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Viscous fan pulley squeaking

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Viscous fan pulley squeaking

Postby AdamDavo » Wed Mar 08, 2023 8:53 am

Hello,

I have a 1992 Isuzu Mu with the 4JB1T engine in it.
We recently swapped back from thermo fan to viscous fan due the the thermo fan being faulty and unreliable. After fitting the new fan the pulley that it attaches to has started to squeak/squeal when you rev the engine and also when the engine is cold.

Would this be due to the pulley being warn or the belt needing to be tensioned more?

Feels like with the addition of the viscous fan, the belt is now slipping on the pulley, or pulley is under more strain due the slightly more torque required to spin the fan and clutch assembly.

If someone could share some light and point me in the right direction that would be great.
Cheers guys
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Re: Viscous fan pulley squeaking

Postby geeves » Wed Mar 08, 2023 5:01 pm

3 possible causes.
belt loose
belt worn
wrong pulley installed.
Dont laugh at the last one. My last new alternator plus thge one I got from a wrecker had the wrong pulley installed from factory.In both cases the pulley had a larger groove. Luckily I still had the old alternator
Other 2 options check the belt is in good condition and tensioned correctly. One common trick is that Different belts are measured differently but numbered the same. Result is a replacement belt that is just too long for the alternator adjuster. If you have run out of travel fit a smaller belt
Sanding your knuckles before starting work can help. That way you cant skin them
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Re: Viscous fan pulley squeaking

Postby AdamDavo » Thu Mar 09, 2023 6:32 am

Thankyou very much,

What size or part number is the fan belt for 4JB1T and how is the best way to tighten?

Cheers
AdamDavo
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Re: Viscous fan pulley squeaking

Postby pig75 » Thu Mar 09, 2023 6:33 am

Are you using this belt for the ALT/FAN belt 17A1055
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