Hi, I have a 96 XJ6 with 99,000 miles. It has been well cared for and has always been a very strong runner. Within the past few days, I've noticed a screeching sound when I accelerate. It lasts maybe 2-3 seconds, then stops. It will happen whether the transmission downshifts or not (e.g. I don't need to floor it - just moderate acceleration in pretty much any gear will cause the noise). I can accelerate very slowly from a stop and it doesn't happen, but pretty much anytime I accelerate while driving (unless I try not to make the noise), she'll screech. I tried to rev the engine while in park to see if it would make the sound, but it did not. It only seems to happen when I am moving.

It's hard to tell where the sound is coming from, but it seems like it's under the hood, but I suppose it could be transmission related. I wondered if it could be related to the air pump? I do occasionally throw a P0341 code (maybe 3 times per year?). Someone had posted up here one time that most of the time, the catalytic converter and O2 sensors are fine - it's a faulty airpump that causes this SES light. Any ideas?

 

Sorry, make that OBD-II code P0431, not 341...

 

any chance it is belt-squeal? If so, I'd think you could reproduce it by accelerating the engine briskly in P or N.

....or maybe you are just "bawling" the rear tires every time you blip the throttle?

I believe air pump only runs as a test on each start-up, otherwise only truly "active" after cold starts, to pump air into the exhaust stream until the cats heat up.- but I'm not entirely sure about this....

 

Not a belt squeal, it has more of a "metal w/o lubricant" kind of sound.. But not a flat out grinding noise. Hard to describe.

To my knowledge, no XJ6 will chirp the tires when you accelerate at 60 mph. If I'm wrong, I gotta get me one of those! :-)

I saw another post with a similar problem, but he could get his to squeal while in park. He also has a video clip with audio and the sound is different from mine. In his case, an certified tech who really seems to know his stuff said it is his harmonic balancer or crank dampener (I can't remember for sure what it was - I should have re-read his post before answering!). Someone else suggested fan assembly for that post, but again, that guy can make his engine squeal when in park. Mine only happens when driving.

Hmm. Might have to bring it in and let a mechanic join me for a ride.

 

Although NOT a common issue, I am thinking towards a torque convertor starting to break up.

The ZF is one tough transmission, but IF, and I do mean IF, the trans fluid has been neglected the convertor will suffer.

If it were mine I would give it a simple trans fluid change, and by merely undoing the dipstick nut and letting it drain, about 3 ltrs usually, and then refill with fresh fluid MAY make a change, and then subsequent drain and refills will freshen the total system.

If that first fluid freshen does nothing, then it may be too late. At the miles you have done I am clutching at straws a little, coz, as I said the trans is a tough item.

My TH400 in the V12 had a strange whine at some times, and a number of drain and refills sorted it just fine. It had done 123k kms when I got it, and I reckon the trans fluid had never been changed, it was quite dark and smelly. A very different transmission to the ZF you have, but the principles and nice clean/fresh fluid is still a requirement for long service life.

 

Thanks very much for your help. I did change the transmission fluid and filter about 2 years ago (86,500 miles on the clock). I did the fluid flush, so it was a complete refresh. I thought the same as you, that it might have never been changed and I wanted to properly care for the car.

I did check the trans fluid to make sure there was no leak or discoloration (I doubted the leak idea since there is no puddle of fluid). Level reads full and fluid looks clean and has no unusual odor.

Hmm. I did have a dust shield on my driver front wheel come loose and it made a screeching noise when I applied the brakes. Maybe this is also a simple issue that a certified tech would spot? I hate to bring it in, but it seems this is a hard one to diagnose using only text...

 

Bump.

Still hoping to figure this out. I tried to make it happen while driving, putting the car in N and revving engine past 1500 rpm (about where it usually happens under acceleration in D). No noise. If I accelerate very gently in D and keep the r's under 1500, no noise.

Even though trans fluid has been flushed and filter replaced, I'm starting to wonder about the tranny. It shifts fine and no issues in or out of gear ever, but maybe?

Still open to input. Thanks in advance.

 

Okay... brought it in to two different repair shops. The first couldn't find any reason for the noise, but did hear it. I mentioned possible crank damper bushing wear, but they checked and said that is fine. I asked about torque converter, but they said transmission was fine and that the noise isn't coming from the tranny (I agree). We put it up on the hoist, and after looking hard at the exhaust system, he found a slight "bright silver" line near a joint off the front passenger side exhaust. He surmized this was the result of a slight vibration. He put a hose clamp on it and said if it gets worse, he'd suggest cutting off sections of the exhaust and relacing until the noise is gone. The hose clamp made no difference whatsoever, and the approach didn't inspire confidence, so I paid my $100 and drove to another shop.

The second shop agreed that the crank damper and tranny are fine. They determined the front rotors were at their end of life thickness (the first shop mentioned I should replace front pads/rotors soon as well). They also said the front left wheel bearing was shot. They wondered if replacing the pads/rotors and the wheel bearing would fix the sound..? Did the repairs ($1,000) and was told the noise was gone. Drove it about a half mile down the road and yes, there it was, still the same as before (but, the bearing noise is gone and I have no doubt the car is safer to drive, so the repairs were necessary anyways). They said the exhaust was solid as a rock and vibration free. They didn't buy the other technicians diagnosis.

So, here I sit, pretty much the same as before with regard to this strange screeching noise. It does seem worse when I am turning that going straight, but I can make it happen either way. Occurs quite regularly between 1800-2300 RPM. I have noticed a very subtle - and I mean subtle, sqealing sound when the car is at idle and in gear with the brake applied. I set the park brake and popped the hood to get a better listen. The sound seemed to be coming from the front of the engine, near the pulleys, fan, water pump, etc. There is absolutely no seepage of coolant, so I wonder about the water pump possibility. Could be a pulley or maybe the fans? Belts all have been inspected and deemed to be in good operating condition.

One more time - any ideas? The car drive fine, but the noise drives me crazy. I'd be very happy if we could figure this one out.

 

I would put some marks on the front pulley between the inner and outer hub to absolutely prove the front pulley is not slipping. You say you do not hear it at idle, and that is when the pulley isually makes it's screech, but you are running out of things to look for.

 

Yep, I agree.

That front pulley may be delaminating. Checking that insitu is not easy until they get REAL sad. The 2 paint marks will sort it very quickly.

The steer pump is not belt driven, so the fact it is slightly more audible when turning is not related to that. Unless the steer oil is waaaay too old, that will give some wierd noises on any car.

These "flat belts" are known to loose their "bite" with age, and the "V" grooves of the pulleys can get packed with crud, which will reduce the ability to drive properly. I replace mine every 2 years no matter, and simply wire brush the grooves of the pulleys.

The other thing with AJ16 engines is the upper timing chain tensioner issue, and that causes more of a rattling noise at 1500rpm os so, and is easy to nail down. This is a fairly common issue with these engines at about 140000kms or so, even earler with lousy oil and or oil servicing practice from a previous life.

 

I had a similar noise on my 90 xj6,what was causing it was a blown exhaust manifold stud letting the gasket act like a reed in a saxaphone.The sound was very metalic(i bought the car for very short money as the previous owner spent a small fortune having it checked by various dealers and other experts and none of them found it).

 

So, the "screeching" sound seemed to be getting worse, which my mechanic said was good. Gives him better odds of diagnosing the problem... And he tells me to run it until after the first of the year, when I should bring it in and let him keep it for a few days to drive it. I reluctantly agree.

Today, I'm driving home from work and the oil light comes on briefly. It's been 2500 miles since the last oil change, which I suddenly realize kind of coincided with the onset of the noise. I take a right hand turn a little faster than normal in an attempt to get the light to come back on. It doesn't, but I notice the oil pressure needle drop significantly, then rebound when I get straight again.

I come home and turn off the engine. I let it sit for a minute and check oil level. Doesn't even register. I add 2.5 quarts of oil and take it for a drive. No screech. I come home, turn off the engine, let it sit for a minute and check oil level. Still doesn't even register, meaning it was >2.5 quarts low. Good grief...

So, I plan to add more oil tomorrow (didn't want to add cold oil to a hot engine). Maybe the mechanic didn't fill the car with oil after the last change? I guess the problem is solved, but I wonder what kind of damage has been done to my oil pump and engine by running it damn near dry for 2 months. The lifters never ticked, nothing sounded odd besides the screech. Geez.

 

Ummmmm, The fact it is running at all, ALCOHOL, and lots of it, for you not the car.

The damage question, unanswerable really, but if it aint "knocking" from down below, you are one lucky 9 live ***** cat trust me.

The squealing was possibly numerous items telling of their grief, and until you know how many quarts you actually add you want know how low it was. With about 8quarts in there, if you were 5 down, NOT GOOD, but at least it had oil to pick up, not enough, but better than none.

The lifters are "solid" so would not tick as a hydraulic would.

If the mechanic "forgot to fill it", I believe the engine would have siezed long before now, so the loss of oil needs investigating, again in my opinion.

 

Thanks, Grant. I suppose I was a bit overly dramatic by saying the mechanic left the car void of any oil... My guess is he added 5 quarts, and after driving for 2500 miles, I probably burned a quart(?), leaving me 4 quarts low.

I checked the coolant level and condition - full, no oil or gas smell, no discoloration. No oil on the floor or anywhere under the hood. I guess I can't think of anything else that seems plausible.

You'd think a decent mechanic would check the oil level before he let a car roll out of his garage, but I guess for many, quality is just an afterthought...

 

Afterthought, HAHAHAHAHAHA, "your money in my pocket, see ya next round, its a Jag, that wont be long". That is the mentality that gets right up my nose.

With the basics required for an X300 I would consider SERIOUSLY doing your own servicing, and its not that involved or hard.

Since it has been running a tad light on oil, that oil has had a damn HARD time, so my suggestion is to get it, and the filter, changed again, and if you are not up to it for whatever reason, find a better mechanic to do it, they are out there, and generally DO NOT advertise, they dont have to, the word of mouth of loyal satisfied customers is more than enough.

Someone on here that knows which bit of "USA" you are at, "may" give you a steer.

 

My thought is, did the mechanic only fill it with 5 quarts of oil to begin with?

If I were you I would find your last oil change receipt and look it over. If he charged you for 8, then assume he probably did put 8 in and you have another situation on your hands.

Jags take A LOT more oil than the normal car. My Dodge Durango with a 5.9L V8 only takes 5 qts. I just started doing some general maintenance service on a couple XJs and I was amazed at how much oil is in the engines.

 

From the "Kick you when you're down department"-
You should never run a car , especially an older one, for 2 months without checking the oil level.

 

All good points. I checked the receipt and verified that the service guy only put in 5.5 quarts of oil at the last change... Lesson learned.