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FE Power Forums => FE Technical Forum => Topic started by: Yellow Truck on May 30, 2016, 05:54:42 PM

Title: Question about the rear cam seal.
Post by: Yellow Truck on May 30, 2016, 05:54:42 PM
I had the engine mostly assembled when I realized the machinist had put the rear cam plug in backwards (concave rather than convex). To remove it I had to drive it out from one side and did a little damage to the chamfered lip. Being a rookie at this I have no idea what kind of pressures this seal will be exposed to, I realize it is right up at the end of the cam which will be spinning at 1/2 engine rpm, so there may be considerable local oil pressure.

My question - is the Motorcraft diesel silicone good enough or should I consider something else, such as epoxy to complete the seal? Do I need to worry about the new seal (I have the right part) going in too far and taking the endplay out of the cam?

(http://i1135.photobucket.com/albums/m637/410dyno/2016-05-30%2016.23.18.jpg)
Title: Re: Question about the rear cam seal.
Post by: jayb on May 30, 2016, 06:05:25 PM
If you have a new cam plug it should stop on a lip in the block, before it comes close to hitting the cam.  The Ford TA-31 diesel sealer should be fine to seal it, because there really shouldn't be much pressure at the plug, but having said that I have had them pop out.  I've put mechanical stops there in the past, drilling and tapping a couple of 8-32 holes on either side of the hole boss and using some short screws and either washers or a strap to keep the plug in place.  Almost nobody does stuff like that, but after you've had one pop out you take precautions...
Title: Re: Question about the rear cam seal.
Post by: blykins on May 30, 2016, 06:31:59 PM
You'll be fine.  Put some silicone around the lip of the new plug and drive it in.  There's a shoulder that it sits up against, so you can't drive it in too far.  That's the beauty of installing it the correct way, there is a mile of room between the end of the cam and the plug. 

I usually take some silicone and fill in the gap around the plug after you drive it in.  Smooth it out with your finger, wipe off the excess, and you're done. 
Title: Re: Question about the rear cam seal.
Post by: fekbmax on May 30, 2016, 08:07:26 PM
I noticed on the pond block I have that there are 3 small threaded holes around the outside of the cam plug for some kinda strap or restraining plate. They look factory but I guess could have been done by the previous owner. It's a good idea.
Title: Re: Question about the rear cam seal.
Post by: C6AE on May 30, 2016, 08:29:55 PM
There is theoretically no oil pressure there. If you notice on your posted image there is a drilled hole through the rear of the cam next to the center drill. (Your cam may have 2 drilled holes) This hole allows all oil pressure in the void between the cam plug and the cam to vent through that drilled hole to the crankcase.

I have drilled and tapped screws into my Pond block, but because of the different expansion rates of steel plug/aluminum bloc. I also made up my own aluminum plug with an o-ring seal

(I have also had a cam plug pop out...)
Title: Re: Question about the rear cam seal.
Post by: Nightmist66 on May 30, 2016, 08:57:58 PM
I put the plug in dry and finish with a multi-purpose epoxy. The multi-purpose epoxy comes off decent with a chisel and chips right off. JB Weld seems to be very difficult to get off later. JMO
Title: Re: Question about the rear cam seal.
Post by: Yellow Truck on May 30, 2016, 09:31:16 PM
I love this forum.

I was thinking I was ready to put in the bushing, mount the flywheel and clutch and find out if I can get the engine in with the headers on (on the 4WD trucks one header wraps around the engine mount) - but when I put in the new throw out bearing I noticed the points of the clutch fork are worn flat. I think I'll get a new one while I can get at it. New boot and spring while I'm at it. It will slow me down a little but better than having to go back later.
Title: Re: Question about the rear cam seal.
Post by: Yellow Truck on May 31, 2016, 10:42:28 AM
The fork - C3AZ-7515-C - does not seem available at any price. Will have to use the old one, at least I can get on with the installation.
Title: Re: Question about the rear cam seal.
Post by: 66FAIRLANE on May 31, 2016, 06:56:46 PM
You may be able to build it up with weld and grind/file it back to shape.