Intercooler Pump Cavitation & Shutdown
07-08-2016, 08:35 PM
#1
Supporting Vendor
Thread Starter
Intercooler Pump Cavitation & Shutdown
We've been developing a new cooling system for the temperature-challenged Z06s, and one odd issue we found was repeated temperature spikes in intercooler fluid temperatures when on track. We attributed it to a pump shutdown for some reason, but were unable to pinpoint the problem until now.
This graph from our Cooling Development Thread shows the temperature spikes we were talking about:
We set up a "test loop" to simulate on-track conditions in the shop. The intercooler pump is laying on the ground under the wheel, hardwired to a battery (with an inline switch). It's drawing from the big steel pot, and running through the intercooler radiators, intercooler, and back into the pot. Just like in the car, so pressure load on the pump is very similar.
Looking over a datasheet for the pump, we saw that it does have the onboard smarts to protect itself if need be. We thought we were getting an overheat condition, so we heated the water up to 180°-200°F and kept it there for 20 minutes. The pump didn't care, and continued happily pumping water the whole time.
We played with starving the pump, and injecting air into the system, and finally figured it out.
Excess air in the system will cause the impeller to cavitate, and enter a three minute shutdown period to recover. That matches our observations on track exactly.
Here's a video of our test. We inject air into the line with a blow gun, and a few seconds later, the pump shuts off. Exactly three minutes later, the pump restarts.
This is HUGE, and gives much more importance to the bleeding process and tank design. Previously, everyone thought that air in the system just hurt the heat transfer and pumping ability, when the reality is much more dire. The system will shut down entirely for three minutes, which is more than enough time for the engine to overheat and go into limp mode.
What also worth noting is that the ECU has nothing to do with this. Throughout our entire test shown in the video, the pump was hooked up to a battery. The ECU has no idea the pump is shutting down until temperatures reach unsafe levels.
Lesson here: Make SURE your intercooler system is bled properly.
This graph from our Cooling Development Thread shows the temperature spikes we were talking about:
We set up a "test loop" to simulate on-track conditions in the shop. The intercooler pump is laying on the ground under the wheel, hardwired to a battery (with an inline switch). It's drawing from the big steel pot, and running through the intercooler radiators, intercooler, and back into the pot. Just like in the car, so pressure load on the pump is very similar.
Looking over a datasheet for the pump, we saw that it does have the onboard smarts to protect itself if need be. We thought we were getting an overheat condition, so we heated the water up to 180°-200°F and kept it there for 20 minutes. The pump didn't care, and continued happily pumping water the whole time.
We played with starving the pump, and injecting air into the system, and finally figured it out.
Excess air in the system will cause the impeller to cavitate, and enter a three minute shutdown period to recover. That matches our observations on track exactly.
Here's a video of our test. We inject air into the line with a blow gun, and a few seconds later, the pump shuts off. Exactly three minutes later, the pump restarts.
This is HUGE, and gives much more importance to the bleeding process and tank design. Previously, everyone thought that air in the system just hurt the heat transfer and pumping ability, when the reality is much more dire. The system will shut down entirely for three minutes, which is more than enough time for the engine to overheat and go into limp mode.
What also worth noting is that the ECU has nothing to do with this. Throughout our entire test shown in the video, the pump was hooked up to a battery. The ECU has no idea the pump is shutting down until temperatures reach unsafe levels.
Lesson here: Make SURE your intercooler system is bled properly.
Last edited by GSpeed; 07-08-2016 at 09:49 PM.
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Popular Reply
07-09-2016, 12:36 PM
Hey G-man. Just want to compliment you on your level headed professionalism. You seem to have a great way of dealing with all these arm-chair /back-seat posters. You sir are a gem. You obviously accept the fact that two heads are better than one, and are truly open to anyone's suggestions, or opinions. That shows your commitment to this project. It is really exceptionally nice to see someone with such knowledge, and no real ego/attitude that usually accompanies that. My hat is off to you, and THANKS from our Z family.
07-08-2016, 08:40 PM
#2
Safety Car
Whoa this is huge! Another great article from you guys in the technical journal. 
You guys were running the stock pump on those two HE the whole time correct? That means we could all be getting the troublesome shut down stock.
Are there any sensors we can monitor through the OBD port to see if the pump is running or the temps are skyrocketing in the intercooler chain?
You guys were running the stock pump on those two HE the whole time correct? That means we could all be getting the troublesome shut down stock.
Are there any sensors we can monitor through the OBD port to see if the pump is running or the temps are skyrocketing in the intercooler chain?
07-08-2016, 08:41 PM
#3
Le Mans Master
Does the intercooler circuit share pressure with the cooling system? In other words, is the intercooler circuit under 10-12psi of pressure when the engine is fully warmed up? That goes a long way towards preventing pump cavitation relative to what you're seeing at ambient pressures.
I've long argued that intercooler fill varies by car, and, if sufficiently bad, will cause increased IATs that lead to detonation, and detonation leads to reduced timing, and reduced timing creates a lot more heat... a vicious cycles that spirals down into overheating. Can't prove it though!
Of course I had no idea that the pump was actually shutting down, quite the discovery!
I'm not going to break out the wiring diagrams unless it's sufficiently interesting, but if the pump is on the LIN or CAN network its possible, even probable, that it sends out a packet indicating that it's shutting down and/or starting back up. What, if anything, the ECU even does with that potential information I have no idea.
The C20, P50, and P80 pumps all support the LIN network - do you happen to know which of the pumps on the datasheet we actually use?
I've long argued that intercooler fill varies by car, and, if sufficiently bad, will cause increased IATs that lead to detonation, and detonation leads to reduced timing, and reduced timing creates a lot more heat... a vicious cycles that spirals down into overheating. Can't prove it though!
Of course I had no idea that the pump was actually shutting down, quite the discovery!
The ECU has no idea the pump is shutting down until temperatures reach unsafe levels
The C20, P50, and P80 pumps all support the LIN network - do you happen to know which of the pumps on the datasheet we actually use?
Last edited by davepl; 07-08-2016 at 08:46 PM.
07-08-2016, 08:46 PM
#4
Supporting Vendor
Thread Starter
Whoa this is huge! Another great article from you guys in the technical journal.
You guys were running the stock pump on those two HE the whole time correct? That means we could all be getting the troublesome shut down stock.
Are there any sensors we can monitor through the OBD port to see if the pump is running or the temps are skyrocketing in the intercooler chain?
You guys were running the stock pump on those two HE the whole time correct? That means we could all be getting the troublesome shut down stock.
Are there any sensors we can monitor through the OBD port to see if the pump is running or the temps are skyrocketing in the intercooler chain?
There are no sensors you can monitor, no. That was why we had to do this test. The first thing that will show it will be a rise in IAT2 (post-supercharger intake temps) and Aim products do not log that data. VCM Scanner does, but that doesn't have a display. Just a laptop logger.
Does the intercooler circuit share pressure with the cooling system? In other words, is the intercooler circuit under 10-12psi of pressure when the engine is fully warmed up? That goes a long way towards preventing pump cavitation relative to what you're seeing at ambient pressures.
I've long argued that intercooler fill varies by car, and, if sufficiently bad, will cause increased IATs that lead to detonation, and detonation leads to reduced timing, and reduced timing creates a lot more heat... a vicious cycles that spirals down into overheating. Can't prove it though!
Of course I had no idea that the pump was actually shutting down, quite the discovery!
I'm not going to break out the wiring diagrams unless it's sufficiently interesting, but if the pump is on the CAN network its possible, even probable, that it sends out a packet indicating that it's shutting down and/or starting back up. What, if anything, the ECU even does with that potential information I have no idea.
I've long argued that intercooler fill varies by car, and, if sufficiently bad, will cause increased IATs that lead to detonation, and detonation leads to reduced timing, and reduced timing creates a lot more heat... a vicious cycles that spirals down into overheating. Can't prove it though!
Of course I had no idea that the pump was actually shutting down, quite the discovery!
I'm not going to break out the wiring diagrams unless it's sufficiently interesting, but if the pump is on the CAN network its possible, even probable, that it sends out a packet indicating that it's shutting down and/or starting back up. What, if anything, the ECU even does with that potential information I have no idea.
There is no CAN connection to the pump, just power and ground. You can verify this with an ohmmeter. Although the pump does have the hardware to provide diagnostic information, this is NOT in use. It's just simply not wired up, those two pins on the pump are not connected.
Last edited by GSpeed; 07-08-2016 at 08:46 PM.
07-08-2016, 09:01 PM
#5
Safety Car
Yes, stock pump. It has no problem providing enough flow rate, which was also a beneficial result of this test.
There are no sensors you can monitor, no. That was why we had to do this test. The first thing that will show it will be a rise in IAT2 (post-supercharger intake temps) and Aim products do not log that data. VCM Scanner does, but that doesn't have a display. Just a laptop logger.
The pump does not share any fluid with the engine cooling system, no.
There is no CAN connection to the pump, just power and ground. You can verify this with an ohmmeter. Although the pump does have the hardware to provide diagnostic information, this is NOT in use. It's just simply not wired up, those two pins on the pump are not connected.
There are no sensors you can monitor, no. That was why we had to do this test. The first thing that will show it will be a rise in IAT2 (post-supercharger intake temps) and Aim products do not log that data. VCM Scanner does, but that doesn't have a display. Just a laptop logger.
The pump does not share any fluid with the engine cooling system, no.
There is no CAN connection to the pump, just power and ground. You can verify this with an ohmmeter. Although the pump does have the hardware to provide diagnostic information, this is NOT in use. It's just simply not wired up, those two pins on the pump are not connected.
I can try to force Torque app to read IAT2s.I'll post up my results from the track day tomorrow!
07-08-2016, 09:07 PM
#6
Supporting Vendor
Thread Starter
We have seen this issue on stock configurations, as well as our modified configuration. We attributed it to oil temp, which was 300 each time the car misbehaved. Now that all temps are cool as a cucumber, this issue was still at large, until now.
07-08-2016, 09:23 PM
#7
What a fantastic find. It really makes you wonder how many of these reported issues have been a result of an improper intercooler fill.
Just to clarify, you say "Excess water in the system will cause the impeller to cavitate." So is it an air bubble in the system, not enough coolant in the reservoir, or is it really possible that too much coolant in the system is a problem?
Just to clarify, you say "Excess water in the system will cause the impeller to cavitate." So is it an air bubble in the system, not enough coolant in the reservoir, or is it really possible that too much coolant in the system is a problem?
Last edited by Poor-sha; 07-08-2016 at 09:26 PM.
07-08-2016, 09:33 PM
#8
Burning Brakes
[QUOTE=Poor-sha;1592591530]What a fantastic find. It really makes you wonder how many of these reported issues have been a result of an improper intercooler fill.[QUOTE]
Or conversely, why some Z06's do not seem to have an overheat problem.
Or conversely, why some Z06's do not seem to have an overheat problem.
07-08-2016, 09:41 PM
#10
Supporting Vendor
Thread Starter
What a fantastic find. It really makes you wonder how many of these reported issues have been a result of an improper intercooler fill.
Just to clarify, you say "Excess water in the system will cause the impeller to cavitate." So is it an air bubble in the system, not enough coolant in the reservoir, or is it really possible that too much coolant in the system is a problem?
Just to clarify, you say "Excess water in the system will cause the impeller to cavitate." So is it an air bubble in the system, not enough coolant in the reservoir, or is it really possible that too much coolant in the system is a problem?
The pump cavitating, still
Maintained a decent air temp and water temp on the blower, but then it just shuts down. You can hold the pump in your hand, and give it a little water, it starts to surge, then stops. Immediately starting a 180 second shut down sequence, before it restarts.
The driver did not notice it, one session. As we run the car longer, it rears its ugly head and a noticeable feedback to the driver, as the throttle is limited (no code) and power is significantly de-rated until the pump turns back on.
07-08-2016, 09:43 PM
#11
Supporting Vendor
Thread Starter
The ZR1 pump is 1000$, and it's a mean pump. Really nice, but not a "smart pump" no diagnostics, no safety's. IT just runs. And runs.
We thought we may have had a flow issue, or boiling over issue, but the duration of the IAT2 increase every session, was exactly 180 seconds, to the T. Every time.
We thought we may have had a flow issue, or boiling over issue, but the duration of the IAT2 increase every session, was exactly 180 seconds, to the T. Every time.
07-08-2016, 09:46 PM
#12
Supporting Vendor
Thread Starter
This could be why "performance" was hindered, or the car was slow, but it's not related to the poor engine cooling.
Two separate systems, two issues, that we thought were related, before we reduced everything temp wise.
Two separate systems, two issues, that we thought were related, before we reduced everything temp wise.
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07-08-2016, 09:48 PM
#13
Le Mans Master
As someone who worked a long time in PC software, I have to ask:
Did you try rebooting the pump?
I'm wondering if a reset will "fix" the pump or if it has an internal clock that survives a "reboot" and still forces the 3 minute wait. Otherwise one could build a circuit to, for example, reboot the pump every time you hit the brakes (or some smarter algorithm). Total bandaid, I know.
Did you try rebooting the pump?
I'm wondering if a reset will "fix" the pump or if it has an internal clock that survives a "reboot" and still forces the 3 minute wait. Otherwise one could build a circuit to, for example, reboot the pump every time you hit the brakes (or some smarter algorithm). Total bandaid, I know.
Last edited by davepl; 07-08-2016 at 09:48 PM.
07-08-2016, 09:49 PM
#14
Le Mans Master
Member Since: Sep 2003
Location: Norwalk ohio
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2019 Corvette of the Year Winner
St. Jude Donor '15
pumps don't cavitate because of too much fluid in a system. They cavitate because there is air at the inlet and not fluid (they pump not suck) OR if the feed of fluid to the inlet doesn't keep up with the output then same problem, the pump isn't pumping it is trying to suck....these kind of pumps don't suck.....
35 years in pumping fluids of one sort or another...pumping everything from water (1 centipoise) to liquid paints (15 to 50 centipoise) to windshield urethanes in the assembly plants (8 to 10 million centipoise). They all share the same common issue.....the pump must have the inlet flooded with fluid or it will cavitate and not pump.....
35 years in pumping fluids of one sort or another...pumping everything from water (1 centipoise) to liquid paints (15 to 50 centipoise) to windshield urethanes in the assembly plants (8 to 10 million centipoise). They all share the same common issue.....the pump must have the inlet flooded with fluid or it will cavitate and not pump.....
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07-08-2016, 09:49 PM
#15
Safety Car
What a fantastic find. It really makes you wonder how many of these reported issues have been a result of an improper intercooler fill.
Just to clarify, you say "Excess water in the system will cause the impeller to cavitate." So is it an air bubble in the system, not enough coolant in the reservoir, or is it really possible that too much coolant in the system is a problem?
Just to clarify, you say "Excess water in the system will cause the impeller to cavitate." So is it an air bubble in the system, not enough coolant in the reservoir, or is it really possible that too much coolant in the system is a problem?
Currently rigging my test equipment for tomorrow.
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rsilver (07-08-2016)
07-08-2016, 09:53 PM
#17
Le Mans Master
Member Since: Sep 2003
Location: Norwalk ohio
Posts: 8,927
Received 640 Likes
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2019 Corvette of the Year Winner
St. Jude Donor '15
if air is really such a massive problem, a logical design enhancement would be one in which air could be easily bleed and not have to have a vacuum setup since not everyone (ok, almost no one) will have the right equipment to perform a vacuum pull on the system.
07-08-2016, 09:54 PM
#18
Supporting Vendor
Thread Starter
pumps don't cavitate because of too much fluid in a system. They cavitate because there is air at the inlet and not fluid (they pump not suck) OR if the feed of fluid to the inlet doesn't keep up with the output then same problem, the pump isn't pumping it is trying to suck....these kind of pumps don't suck.....
35 years in pumping fluids of one sort or another...pumping everything from water (1 centipoise) to liquid paints (15 to 50 centipoise) to windshield urethanes in the assembly plants (8 to 10 million centipoise). They all share the same common issue.....the pump must have the inlet flooded with fluid or it will cavitate and not pump.....
35 years in pumping fluids of one sort or another...pumping everything from water (1 centipoise) to liquid paints (15 to 50 centipoise) to windshield urethanes in the assembly plants (8 to 10 million centipoise). They all share the same common issue.....the pump must have the inlet flooded with fluid or it will cavitate and not pump.....
Correct. We edited the post, as we mistyped water for air
The amount of air in the system was in the tablespoons volume. We bled all the systems, as we have been bleeding these systems on various supercharged cars for years.
What we didn't expect, was the pump to shut off. And shut off for not one minute, or even two. But 3 full minutes.
07-08-2016, 09:57 PM
#20
Supporting Vendor
Thread Starter
What a fantastic find. It really makes you wonder how many of these reported issues have been a result of an improper intercooler fill.
Just to clarify, you say "Excess water in the system will cause the impeller to cavitate." So is it an air bubble in the system, not enough coolant in the reservoir, or is it really possible that too much coolant in the system is a problem?
Just to clarify, you say "Excess water in the system will cause the impeller to cavitate." So is it an air bubble in the system, not enough coolant in the reservoir, or is it really possible that too much coolant in the system is a problem?
As someone who worked a long time in PC software, I have to ask:
Did you try rebooting the pump?
I'm wondering if a reset will "fix" the pump or if it has an internal clock that survives a "reboot" and still forces the 3 minute wait. Otherwise one could build a circuit to, for example, reboot the pump every time you hit the brakes (or some smarter algorithm). Total bandaid, I know.
Did you try rebooting the pump?
I'm wondering if a reset will "fix" the pump or if it has an internal clock that survives a "reboot" and still forces the 3 minute wait. Otherwise one could build a circuit to, for example, reboot the pump every time you hit the brakes (or some smarter algorithm). Total bandaid, I know.
But, hey if this was a real racecar with a PDM, we could totally restart the pump on demand whenever it shut down.
