I want to check for a noise under my 97 XK8. I would like to do that with the car running and rear wheels turning.... is there any harm in this other than obvious safety concerns?? I thought i read somewhere that this approach was not recommended.
Mike in TN

 

I've done this on a hoist at work, but not at home on jack stands.


What sort of noise are you chasing, wheel bearing / diff?

 

JB,
The noise is in the trans, in high gear, that is why I want the wheels turning. Then maybe I can use a hose or stethoscope to find the noise.
Mike in TN

 

Have you tried driving the car in a manually selected lower gear to see if the noise is gear related or speed related. To get in high gear on a lift that rear end is really going to be spinning and without a load it may not shift into high gear since the ECM (engine control module) and the TCM (Transmission Control Module) communicate load on the engine for gear selection. With no load you may never get out of 1st or 2nd gear.

 

It will go up to highway speeds, just have to be careful when doing this. I don't condone this to be done at home.


Do you have access to a hoist to check?


As for that noise from trans - I've had a few in the past be noisy, but it would do it on bumpy roads. Turned out to be the bearing for output shaft to driveshaft was the issue. However yours may be different.


It " could " be in driveshaft, have seen occasional carrier fail. Also check the donuts on each end of the driveshaft, have seen lots of these fail even though they make more a knocking noise, still worth checking.

 

Vern, JB....
I took the car on a drive through the mountains today, 200 mile round trip down to Chattanooga. The noise is only in "drive" and "4th gear"..... 1-2-3 have no noise at any speed. The noise completely quits when you get to 65-75 MPH. At the lower speeds any gas on a slight up hill will make the noise.... down hill never has a noise. The noise is kind of a scraping sound, but definately in the trans. I can't believe that i am the first person to have this noise.
Mike in TN

 

Yes as I think about it, the one with the bad bearing in rear of trans for output shaft was making a scraping noise as you'd drive down the road, cant remember what speed though. I think mine was lower than 65 as I was only on the feeder road when I was able to duplicate it.


In order to check this - will require some disassembly, maybe even removing trans altogether...

 

JB,
Today I pulled off the Trans pan to look for "metal" and found none. There was the usual amount of crud on the magnets, and the oil looked like is was original, but no bits of metal. I have ordered the new filter and gasket and will see if it sounds the same when I get it back together. Don't know how I would check the bearing on the output shaft...??
Mike in TN

 

Hmm, have you checked the fuel trims? Mine was doing that when the trims were high (15%), but not high enough for a code (25%). I took it to be detonation. Same condition as you: high load, low rpm. Sounds a bit like a bearing with sand in it, and sort of faint. Maybe also sounds a bit like water on a stove ready to boil. Getting a bit off the gas would stop it instantly (lower the load), as well as downshifting.

Ended up being air leaks. Replaced bunch of individual o-rings and the VVT seals, brought the fuel trims back down to less than 5, and noise is gone!

Best of luck, keep us posted.

 

Fmertz,
interesting idea that my noise might be something in the fuel trims... but i don't know anything about how to check them. I did pull the trans pan and filter looking for any debris and found none. Put it all back together with new oil and filter and still have the same noise.... RATS ! I may be taking the car to a "professional" at a shop near by to get their opinion.
Mike in TN

 

Cheap and easy, they are data points part of OBDII. Get a cheap ELM327 from eBay/Amazon with the corresponding phone app (I use TorquePro).

Basically, trims are any extra fuel the computer adds in addition to what is dictated by the air flow meter, based on the input of the upstream wideband O2 sensors. It is a correction by feedback. In theory, it should be zero, but anything under, say, 5 is fine. Anything in the teens needs to be addressed. At 25, you get a code. Trims are divided in long term and short term. Short term are "instant", and get averaged out to update the Long Term data (every 2 minutes, or so). Long Term is what you should look at. Last, fuel trims are to be seen as an "elevation map" where the 2 dimensions are the engine load and RPM, i.e. it's not just one number.

Trims at idle are good to check because the high vacuum and low rpm make air leaks more apparent. Trims at some RPM can show problems with the air flow meter.

Trims can go negative, too, in case there is extra fuel being introduced, like a failed evaporative system.

In short, these trims are your friends.

 

Fmertz,
Understood..... I have an Ultragage bluetooth in my truck that gives me hundreds of data points, much more than I could possibly use. I will see if it can be used on the Jag also, as it is capable of handling 5 different vehicles through my phone.
Mike in TN

 

There was a recent post about this tool, and the person was not able to make it work (and returned it). FWIW, the OBDII data is only available over the ISO9141 connection, even if the car has CAN and SCP as well. You might have to "force" this type of connection for the Jag.

Best of luck.

 

Two comments: With a 97 you may well have to force ISO9142 as FM suggests. The procedure is in the instructions. Also, while you have the pan off upgrade the main pressure valve, either with the ZF part or the transgo.

http://jagrepair.com/images/AutoRepa...%20ZF5HP24.pdf

 

RJ, FM, et al
I took the car out for about a 10 mile drive and it seems the noise is completely gone.... I made numerous efforts to get it to make the noise, and got NOTHING. I plan to drive over to Sparta TN today to a recommended shop just to verify that all is well. I will report back should they find anything. :-)
Mike in TN

 

MYSTERY SOLVED
I took the jag to a shop this morning, but by the time i got there I realized that the noise I had been hearing was all gone. A talk with the Jaguar tech explained that I had fixed the problem by changing the 20 year old filter and adding the missing one qt of oil. He said that the filter will get so clogged that the oil cannot get to the pump and then you have cavitation, which is the noise I was hearing.The new clean filter and the extra oil solved the issue... I drove the car all day and had no more noise.... hope this helps someone else with the same problem. Thanks guys !!
Mike in TN

 

The good old sealed for life transmission that never needs servicing.

 

Thanks for posting Mike.

The funny thing is tonight I was browsing the forums looking for other reports of a noise like you describe since I'm getting it on my own '97 XK8.

Your solution gives me an extra kick in the pants to get the transmission filter changed, and then I noticed the date. It wasn't some ancient post but just something from a few weeks ago!

It made me laugh. I mostly expect these forums to have solved every problem a decade ago, but people are still popping up with these problems and quests for solutions. And I guess now I'm one too.