I need some help with the TH400 transmission in my '83 XJS.
I dropped the oil pan to replace the filter and the gasket. I also replaced the gasket for the governor cover, as well as fitting a new bushing to the rear mount.
Now it makes a whirring whining noise when driving, that it didn’t do before… Pretty loud, almost like a straight cut transmission.
It’s loudest in 1st gear and gets a little quieter in 2nd. Haven’t tried 3rd.
When standing still it’s silent, but makes a noise as if something spins to a stop when I go from reverse to P or N. Nothing from D to N.
When driving it also goes away completely when coasting.
It’s not low on fluid (I checked when it was cold and warm, running and not) It’s the right kind of fluid and the filter and gaskets were from a very reputable dealer.
What could be the issue?
My experience leads me to think that you are simply hearing the normal gearbox noises amplified by the mount being too tight. My 82 has a mount with differences to the diagrams (web and book) namely the new rubber cotton reel bush is much longer than the shaft can take. I cut a 20-25 mm section out of the middle of mine before the driving noise disappeared.
By pickup tube, do you mean the one that you stick into the filter? In that case no. Everything felt firm.
As for the governor, also no. I just noticed it felt loose and easy to remove, but decided not to mess with it…
And the mount; It was a bit of a b*tch to install, but I believe the rubber was a jaguar NOS part so I made it work. But you mean that the stock bushing is too stiff?
And, side note; usually how slow are these th400s to downshift when you give it some gas without kickdown?
Sounds about right. But i don’t see how a trans mount can cause a whining noise. If it’s wrong, you usually get a clunk or vibration.
Whining is usually pump sucking air. (Or the atf is wrong viscosity) With the pan off, if one is replacing filter, its so easy and inexpensive to replace pickup and the orings (two are recommended). I’m sorry you didn’t.
Just takes bad o-ring or crack in plastic to suck air. Yours may be good, but at least we’d be eliminating that as the issue.
Did you switch to synthetic fluid? When I put Mobil 1 full synthetic in my TH400 it was whiny and shifted sloppily. I went back to plain ol’ Dex/Merc. Did you use a different fluid from what was in it previously?
I don’t think I can move the trans up and down. The rubber bushing felt on the large side when istalling it I think. And there was no clunking when driving it.
The old bushing had turned to dust, so it was just resting on the spring.
Prior to dropping the pan, to be able to drive the car into my garage, I filled it with a dx3 fluid that was primarily meant for heavy machinery. It worked perfectly and had no noise. The fluid was pretty thick and it said nothing about viscosity or whether it was synthetic or not. Which I found strange.
When filling it back up, I couldn’t get hold of more of that same fluid. So I poured what I had left of it in and bought a different brand of dx3 (I read that I could mix brands as long as it was dx3, but I know very little about auto trannies). The other fluid was thinner in viscosity and smelled differently, but met the right classifications. It was also a lighter red than the first one.
I was kinda ready for having to replace that fluid, but the car drove absolutely fine.
Perhaps I should look for a video on the mount and try that first, and if it’s still noisy I should change to the thicker fluid and check the pickup?