I have a really irritating wobbly noise coming from the front of the engine that I was hoping would go away after the TB/WP work, but it hasn't. I finally took a video of it to post and I'm hoping it is an accessory and not the engine itself. The parts I replaced/rebuilt when I was in there are: replaced water pump, replaced oil pump, rebuilt p/s pump. The fan bearings were replaced when I did the intake refresh back in 2019.
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Re: Mystery Sound from front of engine
Posted: Wed Apr 07, 2021 9:56 pm
by MFranke
Have you tried using an engine stethoscope, or a long screwdriver (with your ear on the end) to locate the source?
Re: Mystery Sound from front of engine
Posted: Wed Apr 07, 2021 9:57 pm
by worf
aridaen wrote: ↑Wed Apr 07, 2021 9:51 pm
I have a really irritating wobbly noise coming from the front of the engine ...
Get a 'short' fan belt and eliminate the air pump and see if the noise goes away.
Re: Mystery Sound from front of engine
Posted: Wed Apr 07, 2021 10:12 pm
by Addlight
I agree with Worf on seeing if the air pump is the culprit. I had a similar sound on my 86.5 from an air pump with a bad bearing. This is a fairly easy thing to check.
You need a 21" belt for this.
Matt
Re: Mystery Sound from front of engine
Posted: Wed Apr 07, 2021 10:20 pm
by SeanR
Yep, it's the air pump.
Re: Mystery Sound from front of engine
Posted: Wed Apr 07, 2021 10:35 pm
by aridaen
MFranke wrote: ↑Wed Apr 07, 2021 9:56 pm
Have you tried using an engine stethoscope, or a long screwdriver (with your ear on the end) to locate the source?
I haven't done that yet, typically I don't have much luck with that method.
Re: Mystery Sound from front of engine
Posted: Wed Apr 07, 2021 10:38 pm
by aridaen
SeanR wrote: ↑Wed Apr 07, 2021 10:20 pm
Yep, it's the air pump.
And to think I actually flipped a coin on the keep/delete the air pump. I think I was in a hurry to drive it and it was easier to keep than delete (waiting for a belt).
Re: Mystery Sound from front of engine
Posted: Wed Apr 07, 2021 11:45 pm
by Addlight
Take the old belt to NAPA and they can find you a 21" belt of the same width. That's what I did. I think my belt is actually intended for a tractor or something, but it's the right length and shape.
Re: Mystery Sound from front of engine
Posted: Thu Apr 08, 2021 12:49 am
by Schocki
There are two different belts for two different pulleys (better measure before).
The Fan pulley with 106 mm uses the 21" belt.
86 mm uses a 20" belt.
The belts are normally used for the rotating blades on a riding lawn mower.
Re: Mystery Sound from front of engine
Posted: Thu Apr 08, 2021 7:34 am
by linderpat
Schocki wrote: ↑Thu Apr 08, 2021 12:49 am
There are two different belts for two different pulleys (better measure before).
The Fan pulley with 106 mm uses the 21" belt.
86 mm uses a 20" belt.
The belts are normally used for the rotating blades on a riding lawn mower.
exactly - you can buy these belts at any lawnmower store. That's where I get mine (my 78 has the air pump deleted )