)
When water pumps attack!
Much missed
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From: In my exclusive Cayenne
7th Gear
Joined: Sep 2008
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From: Schenectady NY
New series, starting this weekend.... 9am central
Anyway. The coolant leak is not a hose its the water pump. Its a slow leak but its getting worse. This may sound like a silly question but the reason I ask is becasue on a 928 if you drive with a bad water pump the impeller can dig into the block and ruin the block.
I ordered a new pump today and of course the weather is great this week. When water pumps attack on the 996 can the destroy anything when they do? Or do they simply just leak more and more? Basically is it safe to drive while I wait on my new pump to arrive?
Anyway. The coolant leak is not a hose its the water pump. Its a slow leak but its getting worse. This may sound like a silly question but the reason I ask is becasue on a 928 if you drive with a bad water pump the impeller can dig into the block and ruin the block.
I ordered a new pump today and of course the weather is great this week. When water pumps attack on the 996 can the destroy anything when they do? Or do they simply just leak more and more? Basically is it safe to drive while I wait on my new pump to arrive?
Last edited by odhogie; Jun 9, 2010 at 12:58 AM.
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Joined: May 2008
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From: Northern NJ
sbpsu354:
"I've noticed that the water temp in my 997 hits the 175 mark and then the needle never moves from there."
If you look closely at the gauge you will see a small pin at the 175 mark. If you overheat a 997 you could bend the needle as it tries to pass that pin.
Wonder if Jake and 1999porsche911 know about this? I wonder how they keep the temp below the 180 thermostat? Porsche surly would not believe that a lower temp T- stat could help lower the operating temp? The 997 fans must run on high speed all of the time.
"I've noticed that the water temp in my 997 hits the 175 mark and then the needle never moves from there."
If you look closely at the gauge you will see a small pin at the 175 mark. If you overheat a 997 you could bend the needle as it tries to pass that pin.
Wonder if Jake and 1999porsche911 know about this? I wonder how they keep the temp below the 180 thermostat? Porsche surly would not believe that a lower temp T- stat could help lower the operating temp? The 997 fans must run on high speed all of the time.
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Joined: Oct 2001
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From: LI NY
http://www.youtube.com/watch?v=h0L0klF8lVo
Good video!!
Id use better coolant and less silicone...but overall gives you a good idea where everything is located!!
Good video!!
Id use better coolant and less silicone...but overall gives you a good idea where everything is located!!
Burning Brakes
Joined: Nov 2008
Posts: 779
Likes: 5
From: Cleveland GA USA
New series, starting this weekend.... 9am central
Anyway. The coolant leak is not a hose its the water pump. Its a slow leak but its getting worse. This may sound like a silly question but the reason I ask is becasue on a 928 if you drive with a bad water pump the impeller can dig into the block and ruin the block.
I ordered a new pump today and of course the weather is great this week. When water pumps attack on the 996 can the destroy anything when they do? Or do they simply just leak more and more? Basically is it safe to drive while I wait on my new pump to arrive?
Anyway. The coolant leak is not a hose its the water pump. Its a slow leak but its getting worse. This may sound like a silly question but the reason I ask is becasue on a 928 if you drive with a bad water pump the impeller can dig into the block and ruin the block.
I ordered a new pump today and of course the weather is great this week. When water pumps attack on the 996 can the destroy anything when they do? Or do they simply just leak more and more? Basically is it safe to drive while I wait on my new pump to arrive?
I have two cars down stairs right now that have suffered from this mode of failure, neither was caught early enough in the intermix cycle to salvage the engine.
Its not miles that causes this to occur, its the age of the plastic impellers... This is another one of those instances where a simple primary failure can lead to a much more serious secondary failure. Neither of the engines that are down stairs failed right now had high coolant temps, that one hot spot led to the issue.
We've had a rash of cracked heads for the past year, in EVERY one of those instances the water pump impeller had chips missing from it. In several of those situations the chips of plastic were found inside the cylinder head's coolant passages when the crack was milled away for our crack repair to be carried out. This is how we determined that the pump impellers were the actual primary failure leading to this mysterious cracking issue stemming from engines that had never "overheated". The chipped impeller pieces are another reason why the engine cracks a head before it blows a head gasket. This is because only a very small (and weak) portion of the head contains these capillaries and when that one spot gets hot enough the crack forms..
The cracked heads are occurring on pre-02 996 and pre-03 Boxster engines primariily. When the cylinder heads were changed for vane cell vario cam (and VC+ in the 996) the cylinder head casting was completely changed and no longer includes these small capillaries.
The ultimate solution is a billet water pump impeller. Here is a 18,000.00 crack.
Last edited by Jake Raby; Jan 11, 2015 at 11:56 PM.
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Race Director
Joined: Sep 2007
Posts: 11,801
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From: Kittery, Maine
Jake,was there any warning to the owners of the 2 cracked heads, such as noise/sound before the impellers fragmented in their water pumps, which then caused blockage of coolant? Curious because you are suggesting mileage has no bearing(no pun initially intended). Thanks
Parts Specialist
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plastic... again with the plastic parts! 
have any of you (other than Jake) seen the "button" on the IMS chain tensioner arm
This is one more case where you have to change these parts based on age not miles. (that said my 86' just broke a plastic gear on the odometer, but it isnt a big $$$$ repair, just another case where plastic ages and oils degrade the plastic to the point of being very unpredictable when they will fail)
have any of you (other than Jake) seen the "button" on the IMS chain tensioner arm
This is one more case where you have to change these parts based on age not miles. (that said my 86' just broke a plastic gear on the odometer, but it isnt a big $$$$ repair, just another case where plastic ages and oils degrade the plastic to the point of being very unpredictable when they will fail)
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Joined: May 2005
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plastic... again with the plastic parts!
have any of you (other than Jake) seen the "button" on the IMS chain tensioner arm
This is one more case where you have to change these parts based on age not miles. (that said my 86' just broke a plastic gear on the odometer, but it isnt a big $$$$ repair, just another case where plastic ages and oils degrade the plastic to the point of being very unpredictable when they will fail)
have any of you (other than Jake) seen the "button" on the IMS chain tensioner arm
This is one more case where you have to change these parts based on age not miles. (that said my 86' just broke a plastic gear on the odometer, but it isnt a big $$$$ repair, just another case where plastic ages and oils degrade the plastic to the point of being very unpredictable when they will fail)
Burning Brakes
Joined: Nov 2008
Posts: 779
Likes: 5
From: Cleveland GA USA
Had we not seen so many of these issues and found plastic impeller pieces inside cylinder head coolant passages we never would have figured out why the cracks magically appear when the engine never overheated. I'd like to start keeping a tally of how many water pumps that are replaced have a small chip of an impeller blade missing.. That small chip floats around until it finds a capillary that it can't pass through, then its game over.
plastic... again with the plastic parts!
have any of you (other than Jake) seen the "button" on the IMS chain tensioner arm
have any of you (other than Jake) seen the "button" on the IMS chain tensioner arm
Here are some pictures of that plastic part compared to the updated billet part. Here is also a picture of what happens when the plastic part fails, the tensioner slips and jams the tensioner paddle resulting in a catastrophic failure.
Last edited by Jake Raby; Jan 11, 2015 at 11:56 PM.
Thread Starter
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Joined: Oct 2005
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From: Southern Utah
I had mine replaced last year after I blew a seal (I know that doesn't sound right) during a DE.
Filled it up with water and drove home. It did not appear to leak while driving but only after the car sat for 15 minutes. I think you are fine as long you check the levels.
Filled it up with water and drove home. It did not appear to leak while driving but only after the car sat for 15 minutes. I think you are fine as long you check the levels.
Penquin comes into the garage and says "fix my car I am going across the street"
He comes back an hour later and asks "what was the problem"
The wrench says "oh you blew a seal"
The penquin wipes his lips and says "oh no, thats just ice cream"
As usual the very imformative and helpful knowledge of one of my favorites on this board. I agree.. It sat at home today and the pump is to be here tomorrow.
http://www.youtube.com/watch?v=h0L0klF8lVo
Good video!!
Id use better coolant and less silicone...but overall gives you a good idea where everything is located!!
Good video!!
Id use better coolant and less silicone...but overall gives you a good idea where everything is located!!
With the M96 when the plastic impellers begin to age and chip, those chips find their way into the tiny capillaries within the coolant passages of the cylinder heads.. This blocks coolant flow and creates hot spots and ultimately leads to a cracked cylinder head.
I have two cars down stairs right now that have suffered from this mode of failure, neither was caught early enough in the intermix cycle to salvage the engine.
Its not miles that causes this to occur, its the age of the plastic impellers... This is another one of those instances where a simple primary failure can lead to a much more serious secondary failure. Neither of the engines that are down stairs failed right now had high coolant temps, that one hot spot led to the issue.
We've had a rash of cracked heads for the past year, in EVERY one of those instances the water pump impeller had chips missing from it. In several of those situations the chips of plastic were found inside the cylinder head's coolant passages when the crack was milled away for our crack repair to be carried out. This is how we determined that the pump impellers were the actual primary failure leading to this mysterious cracking issue stemming from engines that had never "overheated". The chipped impeller pieces are another reason why the engine cracks a head before it blows a head gasket. This is because only a very small (and weak) portion of the head contains these capillaries and when that one spot gets hot enough the crack forms..
The cracked heads are occurring on pre-02 996 and pre-03 Boxster engines primariily. When the cylinder heads were changed for vane cell vario cam (and VC+ in the 996) the cylinder head casting was completely changed and no longer includes these small capillaries.
The ultimate solution is a billet water pump impeller. Here is a 18,000.00 crack.
I have two cars down stairs right now that have suffered from this mode of failure, neither was caught early enough in the intermix cycle to salvage the engine.
Its not miles that causes this to occur, its the age of the plastic impellers... This is another one of those instances where a simple primary failure can lead to a much more serious secondary failure. Neither of the engines that are down stairs failed right now had high coolant temps, that one hot spot led to the issue.
We've had a rash of cracked heads for the past year, in EVERY one of those instances the water pump impeller had chips missing from it. In several of those situations the chips of plastic were found inside the cylinder head's coolant passages when the crack was milled away for our crack repair to be carried out. This is how we determined that the pump impellers were the actual primary failure leading to this mysterious cracking issue stemming from engines that had never "overheated". The chipped impeller pieces are another reason why the engine cracks a head before it blows a head gasket. This is because only a very small (and weak) portion of the head contains these capillaries and when that one spot gets hot enough the crack forms..
The cracked heads are occurring on pre-02 996 and pre-03 Boxster engines primariily. When the cylinder heads were changed for vane cell vario cam (and VC+ in the 996) the cylinder head casting was completely changed and no longer includes these small capillaries.
The ultimate solution is a billet water pump impeller. Here is a 18,000.00 crack.
From what I can tell this is the original, I'm 11 years old and 112,000 miles