Frame rust and leaky seals

[Chippy]

Hi everyone,

Picked up a TJ with 45k miles last weekend, and some problems I notice straight away are a bit of rust, and the pinion seals on both differentials are leaking a little. I will attach pictures and I’d like to know some opinions.

I checked inside the frame with a borescope and it doesn’t look bad inside. Either it’s clean or it has a little surface rust. I was planning to spray a bit of fluid film under there after cleaning. Below are pictures of a few problem areas.

You can see in the first picture my leaky pinion seal. Is Dana 50660 the correct part to fix it? I have the Dana 30 in the front and the 44 with limited slip in the rear. I was going to drain it as well and put new 75w-90 conventional gear oil in and use a lube locker gasket and new bolts. also I see some people say conventional gear oil is preferred over synthetic?

Lastly, the area around the transfer case in the middle looks like it is coated in oil. Does this look like any cause for concern?

Sorry for the long winded post! Excited to get to work on this thing.

 

[Moglocker]

Hi everyone,

Picked up a TJ with 45k miles last weekend, and some problems I notice straight away are a bit of rust, and the pinion seals on both differentials are leaking a little. I will attach pictures and I’d like to know some opinions.

I checked inside the frame with a borescope and it doesn’t look bad inside. Either it’s clean or it has a little surface rust. I was planning to spray a bit of fluid film under there after cleaning. Below are pictures of a few problem areas.

View attachment 626424


View attachment 626425
View attachment 626426

You can see in the first picture my leaky pinion seal. Is Dana 50660 the correct part to fix it? I have the Dana 30 in the front and the 44 with limited slip in the rear. I was going to drain it as well and put new 75w-90 conventional gear oil in and use a lube locker gasket and new bolts. also I see some people say conventional gear oil is preferred over synthetic?

Lastly, the area around the transfer case in the middle looks like it is coated in oil. Does this look like any cause for concern?

Sorry for the long winded post! Excited to get to work on this thing.

Frame rust?

 

[Cooper Smith]

Hi everyone,

Picked up a TJ with 45k miles last weekend, and some problems I notice straight away are a bit of rust, and the pinion seals on both differentials are leaking a little. I will attach pictures and I’d like to know some opinions.

I checked inside the frame with a borescope and it doesn’t look bad inside. Either it’s clean or it has a little surface rust. I was planning to spray a bit of fluid film under there after cleaning. Below are pictures of a few problem areas.

View attachment 626424


View attachment 626425
View attachment 626426

You can see in the first picture my leaky pinion seal. Is Dana 50660 the correct part to fix it? I have the Dana 30 in the front and the 44 with limited slip in the rear. I was going to drain it as well and put new 75w-90 conventional gear oil in and use a lube locker gasket and new bolts. also I see some people say conventional gear oil is preferred over synthetic?

Lastly, the area around the transfer case in the middle looks like it is coated in oil. Does this look like any cause for concern?

Sorry for the long winded post! Excited to get to work on this thing.

The rust: grind it down with a wire wheel and paint it with a good frame paint. I used Krylon Rust Tough in Flat Black. You can fluid film over top of it if you want, but may not be necessary if you're not in the rust belt or are far away from the ocean. It's cheap insurance though and it works well. Just sucks ass come time to do work under the rig. Get cheap coveralls if you use oil based undercoatings (really the only type you should use, NEVER rubberized).

The transfer case: your speedometer gear is inside there, and the leak is around your speed sensor. It's just an o ring. Dirt cheap and quick fix. Break your fill plug free and top off the fluid if needed. If it smells bad and is dark, break the drain plug free and replace the fluid. 45k or not, fluids still break down over time. It only holds I think a little over a quart, unless you have a Rubicon (you don't obviously but I'll be thorough). ALWAYS break the fill plug free first. If you don't and you drain the fluid while the fill plug is seized, you're shit outta luck and can't drive it until you get it out.

 

[hear]

That’s pretty much the cleanest jeep underside I’ve ever seen.

 

[Chippy]

The rust: grind it down with a wire wheel and paint it with a good frame paint. I used Krylon Rust Tough in Flat Black. You can fluid film over top of it if you want, but may not be necessary if you're not in the rust belt or are far away from the ocean. It's cheap insurance though and it works well. Just sucks ass come time to do work under the rig. Get cheap coveralls if you use oil based undercoatings (really the only type you should use, NEVER rubberized).

The transfer case: your speedometer gear is inside there, and the leak is around your speed sensor. It's just an o ring. Dirt cheap and quick fix. Break your fill plug free and top off the fluid if needed. If it smells bad and is dark, break the drain plug free and replace the fluid. 45k or not, fluids still break down over time. It only holds I think a little over a quart, unless you have a Rubicon (you don't obviously but I'll be thorough). ALWAYS break the fill plug free first. If you don't and you drain the fluid while the fill plug is seized, you're shit outta luck and can't drive it until you get it out.

Thanks! That’s helpful. Might be a dumb question but what weight oil is recommended for the transfer case? I might go ahead and change the fluid and the o ring on the speed sensor then.

As far as fluid film goes. I am not in the rust belt but I’m pretty close to the ocean.

 

[macleanflood]

For reference...this is rust...

-Mac

 

[hear]

Thanks! That’s helpful. Might be a dumb question but what weight oil is recommended for the transfer case? I might go ahead and change the fluid and the o ring on the speed sensor then.

Assuming that’s a 231 t-case, ATF+4 is good, although I think any ATF will probably be fine.

 

[Cooper Smith]

Thanks! That’s helpful. Might be a dumb question but what weight oil is recommended for the transfer case? I might go ahead and change the fluid and the o ring on the speed sensor then.

As far as fluid film goes. I am not in the rust belt but I’m pretty close to the ocean.

ATF+4. Pretty close to the ocean, I'd fluid film it just cause.

 

[DuckNut]

If you ever plan to restore/paint yhe frame and undercarriage parts do it before coating it. Once you spray the waxy film on it is a nightmare to remove.

 

[Vtx531]

Frame and body look amazing and untouched. Please don't go mess it up by grinding or painting or any other nonsense. It's too nice to screw with it imo.

 

[Cooper Smith]

Frame and body look amazing and untouched. Please don't go mess it up by grinding or painting or any other nonsense. It's too nice to screw with it imo.

You're not gonna mess up rust (which tends to spread rapidly near the ocean) by getting rid of it. Not saying do a frame off, but there's no reason not to contain the rust on that skid. Why wait and let it get worse? Just more work later on.

 

[JEEPCJTJ]

Frame and body look amazing and untouched. Please don't go mess it up by grinding or painting or any other nonsense. It's too nice to screw with it imo.

You're not gonna mess up rust (which tends to spread rapidly near the ocean) by getting rid of it. Not saying do a frame off, but there's no reason not to contain the rust on that skid. Why wait and let it get worse? Just more work later on.

Messing up the rust is exactly what needs done. Messing up that nearly perfect frame by using a grinder anywhere near it definitely needs to be avoided.


Unless the goal is a complete restoration I'd probably just Fluid Film the frame inside and out along with the torque boxes too, to stop them all from getting anywhere past their current condition.

Removing the surface rust and painting the areas first would be a farther step but that could easily end up looking like someone touched it up in several places which may cause observers to question someone's restoration abilities.

 

[Hopper]

When rust starts, stop it. I'd wire wheel, rattle can rust primer the frame and Fluid film the inside. Yours ain't bad in my opinion.