Failed idler pulley and a fire
#1
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Join Date: Jul 2003
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Failed idler pulley and a fire
In all my years working on cars, I have never seen a failed idler pulley cause this. So far damage to the shifter cables and two A/C lines. I'm afraid to look at the wiring harness.
#3
The engine bay insulation on my 1998 was dry rotted and falling apart. It had split right above the pulley and was laying on the pulley with a cut half way through it from rubbing on the pulley. I imagine that could help get things lit up fast.
#4
Was it making any noise before it failed? My 1999 has started making a chirping noise and my mechanic says it's a hydraulic exhaust lifter not closing all the way. Problem is it's intermittent and makes the same sound a loose spark plug made.
#5
Race Director
That's not a usual failure mode for exhaust lifters. BTW, if the lifter doesn't close all the way and the noise is combustion gas leaking past the exhaust valve that valve will be burned in no time. One would think then the tech would be urging you to get the car in to have this addressed to save yourself some bigger expense further down the road.
A bum lifter just requires the camshaft cover be removed and the cams. To address a burned valve requires the head be removed.
A "chirping noise" from my 996 Turbo proved to be an idler/tensioner roller bearing.
However, a bad water pump is also a possibility. If it is a water pump it is not wise to delay getting this taken care of. If the pump bearings get too lose the impeller will make contact with the block and the plastic impeller blades get torn away and the pump no longer pumps much if any coolant. The blade debris can block any coolant flow so when a new water pump is installed coolant flow to some parts of the engine (heads) can be compromised and engine killing localized overheating can occur.
#6
If there is no CEL I have to question the diagnosis.
That's not a usual failure mode for exhaust lifters. BTW, if the lifter doesn't close all the way and the noise is combustion gas leaking past the exhaust valve that valve will be burned in no time. One would think then the tech would be urging you to get the car in to have this addressed to save yourself some bigger expense further down the road.
A bum lifter just requires the camshaft cover be removed and the cams. To address a burned valve requires the head be removed.
A "chirping noise" from my 996 Turbo proved to be an idler/tensioner roller bearing.
However, a bad water pump is also a possibility. If it is a water pump it is not wise to delay getting this taken care of. If the pump bearings get too lose the impeller will make contact with the block and the plastic impeller blades get torn away and the pump no longer pumps much if any coolant. The blade debris can block any coolant flow so when a new water pump is installed coolant flow to some parts of the engine (heads) can be compromised and engine killing localized overheating can occur.
That's not a usual failure mode for exhaust lifters. BTW, if the lifter doesn't close all the way and the noise is combustion gas leaking past the exhaust valve that valve will be burned in no time. One would think then the tech would be urging you to get the car in to have this addressed to save yourself some bigger expense further down the road.
A bum lifter just requires the camshaft cover be removed and the cams. To address a burned valve requires the head be removed.
A "chirping noise" from my 996 Turbo proved to be an idler/tensioner roller bearing.
However, a bad water pump is also a possibility. If it is a water pump it is not wise to delay getting this taken care of. If the pump bearings get too lose the impeller will make contact with the block and the plastic impeller blades get torn away and the pump no longer pumps much if any coolant. The blade debris can block any coolant flow so when a new water pump is installed coolant flow to some parts of the engine (heads) can be compromised and engine killing localized overheating can occur.
When the plugs were changed (not by this shop) the number four plug was not tightened down by the mechanic and it was blowing around it and made the same noise so I'm inclined to think the other plugs may not be torqued properly although he says it's not a plug leak.
He also inspected the tensioners and pulleys so I'm at a loss as the car is running great with no codes or misfires.
#7
Race Director
Thanks Macster the water pump is an OEM and relatively new but it is also the third one in less than 20K miles so it can't be ruled out. The shop that did the diagnosis is a highly regarded shop here in Monterey and the owner did the inspection. I'm also not convinced it is a lifter but I had the oil and filter changed and Swepco put in as well as running a jug of Techron through the last tank.
When the plugs were changed (not by this shop) the number four plug was not tightened down by the mechanic and it was blowing around it and made the same noise so I'm inclined to think the other plugs may not be torqued properly although he says it's not a plug leak.
He also inspected the tensioners and pulleys so I'm at a loss as the car is running great with no codes or misfires.
When the plugs were changed (not by this shop) the number four plug was not tightened down by the mechanic and it was blowing around it and made the same noise so I'm inclined to think the other plugs may not be torqued properly although he says it's not a plug leak.
He also inspected the tensioners and pulleys so I'm at a loss as the car is running great with no codes or misfires.
Which brings me to: OEM? Or OE? There is a distinction. One is a water pump made by the same company that makes the water pumps for Porsche, but may not be the *same* water pump it sells/supplies to Porsche. The other is the same water pump the company sells/supplies to Porsche, the one that for instance the parts manager at the local Porsche dealer shoves over the counter to a tech.
It is a bit of work to check the plugs for proper torque. I hate to raise this issue but saying it is not a plug leak without actually making sure every plug is properly tightened isn't worth anything.
If the exhaust system was removed to facilitate changing the plugs -- I'm not sure this is done on the Boxster for a plug change -- there is the possibility of an exhaust system leak. That the shop left a plug loose doesn't give me a lot of confidence it didn't forget and leave something else loose...
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#8
3 water pumps in 20K miles is insane. There's something amiss.
Which brings me to: OEM? Or OE? There is a distinction. One is a water pump made by the same company that makes the water pumps for Porsche, but may not be the *same* water pump it sells/supplies to Porsche. The other is the same water pump the company sells/supplies to Porsche, the one that for instance the parts manager at the local Porsche dealer shoves over the counter to a tech.
It is a bit of work to check the plugs for proper torque. I hate to raise this issue but saying it is not a plug leak without actually making sure every plug is properly tightened isn't worth anything.
If the exhaust system was removed to facilitate changing the plugs -- I'm not sure this is done on the Boxster for a plug change -- there is the possibility of an exhaust system leak. That the shop left a plug loose doesn't give me a lot of confidence it didn't forget and leave something else loose...
Which brings me to: OEM? Or OE? There is a distinction. One is a water pump made by the same company that makes the water pumps for Porsche, but may not be the *same* water pump it sells/supplies to Porsche. The other is the same water pump the company sells/supplies to Porsche, the one that for instance the parts manager at the local Porsche dealer shoves over the counter to a tech.
It is a bit of work to check the plugs for proper torque. I hate to raise this issue but saying it is not a plug leak without actually making sure every plug is properly tightened isn't worth anything.
If the exhaust system was removed to facilitate changing the plugs -- I'm not sure this is done on the Boxster for a plug change -- there is the possibility of an exhaust system leak. That the shop left a plug loose doesn't give me a lot of confidence it didn't forget and leave something else loose...
The exhaust system does not have to be removed to change the plugs and it definitely is not the ticking sound usually heard from exhaust leaks.
As for the wp the latest was installed by a dealership (I had no choice as the dealer was the closest my tow would take me when the second one went out) so I have no idea if it is OE or OEM I just know that Porsche wp are a pos and from what I've seen the bearing is way to small for a part that is the heart of the wc system.
The last time I heard this noise I drove the car for over a year before someone figured out what it was and no damage was done. I've driven it with the current noise for several months now and got it up to 115 mph on an open stretch of road and nothing failed so until I can find someone with a definitive answer I'm just going to drive it.
#9
I'm with Macster on this. There is likely something amiss with your tensioner or in the system that is causing the loading that is destroying the water pumps. Yes, they fail but not at the rate of one every 20k. Having too much tension will destroy bearings. Rapid acceleration or deceleration of the belt for some other reason is not good for the pump. Sometimes these gremlins can be hard to find but after the 3rd pump I'd seriously be shopping for a better independent mechanic.
#10
Race Director
I don't mean to hijack this post but I'm concerned about the noise I'm hearing and the really disparaging thing is the mechanic who put the plugs in was unable to figure out what was causing the original noise even though he took off the V belt and listened to each pulley and tensioner with a stethoscope while he hand turned them.
The exhaust system does not have to be removed to change the plugs and it definitely is not the ticking sound usually heard from exhaust leaks.
As for the wp the latest was installed by a dealership (I had no choice as the dealer was the closest my tow would take me when the second one went out) so I have no idea if it is OE or OEM I just know that Porsche wp are a pos and from what I've seen the bearing is way to small for a part that is the heart of the wc system.
The last time I heard this noise I drove the car for over a year before someone figured out what it was and no damage was done. I've driven it with the current noise for several months now and got it up to 115 mph on an open stretch of road and nothing failed so until I can find someone with a definitive answer I'm just going to drive it.
The exhaust system does not have to be removed to change the plugs and it definitely is not the ticking sound usually heard from exhaust leaks.
As for the wp the latest was installed by a dealership (I had no choice as the dealer was the closest my tow would take me when the second one went out) so I have no idea if it is OE or OEM I just know that Porsche wp are a pos and from what I've seen the bearing is way to small for a part that is the heart of the wc system.
The last time I heard this noise I drove the car for over a year before someone figured out what it was and no damage was done. I've driven it with the current noise for several months now and got it up to 115 mph on an open stretch of road and nothing failed so until I can find someone with a definitive answer I'm just going to drive it.
(As an aside the accessory drive system of the Turbo is for some reason not as "robust" as that of the Boxster. I don't know if the Turbo accessory drive runs at a faster RPM or runs with more tension, but I've had to replace the Turbo water pump in fewer miles than that of the Boxster and 2 sets of idler/tensioners while the idler/tensioners of the Boxster are original.)
Anyhow, back on the subject at hand: I'm sorry but I have to disagree with the diagnosis of a water pump. No way a bad water pump can last for over a year -- unless the car was driven some ridiculously low miles. Thus I find the diagnosis of water pump hard to accept. And this then can "explain" the 3 water pumps in 20K miles.
So in short, I have no faith in what you are being told regarding the car and the source of the noise.
You can do what you want but no Boxster ever got better being driven that was producing an abnormal noise. Since I have not heard the noise -- and I'm in no way suggesting you provide an audio clip -- I can't say for sure that it is abnormal but you believe it is and that's good enough for me.
My advice is to find another shop that is well regarded by owners of modern Porsches and have this noise looked into.