Hello!

I just brought out my Jag for its bi-weekly exercise, and have found a new noise (oh joy).

For the first 4 or 5 miles of my drive, I noticed a rumbling noise at idle in park. Kinda like a rotational noise. Sounded like it was coming from the engine bay. However, when I got out of the car, I couldn't hear it. Sounded normal. You can only hear it in the car.

After I brought I up to redline and drove it hard, it went away. Thoughts?

 

The engine was happy to have a good workout! No more grumbling. Just a thought.

Pulley/balancer traction bonding for the alternator could be going away. Heat soaking allowing for better grip/less noise later. In this case you will probably soon hear screeching on start up and/or see low voltage at idle. If so, the pulley can be re-bonded by Dale's in Oregon.

 

So the noise came back, but with a little googling, it appears that I have the same noise as in this thread: https://www.jaguarforums.com/forum/x...de-car-137771/

@SleekJag12 where exactly did you put rubber between your brake lines?

 

Isn't it hilarious when you google a problem with this car and end up linking right back here to this forum.....

I didn't think of that rumbling as a possibility, been a while since I dealt with it. There is another thread where it is described as a helicopter noise, heard at idle in park or drive.

I have a short length of rubber hoses around the brake lines just forward of the heater pump, below the brake master (LHD). The pipes there were contacting the horizontal inner body panel. I think that was the main source of my noise because I can't presently find any other inserts I put in along any other brake lines. Check the white clips along the firewall that hold the lines, make sure they are still secure. At the right side, a bunch of lines to/from the ABS/TC unit come together and could use some more isolating. Pushing them around I could tell they might contact each other under certain engine harmonic vibration ranges.

Small diameter hose can be split and put around a pipe wherever you want.

Edit: I looked at the other thread and reminded myself that I had replaced the fuel filter in 2017, and the noise subsided to some degree. Could be that the fluid flow dynamics changed and affected the noise. Doug suggested this possibility back then.

 

Have you checked your idle control valves for carbon? They are real easy to pop off just 4 screws and an air hose. Mine were really black and caused the car to idle rough. That and clean the throttle body intakes if you haven't done that see if that helps your idle.

 

Update (A little late, but I've been traveling)

So the noise thankfully isn't coming from the trans. I got it up in the air and the noise couldn't be heard from underneath. Changed the trans fluid and mount and it was all pretty decent (even the old mount weirdly). I played around with some of the heat sheilds and that helped, but the noise isn't totally gone. Once I get around to doing the subframe out service, I'll go ahead and dive deeper.

In a more concerning turn of events, I had a clunk when entering reverse and a rear diff leak according to the PPI I had done by a "reputable" Jaguar specialist before I purchased it. They claimed that the diff was "weeping a little" and the clunk was due to a "bad bushing in the rear". Welp, the diff is the worst-leaking diff I have ever seen and the clunk is coming from one of the differential wishbones where its body mounting point ripped clean off. Doesn't look accident-related, in fact, it just looks like the factory spot welds failed, and then the whole thing simply sheared clean off. Everything else in the rear looks like a well-maintained 40k mile car. Odd...

It all looks fixable and will require some welding, but I'm shocked a Jaguar specialist missed such a massive issue in a PPI. Thankfully I haven't driven it far and it would explain the reverse clunk.

My plans have changed with this car slightly and I will be installing an air ride kit so I'll get that wishbone mount welded up as I front and rear subframe-out jobs in tandem with an air ride install.

Thanks for the tips on IAC. I'll go ahead and order a pair when I've got the credit card out for engine mounts...

 

So maybe my problem was not an isolated incident:



Right side, apparently the spot welds failed, then the body sheet metal cracked and broke right off!

This is a monostrut I had a shop install in 2017 which definitely stopped the squeaking from the rear end due to the old dogbones.

I had been driving around for "some time" with the right bracket floating in mid-air. By the time I removed the bracket the broken metal edges were all rusted. Oddly I didn't notice a change in the handling of the car (or noise) or I would have discovered it sooner. I can't remember any kind of incident that would have caused that break, or any sudden pop from back there.

The left side is still firmly attached. Not resolved yet, but custom welding will be required. Notice the fuel tank is above this bracket so it seems like a good idea to remove it to weld in this area.

 

Yup! Mine looks exactly like that! Except for me its only on the driver's side. It's odd since I've never had this issue on my XJ6s or XJ8...

I only noticed it when we had to drop the exhaust to change the trans fluid and mount and my roommate asked if I had already undone the wishbone.

In the meantime, I'll just drive it sparingly while I collect parts to install the air ride conversion and the upper oil pan leak...

 

It would seem I have another thingy to look for.