Hum after timing belt job

[Thomas91169]

So just hit the 120k mark on my 98 GST, got the entire timing belt kit from E-PSI.

install went easy, had seasoned veterans with me (first time i did a t-belt job in-car, done it a few times with engine out, so much easier!) so 3 sets of dsmer eyes.

upon startup a slight low end hum that went away after about 20 seconds. didnt think much of it but maybe new timing belt noise. Does it for the first couple seconds anytime its cold, then goes away. I *think* i can hear it on the freeway, but im probably just imagining it like all other noises i think i hear from DSM's (standard paranoid dsmer). So far its gone 100+mi (i drive almost 50mi to work and back daily) and no issues so i doubt its something catastrophic because with my driving it wouldve let loose by now.

Things replaced:
Main timing belt
balance shaft belt (i enjoy smooth idle, its my DD afterall)
tensioner pulley
tensioner
idler pulley
water pump

All pulleys spun free, however the water pump was a bit tight to spin. Im wondering if its just needing to break in, or possibly whats causing the hum? Perhaps it goes away once it warms up?

My water pump acc pulley has a slight dent in the outer grooving surface from using a pair of vice grips to hole the pulley in place while removing the bolts that barely makes contact with the belt. This weekend ill likely pull it off and grind that piece off just in case, as well as take off the case to check for any sort of rubbing.

Its gotten better, earlier tonight i turned it on and it only hummed for about 2-3 seconds and then died out. Really hoping by the end of this week it works itself out, but knowing dsm's

 

[TheGreatGSX]

I'm in the same boat as you, except I didn't replace pulleys or tensionsers, also since I did not have the tools needed so I took it to a friends shop and he did it for me. I replaced timing belt, balance shaft belt, and water pump. Sometimes it hums, sometimes it makes a squealing noise for maybe 20 seconds on cold start then seems to go away.

I know when I had a 95 GS, every time I would replace a belt it would always do this for the first couple hundred miles and then go away completely, but I am definitely more cautious over my GSX (Much more money put into it, PLUS my dream car )

 

[rx7ttlm]

I'm in the same boat as you,

Belt tension or you got fluids on assy belts. If its not that noise video it and post it. It will say 1000x more than you can with words. Like the time my friend recorded his mazda rx7 detonating and didn't know what it was .

 

[DSM1G90]

Humming usually points to a belt that is on too tight ... the teeth on the belt is actually hanging up in the grooves on the sprockets that creates the hum ....

-DSM

 

[Thomas91169]

damn!

however its gone away. both times its started cold today; nothing.

if it was really that tight though wouldnt it show up and get louder with rpm?

 

[Strm Trpr]

I'd pull the auxillary belts and covers.
Mitsu spec'd the gap of .150" - .177" for a reason.

 

[KadieTSi]

Are you sure it's the timing belt?
I did my timing belt and had a slight hum and it was just my water pump pulley not being tightened all the way