Tractor Repair: IH 786 tractor transmission problems

Question
Hi from australia

I have a international 786 tractor.  Has high and low range with 4 speed and torque convertor for additional range.

It kept getting stuck in high range.  If you selected park it would still try to go forward when cluch released but be some clunking noises and stall.  seems as though park and forward both in place at once.  If you selected reverese it would stall when cluch released.  Could not move into low range or high range with lever as it would not move left into the slot.  Eventually after a few tries or leave for a few days then come and try again it would seem to go back to normal and work.  Only seem to occur when used in high range for a reasonable amount of time.  After the last event the park selection no longer works.  You can select park but it does not engadge the park brake (or it is now broken.  I suspect from some other info that it has broken the park pawl and although lever engadges it is not there anymore to engadge in the gearbox.

Biggest concern is the constant locking in forward high range and not being able to work out how to release when it gets stuck other than stop work leave it for a while and then try later and hope it has cleared whatever was the problem.

It is a old tractor and has 5000hrs on it so suspect it must be simply work out somewhere in the gearbox but looks like a very big job to fix ???

Answer
David, i am fairly sure that the parking dog inside the trans is broken and may have done some damage....and, I suspect that a clutch pack replacement is in order, since you have the shift problems in high/low. You'll get a good idea of internal damage if you drain the fluids and check them with a magnetic probe.