Hi guys,

Just had the worst day today .

Installed a new OEM serpentine belt a few days ago , all tight and good. Driven it for 100 kms , today did some pulls.. During the 3rd pull the serpentine belt broke off. When i took a closer look i was amazed to see . The water pump pulley was broken, serpentine belt was torn and idler pulley was loose , so loose that it came off with hands even though we tightened it up at the time of installation.

Can not understand how water pump pulley breaks off like that ?

Has any one experienced such a failure ?

Any advice which belt to use ? what precautions do i have to take so that this does not
happen again.

 

Bump -

 

Wow.

Inspect all rotating assemblies on belt route to ensure nothing is frozen.

 

Its an very common problem of the Evo 4-7 Water Pump pulleys...

They are much lighter than the Evo 8/9 ones, but are prone to split in high RPM when having a lot of miles due to the thickness of the contact area.

We do replace them during service of the Timing belt to the Evo 8 / 9 pulleys on every Evo 7 or earlier when high revving is supposed...

Also Mitsubishi figured that out and so the design were changed for 8 / 9

The crack is always starting on the small lip towards the block side as you see in your picture...

 

Hi 4b..

Yeah inspected all the pulleys , all of them are rotating .

 

german_evoVII - Thanks for the input . I replaced the gates belt with OEM one which broke because of this.
Any advice which belt to use ?

 

Any belt shall work, you just had a pulley failure.

Gates or what ever is more affordable. Now if it was timing belt. Factory parts

 

Some times failures like these make you over think . Its good to have a forum where people having the same interest help each other out.

 

Stock belts are an bit more durable and quiet...but expensive

The gates does do the job fine, but sometimes make a bit of noise bit when cold after you put some miles on it