Race update from sears point (scot is in trouble)
09-04-2006, 03:13 PM
#16
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Thread Starter
Dave,
looks lke the water is exiting the overflow tube, as thats where there is a lot of spray reminance and evidence. the water cant be boiling off, if the temps are still inline. when his temps reach the top white line, it starts to almost boil as you can feel the air escaping out the over flow hole. the pressure cap is new, so is the bottle. since we suspect the cylinder pressures causing the issue, as when scot comes in the pits, temps are near normal and 2 gallons are gone! pressure of the system is only set at 15psi max. when we floor it on the street, the lines are real pressurized, but just below the cap limit. and the pressure stays high for about 1/2 hour. longer than even the holbert car.
again, the water doesnt seem to be burning, no leaks, and it only exits the system under race conditons when cylinder pressures are highest.
I think the only proof will be from the water analysing test.
do you have to have oil in the water? if the crack only crosses the waterjacket, it wouldn have to have oil working in the water.
Mk
looks lke the water is exiting the overflow tube, as thats where there is a lot of spray reminance and evidence. the water cant be boiling off, if the temps are still inline. when his temps reach the top white line, it starts to almost boil as you can feel the air escaping out the over flow hole. the pressure cap is new, so is the bottle. since we suspect the cylinder pressures causing the issue, as when scot comes in the pits, temps are near normal and 2 gallons are gone! pressure of the system is only set at 15psi max. when we floor it on the street, the lines are real pressurized, but just below the cap limit. and the pressure stays high for about 1/2 hour. longer than even the holbert car.
again, the water doesnt seem to be burning, no leaks, and it only exits the system under race conditons when cylinder pressures are highest.
I think the only proof will be from the water analysing test.
do you have to have oil in the water? if the crack only crosses the waterjacket, it wouldn have to have oil working in the water.
Mk
Originally Posted by SharkSkin
The overflow tube should only flow water out of it if there is too much water. IIRC, it sits near the top of the tank. You might consider verifying that coolant is escaping there. For that to happen, you would have to be getting so much high pressure gas in there that it doesn't get a chance to make it to the top of the reservoir so it pushes water out. You say that water is gone out the overflow tube. Is this established fact or conjecture? If conjecture, cut the toe off a sock and tape it to the end of the overflow tube. If it's wet with coolant when this problem appears, then you've proven it.
Have you verified that the cap holds pressure and releases above the set pressure? Pressure testing with the cap in place will tell you this. If it doesn't hold enough pressure, the water could be boiling out as steam.
Have you verified that the cap holds pressure and releases above the set pressure? Pressure testing with the cap in place will tell you this. If it doesn't hold enough pressure, the water could be boiling out as steam.
09-04-2006, 03:24 PM
#17
Nordschleife Master
if you have not done so already replace the cap with a new one, possibly try a 13 PSI cap for the street to see if you can reproduce on the street.
also consider hooking up a remote pressure guage that you can run possibly inside the car to see if you notice a spike in pressure to try and figure out exactly when it is happening
also consider hooking up a remote pressure guage that you can run possibly inside the car to see if you notice a spike in pressure to try and figure out exactly when it is happening
09-04-2006, 08:38 PM
#18
Chronic Tool Dropper
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Mark-
The purpose off the indicator is to detect combustion products in the coolant.
It doesn't detect oil (you can see oil film on top of a coolant sample). Head cracks between coolant and oil passages almost always cause coolant in the oil, rather than the other way around. Unless you happen to crack a pressurized oil galley, coolant will pass to the oil side on cooldown when coolant still has residual heat/pressure and oil system is at ambient pressure.
The purpose off the indicator is to detect combustion products in the coolant.
It doesn't detect oil (you can see oil film on top of a coolant sample). Head cracks between coolant and oil passages almost always cause coolant in the oil, rather than the other way around. Unless you happen to crack a pressurized oil galley, coolant will pass to the oil side on cooldown when coolant still has residual heat/pressure and oil system is at ambient pressure.
09-04-2006, 08:45 PM
#19
Rennlist Member
Hi Mark,it sure does sound like a hairline crack between the valve seats.I've seen many cars overheat the way you describe only when there is an increase in cylinder pressure.dr bob mentioned a combustion gas indicator,it is called block check and can be purchased at napa like he said.Also if you do try the seal on vehicle approach,try moroso ceramic engine sealer.Not sure about the success rate for your application.It is time consuming and a mess when you disassemble but it does seal many kinds of leaks.
09-05-2006, 12:13 AM
#20
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Thread Starter
So, we will try the combusion gas indicator.
Im wondering how a sealer will work, when initiated by the coolant side. since the coolant sealer usually work as the coolant moves through a crack, if the combustion gasses are going into the water jacket, how are those cracks filled? we bought the "nanotechnology" sealant stuff. clean the system, put the stuff in , run for 20min, turn off , drain, let dry open overnight. refill with water and then flush again, and you are good to go! sounds great , dont it?
MK
Im wondering how a sealer will work, when initiated by the coolant side. since the coolant sealer usually work as the coolant moves through a crack, if the combustion gasses are going into the water jacket, how are those cracks filled? we bought the "nanotechnology" sealant stuff. clean the system, put the stuff in , run for 20min, turn off , drain, let dry open overnight. refill with water and then flush again, and you are good to go! sounds great , dont it?
MK
Originally Posted by ZEUS+
Hi Mark,it sure does sound like a hairline crack between the valve seats.I've seen many cars overheat the way you describe only when there is an increase in cylinder pressure.dr bob mentioned a combustion gas indicator,it is called block check and can be purchased at napa like he said.Also if you do try the seal on vehicle approach,try moroso ceramic engine sealer.Not sure about the success rate for your application.It is time consuming and a mess when you disassemble but it does seal many kinds of leaks.
09-05-2006, 12:19 AM
#21
Rennlist Member
Thread Starter
Yeah, no oil at all in the water system. isnt there a way to have a crack in the head that doesnt meet an oil passage? those are not at pressure, obvioulsy , and the water pressure of 14psi max is enough to force water into the oil, but we are not seeing any issuse or water loss, in street driving, even spririted!
only race conditions and 2 gals are gone in 15 minutes! I guess the only way to get oil in the water is the crack in the radiator in the oil and water separation area of the two tanks . oil there is 5 bar, water there is only 1bar.
the more im thinking of this, and the more you guys offer suggestions, im still thinking head gasket or cracked head (hair line)
?????
do you think leak down pressures will indicate an issue, even if we get the pressures up to 200 or 500psi??? (my NOS bottle can do this as long as the leakdown hoses dont blow!)
MK
only race conditions and 2 gals are gone in 15 minutes! I guess the only way to get oil in the water is the crack in the radiator in the oil and water separation area of the two tanks . oil there is 5 bar, water there is only 1bar.
the more im thinking of this, and the more you guys offer suggestions, im still thinking head gasket or cracked head (hair line)
?????
do you think leak down pressures will indicate an issue, even if we get the pressures up to 200 or 500psi??? (my NOS bottle can do this as long as the leakdown hoses dont blow!)
MK
Originally Posted by dr bob
Mark-
The purpose off the indicator is to detect combustion products in the coolant.
It doesn't detect oil (you can see oil film on top of a coolant sample). Head cracks between coolant and oil passages almost always cause coolant in the oil, rather than the other way around. Unless you happen to crack a pressurized oil galley, coolant will pass to the oil side on cooldown when coolant still has residual heat/pressure and oil system is at ambient pressure.
The purpose off the indicator is to detect combustion products in the coolant.
It doesn't detect oil (you can see oil film on top of a coolant sample). Head cracks between coolant and oil passages almost always cause coolant in the oil, rather than the other way around. Unless you happen to crack a pressurized oil galley, coolant will pass to the oil side on cooldown when coolant still has residual heat/pressure and oil system is at ambient pressure.
09-05-2006, 12:36 PM
#23
Chronic Tool Dropper
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Mark--
Don't spend a lot of time trying to figure out where the leak is until you find that you --have-- a combustion leak. Do the chem test, then you know the heads will be off for that, and you'll be able to see what was leaking with a little more sleuthing.
And-- See if you are in fact blowing coolant out the vent hose. It might be coming out of a radiator end tank when air pressure through the front flexes the radiator in its mounts. Lottsa --stooopid-- stuff happens when racing. It's often a lot more simple than what we initially think.
Don't spend a lot of time trying to figure out where the leak is until you find that you --have-- a combustion leak. Do the chem test, then you know the heads will be off for that, and you'll be able to see what was leaking with a little more sleuthing.
And-- See if you are in fact blowing coolant out the vent hose. It might be coming out of a radiator end tank when air pressure through the front flexes the radiator in its mounts. Lottsa --stooopid-- stuff happens when racing. It's often a lot more simple than what we initially think.
09-05-2006, 01:58 PM
#25
Rennlist Member
Originally Posted by mark kibort
Dave,
looks lke the water is exiting the overflow tube, as thats where there is a lot of spray reminance and evidence. the water cant be boiling off, if the temps are still inline. when his temps reach the top white line, it starts to almost boil as you can feel the air escaping out the over flow hole. the pressure cap is new, so is the bottle. since we suspect the cylinder pressures causing the issue, as when scot comes in the pits, temps are near normal and 2 gallons are gone! pressure of the system is only set at 15psi max. when we floor it on the street, the lines are real pressurized, but just below the cap limit. and the pressure stays high for about 1/2 hour. longer than even the holbert car.
again, the water doesnt seem to be burning, no leaks, and it only exits the system under race conditons when cylinder pressures are highest.
I think the only proof will be from the water analysing test.
do you have to have oil in the water? if the crack only crosses the waterjacket, it wouldn have to have oil working in the water.
Mk
looks lke the water is exiting the overflow tube, as thats where there is a lot of spray reminance and evidence. the water cant be boiling off, if the temps are still inline. when his temps reach the top white line, it starts to almost boil as you can feel the air escaping out the over flow hole. the pressure cap is new, so is the bottle. since we suspect the cylinder pressures causing the issue, as when scot comes in the pits, temps are near normal and 2 gallons are gone! pressure of the system is only set at 15psi max. when we floor it on the street, the lines are real pressurized, but just below the cap limit. and the pressure stays high for about 1/2 hour. longer than even the holbert car.
again, the water doesnt seem to be burning, no leaks, and it only exits the system under race conditons when cylinder pressures are highest.
I think the only proof will be from the water analysing test.
do you have to have oil in the water? if the crack only crosses the waterjacket, it wouldn have to have oil working in the water.
Mk
09-05-2006, 06:04 PM
#26
Rennlist Member
Thread Starter
good advice. so, the chemical test you get from the more nuts and bolt auto stores, to check for this?
good idea of the flexing of the radiator causing some leaking (i suppose , you mean, leaking out of the radiator at some crack. . Ill have to wiggle it around to make sure. we still dont know exactly where the water is going, although it it appears to be going out the blow off tube. however, i didnt check after this last run, as we had dark brown barrs stop leak in there, so that would leave a trail, now wouldnt it!!?
Mk
good idea of the flexing of the radiator causing some leaking (i suppose , you mean, leaking out of the radiator at some crack. . Ill have to wiggle it around to make sure. we still dont know exactly where the water is going, although it it appears to be going out the blow off tube. however, i didnt check after this last run, as we had dark brown barrs stop leak in there, so that would leave a trail, now wouldnt it!!?
Mk
Originally Posted by dr bob
Mark--
Don't spend a lot of time trying to figure out where the leak is until you find that you --have-- a combustion leak. Do the chem test, then you know the heads will be off for that, and you'll be able to see what was leaking with a little more sleuthing.
And-- See if you are in fact blowing coolant out the vent hose. It might be coming out of a radiator end tank when air pressure through the front flexes the radiator in its mounts. Lottsa --stooopid-- stuff happens when racing. It's often a lot more simple than what we initially think.
Don't spend a lot of time trying to figure out where the leak is until you find that you --have-- a combustion leak. Do the chem test, then you know the heads will be off for that, and you'll be able to see what was leaking with a little more sleuthing.
And-- See if you are in fact blowing coolant out the vent hose. It might be coming out of a radiator end tank when air pressure through the front flexes the radiator in its mounts. Lottsa --stooopid-- stuff happens when racing. It's often a lot more simple than what we initially think.
09-05-2006, 06:09 PM
#27
Rennlist Member
Thread Starter
we were definitely having this isssue originally, with the cracked expansion tank.
Im thinking maybe after that first overheating due to the cracked tank, we then cracked a head or head gasket.
so, we got great pressure right now, maybe too good, due to what we think the problem is. the pressure doesnt go anywhere until the engine is cool
mine, doesnt even have this pressure, especially after 30min.
thanks for the ideas! hope we find the issue soon!
MK
Im thinking maybe after that first overheating due to the cracked tank, we then cracked a head or head gasket.
so, we got great pressure right now, maybe too good, due to what we think the problem is. the pressure doesnt go anywhere until the engine is cool
mine, doesnt even have this pressure, especially after 30min.
thanks for the ideas! hope we find the issue soon!
MK
Originally Posted by SharkSkin
OK, good -- you have pressure. The reason I asked about that is, if the system does not pressurize you can end up having the coolant boil in the heads or block due to hot spots, even though the average temp of the coolant is below boiling.
09-14-2006, 02:01 AM
#28
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Thread Starter
Ok folks, Scot's overheating issues are driving me up the wall. He just came over and we did a psydo leak down test with 200psi using my NOS bottle. looks like all the cylinder pressures fall at the same rate and no unusual bubbles in the overflow tank. Then, we went to flush the system, but wanted to verify that the water pump was working right. I took the upper hose off at the radiator and made sure it had water up to the end of the hose. then, i took the lower radiator hose off at the engine and attached another hose and filled it with water as well.
I started the engine, and water didnt move. (levels remained constant) We ran it for a while and there was no sign of movement until the upper radiator side started to get hot and expand and slowly seep out .
could this be a sign that the water pump has failed. The holbert did this with the pump rebuild, but was intermittant. maybe scots water pump is like this. works around town at low rpms, but in the race, the impeller fails to turn, and then the water boils off from the inside out.
AHHHHHH
any ideas on a better check of the water pump? even used a stethascope to listen to the waterpump. something is turning, but it may just be the pulley attached to the bearing,and not the impeller.
mk
I started the engine, and water didnt move. (levels remained constant) We ran it for a while and there was no sign of movement until the upper radiator side started to get hot and expand and slowly seep out .
could this be a sign that the water pump has failed. The holbert did this with the pump rebuild, but was intermittant. maybe scots water pump is like this. works around town at low rpms, but in the race, the impeller fails to turn, and then the water boils off from the inside out.
AHHHHHH
any ideas on a better check of the water pump? even used a stethascope to listen to the waterpump. something is turning, but it may just be the pulley attached to the bearing,and not the impeller.
mk
09-14-2006, 06:16 AM
#29
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Originally Posted by mark kibort
Ok folks, Scot's overheating issues are driving me up the wall. He just came over and we did a psydo leak down test with 200psi using my NOS bottle. looks like all the cylinder pressures fall at the same rate and no unusual bubbles in the overflow tank. Then, we went to flush the system, but wanted to verify that the water pump was working right. I took the upper hose off at the radiator and made sure it had water up to the end of the hose. then, i took the lower radiator hose off at the engine and attached another hose and filled it with water as well.
I started the engine, and water didnt move. (levels remained constant) We ran it for a while and there was no sign of movement until the upper radiator side started to get hot and expand and slowly seep out .
could this be a sign that the water pump has failed. The holbert did this with the pump rebuild, but was intermittant. maybe scots water pump is like this. works around town at low rpms, but in the race, the impeller fails to turn, and then the water boils off from the inside out.
AHHHHHH
any ideas on a better check of the water pump? even used a stethascope to listen to the waterpump. something is turning, but it may just be the pulley attached to the bearing,and not the impeller.
mk
I started the engine, and water didnt move. (levels remained constant) We ran it for a while and there was no sign of movement until the upper radiator side started to get hot and expand and slowly seep out .
could this be a sign that the water pump has failed. The holbert did this with the pump rebuild, but was intermittant. maybe scots water pump is like this. works around town at low rpms, but in the race, the impeller fails to turn, and then the water boils off from the inside out.
AHHHHHH
any ideas on a better check of the water pump? even used a stethascope to listen to the waterpump. something is turning, but it may just be the pulley attached to the bearing,and not the impeller.
mk
Won't the thermostat prevent water from flowing trough the radiator until engine is hot?
09-14-2006, 07:16 AM
#30
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Mark
If have read the posts correctly and hence the symptoms correctly - I'll summarise below
Leakdown shows all cylinders not leaking
No oil in the coolant
No coolant in the oil (A classic symptom of a cracked head on an early 32V engine - ask me how I know)
No obvious coolant leaks from duff coolant pipes or tstat bridge or housing or rad
It would probably cause a good non 928 mechanic at this stage to scratch his head.
However I reckon there are only two possibilities left
T stat aint working or
the water pump impeller has "fallen off"
Your last post would suggest the latter. Thats where i'ld go next.
Not related to Scotts car but FWIW I used the "Nanobot technology" ceramic block sealant about 4 years and 30k miles ago to succesfully seal a cracked head on my 88S4SE. no coolant use at all since (until the little hose between the block and heater valve blew!)
Cheers
If have read the posts correctly and hence the symptoms correctly - I'll summarise below
Leakdown shows all cylinders not leaking
No oil in the coolant
No coolant in the oil (A classic symptom of a cracked head on an early 32V engine - ask me how I know)
No obvious coolant leaks from duff coolant pipes or tstat bridge or housing or rad
It would probably cause a good non 928 mechanic at this stage to scratch his head.
However I reckon there are only two possibilities left
T stat aint working or
the water pump impeller has "fallen off"
Your last post would suggest the latter. Thats where i'ld go next.
Not related to Scotts car but FWIW I used the "Nanobot technology" ceramic block sealant about 4 years and 30k miles ago to succesfully seal a cracked head on my 88S4SE. no coolant use at all since (until the little hose between the block and heater valve blew!)
Cheers