Rear Main Seal

S

Super Dave

Member
I have recently (couple of weeks) purchased a 1974 series 100 pickup, step side, with a 345 motor, 2bbl and 727 transmission and 3:73 third member.

The rear main seems to be leaking a good amount, though I suppose it could be coming from some other location and working its way to the rear of the motor.

I know the store sells a rear main seal. It looks to be a one piece seal.

My questions:

1. Do I have to drop the transmission to replace the rear main seal?
2. Are there any other "special" or "unique" considerations I need to be aware of?

Thanks,

dave
 
Yes, the transmission must be removed to service the rear main crankshaft seal. And the flex plate will also have to come off. The starter can stay in place for this job.

The seal kit includes replacement side seals for the main bearing cap. To change those, the pan has to come off.

Once the seal is removed, the crank hub must be inspected carefully for a worn "groove" in it. If a groove is present, then a repair sleeve must be installed or an "alternative" method does exist for placing the new sleeve in a different location on the hub but that process is very tedious.

Anytime the transmission is removed and the torque converter position disturbed, the seal in the front of the transmission where the converter hub penetrates should also be replaced along with the bushing behind it. This can be done without tearing into the transmission however.

When the flex plate is re-installed to the crankshaft, all of the retraining bolts must have clean/dry threads, and then the threads treated with a sealant. Otherwise oil will pour out of all the bolt positions as oil wicks past the threads.

Read through this thread for some information regarding rear main seal replacement:

http://www.forums.IHPartsAmerica.co...tallation-IHOnly-supplied-gaskets-others.html
 
Thanks michael,

in the gasket set, is the repair sleeve and transmission seal in the set or is it ordered separately? Seems prudent to have the sleeve and trans seal in hand.

I will just keep the oil level up until I can do a closer look to see if it actually the rear main leaking or coming from another location.

I also note that the oil pressure gauge is just a couple needle widths from nothing... And another thread was talking about the sending units being problematic... What are the chances that the "possible" rear main and low oil pressure are related... Or is just the sending unit?

My brother owns a front end shop in mcminnville. We did a once over on the front suspension. The driver side lower ball joint is just starting to show signs of needing replacement and the passenger side is not too far behind. The driver side upper ball joint has a torn boot. So, I will be scaring up a full set of uppers and lowers just for giggles.

The motor runs great, pulls strong. The carb was rebuilt to remedy a flat spot that killed the motor every time. I now have a minimal flat spot that I can feather through (but would rather not), but only in (d)rive. When in 2nd or 1st, it purrs like a kitten from a dead stop... Must be something in the vacuum demand cycle.

Speaking of vacuum, my brother and I did a check of all the vacuum hoses and it seems that a po had optimized the motor and left all the spaghetti in place to satisfy prying eyes. We tossed it all. I only need to address the pump and associated hoses to fully optimize the motor... Which is exempt from deq... So who cares. But the real frosting on the cake, was the vacuum hose going the the vacuum advance on the distributor. Seems that someone had cut the plastic end off a cheap ballpoint pen and used it as an "adapter" to join the two different diameters of hose... I practically wet my pants laughing!

Then there is my "special" fuel gauge. It seems I have the only IH self replenishing fuel system... The faster I go the more fuel the gauge registers... But only to 3/4 of a full tank...

Lastly, my temp gauge never moves... Must be the ugly step child to the oil pressure gauge... So I figure a temp sensor is in order, along with a new thermostat, just to be safe. What temp rating is recommended for the thermostat?

Being an old Chevy and chrysler speed freak guy, some of this IH stuff looks to be a real departure from the "norm." should get real interesting...

Dave
 
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