Cat 12F differential crack

[Onfoot]

Old Hanna came to me with a crack in the differential that had been welded. I have attached pics for reference. The problem is that the crack still leaks gear oil. Over the winter it would lose about a pint a week (into a bucket I stuck under the crack).

Mobile Maintenance is a local outfit that services heavy equipment, including sophisticated welding. I will be speaking with them on Monday or Tuesday, but wonder if there is wisdom in the community about this. Perhaps questions that I should put to Mobile Maintenance? Of course the ideal would be to replace the differential housing. But that is well beyond my budget...

Grateful for the wisdom in this community!

 

[skyking1]

I'll just put this out there to see if anyone shoots holes in it.
If the weld/structure is sound, what about some sort of epoxy repair to seal it up?
I say the structure us sound part, because another weld attempt might open up a can of worms.

 

[Onfoot]

If the weld/structure is sound, what about some sort of epoxy repair to seal it up?

Thanks, skyking1. I have been wondering the same thing. The structure is appears sound. There is no visible crack or evidence of structural integrity being compromised. It simply leaks. Have others had success with such issues using epoxy? And, if so, what did you use?

 

[skyking1]

I have not tried, but I would prep same as for a weld, do a little grinding to prep, then drain it out clean it with brakleen or similar several times.

 

[old-iron-habit]

Old Hanna came to me with a crack in the differential that had been welded. I have attached pics for reference. The problem is that the crack still leaks gear oil. Over the winter it would lose about a pint a week (into a bucket I stuck under the crack).

Mobile Maintenance is a local outfit that services heavy equipment, including sophisticated welding. I will be speaking with them on Monday or Tuesday, but wonder if there is wisdom in the community about this. Perhaps questions that I should put to Mobile Maintenance? Of course the ideal would be to replace the differential housing. But that is well beyond my budget...

Grateful for the wisdom in this community!

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After purchasing my 666 Ranger log skidder, I noticed it had a crack in the bottom of the transmission that was welded but leaking. I drained the tranny, cleaned it up and put JB weld on it as it was a bugger to get to it thru the inspection holes in the frame. I put a heat lamp on the JB weld overnight to keep it warm and help it cure. Now, 15 years or more later, it is still dry. If it is holding structurally I would not be concerned with a good epoxy product like JB Weld.

 

[Cmark]

I'll just put this out there to see if anyone shoots holes in it.
If the weld/structure is sound, what about some sort of epoxy repair to seal it up?
I say the structure us sound part, because another weld attempt might open up a can of worms.

I agree. If the existing weld is structurally OK then don't mess with it. I've had very good luck using Loctite 290 to seal up porous castings. Getting all the oil out is the key. Brake cleaner and/or heat to burn out the oil.

 

[Coaldust]

Oh’ No!! Poor Hanna!

Looks like the inside weld already has JB Weld on it. Am I seeing that right?

This is my $.02 cents. Start with the least invasive option, first. Wire brush the old JB weld off the best you can. Clean with brake cleaner and follow up with some heat and alcohol. ( not for you, onfoot, for Hanna).

Get this stuff and coat the welded area on the inside. It’s like epoxy, but more better. Amazing stuff. It’s used at the Cat factory to fix casting pinhole flaws. It’s used to repair cavitation damage on engine blocks. Amazing stuff.
Cat 1U-6142: BELZONA Kit

 

[DB2]

Like that idea Coaldust. Thanks for sharing.

 

[farmerlund]

Belzona is the king of epoxies. great stuff.

 

[Onfoot]

Thanks, guys. Checking with Cat this morning and they no longer supply the Belzona kit. Checking out Belzona directly, their website has a range of products. Will connect with their Canadian supplier tomorrow to see if they can tell me what went into the Cat kit.

 

[Delmer]

You don't need Belzona to seal oil. Buy $20 worth of brake cleaner, and $5 worth of JBweld, warm up the casting and apply to both sides.

If you hadn't drained it already, put a small vacuum pump on the vent, clean the outside with brake cleaner, warm it up a little and JBweld the outside only with the vacuum running a couple hours to cure.

 

[absoluteyukon]

Hey onfoot, come by Precision Engines (40 MacDonald Rd, Whitehorse) on Monday and ask for Ben in the component shop. We should have some Belzona kicking around we can supply and I'd be more than happy to come take a look at ol' Hanna with you. See if we can't get the old girl sealed up. Cheers!

 

[skyking1]

Brilliant idea Delmer.

 

[Onfoot]

Hey onfoot, come by Precision Engines (40 MacDonald Rd, Whitehorse) on Monday and ask for Ben in the component shop. We should have some Belzona kicking around we can supply and I'd be more than happy to come take a look at ol' Hanna with you. See if we can't get the old girl sealed up. Cheers!

Thanks! Not sure if I can get by tomorrow, but Tuesday for sure.

 

[Bluox]

Old Hanna came to me with a crack in the differential that had been welded. I have attached pics for reference. The problem is that the crack still leaks gear oil. Over the winter it would lose about a pint a week (into a bucket I stuck under the crack).

Mobile Maintenance is a local outfit that services heavy equipment, including sophisticated welding. I will be speaking with them on Monday or Tuesday, but wonder if there is wisdom in the community about this. Perhaps questions that I should put to Mobile Maintenance? Of course the ideal would be to replace the differential housing. But that is well beyond my budget...

Grateful for the wisdom in this community!

View attachment 237912 View attachment 237913 View attachment 237915View attachment 237914

Do not use heat with brake cleaner on spray it on heated parts!!!!!!
Always have good ventilation using brake cleaner especially under equipment.
If a weld leaks oil it is not a sound weld, either cracked or bad porosity.
All these homeowner epoxies fixes are guaranteed to fail on a bad weld.
Have the welding outfit take a look at this and they should bs able to make a leak free weld.
Good luck
Bob

 

[Delmer]

Yes, never mix chlorinated/ non flammable brake cleaner with welding or heat, it can make poison gas. The flammable stuff is just flammable.

 

[Coaldust]

Good safety message about brakecleen.

I know it sounds hokey, but Belzone is the real deal. I saved many 3306 blocks from the scrap heap and tens of thousands of dollars with it. NC Machinery had a program called STAR. The STAR engine rebuild came with a extended warranty backed by mother Caterpillar including cavitation corrosion repairs made with Belzone.

Times change. We don’t even talk about cavitation corrosion today. Who needs to, when a MX13 goes 75k and a Cummins x15 goes 250k before the block needs replaced.

 

[Nige]

I would say that the difference between replacing missing material on a cylinder block resulting from liner cavitation and attempting to stop this leakage using Belzona or anything else non-metallic is stress. The differential case is a stressed component in the area where the Belzona would be applied, the cylinder block isn't stressed to anything like the same level. For that reason if there is a porous area of weld or an incipient crack down below the surface right now, sooner or later it will break out and the results may not be pleasant.

I would side with others who have recommended a weld repair. It may well be that aerosol crack detector reveals that it's only a small part of the length of the weld that is leaking. If that is the case it ought to be a relatively simple matter to carefully grind that small area out to eliminate the crack and re-weld it.

Question to the OP. Before disassembly was it possible to see exactly where along the length of the crack the oil was leaking from.?

 

[Coaldust]

For sure. I agree. Especially if it cracked again.

If not cracked and just a leak from porosity, I wouldn’t try welding on a 50 year old casting that has already been welded on. Too risky.

So, what’s the status with Hanna?, Onfoot. Is the old repair cracked or not?

 

[Jonas302]

Agreed no way I would put any more heat or welding rod into that old oil soaked casting or take any more chances of slag going into a bearing I would probably use epoxy on the inside and rtv slathered over the outside and run for another 50 years