Hi there I have recently purchased a low mileage xjs convertible.
iI'v put about 200 miles on it now and it's developed a noise in the gearbox... basically its a whining/grinding noise when I put it into drive and drive off. It's intermittent if I slow down and move it into neutral and back to drive it goes but it comes back as soon as I drive.its getting worse so don't want to drive it until I get it sorted.any ideas??!

 

I would start by checking the driveshaft, rear brakes, etc, as the auto trans usually doesn't make noise. They just quit pulling. I'll bet you find something rubbing as opposed to the trans it's self making the noise. A little looking should reveal the culprit. Hope it helps.

Jack

 

Thanks I'll do that!

 

The TH400 can whine. Though most whining is hidden or muffled by the fluid. Check the fluid level.

Most other whining is the differential. If that is low on fluid or the teeth on the crown wheel or pinion are badly worn it will whine as well.

Does it while when ACCELERATING or when DECELLERATING? Or is it only a brief moment when you go off the gas pedal?

 

Hi it's whines when it's put into drive while idling and gets worse driving but it is intermittent sometimes it will stop if I lift off the gas.its more like a grinding noise when it's driving!

 

Well, that leaves out anything that rotates while the car is moving down the road and also leaves out the often characteristically noisy first gear....as that likewise wouldn't occur when the car is motionless.

A failing torque converter can certainly whine, as can a failing pump. Both can sound similar to the whine you'd hear of the power steering pump was very low on fluid.

Sometimes a poor filter seal can cause a strange whine sound. This occurs when the seal at the end of the filter pick-up gets old/weak and no longer effectively seals....and fluid isn't being sucked up very well.

Have you checked the fluid level, by the way?

Cheers
DD

 

Hi yes I've checked the level it's good..as I said I have just bought it haven't much experience with auto boxes..its got 37k on the clock which seems to be real judging by the rest of the car and paperwork it has only done 1100 over the last 12yrs! going to a local garage now see will they let me put it on the ramp.. thanks for the help will keep you posted

 

And the noise is only when in a drive gear, correct? So in N it isn't there?

 

Can I just check that you followed the correct procedure for checking the fluid level - sometimes people with no auto gearbox experience will check the level without the engine running, leading to incorrect fluid levels.

 

Hi ok so back from looking under the car and car is 100% original and clean underneath no nasty surprises. Yes I was not checking the fluid correctly but did do it ptproper today it was low but not particularly put in some fluid slight improvement but very slight.. noise is only in d 1 and 2 not in n, r or p... I can also feel a corresponding vibration in the foot well it's a rhd car.

 

Sounds like something attached to the forward drum, as the rest are on separate drums and clutches. The torque convertor is out of question, as that would be in all selector positions.

So it is only forward related so that means probably something related to the forward drum brake band... Possibly slipping.

How does the ATF smell? And what colour is it?

 

It's perfect red and no smell...did a bit of town driving now.. maybe my description is not correct..it's definitely more of a grinding feel as I say coming and going..but grinding.. seems to go in 2nd gear but hard to tell as it's a higher speed..but ya it's a rough grinding rotational noise/vibration

 

If it is whining while stationary in Drive as Doug said that rules out everything rearward of the torque converter as the gear train will be stationary..

This leaves the TC and or pump. Also when I removed my trans the flex plate was badly cracked, it still had the factory seals on it.

 

Great thanks so much for the advice! What is the TC?

 

I presume it's the torque converter? Does this mean I have to take out the gear box?

 

Yes and yes.

Cheers
DD

 

Couldn't hurt to take it to your local automatic transmission specialist and have him listen to it

Cheers
DD

 

Not quite Warren. When in D, 2, 1 the front brake band for the directional clutch is applied. Means all parts in the forward section of the transmission is engaged... The torque convertor though will be (the impellor) stationary.

The noise is not there in N and P and R.

 

The exhaust is very close to the transmission, I'd want to make sure that it isn't touching and causing a vibration when in gear.

 

I missed the fact it was not doing it in R, in N and P the TC (torque converter) is rotating as a complete unit no slip. in gear the trans internals are stationary no matter which gear is selected, so thinking about this a bit more it could be the pump as the fluid flow is different in D and R and D puts more strain on the pump or there is a blockage in the fluid path,,,,,,,,, Thinking out loud here............