Screech noise - fan or belt?

Dear all,

My XJC 4.2 recently developed a screech, usually under slight acceleration. I was able to reproduce this, see video below. At first I suspected the fan which seems a little squeaky (second link). It sounds vaguely metallic. But reading the forums a loose belt seems more likely.

It’s not severe and in steady state motoring there is nothing. But accelerating from low speeds especially, even relatively gently, it will give one or two little screeches.

Ideas very welcome as ever.


Nick Hill
XJC SII 4.2, 1976 (Canadian spec)

I was going to say belt, probably alternator because they have the smallest pulley, which allows slippage unless the belt is pretty tight. But your fan clutch is in bad shape. And it sounds just like the screech in the other video–which doesn’t sound like a belt. it will also slip mainly when the engine speeds up–the fan inertia resists angular acceleration.

So it’s a no-brainer. Replace the fan clutch (needed) then see if the noise goes away. IMHO.

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Thanks. My fan clutch was just replaced a few months ago as the old torquatrol thermal clutch was shot … would be disappointed if that was the issue… but of course that doesn’t make it wrong.

are the fans rubbing on metall somewhere, I hear a mettalic clunk, is the belt lose ? alternator belts were poor on both my 89 cars… so I canged them both…have to remove the fan clutch to do this… but now no screaming from the belts and p steering works much better…!

Have you actually checked belts’ tensions, Nick - it is the first step with squeals…:slight_smile:

xj6 85 Sov Europe (UK/NZ)


Earlier on I took another look, gave it some revs while parked up and the noise seemed to disappear. Shortly afterwards I took her out and after 100 yards a clanking sound followed by coolant everywhere. So initial problem “resolved” as the radiator now has a hole in it.

Looking again, I feel lucky to be alive. The rad fan had detached itself and the bolt penetrated the rad. Fortunately this did not happen when I was bending over the engine bay. And I was only doing low revs when cold so the fan was only turning slowly. Could have been more spectacular when hot and at speed, especially if my head had been in its way.

So new radiator time (not a bad thing anyway). Puzzled as to how the fan detached itself.

Anything else I should do while changing the rad?



From the sound the clutch made it is logical that it disintegrated. Or it seized and then something disintegrated as the consequence. You had that coming.
Change the hoses while in there if they are not relatively new still, and see if the water pump got damaged or the fan got warped… i‘m happy for you as it could have hit the bonnet or yes, much worse.

You would think that failure rate would be lowest when a part/assembly is new, then increase monotonically with time as the part/assembly gets old. But failure rate curves are higher when the part is new, then decrease with time, then reverse and increase with time. This is due to defects in new parts or in their installation. They have to be “sorted out.” IMHO.


may I join you in bad luck?

Back in 1992 I changed the viscous fan clutch unit in my Spitfire. Don’t know exactly when, maybe like 2010 I had an occasional screeching sound which always went away immediately. After the last ride before hibernation I parked the car and went for a coffee. When I returned to the garage it looked like in a Quentin Tarantino movie … at the time I used red anti freeze.

It turned out that over time several of the four mounting bolts of the fan had worked loose, lost their respective nuts and then worked their way forward. Before letting go the fan they would cut a nice circle into the radiator, pretty much like the axle spikes in Ben Hur …

I never understood why bolts that had lasted for years and years out of nowhere decided to come loose in the first place. I did understand though why original installation has you put in the bolts from behind and put the nuts on from the front …

Good luck


75 XJ6L 4.2 auto (UK spec)

I would say its the belt.

Thanks all.
Challenge is now to source a replacement radiator fan. Assuming I stick to the mechanical set-up, I am having difficulty sourcing one. Nothing at Barratt’s or Anglo Parts. Any ideas?
Many thanks
Nick Hill
XJC 4.2 (1976, Canadian spec)
Paris, France

You could try…


Is the fan bent? Ouch. I‘d try ebay, there is one for a 2.8 here in Germany, listed for €60 OBO - try 30 if it is the same as your 4.2 which you would have to verify. Maybe there are more available in France.
Fans themselves don’t age, unless they’re plastic in which case they will disintegrate and often mess up the bonnet in the process. I would not look for a new one if it is metal.

Aged metal fans will toss a blade. Aged plastic fans will toss a blade.

Time to consider electric fans. Many advantages. .Not limited to easier installation.

iI only the core of the radiator is damaged, it can be recored with a odern and more efficient part.

Circa 1950 or so, three kids did a last kid hurrah. A trip to California in Roy’s inherited 39 Ford. very nicely kept family car, but with a very tired engine. It ate oil!! Ran nicely, though!! No issue, my job at a full service station got me a case of Texaco 40 at cost. 24 quarts oughta get us there and back!!! Wrong, It got us there!! but, roy’s uncle was connected to Union 76. he contributed a case of 40 to get us back. We had a ball!!

Catastrophe, Not too far after Blythe Ca, the generator mounted fan tossed a blade!! Took a chunk of radiator as well, of course. It was night as the usual time to cross the desert in mid summer… ,We had tools and the skills to use them. Three teens pulled the radiator, removed the remnants of the fan. Pinched off the busted tubes. Put it back together,. added the water we carried. All by flash light Got to Desert center. of course, it had a radiator shop. An ideal place for one!!! .

Awaited opening in their park lot. We their first customer. We had pulled the radiator. No more money for a recore. So, the shop soldered the pinched tubes and closed off the weeps. . We put it together, added water. Hot day, but we drove anyway… No fan, but the engine stayed cool enough to make it. Roy installed a rebuilt engine, and new radiator and got it painted,
Off to California to start his job with Ford Aeronautics…


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Nice story, as usual. Since the blades are spot welded three times or so I think it would be very rusty, on the other hand a good tug will surely show up broken welds? Or are they impossible to find.
Whereas the plastic fans, they get so brittle they fall apart.

Great story, Carl! 24 quarts from Texas (?) to California - was that a Diesel engine;-)?

The steel fan on SII XJs is driven via a viscous coupling, so the physical load on the blades is very limited, while, as David indicated, the part is quite massive. I’d prefer it any time over the plastic SIII fan. While e-fans do have advantages I dislike their hairdryer sound, possibly coming in an on-off mode while you’re waiting at a red light. As long as the original is fine, I wouldn’t replace it. BTW, last Friday I took a trip under serious temperature (around 36°C ambient) and the water temp needle wouldn’t go over 12 o’clock. Without A/C in my car I had bigger problems with the heat than the engine …

Best wishes


75 XJ6L 4.2 auto (UK spec)

Thanks all. The issue is that the metal fan is no longer manufactured. At the moment I seem to have three options:

(1) import a used fan from the US (the only one I have found so far)
(2) work-around solution of Mk 2 fan ( and viscous clutch; I am told that the fan can be readily adapted as it plastic and it can be re-drilled and this set-up is compatible with the XJ6 water fan;
(3) electric fan solution. But this may require an upgraded alternator …

Opinions welcome on the above (or indeed other options)!


75 XJC 4.2 auto (Canadian spec)

PS, I am using this car in the south of France where it needs to cope with 38C in a traffic jam…


if your car is equipped with and you like to enjoy the A/C an upgrade is something to think about. There are uprated radiators available that look fairly original and the twin e-fan SIII setup behind is feasible, even though a lister just reported that things are not as simple as they might be.

Sticking with the original there is a metal fan here, but your engine might be younger, or here|Make%3AJaguar&hash=item2f3eace85c:g:XmAAAOSwzjxeIxNW. I’d take this one though Looks like good value for money.

Good luck


75 XJ6L 4.2 auto (UK spec)

Do the various inline 6’s have the same fittings for the clutch and fan or is everyone different ?
And are the 6’s the same with the V12?
What are the differences between the metal, the white and the V12 yellow fans?

I can confirm that for the V12 :

  • The Hyden 2665 Standard clutch is a direct fit and keeps the engine temp bellow 90°C under all conditions.
  • The radiator fan from the Range Rover P38 and from the Land
    Rover first generation Discovery are bolt-on replacements for the yellow fan.