Please forgive me, but I have a 99 XK8 convertible, that reved up, and hit 1st gear rather hard at 1200 RPM 3 times, once it got to operating temp. When it was cold, you couldn't notice any problem. It didn't do anything harsh, if I took off like my grandmother. I am hoping I can get away with a fluid and filter change. I am also going to put an aux filter on the left strut tower, to help with filtering the fluid.

I have heard of people drilling a hole in their torque converters to drain out all the fluid, and tapping it for a bolt and rubber washer. Is there enough metal on the torque converter to tap it, and do the rubber washer and bolt thing?

My next issue is cleaning out the trans cooler, in the radiator. Mine is full of redish gunk, and I was just going to put a solvent in it, and blow it out a couple of times with compressed air into a bucket. Does this sound OK to you? Please remember I worked on air cooled engines, or on cars mostly under 75k miles most of my life, so this is all kind of new to me.

My next question is what type of fluid to use. I have been told to only use this Pentosin fluid for a ZF trans at $60 for 5 litres. ZF also lists a LT71141 fluid that can be used that Castrol lists on the back of their import trans fluid bottle, as compatible to. This stuff costs around $7 a quart. If I am able to drain the torque converter, I figure I will need about 13 quarts of whatever I get.

The final question is this trans beyond help? I have a chance at an XJ8 trans, that had it's fluid changed at regular intervals, but it it has over 100k miles on it. I am at the age, where I don't really want to wrestle a trans in and out, if I can help it, yet don't have enough money to throw at a dead horse. I would think that an electronically shifted trans, like the 99 has, shouldn't really wear as much as a true automatic. In all the years I dealt with Audi's electronically shifted transmissions, no matter what the mileage, we never had a failure.

I was able to save my Veterinarian's XJ8, by changing the fluid, and flushing out the cooler. We didn't drain his torque converter, because he had the bright idea to buy fluid from the Jaguar dealer at $64 and some change a litre, so we only changed out the filter, and filled his trans according to Jag's specs, using temperature. His car was only slipping a little, and not banging into 1st when driven like a normal human being.

Any and all ideas will be weighed and appreciated.....Thanks....Mike

 

Transmission fluid has good solvent abilities on its own. I think the most conservative approach is to do 3 to 4 standard drain and fills over a period of weeks. Each will be 5-6 litres.

This way you will clean out the vast majority of the gunk and you should see an improvement with each drain and fill. If you do not, you know you are barking up the wrong tree before you outlay much time or cash.

 

You describe a known problem with the ZF transmission. Due to wear on the first gear valve in the valve body the transmission hits the 'A' drum with pressure that physically breaks the drum. There is a ZF service bulletin out with the details.

If this has happened changing the ATF is not going to fix this problem.

Castrol Import ATF meets the ZF specification and should not be a problem at less than $6 a quart at my local auto parts stores. Couple 5+ qt changes and you are 80% new.

How about those within a casual driving distance of the North Georgia Mountains jumping over the the Lower SE forum linked below.

 

Instead of messing around, I think I am just going to buy a rebuilt valve body, that has all the updates, and a one year warranty. I do not think I damaged the drum, because as soon as it happened a few times, once it got up to operating temp(and I don't accelerate hard), I drove slowly back into the garage, where it has been sitting. I think I will flush out the oil cooler with an environmental friendly grease and wax remover and a pump and bucket for about a half hour, after I run a bottle of trans flush through the trans and old valve body for the manufacturers time suggestion. I will replace the old valve body with the rebuilt one, clean the pan, and replace the filter. I will change the fluid again in a couple of weeks, without doing anything except pulling the drain and fill plugs. Depending on how things look while draining, I will decide if I am going to do it a third time. Does this sound like a logical way to go? They say the trans will need to be reflashed. Is this something I can do with a Snapon OBD2 reader, or will I need to go to the dealer? I am thinking of buying from a company called RevMax. Is there anything I should know good or bad about this company? I guess the upholstery will have to wait for awhile. Everything else seems to be OK, except the rear bumper, because I bought it from an old guy who parked by the feel method. That won't take but $40 to fix......Thanks again.....Mike

 

While the valve body replacement is not a huge job the drum may have been damaged to some extent and is waiting on a more inopportune time to completely fail.

 

Maybe I'll pick up that other trans too, for $300. Just to be ready if the worst presents itself. It was maintained, shifts nicely, but just has a lot of miles on it. I could set it in the corner of the garage, and hope nothing happens. There is only one of me, so slamming a trans back in would be difficult, if not impossible. I'm committed to it now. Looking at the transmission disassembly pdf, it looks like I should be able to inspect the clutch drums, once I drop the valve body. I should be able to see any cracks or breakage then, or am I wrong?

I could clean out the updated valve body and reuse it. Pulling the pan to install the rebuilt valve body on the current trans might show a lot of metal, so I may end up using the other trans anyway. Boy are there a lot of bolts just to get this trans out. It's no Chevy 350, for sure.

I may need to hire the hillbilly trans shop in town to do it for me, after we drag the XK8 behind the Porsche 928S through town to get it there. That would be embarrassing. They put in an Audi Quattro automatic trans for me for $400 and a cold case of beer a few years ago, and that was a much bigger job. I would have them just install it, after I put in the new torque converter, tail shaft seal, torque converter seal along with the rebuilt valve body, and filter. I trust them to install it, just not fill it with fluid, or anything too complicated.

I would still try it myself, except the stroke, and hole poked in the top of my head has kind of sapped my strength, and I get dizzy laying on my back for any length of time....Glad I really love this car.....Be cool.....Mike

 

The forward (or 'A' drum) CANNOT be seen without removal from the gearbox!!!
It is INSIDE the 'B' drum.

bob gauff

 

You have convinced me. Since I don't have half the tools required to take apart, inspect, and measure everything in the current transmission, I will buy the XJ8 trans, wash it out, drain and fill the torque converter, install new front and rear seals, and replace what I was replacing on the possibly damaged trans. I have some slave labor down the alley, that work for beer, experience, and hanging out in my garage, so things shouldn't be that bad for me. I have already cleaned out the trans cooler. It wasn't as bad as I thought. I should be back on the road in another week or so......Thanks for talking sense into me.....Be cool....Mike

 

When I bought my 2000 XK8 I replaced the valve body with a rebuilt one that incorporated an improved solenoid valve (with a larger bore), a replacement for the original, which was the cause of the "A" drum failures. Since you are dropping the pan on the replacement transmission, it might be worth considering. There are several threads on this forum which go into greater detail on this.

 

test point supplied you with the BMW pdf that shows the updated main pressure valve. It the bore of the valve body is not damaged, just install the new valve. It looks the same except the last land is about 1/16" longer.

 

Is the replacement drum installed behind the front pump, and relatively easy to replace, instead of taking the whole Christmas tree apart?....Mike