996.2 C2 Engine Bay Rattle

Just picked up a new to me 2001 C2 3.6 Manual and after a spirited drive home (c. 200 miles) she have developed a funny rattling sound from the engine bay that I am trying to ID before I get her towed to my nearest indy. The rattle is not heard from in the cabin with the windows up but is certainly noticeable from outside. The exhaust on the car is in an advanced state of disintegration so I would have thought many of the fixings and heatshield fixings may also be on their way... The car was running very nicely, no warning lights or anything. Temperature just over 80 on the gauge, warm idle about 1.5 bar, full revs 5 bar. I let the car cool down once home, then later restarted it and drove 20m into the garage. No oil or coolant leaks evident. https://youtu.be/-P1CSoAHlgU My preliminary thoughts are an exhaust heatshield rubbing against something; a disintegrating cat; something on the serpentine belt gone bad (water pump, alternator bearings, failed pulley). I wonder if anyone else has had a similar noise to this in the past and found a remedy - obviously i'm a little reluctant to restart the car in case its a failed IMS bearing, or the water pump impeller disintegrating. I was going to remove the serpentine belt and run the car for a few seconds to see if the noise had gone - any tips getting it off? Thanks in advance.

You`ve just missed our resident Porsche mechanic/guru member deMort for the evening, he logs on between 7 and 9pm to help anyone with an issue :grin: I would check water pump first, that sounds suspiciously like mine did when the pump bearings died on my Boxster :sad: Is the noise more from the rear end of the engine ? ( pump/belt end ) It`s easy to pop the belt off and have a good feel of all pulleys, idler and tensioner, big spanner on the tensioner pulley (7) to release the belt tension and pop the belt off. Water pump is no 4 :thumb:

Thanks for that, the noise sounds external to the block and to the near side. I will pull the air box and belt in the coming days and fire her up again to see if that clears the noise. I will give the ancillaries and pulleys a twirl and see if any are obviously rattling. Do I need a spanner behind the tensioner pulley as well or just a 24mm on the front? Is it worth heating the tensioner to free off the red Loctite?

Just a spanner on the Tensioner big hex ( not sure of the size off hand), it is just a spring loaded Tensioner so you are just releasing the pressure on the belt with one hand while trying to pop the belt off with the other :grin: I could wobble my Waterpump pulley by about a quarter of an inch when it sounded like that :sad: Just to add for your peace of mind, if you had an IMS bearing failure you would have had a catastrophic failure with bits of engine escaping through the block and lots of metal, coolant and oil on the floor by now :judge:

from your explanation I would have said heat shield but hearing the video it sounds like something rotating and grinding. Do as Kris says.

When you take the belt off, check the idlers too, the bearings don't last for ever. You can either change the pulley or just the bearing (much cheaper), do a search on here for details.

Sounds like the water pump to me as the noise seems to be n/s and low down .. where the pump is basically ... i would start with removing the airbox , then drive belt ( 24mm spanner ) and feel for play in the pump and spin each pulley in turn . Kris .. bless you .. not a Guru .. just a humble mechanic

Thanks all for the advice. I hope to get a bit of time to pull the belt over the weekend and I'll report back. Is the Meyle pump, belt and thermostat kit at design911 worth doing? The belt isn't cracked. I was considering a low temp stat if I was going to drain the coolant.

I had a similar rattle, not as loud, and turned out to be an exhaust mounting bracket. At the bottom end of the back of the engine, there is a flat bracket, like the shape of 30cm ruler, which connects the engine block to two circular exhaust clamps (one on each side). The bracket can develop vertical cracks which are quite difficult to see, particularly if they are close to the circular exhaust clamps. I would listen from under the back of the car to see if this is the part that's rattling

Picture of the bracket I meant

OK so I removed the airbox and serpentine belt and as predicted above the waterpump is defunct: https://youtu.be/Hy5k_QDPS14 After a good wobble it decided to leak a few drops aiding diagnosis! All other ancillaries seem fine. The two pulleys and the tensioner are still working ok but either a bit rattly sounding or not spinning out for long: https://youtu.be/LCZWif1vT6U I have had a drive belt on a previous car disintegrate from a failed pulley so I'm minded to just replace whilst its open - unless this is what the original parts feel like? So I need a water pump & gasket, new thermostat, new serpentine belt, two pulleys and a belt tensioner (pulley only?), some additional coolant for topping up. I don't have the vacuum gear for refilling the coolant so I may get my indy to do this. Thanks for all your help, it's much appreciated.

Ok so by way of an update I have visited my local OPC and they have quoted me just under £800 for the parts listed above including 12L of concentrated coolant enough to do a full flush. I have arranged to get the car taken to my garage later in the week for the fitting, flushing and refill, and for new silencers to be fitted. Given that the OPC is going to have to order in the parts anyway I think I'm just as well ordering right parts from online suppliers. This is what I'm looking at: Pierburg Water Pump and gasket - £157 inc. VAT: https://www.autodoc.co.uk/pierburg/965622 Low Temp Thermostat - £45 + VAT: https://www.design911.co.uk/fu/prod...orsche-986-Boxster---996---987-Boxster---997/ Drive-belt and three pulleys: OPC looking for nearly £300 for this lot, can anyone advise who is the original manufacturer? I can find Febi Bilstein pulleys for around £50 each and a Continental belt for air-con cars for £20. New Coolant Cap (04 designation): £18 from OPC Coolant: Porsche Coolant is around £13/l from the OPC. As I'm completely flushing should I use this or will 25L Comma G30 ready mix suffice? Anything else I should be doing at the same time? Last service (Major, Jan 19) noted a couple of coil packs were cracked so might do these although the car is running smoothly. Is it worth renewing the engine mounts? The car is on the original mounts and I was considering going for the 993RS mounts. Cheers.