I replaced my belt on my Komatsu D39EX21A , with a NAPA belt. It has made a squealing noise ever since and now has lost one of the v's. Here's my question , is the belt I need a metric belt or should I look for other problems. I checked the alternator and fan pully briefly today. I know I had a 312 Excavator rented and the belts broke on it and I could not find a match , went to a Mitsubishi car dealer and they had what I needed. This noise is getting irritating.
B model Cummins licensed copy engine, should be a Gates K080620 if I crossed the numbers right. 8 ribs, 1-1/8 wide? Double check nothing has shifted out of alignment and the idler wheel on the tensioner spins free is about all I can suggest.
Also make sure that the pivot on the tensioner is not worn causing it to work slightly off center. This was often the problem with the fan belt on the Komatsu WA600 where I worked. If pivot bearing/bushings are getting bad it might not be working free. Last failure, one of the last projects before retiring, was to replace that belt. This time the bearings seized in the idler and burned the into right fast! Not sure about our application, but the WA600 tensioner has an extra rod to counter act the effect of the fan on deceleration. When this gets out of adjustment belt would squeal like crazy when engine was returned to low idle abruptly.
I put a new tensioner on it , cost 280$ from the dealer. I know that don't mean it is good either. I do remember when I put the new belt on it sat high on the pulleys , even above the pulley a bit. Most of them on pick ups I've seen are level or sat down in the pulley.
Might have been one rib too wide?
Is the a/c on or off?
The ac has a separate V belt. The pulley has 8 groves. I think the belt groves were to big or slightly to big. What I do know , the oil filter and fuel filter from my early model D39E-1 will not fit the D39EX-21A. The engine shares many similarities but the thread are different on the filters. I know the tensioner from Cummins is about 120$ versus 280$ from Komatsu. I've got about 10 hrs I need to do then I'm going to remove the belt and inspect the pulleys , water pump alt etc. I'll keep an eye on it for now and will post my findings. Back to the 312 , it took like a 50mm belt , all the parts stores had 1/2 or 5/8. This has me thinking its a metric width.
In my experience replacing a metric specification belt with an inch size one usually ends in tears. However I am slightly confused by your comment about 50mm which is about 2" give or take then in the next breath you mention 1/2" and 5/8". If your belt is between 1/2" and 5/8" then it is most likely a 15mm wide metric belt which is about 40 thousandths less in width than 5/8".
I'm not good with the metric system , so there is a metric belt then?
Yes metric serpentine belts are available. In the US Gates manufacture them ....... http://www.gates.com/products/industrial/industrial-belts/heavy-duty-v-belts/metric-power-belts