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Please help diagnose Cam belt noise?

Eikon

By Eikon,
in General Maintenance

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Eikon Explorer

Eikon

Posted
Posted

First off.... i have an RB20det swapped into a USDM 240sx.

It runs very well, and I am very happy with it, but I have found a noise that bothers me. Can you please help me diagnose and repair this.

When the engine idles, I hear a sound from under the timing belt cover. It sounds like the belt it too tight, like it's lugging a little bit.

So, I took off the CAS and then the timing cover and put the CAS back on with spacers and started the engine.

The noise is almost not there at first, but it gets more pronounced within a few more minutes. There are really two different sounds. One just sounds like the belt rubbing a little bit on something.. that doesn't bother me... it's quiet and normal I beleive.

The second noise drives me crazy, worries me infact. It sounds like ballbearings grinding together. It's not completely constant... sounds like it would be at a certain point on the revolution of the exhaust cam gear.

My original thought was that my timing belt was too tight. But with the cover off, the belt seems to be ok by touch... it gives about the width of my finger when I push on it between the Cam Gears.

I listened very closely in a lot of different areas. The sound seems to come from the center of the cam gear or just a little inside the valve cover. Exhaust Cam gear to be specific.

Could it be a bad CAS? Are there bearing in there that go bad? If so, wouldn't the sound seem to come from the outside cap of the CAS?

Could it be the cam gear itself grinding on something? I don't really know much about the internals of the Cam Gears, the CAS, how the cams themselves attach to the cam gears...

Anyone have any ideas?

Thanks

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https://www.sau.com.au/forums/topic/70824-please-help-diagnose-cam-belt-noise/
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  • 7 months later...
boomtheroom Community Regular

boomtheroom

Posted
Posted
First off.... i have an RB20det swapped into a USDM 240sx.

It runs very well, and I am very happy with it, but I have found a noise that bothers me.  Can you please help me diagnose and repair this.

When the engine idles, I hear a sound from under the timing belt cover.  It sounds like the belt it too tight, like it's lugging a little bit.

So, I took off the CAS and then the timing cover and put the CAS back on with spacers and started the engine. 

The noise is almost not there at first, but it gets more pronounced within a few more minutes.  There are really two different sounds.  One just sounds like the belt rubbing a little bit on something.. that doesn't bother me... it's quiet and normal I beleive.

The second noise drives me crazy, worries me infact.  It sounds like ballbearings grinding together.  It's not completely constant... sounds like it would be at a certain point on the revolution of the exhaust cam gear. 

My original thought was that my timing belt was too tight.  But with the cover off, the belt seems to be ok by touch... it gives about the width of my finger when I push on it between the Cam Gears. 

I listened very closely in a lot of different areas.  The sound seems to come from the center of the cam gear or just a little inside the valve cover.  Exhaust Cam gear to be specific. 

Could it be a bad CAS?  Are there bearing in there that go bad?  If so, wouldn't the sound seem to come from the outside cap of the CAS? 

Could it be the cam gear itself grinding on something?  I don't really know much about the internals of the Cam Gears, the CAS, how the cams themselves attach to the cam gears...

Anyone have any ideas?

Thanks

did u find out what the problem was?

  • 1 month later...
Hootchy Community Regular

Hootchy

Posted
Posted

I've also got a noise similar to that and it gives me the sh!ts

The best way to describe it would be a grinding rattle It's loudest when the car is cold and only happens at about

1600-1800 rpm It seems to be in the end of exhaust cam / CAS area

can anyone help me ?

  • 1 year later...
Dazzler22 Rookie

Dazzler22

Posted
Posted
I've also got a noise similar to that and it gives me the sh!ts

The best way to describe it would be a grinding rattle It's loudest when the car is cold and only happens at about

1600-1800 rpm It seems to be in the end of exhaust cam / CAS area

can anyone help me ?

Did you find out what this was??

Cheers

Dazzler

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