Rear Differentials- getting the gasket seal just right

[farmergiffIV]

Hey there tractor folks,

I got tired of my rear differentials leaking around the oil pans and so I took them off of both my tractors and I figured I would do them the right way finally. These things have sorta always leaked. An inspection found that the thinner metal on the oil pans around where the bolts connect has a little bit of a wave effect on the metal perhaps from the gasket shrinking over time and the bolts being tightened down over a regular period....

So I am going to flatten these pans back out before I reinstall. Anyone do this before? If you have tip I am all ears but I'll probably use some wood blocks and my bench vise.

To me it appears these gaskets haven't been changed in a long time so the metal where the gasket sits is also really hard to get clean. I've used steel wool, naptha solvent, a brass brush, and I went over them slowly and carefully with a clean razer. Yet, there still appears to be some old remaining gasket, do you remove everything till its spikity span clean, I really just want to do whatever will get the job done right so they seal well. ( if this gasket is changed more regularly wouldn't these be a lot easier to replace? I know the manual says something like once every year but I figure every 2-5 should be ok for a working tractor?



Steel wool bits in there, any reason why I should stick the hose in there and flush with water before I reinstall? Or would compressed air work just as fine to get steel wool shreds out from inside the rear diff?


I had some fun with some metal sand paper 220, then my buddy dave told me it was overkill so I figured I'd get some other opinions. I just want these to hold for awhile..



Here you can kinda see the wave in the metal I was describing.

My main question is: how clean do you need the surfaces before the gasket? I plan to use a gasket sealer also well but I heard its not necessary?

[Glen]

Hi,
Your pics look good.
The old gaskets should be removed well, so the surfaces are flat. If they are really stuck on, it can be work to remove them. It looks like you have scraped them enough in the pics, but I don't know if they are flat without being there.

I would use a straight edge, as long, or longer than the pans, and check the top edge for straightness. They can get bent where the bolts tighten.
If they are bent, I use a flat solid surface, and set the edge of the pan on it, and use a hammer to straighten the edge. You could set something thin metal on the edge, so you aren't hammering directly on the pan edge. You might need another person to hold the thin metal piece, with pliers, so they don't get hit with the hammer.
Sealer can be used on the gaskets if they haven't been sealing well.

Below is a listing at TM Tractor for new gaskets, if you want to see it.

http://www.tmtractor.com/new/fr/125fp.htm

[Eugene]

I use RTV suitable for differential covers to seal up mating areas instead of a gasket.

If you need to remove the pans or a differential cover, the cured RTV is an easy removal, just peals off.

[Bill Hudson]

This might be just what you need, scroll down to the bottom, "Sheet Metal Interfaces." https://www.agriculture.com/machinery/repair-maintenance/leakproofing-engine-sheet-metal

Bill

[Matt Kirsch]

I've discovered the 3M ROLOC style polishing disks and a right-angle air die grinder make quick work of gasket residue. They're like scotchbrite pads so they don't actually remove metal, just gunk and goo.

[BigBill]

I repaired oil pans, auto tranny pans from people over tightening them causing the straight line lip to have a wave, I put the pan on a flat surface and use a wooden block and hammer. Take your time it may take a few times to make it like new again.

I use a weather stripping adhesive to hold the gasket on one side. This way the pan can be revoked and replaced without changing the gasket. You could use a light coat of silicone too.

[Dale Finch]

I've discovered the 3M ROLOC style polishing disks and a right-angle air die grinder make quick work of gasket residue. They're like scotchbrite pads so they don't actually remove metal, just gunk and goo.

I use a my angle grinder with those 3M discs for SO much! Very little extraneous debris left behind, and as said, it removes the gunk without removing metal. If you have really bad stuff to remove, you can use one of the sanding discs...carefully though, because they WILL remove some metal. The 3M discs I use are about 2" in diameter, and get into some pretty tight places, as well.
(Note: the 3M pads do come in different coarsenesses)

[farmergiffIV]

Hi,
Your pics look good.
The old gaskets should be removed well, so the surfaces are flat. If they are really stuck on, it can be work to remove them. It looks like you have scraped them enough in the pics, but I don't know if they are flat without being there.

I would use a straight edge, as long, or longer than the pans, and check the top edge for straightness. They can get bent where the bolts tighten.
If they are bent, I use a flat solid surface, and set the edge of the pan on it, and use a hammer to straighten the edge. You could set something thin metal on the edge, so you aren't hammering directly on the pan edge. You might need another person to hold the thin metal piece, with pliers, so they don't get hit with the hammer.
Sealer can be used on the gaskets if they haven't been sealing well.

Below is a listing at TM Tractor for new gaskets, if you want to see it.

http://www.tmtractor.com/new/fr/125fp.htm

Thanks Glen I have some fresh gaskets headed my way!

[farmergiffIV]

I've discovered the 3M ROLOC style polishing disks and a right-angle air die grinder make quick work of gasket residue. They're like scotchbrite pads so they don't actually remove metal, just gunk and goo.

I use a my angle grinder with those 3M discs for SO much! Very little extraneous debris left behind, and as said, it removes the gunk without removing metal. If you have really bad stuff to remove, you can use one of the sanding discs...carefully though, because they WILL remove some metal. The 3M discs I use are about 2" in diameter, and get into some pretty tight places, as well.
(Note: the 3M pads do come in different coarsenesses)

Awesome you guys! this is great tip I'll be getting some of these 3M Roloc scotchbrite like pads for my angle grinder today. Any reason why I shouldn't stick a hose end up there and flush to get the steel wool bits out, I am worried they would eventually cause a seal to break...

[farmergiffIV]

I repaired oil pans, auto tranny pans from people over tightening them causing the straight line lip to have a wave, I put the pan on a flat surface and use a wooden block and hammer. Take your time it may take a few times to make it like new again.

I use a weather stripping adhesive to hold the gasket on one side. This way the pan can be revoked and replaced without changing the gasket. You could use a light coat of silicone too.

Pictures please? This sounds interesting yet are you putting the bolts through this adhesive?

Do you recomend Pan face down on a the clean flat metal surface ? I am worried about causing excess nicks or damages to the gasket side..

[farmergiffIV]

This might be just what you need, scroll down to the bottom, "Sheet Metal Interfaces." https://www.agriculture.com/machinery/repair-maintenance/leakproofing-engine-sheet-metal

Bill

Thanks Bill, I might be adding a ball peen hammer to my tool shop so I can try this tecnique as well.

[Glen]

Hi,
If you need to wash the steel wool pieces out of the final drive case, probably some solvent would be better.
But you could use water if that's all you have. After you are done washing, blow it out with air, the bearings too, try to get all the water out of it. Wear your safety glasses when using the air.

[Urbish]

I've discovered the 3M ROLOC style polishing disks and a right-angle air die grinder make quick work of gasket residue. They're like scotchbrite pads so they don't actually remove metal, just gunk and goo.

Those babies are amazing for a huge number of applications. I used them when I worked in tool & die for paint removal, surface polishing, and sharp edge removal. Too bad they're so dang expensive!

[BigBill]

I repaired oil pans, auto tranny pans from people over tightening them causing the straight line lip to have a wave, I put the pan on a flat surface and use a wooden block and hammer. Take your time it may take a few times to make it like new again.

I use a weather stripping adhesive to hold the gasket on one side. This way the pan can be revoked and replaced without changing the gasket. You could use a light coat of silicone too.

Pictures please? This sounds interesting yet are you putting the bolts through this adhesive?

Do you recomend Pan face down on a the clean flat metal surface ? I am worried about causing excess nicks or damages to the gasket side..

I repaired more auto tranny oil pans in my day because of them being over tightened and distorted. Place the pan upside down, lip down, on a flat surface even a work bench will do, take a piece of wood that fits between the lip and the pan then a hammer to flatten the bent area.

I use the 3m weather stripping adhesive to hold the gasket in place during assembly. It works great on valve cover gaskets too.

[Matt Kirsch]

I don't get the genuine 3M ones, but the Harbor Freight specials.