How to remove/treat rust where differential cover meets housing?

[76cj7chick]

Hi fellow Jeepers!
I'm trying to get my CJ7 working again...
When I bought the jeep the rear diff., housing was leaking.
So, I took the cover off and discovered rust where the cover meets the housing. The cover was junk, so I purchased a new cover. However, the rust on the housing where it meets the gasket/cover was flaky and had some dimpling. I sanded (by hand) all the flaking rust off and then put metal prep (by por 15) on the rusted areas. The rust turned black.

My question is:
Can I put paint on the rusted part that I treated? Or do I have to just use gasket maker and a gasket when I put the cover on the housing ?

Please help!

Any advice, would be appreciated.

PS. At this time I can NOT afford to buy and install another rear diff...

 

[tarry99]

Hi fellow Jeepers!
I'm trying to get my CJ7 working again...
When I bought the jeep the rear diff., housing was leaking.
So, I took the cover off and discovered rust where the cover meets the housing. The cover was junk, so I purchased a new cover. However, the rust on the housing where it meets the gasket/cover was flaky and had some dimpling. I sanded (by hand) all the flaking rust off and then put metal prep (by por 15) on the rusted areas. The rust turned black.

My question is:
Can I put paint on the rusted part that I treated? Or do I have to just use gasket maker and a gasket when I put the cover on the housing ?

Please help!

Any advice, would be appreciated.

PS. At this time I can NOT afford to buy and install another rear diff...

Looks pretty clean...............put a gasket with some silicone sealer on both sides and your good to go..............
Don't squeeze the gasket down to much at first, after it sets up for a while then retighten..........Good Job!

 

[MN CJ7]

a air die grinder with a scotch, abrasive plastic, pad is the best way to clean a gasket surface. Intake, exhaust, carb adapters, valve cover, oil pan, differential covers..... The mating surfaces need to be clean and oil free if you want a good seal. If you have a handy bud in your area ask if they can show how to clean a gasket surface with a die grinder and scotch pad....

then wipe down with rag with some brake cleaner on it to remove the oil and finger prints and debree. You have a new AMC20 Cover so you holes will not be dished or bent lips.... but guys using used parts will need to undish mount holes ( more common on valve cover and oil pan) and fix the lower lip that gets bent while dragging on rocks and obsticles. Use the RTV and gasket as said above. Finger tighten till the RTV starts to flow and oose out a bit..... can snug up 1/4 turn or so STOP THEN..... let the RTV set up over night to 24 hrs. Then snug up gradualy using a cross pattern gradually. Look up the torque spec on the diff covers and after the RTV sets up torque gradually to that spec

note... On valve covers and oil pans start in center and use a circular pattern working your way to the ends to snug up the fasteners... Several steps until you reach the torque spec for the engine and part you are working on....

Where the sun does not shin you do not need to topcoat POR 15. It does not have UV Block so it needs topcoat for in sun applications. Also the top coat of ? "Black Paint" is put on before the Por15 hardenes so it bonds to the POR15.

Not sure what to tell you on the POR15 and putting the gasket over that. Touch stuff so I think it will work.. I painted my AMC cover to areas exposed to elements..... where the Diff Cover sealed with gasket I did not paint the seal surface and cleaned off any over spray. Was afraid the paint would peel or rust again and cause leak. You pic looks to be before the POR15 because it looks to be metal finnish. If you did do the por15 on surface, my guess would be move forward with you gasket work... I put antiseize in the holes so the fasteners do not rust..... I use antiseize on everthing.... esp for the frame bolts and for welded in nuts and on manifolds where there is heat & moisture...

Keep the die grinder/scotch pads in mind and ask local bud to show you....I like the right angle one more. I have straight and right angle. I also have some matco carbide bits for metal removal that work great with die grinder.... elong holes, manifold gasket matching, and did a bit of porting and smoothing on my head. I think if you search "cleaning up gasket surface with die grinder and scotch pad" you would get lots of video examples....

Sorry for book, surface looks petty good, agree go ahead and seal it up. Wait for the RTV to set up then torque it up gradually.

 

[IOPort51]

I like locktite 515 gasket eliminator, it's expensive but a little goes a long way and it holds up very well to oil and solvents. Permatex RTV works fine too.

I like clean paint free for gaskets and sealer but I can't say why exactly.

cross torque/tighten the cover bolts so they seat evenly.

 

[PaRenegade]

A scrubbin' with some scotch-brite, wipe it down with lacquer thinner, and apply a thick bead of rtv silicone. Put the cover on and finger tighten the bolts, wait an hour and tighten to correct torque. Wipe or cut away any that squeezed out, clean it with lacquer thinner, and paint it with a quality paint.
Rust needs moisture and air to form. The silicone should eliminate both and the paint is an added barrier.

 

[76cj7chick]

a air die grinder with a scotch, abrasive plastic, pad is the best way to clean a gasket surface. Intake, exhaust, carb adapters, valve cover, oil pan, differential covers..... The mating surfaces need to be clean and oil free if you want a good seal. If you have a handy bud in your area ask if they can show how to clean a gasket surface with a die grinder and scotch pad....

then wipe down with rag with some brake cleaner on it to remove the oil and finger prints and debree. You have a new AMC20 Cover so you holes will not be dished or bent lips.... but guys using used parts will need to undish mount holes ( more common on valve cover and oil pan) and fix the lower lip that gets bent while dragging on rocks and obsticles. Use the RTV and gasket as said above. Finger tighten till the RTV starts to flow and oose out a bit..... can snug up 1/4 turn or so STOP THEN..... let the RTV set up over night to 24 hrs. Then snug up gradualy using a cross pattern gradually. Look up the torque spec on the diff covers and after the RTV sets up torque gradually to that spec

note... On valve covers and oil pans start in center and use a circular pattern working your way to the ends to snug up the fasteners... Several steps until you reach the torque spec for the engine and part you are working on....

Where the sun does not shin you do not need to topcoat POR 15. It does not have UV Block so it needs topcoat for in sun applications. Also the top coat of ? "Black Paint" is put on before the Por15 hardenes so it bonds to the POR15.

Not sure what to tell you on the POR15 and putting the gasket over that. Touch stuff so I think it will work.. I painted my AMC cover to areas exposed to elements..... where the Diff Cover sealed with gasket I did not paint the seal surface and cleaned off any over spray. Was afraid the paint would peel or rust again and cause leak. You pic looks to be before the POR15 because it looks to be metal finnish. If you did do the por15 on surface, my guess would be move forward with you gasket work... I put antiseize in the holes so the fasteners do not rust..... I use antiseize on everthing.... esp for the frame bolts and for welded in nuts and on manifolds where there is heat & moisture...

Keep the die grinder/scotch pads in mind and ask local bud to show you....I like the right angle one more. I have straight and right angle. I also have some matco carbide bits for metal removal that work great with die grinder.... elong holes, manifold gasket matching, and did a bit of porting and smoothing on my head. I think if you search "cleaning up gasket surface with die grinder and scotch pad" you would get lots of video examples....

Sorry for book, surface looks petty good, agree go ahead and seal it up. Wait for the RTV to set up then torque it up gradually.

I have a wire wheel and drill would that work or too abrasive? I also bought some scotch pads. I've been cleaning all my "covers" pans with Brake-kleen. -Heard that leaves no residue. I've worked with por 15 already. I put some on my jeep's frame and underside since it doesn't have a uv protectant.
Could you recommend a good anti-seize compound?

Thanks for the detailed information.

(PS. I put two BEFORE pics of the diff insides)

 

[76cj7chick]

A scrubbin' with some scotch-brite, wipe it down with lacquer thinner, and apply a thick bead of rtv silicone. Put the cover on and finger tighten the bolts, wait an hour and tighten to correct torque. Wipe or cut away any that squeezed out, clean it with lacquer thinner, and paint it with a quality paint.
Rust needs moisture and air to form. The silicone should eliminate both and the paint is an added barrier.

Good. I've NEVER owned a vehicle with RUST on the inside of the housing (where the cover mates with the carrier) so that scared me...(me killing the rust)
But its good to know other people have experienced it and its not that big of a deal...

Only thing is, I know the diff was leaking gear oil because of the rust...

I bought a pretty shiny cover for the diff and a matching one for the front...
See pic. I haven't installed yet, just wanted to see what it looked like..

 

[76cj7chick]

I like locktite 515 gasket eliminator, it's expensive but a little goes a long way and it holds up very well to oil and solvents. Permatex RTV works fine too.

I like clean paint free for gaskets and sealer but I can't say why exactly.

cross torque/tighten the cover bolts so they seat evenly.

Perhaps next time I will have to try the loctite... (I know I like loctite red and blue for screws/bolts.. Unless, I want to take the bolts off again soon.

 

[76cj7chick]

Looks pretty clean...............put a gasket with some silicone sealer on both sides and your good to go..............
Don't squeeze the gasket down to much at first, after it sets up for a while then retighten..........Good Job!

I like your answer.... :grinjeep: (this is me in my CJ7 , soon)

 

[76cj7chick]

Oh by the way, I didn't put any POR 15 on the mating areas... I only used the Metal Prep to convert the rust to a paintable surface... Perhaps, I should just sand the housing a bit more to get rid of as much rust as I can and smooth it out and then spray with brake-kleen and then put my rtv and gaskets on.. I like to put two bolts through the cover and then the gaskets stay in place. However, since my housing is rusty, should I also put rtv gasket maker on the housing and cover (between the rubber/cork gasket)?

:rock: GUYS! Thanks for the help!

 

[tarry99]

Oh by the way, I didn't put any POR 15 on the mating areas... I only used the Metal Prep to convert the rust to a paintable surface... Perhaps, I should just sand the housing a bit more to get rid of as much rust as I can and smooth it out and then spray with brake-kleen and then put my rtv and gaskets on.. I like to put two bolts through the cover and then the gaskets stay in place. However, since my housing is rusty, should I also put rtv gasket maker on the housing and cover (between the rubber/cork gasket)?

:rock: GUYS! Thanks for the help!

Use the RTV between all the sealing surfaces , make the gasket a sandwich! Use your brake clean on the metal and the RTV will stick and seal just fine.

 

[MN CJ7]

I have a wire wheel and drill would that work or too abrasive? I also bought some scotch pads. I've been cleaning all my "covers" pans with Brake-kleen. -Heard that leaves no residue. I've worked with por 15 already. I put some on my jeep's frame and underside since it doesn't have a uv protectant.
Could you recommend a good anti-seize compound?

Thanks for the detailed information.

(PS. I put two BEFORE pics of the diff insides)

Do not use the wire wheel.... will be tooo abrasive and remove metal from the gasket surface. That is why the die grinder use a scotch pad the size of half dollar. Scotch Pad is plastic, still removes a bunch of stuff and still needs caution but its the way to go. Hand polish with scotch pad is going to be a slow process. Die Grinders and the scotch pads for them are pretty cheap $50 total, if you do this type of work worth it, or ask for local if you can use thiers for a moment....

Your orginal pics or rusted surface on diff would not seal it was too rough wiht rust. The after pics look fine to me so I would seal it up, and said that above too I think.

Std zinc antiseize by permatex or locktite is what you will find at the auto store or other supply location you use. I use it everywhere and every new owner wished the "PO" did the same. Use copper antizeize on your spark plug threads to help them too.

Spray the brake clean on a rag then wipe your gasket surfaces. Brake Clean will bubble up your paint or discolor. The rag wipe will be more than enough to clean the gasket surfaces of oil residue so the RTV/gasket gets a good seal to the clean gasket surface.

 

[76cj7chick]

:ty:

Do not use the wire wheel.... will be tooo abrasive and remove metal from the gasket surface. That is why the die grinder use a scotch pad the size of half dollar. Scotch Pad is plastic, still removes a bunch of stuff and still needs caution but its the way to go. Hand polish with scotch pad is going to be a slow process. Die Grinders and the scotch pads for them are pretty cheap $50 total, if you do this type of work worth it, or ask for local if you can use thiers for a moment....

Your orginal pics or rusted surface on diff would not seal it was too rough wiht rust. The after pics look fine to me so I would seal it up, and said that above too I think.

Std zinc antiseize by permatex or locktite is what you will find at the auto store or other supply location you use. I use it everywhere and every new owner wished the "PO" did the same. Use copper antizeize on your spark plug threads to help them too.

Spray the brake clean on a rag then wipe your gasket surfaces. Brake Clean will bubble up your paint or discolor. The rag wipe will be more than enough to clean the gasket surfaces of oil residue so the RTV/gasket gets a good seal to the clean gasket surface.

:ty::ty::ty: