I’ve been looking into both x308s and x350s, been challenging to find a 350 with good service records at a price that allows me to budget for air suspension and any other issues. On the 308s, my understanding is that the later years worked out timing tensioners and some other kinks but the transmissions regularly give out early. I see a 308 with 92k miles and transmission has been rebuilt but looking to get more info on that and other maintenance info from the seller. I’m curious with others experience if transmission problems are pretty much a guarantee or hit or miss, and even with rebuilds and good maintenance will they last a while or still likely to fail?

The price allows me to budget several grand but I also don’t necessarily want to get into something that would regularly give out no matter what’s done

 

Ask for the receipt on that trans rebuild just to make sure it was done. If there’s a local jaguar independent repair shop, take it there for a PREpurchase inspection, not a POSTpurchase inspection like many people do. The main pressure regulating valve and its bore are the start of the front drum failure of those transmissions. Look at the receipt for a new valve.

The most success you’ll get is when you start it up cold first thing in the morning is to wait about 15-20 seconds for the idle to come down below 900rpm’s before you touch the gear shift.

 

Thanks for the info! So once those are replaced they hold up a lot better as long as you take care of it?

The seller is out of state a couple hours away but I’m definitely wanting to check all that out and see if they’ll do a PPI. There is a local jag mechanic that’s really reputable otherwise I probably wouldn’t consider it, unfortunately finding them has been the biggest challenge as I’m in Oklahoma and you don’t see many older jags here

 

See this on tensioners:
https://www.jaguarforums.com/forum/x...ioners-180430/

 

I bought my Jag about a year ago and the main issue was of course, the transmission. I had to search for about half a year to finally find one with 53k miles. It cost me $1,000 (lucky) but usually it can cost around $1500-$1600. Therefore, I suggest either finding a car with low miles (60k down), or buying the car and then a transmission with low mileage. Then, whichever you do, make sure you do a trans fluid change and valve pressure regulator upgrade. Furthermore, you wanna have enough money and time to allow your typical mechanic to figure out how to work on your x308, as these cars are getting old and not a lot of people learned how to work on them in the first place.You're going to have to learn a lot about them yourself too, as taking it to the shop with every single issue you have will cost more money than doing it yourself. Lucky for you there is an absurd amount of knowledge in this forum and lots of willing people to help you out. These cars need patience and know how, but once you got both, you got yourself a beautiful and unique vehicle that stands above the rest (in my opinion). Take all of this from someone who knew absolutely nothing about Jaguars before buying one. Good luck!

 

Probably seven times out of ten, the trans is rebuilt because of a failed A-drum. Other parts can fail, but this seems to be the achilles heel. Its caused by an overpressurization of the hydraulic system combined with a somewhat weak design for the clutch retaining ring in the A-drum. The overpressurization occurs because the wall of the aluminum valve body eventually wears out inside the main pressure regulating valve as the piston moves back and forth rapidly. Then the piston jams, the A-drum engages at a higher pressure than it can handle. That happens over and over until it breaks. There's multiple options for the transmission rebuild, each with different advantages. Two things really need to be done at that point. The A-drum needs to be replaced. The options are to replace it with a new, but stock A-drum or a company called Kuhle made a batch of upgraded A-drums that are a much more rugged. Some shops have even actually welded the cracked A-drum. Also critically, the main pressure valve needs to be renewed. There are three options there. A company called Sonnax sells a repair kit wherein a repair shop reams out the bore of the valve body and inserts a new, slightly bigger diameter valve. Another option is a company called Transgo sells a new valve piston that is machined such that it rides on an un-worn portion of the bore and no machining is required. A third, more expensive option is to replace the front lower section of the valve body with a brand new unit and a new valve piston of the revised design directly from ZF.

There is some evidence that upgrading the main pressure valve at the time of a fluid service will extend the life of the transmission as if the A-drum has not yet cracked, then maintaining proper hydraulic pressure should prevent it. I had installed a Sonnax kit at about 80K miles after reading on this forum about all this (and the general consensus that the Jaguar service schedule is incorrect and that I was probably already 30K miles too late on the fluid service). But my A-drum still broke at 126K miles. Was it already on its way out and I bought myself another 40K miles? Who knows? Its possible. I wish I could find the post to give credit, but somebody about seven or eight years ago posted "These <XJ8> are really $10,000 used cars. You just pay $5,000 to the seller and the other $5,000 to your mechanic." You can update prices accordingly for inflation. In any case, you are buying a luxury car that is over 20 years old now. If its not the transmission, you can expect to almost immediately shell out some serious coin for something. Go in fully expecting that and it won't bother you. Good luck Jaguar hunting.

 

You have to go x308. From the back x350s look like a Crown Victorias. On the transmission issue, I bought a 2003 XJ8 with about 100k miles and sold after about 50k miles later with no transmission problems. Soon after buying I did the Transgo pressure regulator valve upgrade (not difficult) and a flush (disconnet cooler and suck new from one bucket and dump old in another) with Vavoline AFT. Lots of other member will say must use original trans fluid but that is $$$$.

 

Yeah, in some ways I like the beefed up look of the 350s but I agree about the crown vic part. 308 definitely has a more classic look. I actually found an 03 super v8 with 77k miles for a seemingly good price and the guy appears to have put a lot of care into it the past 10 years. That would I guess alleviate the transmission concerns. It’s about the same price as a local ‘04 x350 with 117k miles on it, also good service records. Trying to do some digging on practicality/maintenance of the SuperV8 vs a base 350. Kind of seems that some modern updates could be beneficial, others adding complexity.

 

thank you very much for the detailed response! The seller hasn’t gotten back to me about the 308 I was looking at so I’m checking other options. I mentioned this in another reply but I also contacted a seller about an ‘03 Super V8. I see on the forum that they have a more reliable transmission for the vehicle, but do you have any experience/opinion on if the supercharged editions of the 308 have any major drawbacks otherwise or are much more cost prohibitive long term? Outside of the air suspension on the 350s I don’t see too many complaints so at a similar price point I’m trying to do as much research as I can to determine if either would be significantly more challenging to take care of the SuperV8 vs base x350.

 

The biggest drawback on my 03’ SV8 is the gas mileage. Even before all my mods, it was at best 14 mpg around town and about 17 mpg highway. With mods is about 12 mpg town and 15 mpg highway. I’ve used nothing but super unleaded. The readiness tests were passed and the LTFT was roughly +3 on both banks when it was stock so I know it’s running properly.

 

That is rough, appreciate the input there. Luckily I don’t drive a lot of miles and gas prices in Oklahoma are at least lower than most states so it’s not as big of a deal as it could be

 

If you actually like the styling of the X350, then I'd say go for the newest one you can find because they made that body style up to 2008 and that literally buys you five to ten more years of reliability. I restore old cars and its like doing a postmortem on why was it "parked when running" especially when the mileage isn't even all that high. What I've observed is that so much of it is that cars less than 50 years old utilize an awful lot of plastic, rubber and vinyl in their construction and that stuff is deteriorating regardless of mileage, ever so much faster when left parked out in the sun or driven in a hot climate like here in Texas. They just get to where it seems its one thing after another, a hose, a seal, a gasket, a plastic switch, etc. Its rarely metal on metal wear that sidelines a car but rather an accumulation of deteriorated organic parts. That's the main reason people buy new cars, so they aren't getting little surprises every month. All else equal, a 2008 is going to be a more reliable car than a 2003.

I bought my X308 Sovereign in 2011 as a dirt-cheap ($6,000) used luxury car for its magic carpet ride. It was just supposed to be for a few months while I healed up from back surgery. I didn't know I was going to like it as much as I did. And it was a rock up until it got to about 15 years old and after that it started leaking and squeaking from everywhere. Its been a constant battle to fix everything that's disintegrated, even stuff you don't think about when buying a used car like the foam around the speaker cones. In 2017, I bought a 2012 X250 so that I'd have a newer, more reliable car for long trips, but that XF is now approaching the point that the X308 was when it started to disintegrate. It just turned 70K miles but at 12 years old I've already had to replace all of the plastic cooling system and rubber suspension bushings. So if you are really most concerned about reliability and you are not fixated on the 308 body style, then just plan for the air suspension and go for a newer X350.

For a collector, now is the time to buy an XJR or SuperV8. They are at their lowest depreciation or just about. You could buy one as a weekend toy, tolerate a few leaks and squeaks and actually make money on the sale in five or ten years as long as nothing critical breaks to disable the car. I don't think you'll ever get one cheaper. But if you are really intent upon daily driving it for a few years and wearing it out, I'd stick with a base trim for the lower initial price, lower cost of repairs and the softer ride.

 

^

As a counterpoint, my daily driver for the past two years has been a 2001 XJR that now has 105k km on it (a little over 65k miles) and it has been dead reliable from +35C to -35C.

Before that my daily driver for 16 years was a 1992 Series 3 V12 VDP that was almost 15 years when I purchased it.

Both cars had impeccable pedigrees but had been “driven” and not stored or put away for the winter etc. albeit they were relatively low mileage cars that had been properly restored/fettled by the person I bought them from.

My cars are garaged and rarely parked outside for lengthy periods of time, they get cleaned regularly (my wife would say fanatically) and they get their regular shop time once a year and anything that crops up in between gets sorted and not put off. Unfortunately I am not mechanically inclined so I probably put my mechanics’s kids through college over the years but it has been worth every penny.

These cars “like to be driven”, not necessarily as if on a track but not like driving Miss Daisy either, and I think they’re happier and probably last longer when they get that.

 

The Super V8 & XJR models don't have transmission issues. They use a stronger Merc box, it's only the non-supercharged cars with the weaker gearbox.