Jaguar Repair: Jag series 3, jaguar series, borg warner

Question
Hi Howard,

I have a 1985 Jaguar series 3 4.2. There are 80,000 miles on the clock. When should the timing chain or belt be replaced?

Also, when the car is cold (morning times), it will not change up gears (or down) for a half minute or so until the car starts to warm up. A mechanic told me its probably a sticking valve in the box and that really the gearbox needs to be stripped down and rebuilt. Have you any advice/ideas? I'd prefer avoid the cost of a rebuild. Thanks for your help.

Martin

Answer
Hi Martin,

The series III XJ-6 has a chain and it does not require changing at any certain mileage. The top chain should be adjusted though. The bottom chain has a spring and oil pressure tensioner.

80 K miles is not a lot of mileage on a 4.2 engine but should be tested for valve carbon. The result of the type of injection system used. Other brand cars had the same problem. This is common from 60K up to 90K miles. Normally a head removal and valve job is required to do the carbon removal. Some BMW shops had a walnut bead blaster that could do the job by just removing the intake manifold.

As far as the transmission, it is a Borg Warner 66 which any good automatic transmission shop can service. A sticking valve is possible but does not usually require an overhaul to correct.

I would just call several transmission shops and ask if they are familiar with an American Borg Warner 66.
And ask about a change of oil (Type F in the US and type G in Europe)and cleaning of the valve body and then they can tell by any metal in the pan as to weather the box needs an overhaul or not.