Fixing a 400 rear main

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Jan 13, 2002 | 08:43 AM

oleblue70

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Fixing a 400 rear main

Jan 18, 2002 | 08:39 AM

Jake65

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From: Osage County

Fixing a 400 rear main

The old 79 250 4X4 I posted about getting last week (I got it) Well I put it in the shop last night to see if it would run. (It has not moved in 7 years) I put the belts on it and poured a little gas in the carb and before long she ran really good.... Then I noticed oil running out near the bell houseing! I'm guessing the rear main?
Does anyone have any other guesses? Is is a lot of work to fix? Whats the easiest/best way to get the job done?

Jan 18, 2002 | 09:36 AM

beartracks

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From: Albuquerque

Fixing a 400 rear main

It may be more likely you've got a valve cover leak. Or maybe the back of the mainfold. Also check the oil pressure sender unit behind the manifold.
Check the simple stuff first!

Bear Tracks

Jan 18, 2002 | 09:54 AM

Jake65

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From: Osage County

Fixing a 400 rear main

[updated:LAST EDITED ON 18-Jan-02 AT 10:55 AM (EST)]This is a fairly sugnifiguent amount of oil running out (when the truck is running). The sending unit is an idea I will look at defenatly. To much oil to be a valve cover though.

Jan 18, 2002 | 11:23 AM

beartracks

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From: Albuquerque

Fixing a 400 rear main

Well usually a rear main isn't a gusher. It's made of neoprene. The valve cover on the other hand may be cork and dry out. The senders can split and leak quite a bit. If you have a mechanical oil pressure gauge it could be the line.

Good luck,
Bear

Jan 18, 2002 | 12:11 PM

Jake65

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From: Osage County

Fixing a 400 rear main

[updated:LAST EDITED ON 18-Jan-02 AT 01:13 PM (EST)]IF the rear main ain't a gusher then thats not it:7 . Cause it leaked a nice puddle when it ran. There is a oil pressure gauge that was installed in the truck and it was jumping like someting was wrong with it. Maybe oughta check that huh:-X11 ?
Thanks I'm gonna be afull glad to not have a rear main leaking. I always guess the worst first.

Jan 22, 2002 | 09:16 AM

Jake65

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From: Osage County

Fixing a 400 rear main

Ok Its not the oil pressure sending unit and its not a valve cover. It seems to be leaking from behing the flywheel cover. Would a pan gasget leak that much?

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Jan 22, 2002 | 10:39 AM

dfisher1

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From: Gainesville, FL

Fixing a 400 rear main

Jake,
A pan gasket can leak that much but, it has to be installed incorrectly. It would not just leak like that even over an eternity of time. Is it possible the motor oil is overfilled? If so, then a rear main could pour oil. Or maybe your just over estimating what your seeing. Could it be automatic tranny fluid? I saw an old pontiac that had wasp nest in the tranny vents and cause it to puke tranny fluid when shut off. Just a guess????
My Way is the Highway
KingFisher

P.S. If the motor had excessive blowby a pressurized crankcase could cause a rear main to leak large amounts of oil.