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Unbearable engine squeal... advice please!

GuyB

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Jun 8, 2015
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Ever since I bought my most recent 80, approaching 3 years back, I've been plagued by what most would conclude must be fan belt squeal. The noise didn't worry me when I bought it, and I took the truck straight to Overland Cruisers for a midlife service, which included all new genuine belts. Sorted... for a couple of days!

Less than a week later the squeal was back. I assumed this was just the new belts having maybe stretched out a little, and tightened them. A few more days and it's back again. 2 sets of genuine belts hence, and it's still there.

The squeal only lasts for about 5 mins from when I start moving (doesn't do it a idle), but if that's in the morning or late at night it's hugely annoying for the whole neighborhood, and the missus has lost all semblance of a sense of humour about it.

It still does it without the ac belt, so it's either the fan belts or maybe a bearing, or something else? It goes away briefly with a liberal dose of WD40, but due to the wind from the fan, I can't be sure where exactly the WD40 ends up! I've been cautioned against over-tightening the belts to avoid excessive wear on the bearings.

I fear Big Red's days are numbered if I can't remedy this soon - so any help very much appreciated!
 
Instead of spraying wd on the belt spray a little on 1 item at a time to.see where the noise is coming from. I expect it will.be a duff bearing in the system.
 
Spraying anything on the belts is only a temp fix and just attracts dust and debris to stick to them and the pulleys. Clean and degrease the belts and pulleys. I had a similar problem on cold starts with a large electrical load on the alternator and cleaning them this way, plus removing the shine from the belts with some wire wool cured it.
 
Sometimes pulleys get worn with constant belt slip. It’s then almost impossible to get a good drive. Belt dressing spray may help diagnose it if Towpac’s suggestion doesn’t sort it. Inspecting the V grooves for wear on the alternator is worth doing. Robson and Francis may be able to supply you a pulley if it’s worn.
 
I had this and a second set of new belts only cured it for a few days , I had the same concerns as you regarding over tightening but because the second set of belts convinced me the inner belt does sit slacker than the outer , i surmised that Toyota added the the outer belt as a sort of sacrificial lamb , if it snaps the truck will still get you home .

Guesswork and i'm happy to be corrected , but i chose to ignore the outer belt entirely while setting the inner belt tension , checking now maybe 1000 miles later no squeals and the outer belt has stretched to be about as tense as i had set the inner .
 
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Big miss conception that belts stretch then just wear thinner so sit lower in the pulley.

I would be surprised if the 2 belts don't tension up the same unless they are different makes
 
Thanks for the input folks - I'll see if any of that leads to a cure!
 
Sometimes pulleys get worn with constant belt slip. It’s then almost impossible to get a good drive. Belt dressing spray may help diagnose it if Towpac’s suggestion doesn’t sort it. Inspecting the V grooves for wear on the alternator is worth doing. Robson and Francis may be able to supply you a pulley if it’s worn.
Agree.. Try some anti slip spray. we used it on all manner of agricultural machinery.. Stops squealing belts instantly.. if it still squeals, it will be a bearing...
 
After it has been slipping, and the engine is off, you can see if any of the pulleys have got hot, the hot one will be the slipping one,
 
The double V belts should be a matched pair .......not just 2 belts with the same numbers and length on them that are both new .
Paired belts come as a pair with usually a cable tie or similar making sure they don't get separated.
This should avoid the symptoms mentioned above of one belt being shorter than the other .....if it's still the case with matched belts then check alignment in both planes of the pulleys all around ......don't forget the crank shaft pulley ....the rubber damper can fail with age allowing the outer not to be square .
 
…And a slipping damper could squeal. Mark across the face of the crankshaft pulley with tippex or similar and see if still aligned after squealing.
 
…And a slipping damper could squeal. Mark across the face of the crankshaft pulley with tippex or similar and see if still aligned after squealing.

Thanks again - pardon my ignorance but what's the damper?
 
The main crankshaft pulley is in two parts. The main hub and the grooved outer pulley (apart from the additional single pulley for the AC) the two parts are linked with a ring of bonded on rubber. The whole unit is a dynamic vibration damper.
A line marked across to the V for the AC from the two Vs for the alternator would also show any relative movement.
 
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I’m with @Grimbo on the matched pair quote, at my first service with my favored workshop, the guys there immediately said that my belts weren’t OEM or matched, and that was an at-a-glance comment.

After removal, he showed me genuine Mt T belts, as said, cable-tied together as delivered from his supplier, and he showed me the difference in the “V” angles between the new OEM belts and those I had inherited on the truck.

They were working OK, but not right. They didnt squeal, but they were a bit squeaky on idle, but that went away at running speed.

Needless to say, I’ve had Mr T matched pairs fitted since then, 12 years ago...
 
I have a Gates pair on mine. I asked if they could be matched at my local well known motor factors who said it shouldn’t be necessary with the Gates ones as they were so accurately made. So far, not a peep out of them.
 
Just to add ......you don't need to get genuine belts for them to be matched.

Most bearing and belt suppliers will be able to source them

If you are South of London I can recommend "Bearings And Belts" 01342 844275 just off the A22 .
Bess and Dave are brilliant , what Bess (the owner)doesn't know about bearings and belts can be written on a postage stamp cut in half .
Just be warned their place is an Aladdins Cave of useful stuff
 
Thanks for that Grimbo. Saved to my contacts for future reference. Always handy to have.
 
I doubt whether belts are matched even if they say they are. Tolerances are so close on belts these days there is no point. Also the inside and outside pulleys wear at different rates so you will have a mis-match. After a couple of hours they will bed in and can be retightened with equal flex.
 
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