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BigJimnyMeet (North) 2024 (12 Jan 2024)


BigJimnyMeet 2024

14th July 2024
Parkwood Nr. Leeds

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Wobbly fan/chirping belt?

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26 May 2024 12:12 #256105 by tomlil01
Hi, all,

Not sure whether anyone has had a similar problem. Basically, I am getting a chirping sound from the drive belt (alternator belt, I think), when going over bumps in the road.

Belts are brand new and tightened correctly. 

I noticed this morning that the fan seems to be wobbling when the car is idling. Also, when the car is stopped I can wobble the fan and it moves a millimetre or two in the viscous fan part (not the part that connects to the water pump, but the part with coil).

Is is possible that this is causing the belt to slip briefly when I go over bumps?
I assume the fan shouldn't wobble at all?

Thanks
Lee

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26 May 2024 14:06 #256107 by facade
Replied by facade on topic Wobbly fan/chirping belt?
If there is that much play in the viscous unit it is worn out, it probably doesn't drive the fan when the engine is hot.

No idea about the chirping over bumps, but I'd check the crankshaft pulley isn't starting to de-laminate, it is very very common, begins with belt squeal at start-up, then as you tighten the belt to eliminate the noise it twists the pulley apart until one day all the grooved part just drops off when you are going along.

If it suddenly breaks, go back to the last thing that you did before it broke and start looking there :)
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26 May 2024 14:16 - 26 May 2024 14:19 #256108 by tomlil01
Replied by tomlil01 on topic Wobbly fan/chirping belt?
Thanks for responding. I don't have any overheating, so assume it is still functional.

Already replaced the crankshaft pulley and the tensioner pulley. Also, replaced the water pump and alternator.

I also spent a long time cleaning up all the pulleys.

Thanks
Lee
Last edit: 26 May 2024 14:19 by tomlil01.

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26 May 2024 20:02 #256110 by GandHisJimny
What's the age and mileage of the vehicle? Because as soon as I heard "chirping over bumps" my thought went to the bonnet adjusters!

I made a thread about this a few months ago and it's actually a really noticeable difference after adjusting it: www.bigjimny.com/index.php/forum/6-jimny...pers-to-stop-squeaks

I've replaced my fan belt and PAS belt too semi recently and the chirping sound was very similar but occured mostly when the alternator was under stress and it was a cold / wet day. And naturally the bonnet squeak is only over bumps.

I'd go check how much play there is the bonnet and also try running your car with all the electrics on (headlights, heated mirrors, A/C if applicable) to possibly rule in for sure that it's the alternator struggling.

Also, as facade mentioned, the crankshaft pulley can go on Jimmys and it seems like it's the alternator, so you tighten it, then eventually the whole thing goes and you realise it wasn't really the alternator..! See this vid: youtube.com/watch?v=mj3uaGm0UKY

Jimmer II (2007 JLX+ auto in black & silver) : Android head unit, Black Raptor Steering Damper, Yokohama Geolandar G015s, rear cabin light, OEM wind deflectors
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27 May 2024 03:45 - 27 May 2024 03:48 #256114 by tomlil01
Replied by tomlil01 on topic Wobbly fan/chirping belt?
Thanks, G. I'll check that out. Very interesting. It's a 2005 with ~90k miles.

Maybe there are multiple problems. The only reason I think it might be the belt, is that sometimes the chirp seems to turn into a brief squeak/squeal after the bump (carrying on briefly). Then it sounds very much like belt squeal.

I've had loads of trouble with belt noise since I got the car a few years ago. Originally I just put new belts on, and that didn't help until I made the belt really tight (too tight, I think), and came back quickly. I think I originally was just masking the problem.

I did have a really bad/loud squeal with all electrics on (particularly revving in neutral, but not only then), however this seems to be gone with the parts I replaced and after cleaning the pulleys. So, now it it is just the annoying chirp
Last edit: 27 May 2024 03:48 by tomlil01.

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28 May 2024 13:29 - 28 May 2024 17:23 #256127 by tomlil01
Replied by tomlil01 on topic Wobbly fan/chirping belt?
Hi G,

I checked my bonnet this morning and it was indeed loose. I could move it a fair amount without releasing the bonnet with the lever in the car.

I adjusted the rubber mounts, and now the bonnet doesn't wobble, and more importantly the chirping is gone.

Like you said, the sound is very similar to the belt squealing, and I did originally have genuine problems with the belts, and therefore I assumed (incorrectly) that this chirping was also originating from the belts.

Thanks again for your help. That's a really good tip.
Cheers,
Lee
Last edit: 28 May 2024 17:23 by tomlil01.

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28 May 2024 15:55 #256131 by GandHisJimny
Amazing! I thought it was a long shot so surprised I was actually right Glad you didn't need to spend hours farting about with belts, pulleys and fans.

Jimmer II (2007 JLX+ auto in black & silver) : Android head unit, Black Raptor Steering Damper, Yokohama Geolandar G015s, rear cabin light, OEM wind deflectors

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