B8200 HST Diesel Exhaust replacement

[Kiwi Craig]

Hi Folks

I need to replace the muffler on my B8200 exhaust system and I'm slightly apprehensive about undoing those 4 nuts that hold the muffler assy to the exhaust manifold. I definitely don't want to go breaking those studs cause then I'll have another mission on my hands. The nuts are in reasonably good condition (I can get a ring spanner on them so they are still pretty much the right shape) and I have been applying CRC / WD40 once a week for the last 8 weeks to them. My question is, I assume it would be best to run up the tractor so that it was hot before I try to undo those nuts (as opposed to trying to do it with the tractor cold)? If I'm right there, how hot do I need to get the engine - can I just idle it for 10 mins and thats enough or do I need to do some real work with it to get it real hot before I attempt to undo those nuts? Doing some real work is not going to be easy as its winter here and the ground is really too wet to take the tractor out. Anyway please let me know your thoughts on this.

Thanks, Craig

 

[D2Cat]

I'd mix up 50% acetone and 50% automatic transmission fluid (or any other thin oil) and apply liberally for a few days.

I don't think the heat from running the engine will help. One thing that makes it somewhat easier to try to remove the rusted nuts off the studs, is they are easy to get to with a drill!!

If you get the nuts to move just a degree to two, then turn them back to the tight position and then loosen them again, while applying more loosening juice. Keep that process up slowly and you will have better luck than just keep cranking them off.

 

[Kiwi Craig]

Hi Again,

Well 3 out of those 4 nuts nuts came off ok but one of them broke the stud off flush with the outside of the muffler assembly flange. So now that I have the muffler assembly off, that broken stud is protruding about a quarter of an inch out of the exhaust manifold. Am I on the right track in thinking that I now need to drill out the centre of that broken stud and use a stud removal tool (or easyout I think I’ve heard them called) to get that broken stud out? Does anyone think trying to use a pipe wrench or some similar type tool on that protruding quarter inch of stud and trying to turn it out is worth trying? Assuming I do get the broken stud out how do you guys go about getting a replacement stud - do I need to go to Kubota for that or should any exhaust/muffler specialist shop be able to supply one of the right size/thread etc? Thanks a lot for any help or suggestions you may be able to offer.

Thanks, Craig

 

[D2Cat]

If you have a wire welder you can take hex nut the next size larger, put it over the piece sticking out and weld the nut to the broken stud. Then use a socket or wrench to remove it. If that doesn't get the job done, then punch a mark in the center and drill it.

If you weld on the stud, let it all cool before trying to twist it out or it will twist off.

 

[Jim L.]

Ditto D2Cat's instructions.

Safe way would be to get Kubota part. Other wise, the only thing to watch is the stud material. You want to match the material which makes the Kubota stud. Reason is that on the exhaust parts, over time, a low level weld is being made.

 

[twomany]

Heat that stud up rosey red with OA torch or even propane.

That will loosen it up. Heat it good and long as the bulk of the manifold will dray the heat.

A "smoke wrench" is my first tool choice when it comes to exhaust work. You might have saved that stud with heat.

 

[Ramos]

Heat that stud up rosey red with OA torch or even propane.

That will loosen it up. Heat it good and long as the bulk of the manifold will dray the heat.

A "smoke wrench" is my first tool choice when it comes to exhaust work. You might have saved that stud with heat.

A rosy red stud will expand, or try to. It WILL NOT loosen it up, at least not while it is still hot.

 

[twomany]

A rosy red stud will expand, or try to. It WILL NOT loosen it up, at least not while it is still hot.

What you say is true IF the threads are not rusted. But then threads that are not stuck due to rust are usually no problem.

Heating rusted parts "drys" the rust and reduces volume. Heck, just getting the parts to move relative to each other is the first step in the process. That's why first tightening a fastener is a good move to get it to come loose.

Try it some time. Heat always works for me if enough is put in.