Hello everyone, need some help. I have a 1988 XJ6 Vanden Plas 115K
The trans stopped working (with no warning) was driving and all of a sudden just stopped like it had been put in N I've checked fluid and it shows full. Is there anything I can check or do I just need a new trans ? after it sits and cools off will work.
Thanks

 

Could be a couple of things, all of which are not quickly fixed...

1) The governor in your transmission is giving up
2) There are broken springs in the transmission valve body or
3) Your torque converter is on the way out
4) Damaged 'a' clutch pack

Governor and valve body are both relatively easy fix with the transmission in situ... torque converter and 'a' clutch means pulling the transmission... not a job for the faint hearted... all of the above will need to be investigated which will mean either a transmission overhaul or replacement.

Two good write ups on the ZF4HP22 Transmission can be found here:

http://www.rangerovers.net/repairdet...ansrepair.html

http://www.disgruntledgoat.com/conte...ar/ZF4HP22.php

 

Hi Bunchy:
I must say I don't at all like the transmission slipping out of gear when warmed up and re-engaging when cool; and Jagfix38 is likely entirely correct. I was prepared to offer you some more hopeful stories of how robust these transmissions are, and how so many of the problems associated with them are generally electrical. Of course, that could still be the case.

My car did a similar thing a couple of years back, though unassociated with temperature. It would randomly slip into neutral and/or low gear. It ended up being the "rotary" switch that needed replacing. I've also heard of the cables between the gear lever and the switch going out of adjustment (due to age, use, or possibly temperature!?!...) Thus, the car thinks it has been put into neutral when in fact the gear lever is still in 'D'. Anyway, it's a possibility I suppose.

I hope others will chime in because I'm really no authority. I would take it to a good, independent Jag technician before hauling off to a transmission shop. I've also heard stories of transmissions getting repaired or replaced, only to the the problem persist because it wasn't properly diagnosed as something electrical. In other words, take your time.

And keep us updated! Cheers,
Scott

 

Thanks for your input Scott... your correct in saying that these transmissions are bullet proof up to the point when they just give up. Just a heads up, the '88 ZF4HP22 doesn't have any electronic solenoids like the ZF4HP24 found in the later models so unfortunately it's all mechanical in the ZF4HP22.

Unfortunately Bunchys' Cats symptoms will be either one or a combination of the problems I mentioned previously... Best thing to do before pulling the transmission is to drain the sump and remove the pan and remove the valve body for inspection looking for a broken spring. If this doesn't yield any concerns then the next step is to overhaul the governor. Both these can be done with the trans still in the car.

If after attending to these two you are still experiencing issues then it will be necessary to remove the transmission from the car for a complete strip down and rebuild. The problem will be in the 'a' clutch pack and there is a modification that is recommended to prevent the problem from reoccurring in the future. Most reputable transmission shops will be aware of this and carry it out as routine.

Just a heads up if you plan on doing the work yourself... It is a lot easier to remove the engine and transmission together in one unit if you have to pull the transmission... It really is a PITA to just remove and reinstall the transmission by itself which is also why I would not recommend buying a second hand transmission unless it has already been rebuilt and guaranteed free of faults. You could end up going to all the trouble to pull yours out and install a second hand one only to find that the replacement is also broken!!!

 

Thanks for your help, I do appresiate it.
Bunchy