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post #1 of (permalink) Old 09-03-2003, 09:52 PM Thread Starter
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oil leak problem on sbc

i'm having some trouble fixing a couple of oil leaks on my 383. i changed the intake manifold and there was no problem for a long time. now it leaks oil like no other. i've replaced the intake manifold gasket twice now and the valve cover gaskets twice also but it always seems like the oil is coming from the top of the engine. is there anything i'm missing? also how hard is it to change the rear main seal? is it possible to do it without pulling the transmission? and anybody in the rapid city area want to show a young college kid some good places to wheel around here?
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post #2 of (permalink) Old 09-03-2003, 10:39 PM
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Re: oil leak problem on sbc

The valve covers are the most likely source for a leak. I just learned this lesson again a few weeks ago. I was sure that I had a rear main seal leak, took all the bolts on the oil pan off to replace the seal when I saw oil drops from the corner of the head. It turned out to be a crack in each of the valve cover gaskets and the oil collected at the bellhousing, just like a rear main seal leak. Fortunately, I had not yet broken the seal between the pan and the block so I was able to just put all the bolts back. When you replace a valve cover gasket, make sure that the lips are flat and straight, especially at the bolt holes, and don't overtorque. Rule out all other possibilities before you work on the rear main seal.

To replace the rear main seal, you need to pull the oil pan, loosen all caps so that the crankshaft drops slightly and tap the old seal out with a brass drift.
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post #3 of (permalink) Old 09-04-2003, 12:05 AM
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Re: oil leak problem on sbc

First off when you do the intake gaskets do you use those little worthless end seals? (the little narrow cork or rubber strips) If you use them they are famous for slipping out of place especially if you use sealant. I throw them as far as i can and just use a GOOD silicone(1/4 " bead) instead and never had one leak that way. I like the Mopar black silicone the stuff is awesome, I don't use anything else and neither has any shop I've worked at once they tried it.

The valve covers can be tricky too, make sure the flanges are straight then use some weather strip adhesive and glue them to the covers. Then clean the block of all oil and old gasket and DO NOT use any sealant. DO NOT over tighten the bolts they are not lug nuts.

Also check your oil pressure sending unit it's right back there below and beside the dist. and it's often overlooked for the source of a oil leak.

Check all of the above first before you jump into the rear main seal. I've seen a lot of rear main seals replaced for nothing. Depending on what year you SBC block is you may or may not have to pull the oil pan and either-way you'll end up pulling the tranny.
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post #4 of (permalink) Old 09-04-2003, 01:01 AM Thread Starter
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Re: oil leak problem on sbc

well i dont think its the oil pressure sender as the oil is only on the one side of the small hump on the back of the engine. the intake gasket was seal with just silicone on the front and back. i'll pull that valve cover and see if its warped at all. got another kinda off the ball question. could you add lucas power steering stop leak to a transmission? it completely stopped my powersteering leak, and it seems only slightly thicker than 75-90w. i have a leak where there is that adapter plate between the 300 and 176
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post #5 of (permalink) Old 09-04-2003, 04:02 AM
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Re: oil leak problem on sbc

I'm not a big fan of any stop leaks as they tend to cause more problems down the road (plugging lines and gunking things up) and I would definitly not use a power stearing product in the tranny (2 very differenty types of fluids). You may also want to check the seal around the distributor. My oil pressure sender on my sbc was giving me the same kind of problems your having, but I had a rear main problem on top of that. As long as it is a 2 piece rear main, you don't have to pull the tranny, you can drop the pan and rear main and then get to the top half of the rear main seal.
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