Timing Belt Problems..

[Benzy]

Hey Guys,

A mate of mine just had his timing belt,w/pump, idlers etc on his R32 replaced by a local mechanic. Anyways two days later he noticed a rubbing noise coming out from under the timing cover. We pull it off, and where the belt runs on the cam pulleys, it is hanging over by about 3-4mm....

We assumed the tension was wrong ,so we reset the tension on the timing belt...but turned the engine over by hand a few times, and within about 5 turns the belt had already started working its way off the cam pulleys..finally it gets to where its about 4mm off then runs steady and doesnt go any further, but our concern is that it may start to wear the belt abnormally quick..

Is this the result of the belt not being tensioned correctly the first time and wearing the belt??

If so he should replace the belt?(car has done about 50kms since th eservice)

Is it the tensioner hasnt been installed properly?

Or is it something more sinister??

If anyone has experienced this before, or has some insight it would be much appreciated!!

Thanks all,

Ben

Edited April 16, 2009 by Benzy

[Godzilla32]

Sounds like the belt guard on the crank pulley is missing. Check to make sure all pulleys are fitted true.

[Fry_33]

Timing belts always track to one side due to the way the tensile cords are put in the belt. The flanges on pulleys/sprockets are what keep the belt from tracking off. The distance between the flanges will be less than the width of the other pulleys in the system.

So I would assume that the problem is something to do with the flagnes, ie the crank pulley as already mentioned. The other cause for the belt tracking incorrectly is misaligned pulleys. Being an engine though this shouldn't normally be an issue unless things haven't been installed correctly. The crank pulley is pushed/pressed on from memory so maybe it just isn't pushed on far enough?

Tension does not make the belt run off of the edge of a pulley.

Either way you don't want the belt running off of the edge of a pulley as it will reduce the belts life.

[Benzy]

Thanks for the responses guys, had a quick squiz this morning, and It looks like the crank TIMING PULLEY could be on too far ?? The gaurd that slips on behind the main pulley is extremley loose (1-2mm play) And just by looking at the belt, it appears to twist back slightly under the tensioner and idler....

But how could that timing pulley move back towards the block? As the mechanic wouldnt have had to touch it..

Only other thing it could be is the main pulley isnt on far enough..(as mentioned above, cheers) ill get a torque wrench and check it this arvo...

Ill get a laser pulley aligner from work too and check they are all level..

But if the bottom timing pulley HAS moved, where do we go from there?? Anyone else ever had this problem??

Any insight is much appreciated,

Thanks again, Ben

[ANVIL]

double check all the idler and tensioner washers per fsm. mine was doing that and i had the washers in the wrong order

[SteveL]

Thanks for the responses guys, had a quick squiz this morning, and It looks like the crank TIMING PULLEY could be on too far ?? The gaurd that slips on behind the main pulley is extremley loose (1-2mm play) And just by looking at the belt, it appears to twist back slightly under the tensioner and idler....

Something is seriously wrong here and your mate shouldn't drive the car or even run the engine until it's been properly investigated. From your description it sounds as if the harmonic balancer hasn't been tensioned correctly or something has been mis-assembled in that area. If it were me I'd be taking the harmonic balancer off, plus all the timing covers and have close look at everything. Certainly if the belt has been rubbing on the covers (or anything else) you should be inspecting it for damage and possibly even replacing it entirely.

Also find another mechanic......

[Benzy]

Yep. Car is never going back to that mechanic... Ok, harmonic balancer is now off, I have checked the engine manual, but cant see anything wrong, apart from the timing pulley doesnt meet the keyway on the shaft...if you get what i mean...The keyway ends then 2mm gap then timing pulley....Is it meant to meet it?? Yep,Have already orderd a new gates racing belt.

Edited April 17, 2009 by Benzy

[Benzy]

Problem SOLVED!!! MECHANIC DIDNT TIGHTEN THE HARMONIC BALANCER!!! After we pulled it off, fitted the new belt and refitted the balancer it tightened the whole way up to the timing pulley. Very relieved. no more overhang..Needless to say, the mechanic is going to be paying us for the replacement belt! Thanks heaps to everone who offered insight and advice both here and via PM. Couldnt ask for a better outcome

Cheers,

Ben

[Godzilla32]

The harmonic balancer bolt on the RB26 needs to be tightened very tight. About double your average balancer bolt tension. From memory its up around 420 ft-lb. If it wasnt tightened correctly then that could have caused it to come loose.

Deren