Author Topic: Oil Leak  (Read 2718 times)

Offline 81chevy350lwb

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Oil Leak
« on: December 13, 2005, 11:09:00 PM »
I have had a persistent oil leak in my 80 Big 10(350). And today I began the process of replacing the rear main, but when I got down there I discovered that the oil pan gasket needed replacing and the oil pan bolts were not snug enough and I think thats where it was leaking.  I didn't replace the rear main as there was no oil on the flywheel or excessive oil on the bearing cap area.  I drove at speeds up to about 50 MPH and it did fine but when I drove home going 70(country back roads) it leaked almost a quart of oil and had a bad knock when I stopped.  Any help would be appreciated, I have been trying to track this thing down for awhile now.  And I use 10W30.


Offline roundedline

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Re: Oil Leak
« Reply #1 on: December 14, 2005, 10:14:00 AM »
How "not snug enough" were the bolts.  The aren't supposed to be very tight, especially if you have a cork gasket.  If it is tight enough to push the gasket out, it is WAY too tight.

After you "fixed" it and it didn't work, did you look under it and see if you can tell where the oil leak is coming from?

Chris Lucas
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Offline 81chevy350lwb

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Oil Leak
« Reply #2 on: December 14, 2005, 06:18:00 PM »
The bolts were almost barely even there. I didn't over tighten when I put it back on.  I didn't get a chance to see where the leak is coming from, but im going to clean under there and see if I can tell this weekend.  Could the oil pump be bad?  The oil didn't leak below the minimum line but there was a bad knock even at idle.


Offline Lt.Del

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oil leak
« Reply #3 on: December 17, 2005, 08:09:00 PM »
Your oil pump would not be bad.  A quart low is a quart low, don't blame it on the pump....what does your oil pressure read?

Put some cardboard under your truck at idle.  See where your leak is.

As for your knock, take your valve covers off and see if your valves are out of adjustment. A valve out of adjustment would cause a heck of a knock.   Hopefully that is your problem.  If not, you got serious problems.


just my 2% of a dollar worth.

SgtDel

Edited by: SgtDel at: 12/18/05 10:22 pm

Offline 81chevy350lwb

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Oil Leak
« Reply #4 on: December 19, 2005, 09:13:00 PM »
Looks like I need a new oil pump. The oil pressure went from 45 at idle to 15 after driving for 15 minutes. Still don't know if I have a leak or not. But my friend who is a mechanic recommended going to a straight grade oil.  Do you guys have any tips or things I should look out for when I replace the oil pump?


Offline Lt.Del

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oil leak
« Reply #5 on: December 20, 2005, 10:47:00 AM »
Changing your oil pump is pretty simple.  Just ensure you torque the two bolts according to specs.

It is a messy job. I would drop the oil pan and let the crank etc. drip for a while ( a long while) while you go inside and have a beer. If not, you will have oil all over you.

Be careful w/ the turning rod from the distributor that turns your pump.  Make sure you seat the pump correctly and don't force it.  You'll know it is fine when the pump fits flush w/ the block.

The hardest part is getting that dang oil pan back on w/ the new gasket.  Lining that turkey up w/ all the little bolt holes can be trying.  I use fishing line and tie line around a few bolt holes after placing the gasket on the pan.   If you have automatic transmission, ensure your metal bracket that holds these trans fluid lines (via a right side oil pan bolt) goes back the same way you took it off. This keeps the trans lines from moving around and getting pinched or punctured.

You mentioned your pump goes from 45 to 15 lbs.  You may wait to get more input on this, but that doesn't seem too bad.  Mine is new and read 60 lbs.  I forget how far it drops at idle. But it is a significant drop at idle, so that 15 may be a little low.   I don't know how many miles are on your motor, if/when you take your oil pan off, look at the pickup screen of the pump to see if it is clogged w/ any debris.

If i recall, you do not have to remove the starter when removing oil pan.

SgtDel
79 383 stroker

 

Edited by: SgtDel at: 12/20/05 10:56 am

Offline ChevyGuy

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Re: oil leak
« Reply #6 on: December 20, 2005, 05:01:00 PM »
The saying about oil pressure is you want about 10lbs per 1000 rpms.... when the oil warms up its going to get thinner. The oil leak might be a small hole in the pan or the back of the intake is leaking.