easy rear main seal replacement? (1 Viewer)

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curtislow

Third fj40
Joined
Sep 2, 2010
Threads
99
Messages
377
Location
Western Massachusetts
I started at the search function and got good info,but I still have a possibly dumb question.Can you replace the rear main seal on my 77 40 without removing the transmission hump, from down below? I've done my f-250 from underneath and know it's probably possible but is it too much of a pain in the a-- to do. I'll be doing this without a lift and will be in no hurry.
Also the reason for this is the ineptitude of the mechanic I had remove and reinstall my rebuilt 2f after a rebuild.He failed to uncap my valve cover vent and created or if nothing else increased my rear main seal leak. Sad thing is I did this rebuild to a pretty good running motor and just wanted to get it done to avoid headaches and ironically leaking oil after I repaired and painted the truck.
Any suggestions would be greatly appreciated,I,ve got all winter to do this.
 
Hi Cortislow
I with Fast Eddy .
Tuff job if you don't remove the gearbox / transfer box.
Remember you have to remove pressure plate clutch plate and fly wheel in order to get to the main seal
Good luck
Cheers



...via IH8MUD app
 
There is a good chance it is not the rear main seal leaking. I have seen more cam plugs leak than main seals. Generally you can tell the difference because the main seal tends to sling oil off the front side of the flywheel as radial streaks, while the cam plug just drips from the passenger side main cap bolt. You need to remove the bellhousing to get to the cam plug.

Removing the seats and the tranny hump is the least of your problems.
 
So you can't remove the shifters and slide the tranny back and out to get to the clutch assembly like I did on my ford.I'm just trying to avoid removing my seats and radio to get to the seal.

If you happen to have a lift, maybe, but for me I always support it from above.

Removing the seats and the tranny hump is the least of your problems.

This. ^^^^
 
If you happen to have a lift, maybe, but for me I always support it from above.



This. ^^^^
If you happen to have a lift, maybe, but for me I always support it from above.



This. ^^^^
Thanks.I kinda figured nothings easy. I've just got bite the bullet and do it the right way and do it myself without trying to skip steps. I'm no mechanic ,but I'm invested.
 
Yes you can change the rear main without removing the transmission hump, but it would be a lot of unnecessary work you will need to remove the trans case shifter which is kinda tough with the hump in place, but it can be done. however it is so much easier to to the job with the hump removed it gives you better access to everything. save yourself the frustration, shortcuts are not the fastest way when it comes to this job I have had to do it twice once when I bought the truck and once when the first FEL-PRO seal failed buy OME if you can.

20150411_190533.jpg
 
Yes you can change the rear main without removing the transmission hump, but it would be a lot of unnecessary work you will need to remove the trans case shifter which is kinda tough with the hump in place, but it can be done. however it is so much easier to to the job with the hump removed it gives you access to the top bell-housing bolts. save yourself the frustration, shortcuts are not the fastest way when it comes to this job
 
If you replace the main seal without checking the cam plug, you may have an unpleasant surprise after you get it all back together.
 
I'd rather empty the coolant which probably needs to be changed anyways... drop the bib, pull the radiator, disconnect driveshafts, and then pull the motor. Easy access easy to analyze where the leak is. While youre in there you will now easily be able to change the side cover gasket, cam plug, oil pan gasket, rear main seal, idler bearing and whatever else you want to do.
 
I'd rather empty the coolant which probably needs to be changed anyways... drop the bib, pull the radiator, disconnect driveshafts, and then pull the motor. Easy access easy to analyze where the leak is. While youre in there you will now easily be able to change the side cover gasket, cam plug, oil pan gasket, rear main seal, idler bearing and whatever else you want to do.
Thanks for the suggestions, do I pull the motor with it connected to the transmission or just the motor? May seem like a dumb question but I didn't remove the motor the first time, my so called mechanic did.Sad thing is I had this motor rebuilt to avoid having to pull the thing after painting it and to avoid having leaks that would mess up my driveway. I ended up with a great running motor that leaks like a sieve. It probably has about a thousand miles on the rebuild at most.Good winter project I suppose.
 
Everything stays connected is one option. Or you can support the transmission/transfercase and leave them underneath the truck.
 
WHOA guys come on! I slapped a rear main seal in a 40 last week in less than 5 hours. WITHOUT pulling the hump or the engine. Granted that was with a lift but wouldn't be much more difficult if you have it raised up on some jack stands.

remove both shifter boots

Pull the transfer shifter. one 17mm nut and a cotter pin

transmission shifter I used some 45 degree pliers needle nose to turn the lock

unhook the parking brake cable 17mm jam nut and sleeve where it enters the floor 2 10mm headed bolts

drop the skid plate and lower flywheel cover 12mm headed bolts

both drive shafts 14mm headed nuts/bolts

unscrew the speedo cable and let it hang

unhook the two bullet connectors for the reverse light

(I didn't have to unhook the exhaust) 2f engine with custom down pipe flange

remove the 4 17mm headed bolts that attach the trans to the bell housing. I used swivel sockets with extensions and a long boxed end wrench to break the passenger side ones loose.

the top of the trans is very tight against the tunnel so you may have to get some one to pull up on the tunnel to get the trans past the opening.

two 14mm nuts hold the clutch slave

6 12mm for the pressure plate

6 17mm for the flywheel
 
WHOA guys come on! I slapped a rear main seal in a 40 last week in less than 5 hours. WITHOUT pulling the hump or the engine. Granted that was with a lift but wouldn't be much more difficult if you have it raised up on some jack stands.

remove both shifter boots

Pull the transfer shifter. one 17mm nut and a cotter pin

transmission shifter I used some 45 degree pliers needle nose to turn the lock

unhook the parking brake cable 17mm jam nut and sleeve where it enters the floor 2 10mm headed bolts

drop the skid plate and lower flywheel cover 12mm headed bolts

both drive shafts 14mm headed nuts/bolts

unscrew the speedo cable and let it hang

unhook the two bullet connectors for the reverse light

(I didn't have to unhook the exhaust) 2f engine with custom down pipe flange

remove the 4 17mm headed bolts that attach the trans to the bell housing. I used swivel sockets with extensions and a long boxed end wrench to break the passenger side ones loose.

the top of the trans is very tight against the tunnel so you may have to get some one to pull up on the tunnel to get the trans past the opening.

two 14mm nuts hold the clutch slave

6 12mm for the pressure plate

6 17mm for the flywheel
thanks Roma! I need to do this I think. I am getting a drip down the driver side back corner of the oil pan. 99% sure it's not the oil pan gasket. Flywheel is clean. Now I am unsure if it's cam seal ???
 
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Cam plug is passenger side, oil gallery plug is driver's side.
yeah, I am seeing that now in the other thread. thanks!
 
I don’t see any oil streaks on the engine side of the flywheel. Where is it dripping from? What kind of oil is it?
 

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