the opposite side, but as I discovered
this was due to a poor resealing from prior maintenance done before export (ironically).

If you are pulling your Tranie for a clutch job or for Tranie service that's the time to think about
digging into this. Pulling the Cam housing also makes replacing the rear main seal a lot easier.
This is definitely a DIY job with a few minor tricks. If your going this route here's a few pointers.

First follow these excellent steps provided by McCall Pinz to get down to the removal of the
Flywheel. viewtopic.php?f=13&t=10780

Next:
1. DRAIN the Oil from the Engine -- the Oil is ABOVE the bottom of the Housing seal.
2. REMOVE the Oil dip stick tube -- put the Acorn nut back on to prevent the Oil cooler seal from failing.
3. REMOVE the Starter and Starter mounting plate.
4. REMOVE 14 M8 nuts and washers -- the washers are special purpose Aluminum don't lose them.
--> If the housing did not separate freely use a Rubber hammer to break the seal -- be gentle.
5. Clean the Housing and all mating surfaces, use plenty of Brake cleaner and Scotch-Brite.

Housing REMOVED and surfaces cleaned:
Timing-2.jpg
Timing-2.jpg (887.43 KiB) Viewed 385 times
6. Knock out the rear main seal DO NOT throw the old seal away just yet.
7. A new seal should be pressed in just below the surface, e.g. should be flush at the back side.
If you do not have a Seal setting tool, I used the old seal as a interposer to drive the new seal
to the proper position.

8. Re-sealing -- The approach I recommend is to use a replacement gasket. Although a reliable seal can
be made W/O a gasket using the proper sealant. Note: Do NOT use RTV -- PERIOD.
8.1 Gasket Sealer: I use Hylomar AF (advanced formula), Permatex Aviation Form-A-Gasket Liquid #3 would be
my second choice. Both are "Zero gap" sealants, e.g. they flow under pressure filling only voids. Not a
commercial, IMHO Hylomar is a superior product -- if you use Hylomar be areful to use only "AF", they
do have a formulation that is also Blue that requires fitting the the components then separating, allow
time to cure then refit.
Hylomar-AF.jpg
Hylomar-AF.jpg (100.13 KiB) Viewed 385 times
8.2 Apply a fine bead of Hylomar to Engine side ONLY. The engine is sectioned so there is the opportunity for
slight height difference between casting surfaces. Use your finger to spread the sealant thin around the
mounting bolts and seam.

8.3 Gasket: OEM gaskets from either EI or SAV. You will most assuredly need to prep the gasket prior to install.
In spite of the packaging, they will have dried out and shrunk, and thus will tear if you attempt to put it on.
To re-establish the proper fit, get a water spray bottle and mist both sides of the gasket. It will twist a bit
but it will expand to proper size withing a few minuets.
8.4 Place Gasket onto studs from the top down, moving it forward to the sealant a little at a time -- be patient.
With fingers, press gasket into the sealant.
8.5 Before installing the Housing, a trick from Jim L. at Goatwerks. Find a large diameter Plastic cup. Cut it
down so that it is just slightly larger in diameter than the Flywheel flange. Place the cup inside the
the rear main seal with the cup bottom facing out (apply a scant amount of vasoline for easy removal). The
cup holds open the so that it holds open the inner portion of the seal for easy insertion and cup removal.
8.5 Install Housing, there are three alignment pins. Torque to spec 22-25Nm ONLY. After initial torque, wait an
hour or two allowing sealant to flow then re-torque. Do one more time for good measure.

Hylomar Blue Bead flowing out of seam:
Hylomar-Bead.jpg
Hylomar-Bead.jpg (738.78 KiB) Viewed 385 times
9. Final reassembly -- follow procedure outlined above for Thrust Bearing, Flywheel, pressure plate etc.

Note: I recommend re-install the Starter after Tranie is installed, although one could do it before hand.
Puller: 71' 710K 2.7L EFI aka Mozo
Follower: Sankey MK 3, 3/4 Tonne
Rescue Pinz: 73' 712M

Driver: Ron // KO0Q

ChickenPinz
United States of America
Posts: 186
Joined: Tue Feb 11, 2020 7:16 pm

Re: Resealing the Cam Housing

Post by ChickenPinz » Wed Dec 30, 2020 5:30 pm

Note: I recommend re-install the Starter after Tranie is installed, although one could do it before hand.
Why afterward?
710K

User avatar
rmel
United States of America
Posts: 1192
Joined: Sun Sep 25, 2011 12:19 pm
Location: Woodside, CA
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Re: Resealing the Cam Housing

Post by rmel » Wed Dec 30, 2020 6:00 pm

It's a possible mis-alignment issue. The Bell housing has two
bolts that go through the Starter mount. One with a capture
nut on a separate floating member. If misaligned you will
have to pull the Starter again.

Therefore, I recommend doing the Starter last.
Puller: 71' 710K 2.7L EFI aka Mozo
Follower: Sankey MK 3, 3/4 Tonne
Rescue Pinz: 73' 712M

Driver: Ron // KO0Q

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