I have a 1998 xk8, 64k miles, the transmission bucks when it shifts into 5th gear, no slippage, just unsteady bucking. It seems that the torque converter is not fully locking up, any ideas?

Jack M

 

When was the gearbox fluid last changed?

Richard

 

Richard, the fluid and filter were changed about 3000 miles ago, I will have the shop change it again and hopefully it works.

Jack M

 

3000 miles should be no problem. Do you know from the invoice exactly which auto fluid the shop used and how many litres they used?

Richard

 

That doesn't sound good. But in this S-Type it seems to be the same problem (I think the automatic transmission is the same). The video is in Spanish. Did they do a proper oil change?

 

Incorrect fluid type could cause all sorts of issues.
I bought an XK8 with a faulty gearbox for cheap and found RED fluid inside.
The guy had receipts for a rebuild less that 30K miles before it failed.
I just set the broken gearbox in my pile-o-parts outside the shop.(maybe the valve body it still good?)

 

Thanks Bob, I did a scan and came up with p1795 and p1799 codes, I am trying to find a shop that can properly service the transmission. It shifts and functions properly until 5th gear, then it lightly bucks as if the torque converter is not fully locking up, any suggestions?

Jack M

 

Excuse me for offering my opinion. I think it's a problem with cleaning and changing the fluid with the correct specifications, as well as ensuring the level is correct. The level should be checked with the engine running (at the correct temperature), not when it's stopped. Some people think hydraulic fluid lasts a lifetime, but that depends on mileage and time. Did they change the fluid or just check the level? I would start there again, and if you can be present during the change, even better. Observe the amount of fluid coming out of the gearbox (even better if you can do it yourself; there are complete kits available on eBay and other websites). The most economical solution is to rule out the above. If the problem persists, you can then opt for repairing the gearbox (at a specialized workshop) or replacing it with a new one (a trusted used one).