OVERHEAT AT RACE AT THUNDERHILL - WATER PUMP ?
09-27-2016, 03:51 PM
#32
Nordschleife Master
Clearly true.
This is wrong.
First off, there is supposed to always be air in the system in the top few inches of the reservoir.
Secondly, it's the pressure of the system that makes them feel hard. The radiator cap is 15psi and that is a lot of pressure and what you should have if the system was overheating from a mechanical failure. (E.g., pump or thermostat or clogged radiator) The hoses are exactly as firm whether pressurized with water, steam or air.
That's why people are saying that there's a leak: you are reporting that there was no pressure in the system and the car was reporting a high (well over 212) temperature. At the point, the coolant will boil and pressurize the system unless there's an outlet for the H2O.
First off, there is supposed to always be air in the system in the top few inches of the reservoir.
Secondly, it's the pressure of the system that makes them feel hard. The radiator cap is 15psi and that is a lot of pressure and what you should have if the system was overheating from a mechanical failure. (E.g., pump or thermostat or clogged radiator) The hoses are exactly as firm whether pressurized with water, steam or air.
That's why people are saying that there's a leak: you are reporting that there was no pressure in the system and the car was reporting a high (well over 212) temperature. At the point, the coolant will boil and pressurize the system unless there's an outlet for the H2O.
Last edited by GlenL; 09-27-2016 at 04:58 PM.
09-27-2016, 05:17 PM
#33
Rennlist Member
Thread Starter
Clearly true.
This is wrong.
First off, there is supposed to always be air in the system in the top few inches of the overflow.
Secondly, it's the pressure of the system that makes them feel hard. The radiator cap is 15psi and that is a lot of pressure and what you should have if the system was overheating from a mechanical failure. (E.g., pump or thermostat or clogged radiator) The hoses are exactly as firm whether pressurized with water, steam or air.
That's why people are saying that there's a leak: you are reporting that there was no pressure in the system and the car was reporting a high (well over 212) temperature. At the point, the coolant will boil and pressurize the system.
This is wrong.
First off, there is supposed to always be air in the system in the top few inches of the overflow.
Secondly, it's the pressure of the system that makes them feel hard. The radiator cap is 15psi and that is a lot of pressure and what you should have if the system was overheating from a mechanical failure. (E.g., pump or thermostat or clogged radiator) The hoses are exactly as firm whether pressurized with water, steam or air.
That's why people are saying that there's a leak: you are reporting that there was no pressure in the system and the car was reporting a high (well over 212) temperature. At the point, the coolant will boil and pressurize the system.
i have seen where there is air pockets in the hose area and pump, that the hoses dont feel like they have pressure. like when scots car puked all the water out (half gone) the hoses were not pressurized
i guess i can do a test. get it hot again, open the overflow, let it boil over and then replace the cap and see if it can build pressure again.... .i think ive done that before and it proves my point...... i cant remember though.
09-27-2016, 05:37 PM
#34
Rennlist Member
Thread Starter
Glen, also think about what happened at the track... going average speed of 80 mph, the radiator and engine boil the water , its pressed out the cap........ i back down and allow for cooling (get passed by my competitor that im in an angry battle with. 
) and then come in to the pits with the temp at the top white line, no further......... the system is still closed. its not boiling anymore the steam condenses again, and now the volume is lower with the water missing and the steam condensed.
I can test that... ill get the gauge up to top white line, and open the reservoir. wait until it finishes boiling over.. ill have cavities in the mid section of the hoses and pump ,and then put the cap back on . i bet it will be soft at the hoses and not change even though the temp will be at the upper white line.
) and then come in to the pits with the temp at the top white line, no further......... the system is still closed. its not boiling anymore the steam condenses again, and now the volume is lower with the water missing and the steam condensed. I can test that... ill get the gauge up to top white line, and open the reservoir. wait until it finishes boiling over.. ill have cavities in the mid section of the hoses and pump ,and then put the cap back on . i bet it will be soft at the hoses and not change even though the temp will be at the upper white line.
09-27-2016, 05:39 PM
#35
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09-27-2016, 05:42 PM
#36
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Freudian slip? The word I would choose might be "methodically"
Exactly the lesson I shared, grasshopper.
Poor assumption. The fact the the coolant boiled has no relationship with air in the system. Boiling coolant does not make air.
While your "test" may satisfy you, it hasn't done anything to help you find the leak. Meanwhile, testing with the system cold means that any water that leaks out won't immediately evaporate before you get a chance to find the leak. You are chasing your tail doing a drive-and-look test.
Something happened at the track that caused the system to not hold pressure. Had teh system run completely dry, we could discuss the reasons for no pressure. But the two quarts you say you were "short" is about what you'd normally find in the reservoir. All of the heated surfaces of the block were still full of water. Or more likely had local boiling that made the system look full when it wasn't. Regardless, if there was ANY liquid in there boiling to steam, you would have seen pressure at the same time. Since you didn't find pressure and you were low on water, you need to find out where the leak is. Rather than throw parts or theories at the situation, follow a logical diagnostic method.
This is my last post to your thread. Good Luck!
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)
Something happened at the track that caused the system to not hold pressure. Had teh system run completely dry, we could discuss the reasons for no pressure. But the two quarts you say you were "short" is about what you'd normally find in the reservoir. All of the heated surfaces of the block were still full of water. Or more likely had local boiling that made the system look full when it wasn't. Regardless, if there was ANY liquid in there boiling to steam, you would have seen pressure at the same time. Since you didn't find pressure and you were low on water, you need to find out where the leak is. Rather than throw parts or theories at the situation, follow a logical diagnostic method.
This is my last post to your thread. Good Luck!
09-27-2016, 05:50 PM
#37
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Same here - my vote is two fold. Water pump failed, caused the over heat and the head-gasket blew which is where all the coolant went.
Yup....keep driving it around. Heads are cheap and no worries about the water pump damaging the block. It's not like that is some kind of custom block that would cost $$thousands to duplicate or something..... Any old junk yard lower end will work just the same.
Yup....keep driving it around. Heads are cheap and no worries about the water pump damaging the block. It's not like that is some kind of custom block that would cost $$thousands to duplicate or something..... Any old junk yard lower end will work just the same.
09-27-2016, 06:51 PM
#38
Rennlist Member
Thread Starter
hey, dont go anywhere.. im listening... just thought that the higher temp might force the leak if there was one. (vs just a cold test)
but, if you think i blew a head gasket, you mean the water was forced out or injested. usually, when they blow, the water gets forces out of the cylinder,
so, what do you recommend.. do the pressure test with the pump and cap
then do compression test?
no! dont go ! 
im following you ... really, but my logic that there was boiling due to the pump failing, and then water was pushed out creating the void.. as it cooled (as i stopped redlining the engine and only half throttle , while still goiing 100mph , the coolant cooled and the boiling stopped and there was no pressure in the system. maybe partial pump capability moved a little water. as i said before, ive had failed impellers that just went to red and light came on.. intermittantly as well, and of couse the standard leak and make bearing noise failure.
the point is... i got it really hot.. lots of pressure ... that pressure lasted for 30min before the hoses were soft. isnt that better than a cold pressure test?
so, what do you think i should do first. pressure check and then compression test? then replace the water pump?
btw... if i dont have to replace the belt (which is new) can i do the pump without pulling the crank balancer? i seemed to remember that being possible and having just enough room to replace the water pump..... no????
but, if you think i blew a head gasket, you mean the water was forced out or injested. usually, when they blow, the water gets forces out of the cylinder,
so, what do you recommend.. do the pressure test with the pump and cap
then do compression test?
Same here - my vote is two fold. Water pump failed, caused the over heat and the head-gasket blew which is where all the coolant went.
Yup....keep driving it around. Heads are cheap and no worries about the water pump damaging the block. It's not like that is some kind of custom block that would cost $$thousands to duplicate or something..... Any old junk yard lower end will work just the same.
Yup....keep driving it around. Heads are cheap and no worries about the water pump damaging the block. It's not like that is some kind of custom block that would cost $$thousands to duplicate or something..... Any old junk yard lower end will work just the same.
Exactly the lesson I shared, grasshopper.
Poor assumption. The fact the the coolant boiled has no relationship with air in the system. Boiling coolant does not make air.
While your "test" may satisfy you, it hasn't done anything to help you find the leak. Meanwhile, testing with the system cold means that any water that leaks out won't immediately evaporate before you get a chance to find the leak. You are chasing your tail doing a drive-and-look test.
Something happened at the track that caused the system to not hold pressure. Had teh system run completely dry, we could discuss the reasons for no pressure. But the two quarts you say you were "short" is about what you'd normally find in the reservoir. All of the heated surfaces of the block were still full of water. Or more likely had local boiling that made the system look full when it wasn't. Regardless, if there was ANY liquid in there boiling to steam, you would have seen pressure at the same time. Since you didn't find pressure and you were low on water, you need to find out where the leak is. Rather than throw parts or theories at the situation, follow a logical diagnostic method.
This is my last post to your thread. Good Luck!
Poor assumption. The fact the the coolant boiled has no relationship with air in the system. Boiling coolant does not make air.
While your "test" may satisfy you, it hasn't done anything to help you find the leak. Meanwhile, testing with the system cold means that any water that leaks out won't immediately evaporate before you get a chance to find the leak. You are chasing your tail doing a drive-and-look test.
Something happened at the track that caused the system to not hold pressure. Had teh system run completely dry, we could discuss the reasons for no pressure. But the two quarts you say you were "short" is about what you'd normally find in the reservoir. All of the heated surfaces of the block were still full of water. Or more likely had local boiling that made the system look full when it wasn't. Regardless, if there was ANY liquid in there boiling to steam, you would have seen pressure at the same time. Since you didn't find pressure and you were low on water, you need to find out where the leak is. Rather than throw parts or theories at the situation, follow a logical diagnostic method.
This is my last post to your thread. Good Luck!
im following you ... really, but my logic that there was boiling due to the pump failing, and then water was pushed out creating the void.. as it cooled (as i stopped redlining the engine and only half throttle , while still goiing 100mph , the coolant cooled and the boiling stopped and there was no pressure in the system. maybe partial pump capability moved a little water. as i said before, ive had failed impellers that just went to red and light came on.. intermittantly as well, and of couse the standard leak and make bearing noise failure.
the point is... i got it really hot.. lots of pressure ... that pressure lasted for 30min before the hoses were soft. isnt that better than a cold pressure test?
so, what do you think i should do first. pressure check and then compression test? then replace the water pump?
btw... if i dont have to replace the belt (which is new) can i do the pump without pulling the crank balancer? i seemed to remember that being possible and having just enough room to replace the water pump..... no????
09-27-2016, 06:58 PM
#39
Rennlist Member
Thread Starter
Same here - my vote is two fold. Water pump failed, caused the over heat and the head-gasket blew which is where all the coolant went.
Yup....keep driving it around. Heads are cheap and no worries about the water pump damaging the block. It's not like that is some kind of custom block that would cost $$thousands to duplicate or something..... Any old junk yard lower end will work just the same.
Yup....keep driving it around. Heads are cheap and no worries about the water pump damaging the block. It's not like that is some kind of custom block that would cost $$thousands to duplicate or something..... Any old junk yard lower end will work just the same.
why would driving it when the engine temp is normal... only goes higher if i disable the fans, pressure is high in the system and doesnt go anywhere for 10-15min after shut off. no smoke, runs fine...... HOWEVER, i do worry about the block.. you are right about that .. if that pump impeller is migrating to the block, as part of its failure, thats a problem and my main worry. but it sounds like the bearing is bad by the noise its making and im thinking either the water escaped from there or was pushed out when the pump started to fail. or maybe i just overheated and was left with a cavitating pump and didnt birp the system before going out, and the system couldnt ever recover until i actually burped it when it was cool.
the fact that the engine keeps pressure now at normal op temp shows me the system is not leaking, but there could be a small leak for which a cold test might make sense.
09-27-2016, 07:00 PM
#40
Lol, Not even sure why I clicked this thread but am glad I did. Mark never fails to keep it entertaining.
09-27-2016, 09:47 PM
#41
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Semi-retired, as of Feb 1, 2023.
The days of free technical advice are over.
Free consultations will no longer be available.
Will still be in the shop, isolated and exclusively working on project cars, developmental work and products, engines and transmissions.
Have fun with your 928's people!
09-28-2016, 09:33 AM
#42
Three Wheelin'
Mark you turn to this forum for advice and you receive logical advice from many many acknowledged members. What do you do with this advice? You argue and come up with some really lame ways to proceed, never really zeroing in on the problem. It's ashame there are things to be learned but it inevitably turns into a circle jerk.
09-28-2016, 12:30 PM
#43
Rennlist Member
Thread Starter
Seriously, ive thought ive seen it all with the car overheating because of water pump and other issues. i love the advice and listening to all
im following the advice and only suggesting what might be wrong. i appreciate teh advice more than it seems obviously.
im proposing thing that i think might be causing the problem..
one can understand my reluctance to believe that it is a small leak, when i get the engine hot , drive it around, even run the temps up by turniing the fans on and the pressure is very high.... it holds pressure for an hour or so..... dont know how there can be leaks cold, or even if there is a leak that is pressent, and have the pressure stay high for long. ive had the water pump leaks before and they never let the system gain pressure and there is water on the top of the oil pan.
ive also been involved in scots head gasket issue that pushed all the water out in a container we rigged so he could finish a race. the lines were soft with 1 gallon gone... this is the MAIN point here and what im basing my theory on.
i just dont want to start replacing things if i dont know what is causing the issue. certainly dont want to change that pump out... but if its making noise, why risk the block damage, so its coming out...... Mark is warranting the pump and its the first he has ever seen go bad, if its the pump.
im following the advice and only suggesting what might be wrong. i appreciate teh advice more than it seems obviously.
im proposing thing that i think might be causing the problem..
one can understand my reluctance to believe that it is a small leak, when i get the engine hot , drive it around, even run the temps up by turniing the fans on and the pressure is very high.... it holds pressure for an hour or so..... dont know how there can be leaks cold, or even if there is a leak that is pressent, and have the pressure stay high for long. ive had the water pump leaks before and they never let the system gain pressure and there is water on the top of the oil pan.
ive also been involved in scots head gasket issue that pushed all the water out in a container we rigged so he could finish a race. the lines were soft with 1 gallon gone... this is the MAIN point here and what im basing my theory on.
i just dont want to start replacing things if i dont know what is causing the issue. certainly dont want to change that pump out... but if its making noise, why risk the block damage, so its coming out...... Mark is warranting the pump and its the first he has ever seen go bad, if its the pump.
Mark you turn to this forum for advice and you receive logical advice from many many acknowledged members. What do you do with this advice? You argue and come up with some really lame ways to proceed, never really zeroing in on the problem. It's ashame there are things to be learned but it inevitably turns into a circle jerk.
09-28-2016, 12:34 PM
#44
Rennlist Member
Thread Starter
We Tu Hat,
what do you think it is the issue?? your take?
my thoughts are , pump failed (slipping on shaft) and overheated, pushed water out when boiling, temp then came down, water condenced and hoses were soft and pump now cavitating due to inconsistent water supply. this can happen without even a water pump failure. i lost about 1-2 quarts of water and i believe once you have air in the system the pressure never comes back... thats based on when Scot had his overhead due to losing water and a head gasket issue , which actually pushed water under high pressure out the overflow... but when it cooled down before he came in the lines were soft.
what do you think it is the issue?? your take?
my thoughts are , pump failed (slipping on shaft) and overheated, pushed water out when boiling, temp then came down, water condenced and hoses were soft and pump now cavitating due to inconsistent water supply. this can happen without even a water pump failure. i lost about 1-2 quarts of water and i believe once you have air in the system the pressure never comes back... thats based on when Scot had his overhead due to losing water and a head gasket issue , which actually pushed water under high pressure out the overflow... but when it cooled down before he came in the lines were soft.
09-28-2016, 12:37 PM
#45
Rennlist Member
Thread Starter
either way , on the way to pep-boys to get the radiator pressure tester since that is on the top of everyones list to test. if there is no leak.. then what????
i hate the intermittant problems that only show their faces when you are at redline for 30mins !!! (something you cant simulate at home! )
i hate the intermittant problems that only show their faces when you are at redline for 30mins !!! (something you cant simulate at home! )