100K Service...now I Have A Strange Sound... Please Help

[rofocale]

Hi Folks,

Over the weekend, Dad and I did the 100K service on my R33 GTR. This entailed replacing the water pump (with a N1 pump), the seals on the cams, the idler and tensioner bearings and timing belt.(We didn't do the crank seal as I have an upgraded oil pump to put on before long.) The work went well, with much patience and the engine manual at hand.

The car started up well and sounds just right...for about 2 minutes, then a what I can only describe as a whiring sound starts and continues. We have really only let the car idle until we are completely happy with all our work. Other than this sound, the car is running well. This behaviour is also repeatable. When we stop the car and restart it, it runs well for about another 2 minutes and then the whiring sound starts up again.

We haven't taken the cam and timing belt covers off yet, which is our next step this coming weekend. We had a little peek in the top of the cam cover and at first glance the timing belt looks okay(just a that spot, we didn't spin it round).

We used nissan OEM parts for the idler, tensioner, cam seals and water pump and the timing belt is a gates racing belt.

What I'm wondering is if anyone can offer any advice as to what might be causing this. My personal ideas are either the tension on the timing belt is not right, or that either the tensioner or idler bearing is not good. Can anyone offer any advice as to what this might be, or alternatively what it is not?

Thanks in advance,

murray

[89CAL]

The gates racing belts are pretty well known to be louder then the standard/some other timing belts. I have a Dayco timing belt and it hasnt made a noise since I put it in, but i know alot of people with the gates belts experience the whirring noise

I dont think its a serious issue, just a bit of noise, and after the belt wears in a bit it goes away

From what I know about it anyway, its fairly well documented on this site, just search timing belt noise or gates timing belt, something along those lines

[boostn0199]

Yeah its just the gate belt they always make the whirring noise nothing to worry about.

[GTR-N1]

I had a Nismo Timing Belt put on after an oil pump change on a GTR. The whirring sound lasted for about 3000Km until the belt settled.

[rofocale]

Thanks to everybody for their advice - I really appreciate it.

After hearing your responses, Dad and I took the front covers off again and went through the tensioning procedure again and gave the new tensioner and idler an inspection. Everything looked good. With it all in place I gave the crank several rotations, watching the timing belt for lateral travel or anything unusual. Everything looked good so we put it all back together and started the car up. This time the noise was much less. Again it seemed to 'start up' after a minute or two after starting the engine, but the noise was nothing like as loud - it was down to a similar volume as many other regular sounds in the engine area, if it a little less. So considering the advice and experiences of everybody we just kept it idling for a while and then decided to go for a drive as the noise sounded just so much less of problem than after our initial turn on. The volume of the noise when I started this post/topic was really much louder than anything else in the engine area and sounded as something was pretty wrong. Now you would almost just say, that the noise is just how the engine sounds.

Thanks again