High pitched belt type squeal fixed on ZD30

[Piggymac]

Hey Guys,
I have just recently picked up a 3L GU Patrol. When I looked at the vehicle, i new it had a sqealing noise which I just put down to a noisy drive belt and tensioner. I have been a mechanic for the past 25 years, so you can emagine the language I used after I purchased a new belt tensioner and idler pulley, puting them on and still having a horrible high pitched squeal. I have done alot of reading about this problem and it seems alot of ZD30 owners are at thier wits end with this noise that sounds excactly like a squealing belt. Well after using a peice of hose to my ear, I pinpointed the problem down to the alluminium EGR pipe, ( runs from the EGR valve to the inlet manifold, drectly opposit the fuel filter, on drivers side ). Being alluminium, it is susseptable to warping, due to being mounted to a rather hot EGR valve. It was fine to look at, but when I removed the pipe, (4 bolts ) it had carbon on the surface all the way to the edge, ( this is the surface which is mounted on the EGR Valve, not the inlet manifold ). I put a straight edge on it and it had a definate .5mm warp in the mating surface. There is also a thin metal gasket which mounts between the two surfaces, so when the alluminium surface warps, it creates a small gap and when you give it revs and the EGR Valve opens and exhaust gas that escapes through the gap causes the thin metal gasket vibrate, kind of like the reed in a saxaphone, which causes the high pitched noise you can hear. Ive got a Mate at work with the same vehicle as mine, which was making the same noise and when I checked the EGR pipe, it was warped excactly like mine was.
My fix was to remove the pipe and use a flat file accross it and create a flat surface for the gasket to seal properly. I also used a light smear of Ultra Copper Hi Temp Silicone, which is also sensor safe. Worked like a charm and it made a new vehicle of them both to drive.
Judging by the amount of people having unresolved belt type noises with ZD30 engines, I suspect this may be a common fault.
Another way to diagnose this is to disconnect the electrical plug from the EGR Valve and see if the noise is still present. This prevents the EGR Valve from opening and prevents gas exiting through the warped joint. This will norrow it down to either the EGR Valve itself, or the warped EGR pipie mating surface.
Im not sure if you guys know of this problem, but judging by the forums, it should help someone out there.

[big_fletch]

Welcome to the forum mate and thanks for the info, as a zd30 owner it is something I will keep in mind..
Feel free to stick around, join in the convo's and have a laugh with us. Great to have another member aboard.
Also feel free to post up some pics of your new troll..

Fletcha

[Bigrig]

G'day mate - welcome aboard. Great people, information and laughs on here mate, so feel free to join in and make the most of it. Enjoy!!

[Piggymac]

Cheers Guys, Will do. Alot of good info on here.

[Bob]

welcome mate. join in and enjoy

[Cadbury]

Hi there,
I have a high pitch squeel every now and then too, but I got a petrol engine.
Any ideas.
Cheers
Tim

[Bigrig]

Hi there,
I have a high pitch squeel every now and then too, but I got a petrol engine.
Any ideas.
Cheers
Tim

Belts more than likely - is it when cold? Only when starting? Etc

[Cadbury]

Not it is every now and then hot, cold anytime.

[pjg4wd]

Hi Piggymac,
Thanks for the information on this noise. I have it but only when I and going up hills and then not always, depends on how much acceleration it an doing. If I back off slightly it goes away. Anyhow, I need to book the patrol in for a service and I will get them to look at this specifically. Again, thanks.
Cheers,
Peter

[Piggymac]

Hi Peter,
Your symptoms sound very similar to mine. A quick check would be to disconnect the electrical plug to the EGR valve and see if the noise still exists. This is simple enough to do yourself. Mine made the noise on ecceleration and dissapeared when I backed off the throttle also. If I held revs at about 2500rpm in neutral it would make the noise aswell, but if the pipe is not warped as much as mine was, it may not occur in neutral, so best to take it for a spin with the valve plug off and see if it still squeals. (Doing this may cause the check engine light to come on, but it will go off when you hook the plug back up again). If it does still squeal, then it is more likely to be the belt/tensioner, or maybe even the alternator.
Hope this helps.