I have this weird grinding noise during cold mornings that doesn't go away until the car is fully warmed up. Not sure what it is.
I've already replaced the water pump but the noise was still there so I removed the a/c compressor belt thinking that was it but this morning I go to start it up and the same exact noise is there.

I am now lost as to what it could be. Would an aging power steering pump make this type of noise? Starts at about 4 seconds into the video

 

Hrmm, how long does the sound last? Is it a few minutes long until the engine warms up?

I have an odd sound like that, but it clearly is the starter 'dragging' and only lasts a few seconds but is VERY noticeable. I should try to clean the mechanism before it kills it, but even then its days are probably numbered. Starters are a wear item to some degree and this one is 16 years old.


If your noise actually lasts 'minutes' I'm not sure what it is though, although I guess it could be the starter. But that would be an unusually long time for it to finally disengage.

Have you tried using a mechanics stethoscope to locate the vicinity of the noise?

.

 

Al,
The sound lasts for at least 5 minutes. Sometimes I just hold the pedal at 1200-1500rpm so the sound isn't heard while warming up. I don't think it's the starter because I've actually had the starter stay engaged even after engine start up.

I have tried using a stethoscope yesterday and that is what led me to disconnect the a/c compressor belt since it sounded like it was coming directly from there but going to start it up this morning, the sound was still there. Now I'm starting to think it's the power steering pump as it's somewhat directly connected to the mounting bracket of the a/c compressor

 

Just a WAG here but could it be a belt?

Try spaying some wd40 around the belt areas and see if it goes away?

Larry

 

And don't forget the tensioner.

 

I've already replaced the tensioner pulley for the supercharger belt and the a/c belt is removed. A few weeks back I also started it up without the supercharger belt installed so just the water pump and alternator belt and it still made the sound but since then I've replaced the water pump.

Someone also told me it could be the air/smog pump?

 

Let others chime in, but could be the start of the dreaded harmonic balancer delamination. The slight 'wiggle' as it starts to delaminate would cause that intermittent "warble" sound

 

Sounds like the noise caused by a worn pulley to me. If it also happens when suddenly accelerating, then it would be almost certain.

 

+1 Suede, I think it is the pulley delam too. A little squeak, rattle & grind are telltale signs. If you can watch the pulley spin you might see vibration coincide with the noise. Also if the voltage fluctuates with lights on, and coincides with noise. All signs that I experienced with my VDP. Sorry Alb, but I hope I'm wrong here!

 

I had a failed relay on the air pump, replaced it and noise went away so maybe worth a try?


Larry

 

Just pull the relay for the airpump to check that.

 

Hmm been trying to pin point where this sound is coming from for the past few days but still can't figure it out.

This morning I tried removing the relay for the air pump but still the noise is there.

As of right now I have my IACV unplugged so there is no high rpm cold start (idles at 700) and that is when the noise is the worst. When I have the IACV plugged in the cold start rpms are at about 1200-1300 and the sound is there for maybe half a second but then goes away right away.

Could it be that the harmonic balancer expands slightly at higher rpms so it doesn't slip?

 

The pump relay may not be the problem, but to check, you have to swap the relay out with a known good one, not just remove it - removing it will cause the same symptoms as a non-working relay!

Larry

 

Yes Alb, the sound can be hard to localize. In my car the pulley caused a rumble through the whole engine that really sounded awful. As it warmed up, the rumble was not as frequent. Also at higher rpms there didn't seem to be any problem at all! But the car became undriveable because of the low rpm shudder and lack of battery charging due to low alternator rpms. The battery then died.

I don't think the air pump is the issue here because it only runs for a short time anyway.

You could take off the alt/water pump belt and run for a very short time (like 20 sec) to see if the noise goes away. Does the XJR have an electric coolant pump? If so you could run it longer, but don't overheat.

 

It might be worth a BRIEF run with all the belts off, ideally from a cold start. I am wondering whether it is one of the plastic tensioner or idler pulleys, as the noise sounds like a dry bearing to me, and with the belts off, it should disappear.

 

Hey guys,
Was finally able to pin point where the noise was coming from. Started the car up this morning with all belts removed and no noise. Since I had already replaced the water pump, I was hoping it was the alternator and not the dreaded harmonic balancer. I installed the water pump/alternator belt and started it back up and the noise came back.
So now it looks like I need to replace the alternator, which I've heard is not a fun job on the XJR6.

Could someone link me to a parts diagram of the alternator and brackets that hold the alternator in place so I know what to remove?

Not sure if I should tackle the sway back end links and bushings at the same time since it looks like I'd have to remove that also?