Rear Main Seal Replacement Question

Pete1325 · Post by **Pete1325** » Mon Mar 09, 2009 9:27 am

What's involved in replaceing the rear main seal? I can buy the "two peice" seal from the local parts store for under $25. I heard you don't have to remove the engine due to it's a two peice design.

Can I do this in my garage with my hydraulic jack, jack stands and normal tools or do I need a special tool? Or should I just take it a mechanic with the proper equipment?

I haven't received my shop manual yet but I'm getting impatient and want to drive the car (I won't drive it with the leak) so any insight will help.

If someone can walk me throught it I think I can handle the job.

Thoughts??

Thanks,
Pete

Wildcat · Post by **Wildcat** » Mon Mar 09, 2009 4:06 pm

Have you ever done anything like this before? If it is a 390, it can most likely be done with the block in the car. It usually requires removal of the motor mount nuts, carefully raising the engine (on the crank not the pan)enough to put small temporary wood spacers between the block and motor mount. You will want to drain the coolant and maybe remove rad hoses and watch that the fan clears the shroud while jacking. Then usually you can drop the pan enough to remove the oil pump pickup tube and slide the pan out. When this is all done, pull the rear main cap. I would suggest a split lip rear main seal. If the old seal is the rope type variety, there is a tool that works like the old Chinese finger toy for pulling the top half of the seal or I have seen some guys thread a screw into one side of the rope and then while slowly pulling with some VGs on the screw at the same time as turning the crank the top half will slide out. There are specific instructions for the new seal installation. Then question if now is a good time to replace the oil pump. Be sure to clean the old oil pickup screen before everything goes back together.

Pete1325 · Post by **Pete1325** » Mon Mar 09, 2009 5:06 pm

Hi...........thanks for replying. No, I've never done one and by the sounds of it I might leave this one to an expert.

I'm just nutty enough to try anything after I do the research, but laying on my back on a cold garage floor in Chicago not knowing exactly what I'm doing does not sound like fun.

I spoke to a local Ford dealer, their labor rate is pretty high (I thought) at $104 an hour. They said it will take 6 hours to do it??????? Plus the part.

Does this sound right?

Thanks again,
Pete

Joe Johnston · Post by **Joe Johnston** » Mon Mar 09, 2009 6:02 pm

Don't know what the labor rates are in the Windy City but you might call a couple of shops that specialize in vintage car repair to get a comparrison, or even a different Ford dealer. I know what is involved, and would think a mechanic that does this by himself in 6 hours will be hustling. I'm sure it can be done in less time, but that is probably the flat rate from their shop quote book and a fair representation of the time involved. I am facing the same problem and will take it to a mechanic to do for me and with the way he operates I hope it gets done in a week!!

Pete1325 · Post by **Pete1325** » Mon Mar 09, 2009 6:32 pm

Thanks for your input, I'll call around.

I wouldn't care if it took a week........as long as he only charged me for three hours of work. LOL!

Pete

redstangbob · Post by **redstangbob** » Mon Mar 09, 2009 6:43 pm

There's at least a couple of guys in your area that might be able to steer you to a good shop

6 hours is fair, labor rates sure seem to keep going up!! Lets see who comes along here in a little while. Bob C

tbirdjim · Post by **tbirdjim** » Wed Mar 11, 2009 2:53 am

Are you sure it is the rear main seal?

sometimes the intake gaskets leak at the back of the motor and it looks like it's coming from the rear main if all you see is oil on the floor.

boaterbob · Post by **boaterbob** » Wed Mar 11, 2009 7:24 am

Yes, I agree with Jim also the the gasket along the back of the intake. Check it good.

Pete1325 · Post by **Pete1325** » Wed Mar 11, 2009 9:15 am

If it's only oil on the floor does that mean it could be the intake manifold gasket?

If it's the rear main seal what else beside oil would be leaking?

Thanks,
Pete

60fore · Post by **60fore** » Wed Mar 11, 2009 9:51 am

Pete, if the rear main was leaking it would only be oil. I think what TBirdJim means is that an oil leak on your floor near the back of the engine isn't necessarily coming from the most obvious place - the oil pan area. Sometimes it's a leak from higher up on the engine (the back of the intake manifold) and the oil runs down and drips from the back of the oil pan area. The rear intake is a common place for 390's to leak oil so make sure to check this out carefully before you condemn the rear seal.

Pete1325 · Post by **Pete1325** » Wed Mar 11, 2009 4:19 pm

Thanks, I'll check. I haven't had time to pressure wash the engine yet, it's been freezing or below freezing temps here in the Chicago area.

I did crawl around under the car. I snugged up the oil pan bolts and wiped it down pretty good. It doen't look like the oil is coming from the pan gasket.

I did notice that oil is dripping on "top" of the exhaust pipe on the one side. The oil is dripping from both sides of the trans housing and in a few puddles under the car.

If it is the rear seal would it drip in one spot or several spots?

Would oil drip under pressure only? Also, it doesn't start dripping until the engine is running a few minutes and then drips for a while after I turn it off.

Does this help figure out anything?

60fore · Post by **60fore** » Wed Mar 11, 2009 6:02 pm

Somebody please correct me if I'm wrong, but I think there's a flourescent dye you can add to your engine oil to help in finding the source of leaks. This may be an option to help you track it down.

TsNStangs · Post by **TsNStangs** » Wed Mar 11, 2009 6:24 pm

Absolutely! I used to have a mechanic that sweared by the stuff.
Check here: http://www.autobarn.net/fluorleakdet1.h ... oogle_base

tbirdjim · Post by **tbirdjim** » Thu Mar 12, 2009 3:12 am

Pete1325 wrote:
I did notice that oil is dripping on "top" of the exhaust pipe on the one side. The oil is dripping from both sides of the trans housing and in a few puddles under the car.

If it is the rear seal would it drip in one spot or several spots?

Would oil drip under pressure only? Also, it doesn't start dripping until the engine is running a few minutes and then drips for a while after I turn it off.

Does this help figure out anything?

Possibly, it could just be the valve cover gaskets, that would explain leaks on both sides,

as for a rear main seal, you can pull the inspection cover from the bell housing and see if there is any oil inside, let it run and see if any oil comes from inside the bell. also, you can either drive it a while with the cover off and see if the leak is from inside, or put the cleaned out cover back on drive it and pull it to see if there is fresh oil.

the problem with some of this is, if it is coming from somewhere else, and it is not addressed , it will just be a mess anyway.

Pete1325 · Post by **Pete1325** » Thu Mar 12, 2009 9:48 am

Thanks for all the help thus far, I looks like I'll be busy this weekend trying to find the problem. I'll keep you guys posted.

Thanks,
Pete