I'm back for more! Sold our '99 VDP a few years ago when transmission went South at 130K. Wife wants another pre-'04 car and forums suggest getting an '03 will eliminate the tensioner/water pump/thermostat housing/ABS bugaboos. (for sure?) Which leaves the transmission concern. Am looking at an excellent '03 with 100K that drives fine...today. Generally, what are the odds that the ZF will do another 20K @ 5K/year?

(also considering an always-dealer-serviced '98 with only 70K on it, but am concerned about endless repairs & updates which I don't have the heart for)

Opinions? Thanks everyone!

 

There seems to be a great deal of documentation suggesting that there is nothing inherently wrong with the ZF box but rather that the trouble arises from wear in the bore of the main pressure regulating valve of the valve body. When I noticed twice that mine hesitated engaging going from park to reverse (ostensibly an early sign of trouble), I pulled and dismantled the valve body and indeed found the described "ridge" inside the bore which should have been smooth. It's a steel piston that oscillates rapidly inside an aluminum housing so its prone to wear. This wear causes the pressure regulation to fail, ultimately leading to harder than normal shifts and failure of one or more drums. For about $600, I bought a rebuilt valve body with an upgraded Sonnax sleeved pressure valve and installed it myself. Its a messy job but really rather easy to access so I would think it shouldn't cost much more than $1000 at a competent shop.

 

I have replaced the valve with the upgrade, but the valve body was not damaged so I put it back together. The valve costs less than $30 and appears to be made of a material like delrin.

 

You could just get an XJR or VDP Supercharged and avoid the problem completely

 

Thanks for the original thought. I have seen conflicting info, but it seems that the supercharged cars also have the tensioner issue. Yes/no? They also have an entirely different transmission?

 

Yes, the tensioner issue is the same in XJ8 or XJR cars, but you would be safe with a 2003 model year either way. The supercharged cars use the Mercedes transmission which has proven to be a more robust unit than the ZF.

 

Yep, same tensioner issue on the earlier cars, but the 01 and up cars all came with metal tensioners, as did some late build MY2000 cars (at least mine had metal tensioners in it already). But yes, the supercharged cars use the Mercedes 722.6 transmission, which is MUCH more robust, and largely trouble free with the exception of a wiring harness connector that almost always fails (but the fix is cheap/easy).

 

I purchased a 2003 XJ8 last year. I had a transmission re-build after I drove to my local shopping center twice with the parking brake ON! Would I have had the problem without such dumb driving?

 

Based on consistent info on our site, metal-tensioner engines weren't first assembled (let alone installed in cars) until August 13, 2001--which would have been a couple months into 2002 model year production. Unless I'm missing something, I don't see how any 2001s could have Gen III tensioners from the factory, and certainly no 2000s.

 

It may be possible that the metal tensioners ended up in some 2001 cars, but it's more likely that pre 02 model year cars with metal had them replaced after sale.
To clarify the transmission comment, The 4.2L cars have a 6 speed ZF, not Mercedes transmission.

 

Hi everyone, am new to jag and would like some help please. Am looking to buy an xjr and would like to know what is the best year to buy. Am now looking at a 2001 xjr with 110k miles is this a good year? Thanks

 

They are all good years. It is the condition of the individual car and how much work has been done on known issues (see above): but safest bet is a low mileage 03 with a blower. Newest one, tensioner problem solved, has the Mercedes transmission, yada yada.

Good luck on finding one. I couldn't a couple of years ago and settled on the one I have but had lots of work to bring up to spec (and holding my breath on Transmission, rear axle, wheel bearings, throttle body, steering gear . . . .but still a great drive).

 

If you change the filter and fluid that will help it last a bit longer. Some fail at 80,000 miles and others go to 160,000. Drive it till it fails, spend $2,600 on rebuilding and go another 100,000

 

L45: dat be da plan, ATT.