Help- oil leak
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Elder User
Joined: Apr 2001
Posts: 673
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From: San Diego
Help- oil leak
Hi guys,
I ran my engine (1978 302) for a while today and dialed in my timing, voltage, cooling. Everything works fine, but I have this oil leak. It has been so long since I ran my truck, I forgot about it. When the engine was out, I replaced the gaskets, but Im still leaking oil from the back of the pan where the engine meets the transmission. Im sure I installed the gaskets right, but maybe not. Im also thinking I might have blown something loose when I ran the engine with minimal oilpan bolts. Is there any way to tell if its the pan seal, or a rear main seal?
Where is the rear main located? Ive heard the term, but Im not familliar with the rear main. I do know that ever since Ive had my truck, oil has leaked from that same spot, and Ive put 3 different gasket sets in there.
Any insight?
Thanks!
Rich
I ran my engine (1978 302) for a while today and dialed in my timing, voltage, cooling. Everything works fine, but I have this oil leak. It has been so long since I ran my truck, I forgot about it. When the engine was out, I replaced the gaskets, but Im still leaking oil from the back of the pan where the engine meets the transmission. Im sure I installed the gaskets right, but maybe not. Im also thinking I might have blown something loose when I ran the engine with minimal oilpan bolts. Is there any way to tell if its the pan seal, or a rear main seal?
Where is the rear main located? Ive heard the term, but Im not familliar with the rear main. I do know that ever since Ive had my truck, oil has leaked from that same spot, and Ive put 3 different gasket sets in there.
Any insight?
Thanks!
Rich
Senior User
Joined: Oct 2003
Posts: 410
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From: Texas
I would have to say its probably the rear main seal, is it leaking while running? the last leak I had like that was a 302 and it leaked bad while running and stopped while it was off. if you have room to drop the pan, you can change the seal with the engine in the truck.
Thread Starter
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Elder User
Joined: Apr 2001
Posts: 673
Likes: 1
From: San Diego
It leaks while running. When I turn it off, it leaks for a few minutes, and eventually stops. I can remove the pan, but even with my truck on stands, its a chore- and Im skinny!
~Rich
~Rich
Senior User
Joined: Oct 2003
Posts: 410
Likes: 0
From: Texas
then I would say almost 100% that it's the rear main seal. they will dry out if the motor is not being used and will leak. The best thing to do is to replace it. Like I stated earlier, if you can drop the pan, you can change it out fairly easy while the motor is in the truck.
Senior User
Joined: Oct 2003
Posts: 410
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From: Texas
The rear main is located at the back of the motor, you have to remove the main cap at the back of the motor to access the seal, half of the seal is in the cap you removed and the other half is in the upper part of the motor. Most of the time you can push out the upper half of the seal using a small piece of stiff wire such as a coat hanger you just have to be careful not too damage the crank or the bearings.
Thread Starter
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Elder User
Joined: Apr 2001
Posts: 673
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From: San Diego
Im assuming the rear main seal is not the rear PAN seal right? Im familiar with the "U" shaped rubber gasket on either ends of the pan, but where is the rear main located? Will I see it once I get in there?
Thanks!
~Rich
Thanks!
~Rich
Senior User
Joined: Oct 2003
Posts: 410
Likes: 0
From: Texas
you are correct, it's not the two pieces of the gasket for the oil pan, you have to remove the rear main cap to get to the seal, part of the seal, the bottom half will be in the cap you remove and the upper half will be in the block. you will need some elbow room, for the main cap bolts will need to be re-torqued. The seal looks something like this, check out this link.
http://www.dallasmustang.com/page/pr...p?product=2723
http://www.dallasmustang.com/page/pr...p?product=2723
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Tuned
Joined: Jun 2005
Posts: 372
Likes: 1
From: Walnut Creek, CA
The rear main seal comes in two halfs. There are two different types available. I got mine from John Mummert at ford-y-block.com. I purchased a graphite rope kind instead of the rubber one. Replacing the "bottom" half that comes out with the main seal retainer is easy the upper half needs to be pulled or pushed out. THere is a tool called a sneaky pete made but Lisle(sp) that you can buy for about $8 which helps to remove the upper half. THe problem is trimming it to the correct length with the crank in place. There is still the possibility of leaks even after replacing if the main seal retainer is warped or the shaft itself is worn and doesn't contact the seal well. You can buy a new main seal retainer from Mummert as well since you can't find them repro anywhere anymore.
Chris
Chris
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Post Fiend
Joined: Sep 2004
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From: Near Fresno, California
Replacing the rear main seal is a big job - and the first time you do it you are likely to damage the upper rubber or rope - which ever one you use. I suggest you get a good manual and follow the directions carefully. It helps to loosen the other main bearing caps so the crank can drop down a bit.
When I was a kid and all you could get was the rope type, the line mechanics would wrap the rope seal with a soft copper wire and pull it into place. They would then cut the wire, leaving the part that was around the seal. They claimed the soft wire would not hurt the seal or the crank, and would eventually wear down anyway.
Good luck - it is a tricky job easy to screw up, but well within the ability of most home mechanics.
When I was a kid and all you could get was the rope type, the line mechanics would wrap the rope seal with a soft copper wire and pull it into place. They would then cut the wire, leaving the part that was around the seal. They claimed the soft wire would not hurt the seal or the crank, and would eventually wear down anyway.
Good luck - it is a tricky job easy to screw up, but well within the ability of most home mechanics.
Posting Guru
Joined: Aug 2003
Posts: 1,243
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From: Michigan
Rich, Just to have something to do check the seal at the rear of the intake manifold. See if there is oil on the rear of the heads and the top of the trans. They will leak at the corner where the intake meets the head and block if no sealer was applied to the sharp corner and then run down the block and drip off the edge of the pan.
Chuck
Chuck
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