340 Rear main seal

-
Vitamin c

Vitamin c

Vitamin c
FABO Gold Member
Joined
Dec 1, 2009
Messages
1,264
Reaction score
46
Location
Holland, MI
unfortunately it looks like I have a leaking rear main in the 70 Dart. I have a replacement Fel Pro seal to install. My Goal would be to change it in the car, without jacking up the motor, by pulling the steering linkage. Anyone have any tips, tricks, do's don'ts? I don't understand why it would be leaking, but I've confirmed it with an ultraviolet leak detection kit. It was assembled by the machine shop, so its all a mystery at this point.
 
Don't be surprised if you have to raise the engine, sometimes, to get enuff room for front of pan to get under front crank jounal/weights. I lift it enuff to put sockets between the mount pads and frame, about an inch..

Use glue, to stop the gskt falling in your face, or worse, shifting as you wiggle the pan up there.. I prefer 3M weatherstrip snot,, but any contact cement will likely work,.

4 dabs of RTV only where gskts overlap in the corners..

Make sure rear main cap has no debris on mating surfaces,

Make sure you install the main seal correctly.

Hammer/tap the pan mating suface flat at bolt holes..

hope it helps..
 
Be sure its not the oil sending unit or the back of the intake leaking also check the back of the valve covers and the filter plate to be sure before you start digging into it.

So does the ultra violet kit come with a dye for the engine oil? Sorry didn't read that far….
 
inertia said:
Don't be surprised if you have to raise the engine, sometimes, to get enuff room for front of pan to get under front crank jounal/weights. I lift it enuff to put sockets between the mount pads and frame..

Use glue, to stop the gskt falling in your face, or worse, shifting as you wiggle the pan up there.. I prefer 3M weatherstrip snot,, but any contact cement will likely work,.

4 dabs of RTV only where gskts overlap in the corners..

Make sure rear main cap has no debris on mating surfaces,

Make sure you install the main seal correctly.

Hammer/tap the pan mating suface flat at bolt holes..

hope it helps..
Click to expand...

Mad Dart said:
Be sure its not the oil sending unit or the back of the intake leaking also check the back of the valve covers and the filter plate to be sure before you start digging into it.

So does the ultra violet kit come with a dye for the engine oil? Sorry didn't read that far….
Click to expand...
Im hoping I don't have to raise the engine, but we'll see. Ive checked the sender and back of the engine, so im almost 100% sure its the seal. ill check it a couple more times with the light before pulling it apart. Yes, the ultraviolet kit come with dye you put in the oil. I am just looking for pointers and what to look for once I get to the rear main cap and seal. Does the rear seal easily push out with the crankshaft installed??
 
Gotcha, ive read what directions come with the seal and understand the inside/outside of the seal so no problem there. The seal also comes with a small plastic tool to aid in the installation. I'm assuming that tool "guides" the seal past the sharp edge of the block.
 
Vitamin c said:
Im hoping I don't have to raise the engine, but we'll see. Ive checked the sender and back of the engine, so im almost 100% sure its the seal. ill check it a couple more times with the light before pulling it apart. Yes, the ultraviolet kit come with dye you put in the oil. I am just looking for pointers and what to look for once I get to the rear main cap and seal. Does the rear seal easily push out with the crankshaft installed??
Click to expand...

Yes it pushes out. I have done this before in the car on a 318 along with replacing a rod bearing. I am almost positive even with the stock pan you will need to raise the engine up and disconnect the steering linkage. You will need enough room for the pan to clear the rotating assembly/k frame and get a clear shot at it for a good seal when you install the pan.

If it was me I would take the engine back out. Especially on that car. By the time you mess with the steering and everything, the engine could be on a stand. 2-3 hours by yourself the engine will be out of the car, pan off fixed and ready to go back in.
 
Mad Dart said:
Yes it pushes out. I have done this before in the car on a 318 along with replacing a rod bearing. I am almost positive even with the stock pan you will need to raise the engine up and disconnect the steering linkage. You will need enough room for the pan to clear the rotating assembly/k frame and get a clear shot at it for a good seal when you install the pan.

If it was me I would take the engine back out. Especially on that car. By the time you mess with the steering and everything, the engine could be on a stand. 2-3 hours by yourself the engine will be out of the car, pan off fixed and ready to go back in.
Click to expand...
Yes, ive considered that. and that may be the route I take.
 
EL5DEMON340 said:
Does it leak bad while running or just when parked
Click to expand...
Well, I would say that it leaks while running. I cleaned the whole area well with brake clean and let it set and no leaks. I then started the car and let it idle for a good ten minutes. After that I noticed the oil coming from the seal, and setting for a day noticed a trail and area on the garage floor.
 
I'm sorry, but I'd be laughed outta my own shop if I yanked the engine to replace a rear main or pan gskt..

Just for reference,,

flat rate to replace the seal in the car is 4 hrs.
flat rate to R&R engine is about 6.5 hrs,, that's experienced people with air tools..

then you gotta start replacing the seal, - another coupla hours.. so about twice as long, and then dealing with the cooling system, empty, fill, purge, etc.. no way..

I do them in the car,, but I've done many dozen , so experience helps...

hope it helps
 
The main reason I would shy away from pulling the engine would be potentially scratching up the engine compartment, engine/trans tunnel. The paint is flawless top and bottom, so I want to be very careful.
 
You all need to see this car. Your thought process would change drastically on how you would attempt to go about fixing it….. & No I am not joking at all.

Drop the complete K with engine in 1 swoop. Would be the safest way to do it without scratching anything.
 
When you get to the seal, it is viton I hope, rotate it slightly so all the joints do not line up. I also put a dab of RTV where the seal ends meet. While your in there, I'd retorque everything I could reach. Torque the pan bolts / studs 3 times with hours in between. As a matter fact, are you sure it is not the rear pan seal?
 
66fs said:
When you get to the seal, it is viton I hope, rotate it slightly so all the joints do not line up. I also put a dab of RTV where the seal ends meet. While your in there, I'd retorque everything I could reach. Torque the pan bolts / studs 3 times with hours in between. As a matter fact, are you sure it is not the rear pan seal?
Click to expand...

I'm not sure if it's Viton or not, it came in a felpro kit. As far as rotating it, that is not possible with the ears that fit in the rear bearing cap. I also checked the rear pan seal, and the leak is up further than that.
 
I cant add much to what has already been said, but reiterate tapping the oil pan flat while its removed. Makes a huge difference in the gasket staying in place. Im pretty sure I laid a thin bead of "Right Stuff" on pan 1st, then the gasket.
 
You will not have to pull the engine or lift it. I did this job 4 or 5 times trying to stop a persistent leak on my '69 Dart 340. You will have to move the centerlink over to one side and then the pan will come out by tilting the pan front down first if I remember correctly. The thing that finally fixed it was using a rear main seal from a 318 Magnum which has a slightly smaller crankshaft rear main seal diameter which makes the seal on a older smallblock fit tighter. The only difference in seals is there were no ears for the cap grooves, but I just used RTV. Leak was finally gone. It was a running joke with my friends that was doing my weekly rear main seal change.
 
Vitamin c said:
I'm not sure if it's Viton or not, it came in a felpro kit. As far as rotating it, that is not possible with the ears that fit in the rear bearing cap. I also checked the rear pan seal, and the leak is up further than that.
Click to expand...

Sorry, I was not thinking about the ears. When I started they were rope seals, then Neoprene, then Viton. It has been a while since I rebuilt an engine. Makes sense to add them to the seal but don't remember the others having a problem sealing. Can't think of anything else to add either. Good Luck!
 
You must log in or register to reply here.
-

Back
Top