P38A Cleaning transmission cooler union stripped threads

[ar1g3]

So I'm having a bit of a battle with the ATF cooler. Mine was leaking from the tanks on the cooler so I bought a Britpart replacement.

However one of the unions on the cooler was seized due to aluminium corrosion, not possible to get it off with heat or wd40 so the threaded part on the old cooler sheared off. Got the threads out of the union but there's still old thread and corrosion inside the union. If I connect it like this to the new cooler I will ruin the threads.

Any tips for cleaning the threads on the cooler hose?

Replacing the hose is not an option, major job to get to where it connects on the gearbox.

 

[MrGorsky]

I'm afraid I've never managed to rescue the threads if they break whilst dissasembling them, and I have tried!

I've always had to just fit new cooler hoses at the same time.

I have mended a leaking swaged joint though by cutting it off and replacing it with compression fittings. To that end, you might be able to cut the swaged joint off, and that might allow you to remove the union nut and clean it out properly, and then replace the swaged joint with a compression fittinfg to join the steel pipe backup to the rubber hose bit. Still probably easier to just buy new hoses though!

 

[Rubberknees]

Many years ago working on flexi hydraulic piping we used to be able to cut off the fixing and fit a new one using an end that fitted with a couple of spanners compressing the joint onto the hose. You could try a hydraulics firm near by to see if they are still available

 

[Rubberknees]

This is what we used . Try the bay, probably on there

 

[Datatek]

A Dremel with a mini wire brush might do it. Better to replace the pipes as if original they must be due to start leaking.

 

[ar1g3]

A Dremel with a mini wire brush might do it. Better to replace the pipes as if original they must be due to start leaking.

Yeah, but that means lowering the gearbox as far as I can see. Not in for that, just got everything back together after getting to the parking pawl assembly.

The threads on the pipe are not damaged but just full of old aluminium thread from the cooler. I was hoping for some magic tap or whatever may have to buy a dremel then...

 

[brianp38dse]

Your fighting a loosing battle the alloy rucks up and buggers the threads, as mentioned new pipes is the way to go, i trued in vain but had to admit defeat

 

[romanrob]

you could try a bit of patience, some 2x magnification glasses and a small jeweller's screwdriver, after a bit of heat from a heat gun to help dislodge the ali. Good luck

 

[ar1g3]

I tried heat and tried scraping some of the aluminium out of the threads. Managed to dislodge all the corrosion and some of the old thread. A bit still left however, don't feel comfortable using it as is.

I have in the mean time determined that this is a standard m20x1.5 thread, apparently commonly used in hydraulics. What I will do is biy a steel fitting and cut some slots in the threads, then use that as a cleaning tap. Much cheaper and easier than replacing the hose, will report how it goes.


Yes I am stubborn.

 

[ar1g3]

I am pleased to report it worked!

I bought a standard m20x1.5 tot 1/4" hydraulic adaptor fitting and cut some slots in the thread. Also had to drill out the ID a little bit (to 17mm). Worked a treat!! New cooler installed!

6.81€ for the fitting vs 60+€ for the hose and X hours of labour. I'm counting that as a win.

This is what my thread cleaning device looked like:

 

[Rubberknees]

I am pleased to report it worked!

I bought a standard m20x1.5 tot 1/4" hydraulic adaptor fitting and cut some slots in the thread. Also had to drill out the ID a little bit (to 17mm). Worked a treat!! New cooler installed!

6.81€ for the fitting vs 60+€ for the hose and X hours of labour. I'm counting that as a win.

This is what my thread cleaning device looked like:
View attachment 318135

Many years ago did that with a spark plug on an alloy head that had started to cross thread. New plug went in easy peasy and no problems. Coated cut spark plug with loads of grease to stop any bits dropping into engine.

 

[Flossie]

Just had a quick look on ebay. Tap for £12-£14. Just an observation.

 

[romanrob]

Just had a quick look on ebay. Tap for £12-£14. Just an observation.

But that's double the price

 

[Flossie]

But that's double the price

But you need a hacksaw and a 17mm drill bit AND you can flog the tap and recoup some money.
I've done the maffs and the tap wins!

 

[ar1g3]

But you need a hacksaw and a 17mm drill bit AND you can flog the tap and recoup some money.
I've done the maffs and the tap wins!

Remember that the pipe is still there so you would need a hollow tap. Or is that what you found?

 

[Flossie]

Remember that the pipe is still there so you would need a hollow tap. Or is that what you found?

Ahh...OK...you win!