Can't Find The Leak???? - Chevelle Tech
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post #1 of 7 (permalink) Old Apr 14th, 09, 1:26 PM Thread Starter
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Can't Find The Leak????

Hey guys, I have an oil leak that i just can't seem to locate, at least sliding under the car on stands without the use of a lift. I tightened every oil pan bolt, some really needed it, so i thought that might be the issue, but not entierly as i still get a drip, although not as big, after driving the car for awhile and parking it.

It does not appear to be the rear main seal either. The car is a 4spd, and looking at the back of the motor from underneath, it is totally dry at the back of the bell housing, where the tranny goes in.

I did notice it extremely 'wet' around the oil filter. I'm wondering if it's the filter housing, or pressure sending unit which is near-by. New filter screws on nicely, so no leak there.

'71 454 big block by the way.
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post #2 of 7 (permalink) Old Apr 14th, 09, 1:33 PM
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Re: Can't Find The Leak????

Here you go, its messy but it will find the leak the first shot out, guaranteed.

Warm up the motor, shut it off so the fan isn't blowing any air around it.

Take a plastic bottle of baby powder, spray it all over where theres oil or a chance of a leak.

Let it set for a while, then don't touch it but take a light and look real good and you will see where the oil will run through the powder leaving a distinct brown line.

And you guys, no comments about the diaper business and the brown streaks.

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post #3 of 7 (permalink) Old Apr 14th, 09, 3:12 PM
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Re: Can't Find The Leak????

sometimes the rear rail on the intake manifold will leak a little bit and it will look like a leak at the oil pan. valve covers can do this, too.
but given where it's leaking for you, i'd guess oil pressure sender. it's kind of a pain to get the fitting to not leak, especially if you've got a T or 90 degree fitting up there somewhere.

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post #4 of 7 (permalink) Old Apr 14th, 09, 3:15 PM
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Re: Can't Find The Leak????

My experience with oil leaks start underneath and go as far forward as you see oil then go up as high as you see it. It will be very close. Remember all engine oil leaks travel down and then back. Usually when you see oil dripping thats not it. Forward and up.
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post #5 of 7 (permalink) Old Apr 14th, 09, 5:28 PM
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Re: Can't Find The Leak????

I had a slow leak recently from the 7/16" allen head plug right above the oil filter boss. I thought it was the remote filter adapter, nope, then I thought it was the rear main seal, nope. Finally, I saw it after looking closely with a flashlight from above.

What sucks about it is I had to have the inner fender out, and take apart the z-bar linkage to get to it with a couple of extensions on the ratchet. This was also put in by the machine shop, so I never checked it before.

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post #6 of 7 (permalink) Old Apr 14th, 09, 7:54 PM
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Re: Can't Find The Leak????

leaky dipstick tube will run down the side of the block,make it look like the filter or oil plugs leaking,then the oil hits the flywheel & get spayed all over just like what i just fixed on the wifes camino
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post #7 of 7 (permalink) Old Apr 14th, 09, 9:07 PM
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Re: Can't Find The Leak????

Rear of valve cover gaskets, oil sender (as mentioned), rear of intake manifold (as mentioned) or dizzy gasket.


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