I'm about to change my transmission fluid and filter and wondering if there's any benefit to not running the engine before draining the old stuff out?

I haven't started the car for months so I could put it on jack stands and not disturb whatever might have sank to the bottom of the fluid pan over that time.... would that be a better clean out than getting the cheap old fluid hot and more viscous?

Thanks!

 

If the car hasn't been run for months, I don't think you'll gain anything by running the motor up to temp. I would just do a drain and either leave the plug out with a catch can underneath, or better - put the drain plug back in and leave for a couple more days before dropping the pan.

I would recommend replacing the main pressure valve 'while you're in there'. It's extra work as you have to remove the lower valve block, but it's good PM given it is a known issue on the 5HP.

 

Thanks Michael!

Is this the replacement valve you recommend changing?

https://transgo.com/product-details/...ulator-repair/

My palms are already sweating at the thought of touching the valve body but maybe it's best to get it while I'm in there!

 

Hi,
Yes, that's the one I used. I did the change when I replaced the trans oil cooler lines/compressor and a bunch of hoses, so the car had been out of use for some time. I'd put the pan back after removing the lower valve block to keep air/dust exposure to a minimum, and I was surprised how much more fluid had collected in there when I came to put it all back together. I guess if you leave it a few years it will stop dripping...

ZF recognised the problem and modified the valvesomewhere around 1999.

I have to admit to being scared of auto boxes, but it really isn't that bad. See this brilliant how-to of BobRoy's if you do take it on:
https://www.jaguarforums.com/forum/x...2/#post1648275


Don't make my mistake

 

So if the valve is faulty what are the symptoms?

 

The trans can bang when engaging gear, ultimately leading to the dreaded 'A' drum failure and loss of drive. I've attached a ZF TSB relating to the issue, courtesy of Gus.

Instances of a cracked valve body have also been attributed to this valve sticking. See the pic in this post from Redstar:
https://www.jaguarforums.com/forum/x...6/#post1591261