Hi!
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?
Thanks
Edit: Is there any way the pickup tube came loose from the valve body? That’s more likely than the filter coming loose…
Did you do any sort of maintenance on the governor?
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?
The pickup tube will suck air at the case end of the tube. Lots of people put in two o-rings on the case side to avoid it.
Consider as an experiment slightly overfilling the transmission. You know you’re going to have to take the pan off and see what the heck you did anyway so really no harm to try.
All XJS want a 5 speed, yours just isn’t waiting for you to agree.
If it’s a high pitch whine it’s the transmision, most probably the pick-up tube as mentioned.
If it’s more of a rumble and some vibration, you haven’t set the transmission mount properly.
I agree with those who suspect the rear mount. I think your transmission is now metal to metal with the car body, which is why you hear the noise. First gear especially.
I feel like I really checked the pickup tube and it wasn’t loose. Where should I put the O-rings if that’s the fix?
The mount might be the first thing I look at, as that doesn’t include dropping the pan. Should I just remove the rubber and listen?
As someone said in an older thread; describing a sound could be almost impossible. But you could say it’s a mix of whine and rumble, and it definetely has vibration to some extent.
And yes, If I end up getting to keep this car (it actually belongs to my step father) I will definitely look at a 5 speed conversion when I can pour the money into it…
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?
Sounds like the mount to me, or a combination of the two…
As Bob said, the trans should bounce freely up and down, without hitting or touching anything and with out any noise.
The big plate has oversized holes so you can adjust it.
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?
I have an uneasy feeling about ‘thick’ automatic transmission fluid. ATF is thin; low viscosity; like 0/5 or 0/10 weight. Something like that.
I have to wonder if the fluid is flowing easily thru the pump and converter?
I would check the trans mount first…as it’s the least messy first step
After that drop the pan and check the pickup tube.
In any case I’d be sorely tempted get any ‘thick’ fluid out and replaced with fresh, correct ATF…which might take 2 or 3 drain-and-refills to accomplish.
