Timing Belt Whine - How Much is Normal?

[cammmy]

Hi Guys

How much whine is normal for the timing belt? I'm running a gates HTD belt from PNM (not the blue one).

The gates app shows 120 at 30btdc when cold. I realise this is a bit high but it's only 10hz out of spec? I didn't have time to adjust it again today.

The car doesn't whine at idle but at above that it does.

Would 10hz make that much difference or do these generally whine? Reasonably small movements of the tensioner where making quite big differences to the reading, so i don't think there's that much in it. I tried a few times to get it at 100-110 but ended up down at 80 and then back up to 120 (rotating the motor after each adjustement).

Edited May 31, 2015 by cammmy

[CarBuff]

Black timing belts should NOT whine.

 

But realize, a non-Lotus belt could be stiffer than a stock Lotus belt (which is generally a bit narrower). So, the frequency at which it vibrates when strummed is probably different.

 

If you are using a phone app to measure frequency, it helps to try and get the mic (Phone) as close as possible to the belt. I had frustrations as well with belt tension.

[ramjet]

A normal whine from the belt could be:

Can't you go any faster?

You call that hitting the apex?

etc.

Glad to help.

[cammmy]

Cheers, I had the mic right near the belt and the readings were generally consistent. If I get it down to ~100hz and it still whines, should I keep backing it off until the noise stops as long as I can't twist the belt 90 degrees?

Edited June 1, 2015 by cammmy

[cammmy]

I'll add that the car had the whine when I bought it and it was a Gates belt that came off.

[CarBuff]

A little whine is better than a slipped belt. So, as long as your readings are repeatable, I'd not go below 100HZ.

 

 

(Oh and to clarify my earlier post:  Lotus brand belts are more than 1mm WIDER than the aftermarket Gates belts. This could affect the tension frequency. Sorry.)

[cammmy]

Cool, I'll try and drop it to 100.

 

Also, do v-belts whine when too tight? Just realised my waterpump/PAS belt could be a bit tight.

[CarBuff]

V belts do not whine in my experience.  It's the teeth (shape and spacing) of a toothed belt that creates the whine.

 

 

 

 

Tight V-belts wear-out the components they drive. Rule-of-thumb:  V-belts should be just tight enough not to slip.   Once a V belt slips, the drive surface becomes glazed, so it needs to be replaced...

[cammmy]

Great, thanks. I'll try and get it down to 100hz tomorrow.

[molemot]

Are you sure it's the belt? Did you check the bearing on the tensioner??

[cammmy]

Tensioner and waterpump are both new.

 

Tensioner bearing is an SKF part.

[Mysterae]

When I did my timing belt I got around 108Hz and settled there. Once the engine had been running to get up to temperature I was really surprised at how damn tight it felt. The car's not been on the road since and your post has reminded me to check it again when I can.

[Vulcan Grey]

120Hz is way too high, guaranteed to whine.

 

Shoot for 100-105 normally.

[ramjet]

Also check your tensioner bearing as well. A reputable repairer here in Australia got a bad batch of tensioner bearings (all SKF he was told) that were under lubricated and all very noisy. It was awhile back though. The post about it is here.

[cammmy]

Cool, I'll try and get it down to 100 tonight and report back.

 

I had heard about dodgy bearings before buying, not a lot that I could do though other than hope they had been identified and returned. PNM didn't list these as SKF, it was etched into the edge of the outer race along with a part number that I can't remember.

[cammmy]

Well, checked the tension and it was was 100-105 almost every time? Would the belt have stretched a bit with those first 10 minutes of running? The evening was cool but not cold; not sure how big an impact that would have? Didn't have time to fire it and wait for it to warm up as I've got an early MOT on sat and needed to get it ready and back on the ground.

Will report back with how it sounds.

[mdw]

I think its meant to be set to the correct tension at  between 10 and 25 degrees C .

[cammmy]

Apparently it's about 15 degrees here at the moment so that should be fine. Definitely wasn't 25 on Sunday

[ragingfool35]

just to be sure, are you following the acoustic method detailed in section EF?

as Travis has indicated in several previous posts, it is has to be at 30 BTDC

[cammmy]

Assuming that the lines on the marker are 0, 10, 20 and 30 deg BTDC? then yeah. I've cranked the motor over by hand a number of times and repeated the measurements too just to make sure. Each time the cam dots both point inwards but are out of alignment. I'm measuring the run between the inlet and oil pump pulleys.

 

The nut on the tensioner is also fully tightened, so shouldn't be moving.

Edited June 5, 2015 by cammmy

[ramjet]

A normal whine from the belt could be:

Can't you go any faster?

You call that hitting the apex?

etc.

Glad to help.

I thought that was funny. Maybe not then?

[Andyww]

Are you sure its not the alternator whining?

[cammmy]

The belt or alternator itself?

 

The belt definitely isn't whining, If anything it could use more tension.

It was amusing Ramjet, I was going to comment about not having any apexes to hit in Essex but got side-tracked.

[Andyww]

The alternator itself. Quite common for them to whine.

[cammmy]

Okay cheers, I'll check that out.