OVERHEAT AT RACE AT THUNDERHILL - WATER PUMP ?
09-26-2016, 05:06 PM
#16
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I get it..... yes, ive had this happen many times, but never loss of pressure.
im betting, like you said, the boiling created some air pockets and that caused cavitation or just lack of positive pressure.
what i was hearing was actual bearing noise, but maybe it was just the pump running dry. usually , the noise that i was hearing, sounded like a dry pump impeeller spinning. usually that water in the system damps the noise a little too.
im betting, like you said, the boiling created some air pockets and that caused cavitation or just lack of positive pressure.
what i was hearing was actual bearing noise, but maybe it was just the pump running dry. usually , the noise that i was hearing, sounded like a dry pump impeeller spinning. usually that water in the system damps the noise a little too.
Just eidted my last post as I wrote it the wrong way round [brain fart moment].
If the system cannot hold pressure then cavitation is going to be inevitable if the coolant is at or near its boiling point. During cavitation the liquid film breaks down and voids are filled by vapour with the forces in play shooting tiny particles of liquid like bullets that ultimately will turn metal into something that looks like "Aero Chocolate bar" if you are familiar with such Briitish delicacies. The onset of cavitation is defined by a sudden and sharp drop in delivery pressure/flow [basically it cannot pump properly any more].
Thus your water pump may well be the victim of the piece not the culprit but the first thing is to determine why the system is not holding pressure. Te pump may well have a problem but there are other fish to fry first.
By the way if you do not have that small section of hose in the system that may be asking for trouble. As I understand that thing is designed deliberately weak so that if the tank cap does not blow it then becomes the next element to fail to prevent something expensive from going pop.
Rgds
Fred
09-26-2016, 05:19 PM
#17
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Mark,..........
By the way if you do not have that small section of hose in the system that may be asking for trouble. As I understand that thing is designed deliberately weak so that if the tank cap does not blow it then becomes the next element to fail to prevent something expensive from going pop..........
Rgds
Fred
By the way if you do not have that small section of hose in the system that may be asking for trouble. As I understand that thing is designed deliberately weak so that if the tank cap does not blow it then becomes the next element to fail to prevent something expensive from going pop..........
Rgds
Fred
09-26-2016, 05:22 PM
#18
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Thread Starter
got it. thats what i was thinking too.
you must have missed my post from the SCCA runoffs last season. i was listening to my car engine in the pits after the qualifying and heard an exposion.... it was the weak , old upper radiator hose!
i have no small hose to be the "fuse". however there is a short circute hose in the rear of the engine, but the things that blow seem to be the feeder lines to and from the reservoir. but i have had the rear one blow one time on the street car.
on to checking for the air or water leak in the system and then the pump if that seems to make any more noise. right now, i cant seem to hear anything, but its cold and havent warmed it up yet.
thanks!!!!
you must have missed my post from the SCCA runoffs last season. i was listening to my car engine in the pits after the qualifying and heard an exposion.... it was the weak , old upper radiator hose!
i have no small hose to be the "fuse".
however there is a short circute hose in the rear of the engine, but the things that blow seem to be the feeder lines to and from the reservoir. but i have had the rear one blow one time on the street car.on to checking for the air or water leak in the system and then the pump if that seems to make any more noise. right now, i cant seem to hear anything, but its cold and havent warmed it up yet.
thanks!!!!
Mark,
Just eidted my last post as I wrote it the wrong way round [brain fart moment].
If the system cannot hold pressure then cavitation is going to be inevitable if the coolant is at or near its boiling point. During cavitation the liquid film breaks down and voids are filled by vapour with the forces in play shooting tiny particles of liquid like bullets that ultimately will turn metal into something that looks like "Aero Chocolate bar" if you are familiar with such Briitish delicacies. The onset of cavitation is defined by a sudden and sharp drop in delivery pressure/flow [basically it cannot pump properly any more].
Thus your water pump may well be the victim of the piece not the culprit but the first thing is to determine why the system is not holding pressure. Te pump may well have a problem but there are other fish to fry first.
By the way if you do not have that small section of hose in the system that may be asking for trouble. As I understand that thing is designed deliberately weak so that if the tank cap does not blow it then becomes the next element to fail to prevent something expensive from going pop.
Rgds
Fred
Just eidted my last post as I wrote it the wrong way round [brain fart moment].
If the system cannot hold pressure then cavitation is going to be inevitable if the coolant is at or near its boiling point. During cavitation the liquid film breaks down and voids are filled by vapour with the forces in play shooting tiny particles of liquid like bullets that ultimately will turn metal into something that looks like "Aero Chocolate bar" if you are familiar with such Briitish delicacies. The onset of cavitation is defined by a sudden and sharp drop in delivery pressure/flow [basically it cannot pump properly any more].
Thus your water pump may well be the victim of the piece not the culprit but the first thing is to determine why the system is not holding pressure. Te pump may well have a problem but there are other fish to fry first.
By the way if you do not have that small section of hose in the system that may be asking for trouble. As I understand that thing is designed deliberately weak so that if the tank cap does not blow it then becomes the next element to fail to prevent something expensive from going pop.
Rgds
Fred
09-26-2016, 05:23 PM
#19
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That "theory" was proposed by Mark Thomas of DEVECK .....and is beyond stupid..The radiator cap is the "fuse" if that was insufficient they could and would have added a second radiator cap. Truth is that hose gets neglected and ignored by most until it finally ruptures. It does PERHAPS help clear out any air bubble from the back of the passenger side head but then the drivers side head on all 1980 up has no such vent. The 78-79 heated oil vapor tube vented those 78-79 heads.
Yep, if the cap pressure is exceeded that little spring allows for all the pressure over 14psi or so, to vent (water and air) until it isnt at 14psi... hoses that blow at 13psi, will blow before the cap lowers pressure.
09-26-2016, 05:53 PM
#20
Chronic Tool Dropper
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Like many things, driving a race car with ancient cooling system components (like hoses...) amazes me.
Meanwhile, find out why the system doesn't hold pressure. Go borrow/free-rent a cooling system pressure tester at your favorite FLAPS, pump the system up and see where the system leaks.
Besides the ancient hoses, common places include a cracked reservoir, tired/failed reservoir cap, water pump seals, thermostat hosing and water bridge gaskets/seals, heater core, radiator and fittings.
By this time your heater core should be isolated and the fittings capped at the block. You should be able to use a fitting for the front of driver's side head to block off the rear of the passenger-side head, if such a thing exists. I don't remember specifically. With that, you can replace the rusting Y-pipe that runs down the passenger side fenderwall with a non-Y bit of tubing, just the reservoir connected at the back end. Making this mod will eliminate the heater valve and its heat-fragile connecting hose, the heater core and its connecting hoses.
If you are not running coolant, you MUST provide an alternative lubricant for the water pump seal. A couple bottles of Redline Water Wetter will take care of that. The pump has a mechanical seal that relies on a thin fluid film for lubrication. Plain water may be enough, but you MUST maintain a liquid film. With just water, any overheating risks replacing the liquid film with a non-lubricating vapor (steam), and almost immediate seal failure. Water Wetter or other soluble oil will leave enough lubricating film to let the seal survive short periods without coolant. Simple as that.
It's quite possible that the sequence of events started with whatever alllowed the engine to run too hot. Then there was boiling in the system that includes the pump suction cavitation that Fred described. Cavitation with tiny bubbles is like running BB's through the pump or worse; the expansion and subsequent collapse of the steam bubbles as they move through the pump are like setting off firecrackers at the impellor. Further, the vibration from those "explosions" will trash seals and bearings over time.
Start off with the pressure test and figure out why the system doesn't hold pressure. If the pump seal has failed you'll have a trickle of water from under the lower belt cover. Other leaks except for head gasket will be obvious.
Headgaskets will leak into the cylinders, so plan on pulling the plugs for inspection (white-white is steam cleaned...), leave them out for leak check. Then with EZK relay removed, spin the engine a few times on the starter with plugs still out, newspaper draped over the cam covers. If your newspaper gets wet, likely it's liquid ejected from a cylinder and a headgasket failure. Good time to try a compression test, BTW.
Meanwhile, find out why the system doesn't hold pressure. Go borrow/free-rent a cooling system pressure tester at your favorite FLAPS, pump the system up and see where the system leaks.
Besides the ancient hoses, common places include a cracked reservoir, tired/failed reservoir cap, water pump seals, thermostat hosing and water bridge gaskets/seals, heater core, radiator and fittings.
By this time your heater core should be isolated and the fittings capped at the block. You should be able to use a fitting for the front of driver's side head to block off the rear of the passenger-side head, if such a thing exists. I don't remember specifically. With that, you can replace the rusting Y-pipe that runs down the passenger side fenderwall with a non-Y bit of tubing, just the reservoir connected at the back end. Making this mod will eliminate the heater valve and its heat-fragile connecting hose, the heater core and its connecting hoses.
If you are not running coolant, you MUST provide an alternative lubricant for the water pump seal. A couple bottles of Redline Water Wetter will take care of that. The pump has a mechanical seal that relies on a thin fluid film for lubrication. Plain water may be enough, but you MUST maintain a liquid film. With just water, any overheating risks replacing the liquid film with a non-lubricating vapor (steam), and almost immediate seal failure. Water Wetter or other soluble oil will leave enough lubricating film to let the seal survive short periods without coolant. Simple as that.
It's quite possible that the sequence of events started with whatever alllowed the engine to run too hot. Then there was boiling in the system that includes the pump suction cavitation that Fred described. Cavitation with tiny bubbles is like running BB's through the pump or worse; the expansion and subsequent collapse of the steam bubbles as they move through the pump are like setting off firecrackers at the impellor. Further, the vibration from those "explosions" will trash seals and bearings over time.
Start off with the pressure test and figure out why the system doesn't hold pressure. If the pump seal has failed you'll have a trickle of water from under the lower belt cover. Other leaks except for head gasket will be obvious.
Headgaskets will leak into the cylinders, so plan on pulling the plugs for inspection (white-white is steam cleaned...), leave them out for leak check. Then with EZK relay removed, spin the engine a few times on the starter with plugs still out, newspaper draped over the cam covers. If your newspaper gets wet, likely it's liquid ejected from a cylinder and a headgasket failure. Good time to try a compression test, BTW.
09-26-2016, 06:51 PM
#21
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That "theory" was proposed by Mark Thomas of DEVECK .....and is beyond stupid..The radiator cap is the "fuse" if that was insufficient they could and would have added a second radiator cap. Truth is that hose gets neglected and ignored by most until it finally ruptures. It does PERHAPS help clear out any air bubble from the back of the passenger side head but then the drivers side head on all 1980 up has no such vent. The 78-79 heated oil vapor tube vented those 78-79 heads.
Did you ever ask Marc where he got "his theory" from?
Many years ago I replaced all my hoses with OEM parts. After a year or so the short hose blew for some reason and I did not have a replacement in my kit. I had some heavier wall hose so cut a piece and installed it. When I asked Porsche about this they recommended removing the heavier wall stand in ASAP and fitting the stock part for the reasons I mentioned and they most certainly did not know Marc. Clearly they did not recommend this to bolster their stock price.
When designing a protective system the most stupid thing an engineer can do is fit two parts the same on the basis that if one fails the other will work given that sound logic understands that if one item fails another of the same age/type is just as likely to fail. As to what pressure that hose component fails at I have no idea but it does seem rather thin walled. I do not think I would have designed something like that but unless and until I hear a better reason as to why they did this I will stick with what I was advised.
Despite their brilliance Porsche do some seemingly baffling things like the flexplate clamp that clearly has issues but can be made to work with a $6 bottle of loctite.
Rgds
Fred
09-26-2016, 08:47 PM
#23
Bad caps can do weird stuff. My car came with a bad coolant cap that would hold vacuum, but not pressure, so it acted like a check valve. So as the coolant heated up it would expand and overflow. Then when I shut off the engine it would contract and suck in air through a tiny leak in the system somewhere. So the level in the tank looked fine until the air bubble cooled down. When I realized there was always a bubble in the system it made me think I had a bad head gasket, but replacing the cap fixed it.
09-26-2016, 09:29 PM
#24
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Thread Starter
Bad caps can do weird stuff. My car came with a bad coolant cap that would hold vacuum, but not pressure, so it acted like a check valve. So as the coolant heated up it would expand and overflow. Then when I shut off the engine it would contract and suck in air through a tiny leak in the system somewhere. So the level in the tank looked fine until the air bubble cooled down. When I realized there was always a bubble in the system it made me think I had a bad head gasket, but replacing the cap fixed it.
the air in the sysetem makes sense, from boiling locally, because after cooling the level is down two quarts.
Like many things, driving a race car with ancient cooling system components (like hoses...) amazes me.
Meanwhile, find out why the system doesn't hold pressure. Go borrow/free-rent a cooling system pressure tester at your favorite FLAPS, pump the system up and see where the system leaks.
Besides the ancient hoses, common places include a cracked reservoir, tired/failed reservoir cap, water pump seals, thermostat hosing and water bridge gaskets/seals, heater core, radiator and fittings.
By this time your heater core should be isolated and the fittings capped at the block. You should be able to use a fitting for the front of driver's side head to block off the rear of the passenger-side head, if such a thing exists. I don't remember specifically. With that, you can replace the rusting Y-pipe that runs down the passenger side fenderwall with a non-Y bit of tubing, just the reservoir connected at the back end. Making this mod will eliminate the heater valve and its heat-fragile connecting hose, the heater core and its connecting hoses.
If you are not running coolant, you MUST provide an alternative lubricant for the water pump seal. A couple bottles of Redline Water Wetter will take care of that. The pump has a mechanical seal that relies on a thin fluid film for lubrication. Plain water may be enough, but you MUST maintain a liquid film. With just water, any overheating risks replacing the liquid film with a non-lubricating vapor (steam), and almost immediate seal failure. Water Wetter or other soluble oil will leave enough lubricating film to let the seal survive short periods without coolant. Simple as that.
It's quite possible that the sequence of events started with whatever alllowed the engine to run too hot. Then there was boiling in the system that includes the pump suction cavitation that Fred described. Cavitation with tiny bubbles is like running BB's through the pump or worse; the expansion and subsequent collapse of the steam bubbles as they move through the pump are like setting off firecrackers at the impellor. Further, the vibration from those "explosions" will trash seals and bearings over time.
Start off with the pressure test and figure out why the system doesn't hold pressure. If the pump seal has failed you'll have a trickle of water from under the lower belt cover. Other leaks except for head gasket will be obvious.
Headgaskets will leak into the cylinders, so plan on pulling the plugs for inspection (white-white is steam cleaned...), leave them out for leak check. Then with EZK relay removed, spin the engine a few times on the starter with plugs still out, newspaper draped over the cam covers. If your newspaper gets wet, likely it's liquid ejected from a cylinder and a headgasket failure. Good time to try a compression test, BTW.
Meanwhile, find out why the system doesn't hold pressure. Go borrow/free-rent a cooling system pressure tester at your favorite FLAPS, pump the system up and see where the system leaks.
Besides the ancient hoses, common places include a cracked reservoir, tired/failed reservoir cap, water pump seals, thermostat hosing and water bridge gaskets/seals, heater core, radiator and fittings.
By this time your heater core should be isolated and the fittings capped at the block. You should be able to use a fitting for the front of driver's side head to block off the rear of the passenger-side head, if such a thing exists. I don't remember specifically. With that, you can replace the rusting Y-pipe that runs down the passenger side fenderwall with a non-Y bit of tubing, just the reservoir connected at the back end. Making this mod will eliminate the heater valve and its heat-fragile connecting hose, the heater core and its connecting hoses.
If you are not running coolant, you MUST provide an alternative lubricant for the water pump seal. A couple bottles of Redline Water Wetter will take care of that. The pump has a mechanical seal that relies on a thin fluid film for lubrication. Plain water may be enough, but you MUST maintain a liquid film. With just water, any overheating risks replacing the liquid film with a non-lubricating vapor (steam), and almost immediate seal failure. Water Wetter or other soluble oil will leave enough lubricating film to let the seal survive short periods without coolant. Simple as that.
It's quite possible that the sequence of events started with whatever alllowed the engine to run too hot. Then there was boiling in the system that includes the pump suction cavitation that Fred described. Cavitation with tiny bubbles is like running BB's through the pump or worse; the expansion and subsequent collapse of the steam bubbles as they move through the pump are like setting off firecrackers at the impellor. Further, the vibration from those "explosions" will trash seals and bearings over time.
Start off with the pressure test and figure out why the system doesn't hold pressure. If the pump seal has failed you'll have a trickle of water from under the lower belt cover. Other leaks except for head gasket will be obvious.
Headgaskets will leak into the cylinders, so plan on pulling the plugs for inspection (white-white is steam cleaned...), leave them out for leak check. Then with EZK relay removed, spin the engine a few times on the starter with plugs still out, newspaper draped over the cam covers. If your newspaper gets wet, likely it's liquid ejected from a cylinder and a headgasket failure. Good time to try a compression test, BTW.
yes, 2 water wetter bottles.. and a little antifreeze, but (dont tell anyone.. only a pint or two).
cap is probably good.. its been working well thus far .
my one suspect hose blew last seasson, so its new . water pump is new (just this season)
but the water pump has a lot of responsibility here, which sometimes it doesnt live up too.. ive seen it often, so im always leaning toward blaming it.
the overflow was new a long time ago.
so, its possible it has cracked. that would make the most sense.didnt think about major engine damage. usually, with head gasket, you pressurize the water jacket and eject all the water.. not the case. (plugs will be clean etc) no oil in water or water in oil.
so, doubtful it is a headgasket, but you never know , so ill check the plugs and do a compression just to be sure.
headgasket failures that leak into the cylinders, dont do that when its running, thats when you shut it down.. but before hand, it would have been pushing water out of the system and hoses would be very pumped up. after shut down, it can leak in to the cylincers, and then you get that white puff of smoke, i dont have that. the 90 hours of racing on the stroker seems to have been easily handled, expcept for these little issues!
hope its something obvious when i start this thing up tonight or tomorrow.
09-26-2016, 09:41 PM
#25
Chronic Tool Dropper
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Mark --
Borrow the tester and test the system, and use the included adapter to test the cap too. Waste no time speculating, or ruling things out because it worked fine before. Everything on the car has worked well at some point prior. Now not everything is working well. I wonder what it is that's not working so well. So do you.
You state that the car is down on coolant after it cooled off, so it went somewhere. Borrow the tester and find out. Next post should probably include what you found when testing the system. Anything less is a bunch of bench-tech speculation. Nothing more. Find out for sure.
Borrow the tester and test the system, and use the included adapter to test the cap too. Waste no time speculating, or ruling things out because it worked fine before. Everything on the car has worked well at some point prior. Now not everything is working well. I wonder what it is that's not working so well. So do you.
You state that the car is down on coolant after it cooled off, so it went somewhere. Borrow the tester and find out. Next post should probably include what you found when testing the system. Anything less is a bunch of bench-tech speculation. Nothing more. Find out for sure.
09-27-2016, 01:43 AM
#26
Rennlist Member
Mark -- If you don't have quick access to a pressure tester, try draining the system and catching all the coolant. Just because the reservoir bottle is full doesn't mean rest of the system isn't low on fluid. (If there's a leak in the system, there may not be sufficient vacuum to draw the fluid from the reservoir into the radiator.) So, by comparing the amount of fluid you drain out with the capacity of the system, you should be able to determine if there is a leak. It won't tell you where the leak is, but it will prove whether there is a leak. And, if there was a leak, that could answer you conundrum of how things could be so hot with no pressure in the system.
Good luck.
Good luck.
09-27-2016, 01:13 PM
#28
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Thread Starter
it sounds bad
cap is good.. they are usually not the issue.
hoses are new.
i just checked the system out on the road, full test................
09-27-2016, 01:23 PM
#29
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09-27-2016, 01:26 PM
#30
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Thread Starter
Mark --
Borrow the tester and test the system, and use the included adapter to test the cap too. Waste no time speculating, or ruling things out because it worked fine before. Everything on the car has worked well at some point prior. Now not everything is working well. I wonder what it is that's not working so well. So do you.
You state that the car is down on coolant after it cooled off, so it went somewhere. Borrow the tester and find out. Next post should probably include what you found when testing the system. Anything less is a bunch of bench-tech speculation. Nothing more. Find out for sure.
Borrow the tester and test the system, and use the included adapter to test the cap too. Waste no time speculating, or ruling things out because it worked fine before. Everything on the car has worked well at some point prior. Now not everything is working well. I wonder what it is that's not working so well. So do you.
You state that the car is down on coolant after it cooled off, so it went somewhere. Borrow the tester and find out. Next post should probably include what you found when testing the system. Anything less is a bunch of bench-tech speculation. Nothing more. Find out for sure.
think about this.. if the system has boiled , there is air in the system and the hoses will be soft, no matter how hot it gets, if the hoses are not filled with water, they are soft. i forgot about that fact.
I just went out and warmed it up. fans come on at operating temp and keep it in the temp in the middle of the gauge. took it for a drive. came back looked at thigns. pressure building..... then , turned off the fans and let temp rise to first white liine..... presssure as high as i have ever felt.. system holding pressure well.. this is more of a valid test, as it is actual and under high pressure ,and HOT too. (and running in case there was a head gastket leak)
took it out again and drove it hard.. just seems to be running hotter than usual, but could be my imagination.
took the stethascope and listened at the metal flat screw hole spot (boss) at the center of the pump... sounds like things are rattling around in there. reving the engine , and it gets worse.
my guess at this point was. the pump started to slip and not circulate the water, it started to overheat and boil fluid, that created air in the lines which stalled the pump, the engine oil started to rise higher than normal and started to show signs of viscocity break down. OR, the oil level was too low to start. i only put in a half of a quart when it was down to the low level after qualifying, and just coming home after the race, its at that same level now..... just put in a full quart and its where it should be. i usually always run near full or full.
Mark -- If you don't have quick access to a pressure tester, try draining the system and catching all the coolant. Just because the reservoir bottle is full doesn't mean rest of the system isn't low on fluid. (If there's a leak in the system, there may not be sufficient vacuum to draw the fluid from the reservoir into the radiator.) So, by comparing the amount of fluid you drain out with the capacity of the system, you should be able to determine if there is a leak. It won't tell you where the leak is, but it will prove whether there is a leak. And, if there was a leak, that could answer you conundrum of how things could be so hot with no pressure in the system.
Good luck.
Good luck.
However, with air in the lines,, i forgot, this IS the reason the system cant build pressure. i just tested it.. for the last hour the hoses are pumped up, no leaks and no sounds , noises of air leaking or water leaking.. all i have is noise from the water pump................ so, it has to come out!!!!!