Timing belt tightness

[just-in]

Hey guys/girls, i'm having a wierd issue with what i think is the timing belt, me and my friend changed the water pump on my RB20 just a few days ago, everything is nice and tight no leaks...basicly everything went well except for when we started it

At idle the motor runs smooth but as soon as i rev it, between 2k-3k its as if theres some type of vibration its coming from inside the timing belt cover, we checked the tensionners and there in good shape they've been done not long ago with the belt, anyways is it possible that a timing belt be too tight? Its as if its metal vibrating for a split second when i rev it..

Any input is appreciated

Thanks

[nelsonmxmarc]

Possible the tensioner bolt is loose, or even broken? Look at the "Grocery getter" Gtst build for reference. Not a good thing!

[Skym]

Vibration = timing belt is too tight. Common mistake.

Also should change idler, tensioner bearings and tensioner, idler mounting bolts, cam, crank seals, waterpump, auxilary belts.

[gtrjon]

a timing belt should be taught not tight.

[evilgtr]

To be more specific can some of you guys with hands on experience explain how tight it should be exactly ? I was looking at mine the other day and although it isnt vibrating or "whining" I feel it may be to tight. Iv heard guys say if you can move it 1/2" or a little more up and down ( from in between the timing gears) that this is acceptable ???

thanks

[nelsonmxmarc]

For specifics, the belt tension should be "20 kg" I guess you could measure that with a fish scale? lol

[evilgtr]

hahaha or it that 20kg tension on the tensioner measure with a torque wrench ?

[nelsonmxmarc]

As far as i can tell, the manual simply states that the belt should have "20kg" of tension, lol. Makes as much sense to you as i!

[DarkCaporaL]

Honestly if your not getting any vibrations or whining, just leave it be.

[Supraclean]

Honestly Did the exact same thing once we changed my Buddies timing belt. We even took everything off and put it back on. Came to the conclusion that driving around for half hour and warming it up/break in the belt so to speak and the noise was gone. I say just drive it!

[BenC]

You can get a belt tension gauge but they are around $150

[just-in]

I might just have too take the whole front appart again...fack lol better be safe than sorry i guess, it might even be the lower metal shroud or something similar, someone told me a half inch of play up and down in between the cam gears

Thanks for the input

[nelsonmxmarc]

Half inch up and down sounds about right!

[Brody_Howell]

Today in my AST class in college, my instructor said as a "General Rule of thumb" if you cannot find a spec in a manual for timing belts, the tension should be enough so you can just barely twist it 90 degrees. But again, just a rule of thumb, manufacturer's spec is better obviously.

[jdms13rhd]

I once had a similar noise after a pump/belt install.

it was like 4 years ago and was a total disaster! Once I heard the noise, I wanted to figure out where it was coming from. Figured it was behind the belt cover. So i took it apart, did a rotation with a wrench and didnt see anything. so i figured I would start it up. Put the cas back on and fired it. Walked over to the front of the car with a vaccume hose in one ear. Looked at the belt and quickly noticed the belt slipping forward!!!!! i quickly ran back to the drivers door, reached inside to cut ign...... one second too late. belt slipped off. On the tare down, i had the tensioner spring slipped under the mounting surface thus it was on a slight angle and making the belt slip off. So a waterpump job changed into an engine swap :S fawk. my bad. I am now very cautious on that spring! haha. Live and learn.

As for the slack, just dont have it snug. Once the belt warms up it actually tightens and makes it tighter. So, when its cold you should have that 1/2 inch approx. Its more of a sense of how it should be. You know whats too loose and know whats too tight (hopefully :P).