Secondary water pump to cure idle heat up

[kmead]

This thread is from a tangent taken by myself and Hussein in another thread. Rather than drag that one further off track, this thread is to discuss the subject of how our cars tend to heat up noticeably after getting off the highway and then sitting at a light idling.

To get around the potential issues with undersizing of the pipes you could add a helper electric pump on the return line near the radiator. Bob Brown did this on the ‘Queen’ to serve as an assist. I suspect the images are gone from that thread but basically one of the Bosch pumps used as a secondary pump on various German cars. They run 60-90 bucks on eBay.

To which Hussein said:

Going off on the tangent - The 'problem' I have even with increased impeller speed, oversize rad, original model T/stat, baffled expansion tank, etc., etc., is that coming to a stop after a period of at least 15min highway speed results in a estimated 10-20ºF increase in engine temp (based on gauge deflection) when ambient temps are 70 or above. Drops back immediately when moving. SInce it never actually goes over 'normal" that's not really an issue, however, it shouldn't do that - I feel my butt clench anytime that needle tips the 190º mark

Based on the evidence, I'd say it has to be rapid heat soak from the lack of air circulation that the cooling system just can't respond to, given the overall design, distance of rad from motor, etc.. I added the engine bay vent fan(in lid) to suck out that heat soak, but haven't resolved the automated engagement satisfactorily. I need to add a manual switch to confirm that engaging the fan immediately when coming to a standstill resolves the issue.

Sorry to continue the tangent, honestly don’t think it is a heat soak issue.

I think the issue is primarily the idle speed driven capacity of the water pump. At low engine speed the pump is not moving enough coolant to move the heat reservoir in the engine mass which has been running at 4K for miles to the radiator. The radiator and the fan(s) can keep the temp down and you will see that if you rev the engine at 2k while stopped which ensures enough flow through the radiator of the hot coolant out of the engine and the cooled coolant back to the engine.

A secondary pump which could be tipped to run when at idle only by the TPS controlling a relay would ameliorate this tendency. Bob Brown installed his for just their reason oh so long ago in the Which brings us to why cars are moving to electric coolant pumps in general so that cooling can be kept in a tightly controlled range. One of our members has one in his 1.9 without a thermostat to manage the temperature. It would be good to see what his experience is especially since his car can blast down the Autobahn and then have to come to a halt for lengthy periods in traffic.

My car either has a lazy sensor or it cools too well, rarely does my car get to 190, the last time was when I found out my fan sensor wasn’t working at an autox so I hot wired it which brought the temp down nearly immediately with a little revving of the engine.

 

[carl]

There may just be something wrong with your cooling system as my X does not exhibit overheat when coming off the highway and my system is stock.
For those that do have an apparent slow down overheat it might be interesting to do the same drive with the engine cover off and see if this makes a difference.

 

[Dr.Jeff]

I am of the opinion the issue (for those that experience it) is a result of many factors acting in combination. Maybe some hot air hanging around the engine bay, maybe a slightly ill water pump, maybe a slightly ill radiator, maybe the cooling tubes are partially clogged/corroded/damaged, maybe the fans aren't pulling 100%, maybe the water passages in the engine are coated with crud build-up, maybe....well, likely a little of many of those things. Plus many other factors discussed below. Does that mean you can't improve things? Of course not. But what direction you choose to take may effect the results.

In my opinion the X's cooling system is a 'less than ideal' design. Long tubes, small pump, small rad with poor air-flow, mid-engine layout, etc, etc, etc. If any aspect of it becomes compromised (even slightly), it will have consequences. The other day I was inspecting a recent X acquisition and started playing with the digital non-contact thermometer. Wow, the temp differences from point to point are amazing. I've never seen such variance on any other vehicle. This really is OLD design-engineering with OLD technology. My point is to make sure EVERYTHING is 100% up to par before making modifications.

O.k., so everything is new and it still gets a bit warm at times, now what? I agree completely that the cooling system would benefit from improved circulation (reference my findings with the temp gun). However, I'm not sure adding a second electric pump on top of the existing system is the answer. Hopefully a hydrodynamics expert will pitch in here. But my understanding of physics and hydrodynamics (actually hemo-dynamics in my case) says that will result in the two pumps competing with one another, and the overall outcome will suffer. Lots of factors get involved, like possible cavitation, flow rate and volume differences, pressures, control temperatures, and who knows what else. If you go electric (which I believe is a great idea) then eliminate the stock pump and go completely electric with one pump capable of supplying the entire system (this sentence is key).

So why do some people experience lots of cooling issues while others don't? Again, lots of variables at play. In addition to all of items related to the system's condition (discussed above) there are many other things to consider; the ambient temps where you live, how you drive it, geographical differences (hills vs flat), the fuel you use, the speeds and time intervals you travel, the total weight you carry (lets be honest, America has one of the worlds most obese populations, put two of our 'larger' passengers in a sub 100 horse-power vehicle and...well), the tires you have (circumference effects final drive ratio, air pressures make a huge difference in resistance), and more. Combine these numerous factors with the numerous vehicle factors from above and you get a whole lot of possibilities.

In response to Karl, I fully agree there is room for improvement and an electric pump is an excellent option. But I am of the opinion it should be a replacement pump rather than a secondary one.

 

[kmead]

Jeff, I don’t think it would work out that way if properly set up.

Looking back, I like the idea of what Bob Brown did which was to put the electric pump at the radiator outlet which puts the two pumps at the extreme ‘corners’ of the system: the engine driven solution at the base of the block pushing through the engine and to the radiator, the electric pump pushing cooled coolant to the engine driven water pump.

Bob Brown set his up such that he made a Y in the radiator exit hose which gave the standard path with no impedance and then the electric pump with another Y back into the radiator hose to go back to the engine. This ensured that the engine driven pump was never pushing against the electric pump if it wasn’t running. He didn’t put a back flow preventer in the hoses but said that it was never an issue.

The nice thing about coolant is it is relatively non compressible, at least at the pressures of these pumps, so any induced movement by either pump will become flow in the system.

 

[geekdaddy]

Karl I agree. At road speeds I can barely get my needle to rise up to 190. When it eventually does get there it's rock steady on my X. But after running at highway speeds and then sitting at a light at the end of an exit ramp my temp guage will go a notch or so above 190.

It doesn't rise to a danger zons and like you I can help it cool down by blippig the throttle a bit. But this suggests that after a hard run with subsequent idle, a higher rate of coolant flow would be better.

A programmable electric pump would potentially imlrove this situation. Removing the engine cover rain tray might also help. Although probably not entirely necessary I may try to implement an electric pump replacement for the mechanical on someday....

 

[kmead]

I would agree that a single, electric pump system would be the best overall thing to do with a programmable system to run it and hold the temp steady.

I do have a Davies Craig pump which could easily take the place of the mechanical unit. Mounting it after the thermostat housing, likely on the back firewall, and having the hose come around to a hose mount on the former waterpump housing and avoid the exhaust manifold.

Mark Allison offers a kit for 124s which is pretty tidy. You can see it here:
https://allisonsautomotive.com/coll...and-heating/products/water_pump_block_off_kit
Something similar would need to be created to take the place of the pump housing.

 

[LarryC]

I agree with Carl that an off-nominal condition is worth looking into before going into extra engineering. I too experienced some warmer than desirable conditions in 90 degree heat and high speed slow downs. But that was all solved by just a few things. First, a new Stant Superstat and second a new aluminum radiator. Now I can idle all day with the AC running in high ambient temperatures. I now no longer even look at the temperature gauge as it is always just below 190. It was an amazing thing to see an old problem resolved with just a few basic upgrades of the existing equipment.

 

[carl]

Certainly no argument from me that the system is marginal. The X that Dave S has used to be mine. I bought if from a buddy of mine. On the way home from buying it, the car overheated within 20 minutes and had to be towed back to my friend's house. Another used radiator was installed and it worked fine....up to 55 mph where the needle started to go up....continued driving over 55 would push the needle into the red and slowing down put the engine temp back to normal. I installed a third used radiator and the engine temps were just fine at any speed. I mention this only to show the condition of the radiator is critical in these cars and if you are going to start "improving" the cooling system you must start there. Nobody likes to turn the heater on in 90 degree temps to cool the motor (acting as an auxiliary radiator).

 

[lookforjoe]

Thanks Karl.

I think the issue is primarily the idle speed driven capacity of the water pump. At low engine speed the pump is not moving enough coolant to move the heat reservoir in the engine mass which has been running at 4K for miles to the radiator. The radiator and the fan(s) can keep the temp down and you will see that if you rev the engine at 2k while stopped which ensures enough flow through the radiator of the hot coolant out of the engine and the cooled coolant back to the engine.

For the purposes of this discussion, it is assuming that all components are new or checked for proper operation, no clogged or restricted tubing or passageways, collapsing hoses, Header proximity to branch pipe, proper coolant, bled system with no leaks, loose clamps, pinholes, aeration, etc. I have suffered many of those, and they will absolutely detract from proper performance of the system as Jeff pointed out.

We may be talking about two sides of the coin - heat soaking occurring due to coolant flow issues, not so much directly as a result of reduced air circulation - however, increasing air circulation (with an extraction fan) at idle does help, based on previous tests. Nothing I can do about internal coolant flow path in the head/block passages. I changed to a much smaller OD water pump pulley to increase circulation at idle. With my more efficient LH-Jetronic, idle control is a more stable event than it ever was with L-Jet, however that does also mean it is lower, which of course decreases flow...

I went back to the orignal model t/stat on mine to verify that that was not a factor. I was otherwise happy with the SuperStant Tony had recommended years ago. I'm using the stock temp cooling fan switch. The fans kick on as they should, right when the needle ticks over the 190º mark. I had tried a lower temp (VW?) thermoswitch.

Again, the issue here is not overheating per se, it is the deviation that can occur when sitting after a highway run. That specifically is what I am looking to address. It may be impossible, given the inherent flaws in the cooling system, I dunno.

Of all the add-ons I tried over the years, the large extraction fan made the most difference. On that basis, I built a fan (FFD7) into the engine cover. I want the control to be fully automated, and getting the thermoswitch engagement right is the bear. Since I added the exhaust heat shields, the sensor is not responding rapidly enough in the stock (injector fan sensor) location. I need to move it closer to the base of the head, and resolve the trigger signal for the relay to operate correctly. The sensor engages at (edit) 203ºf, and disengages at 194ºf. Don't recall if it is the stock EFI sensor. - May need a lower temp unit.

Some of the mods I experimented with:

Internally baffled expansion tank to prevent aeration that can occur with returning coolant

Revised branch pipe (due to header proximity)

auxilary water pump (removed)

Various T/stats

Setting Impeller offset

Large extraction fan (removed)

Oversize Rad

Reduced OD water pump pulley

 

[autox19]

Thanks Karl.



For the purposes of this discussion, it is assuming that all components are new or checked for proper operation, no clogged or restricted tubing or passageways, collapsing hoses, Header proximity to branch pipe, proper coolant, bled system with no leaks, loose clamps, pinholes, aeration, etc. I have suffered many of those, and they will absolutely detract from proper performance of the system as Jeff pointed out.

We may be talking about two sides of the coin - heat soaking occurring due to coolant flow issues, not so much directly as a result of reduced air circulation - however, increasing air circulation (with an extraction fan) at idle does help, based on previous tests. Nothing I can do about internal coolant flow path in the head/block passages. I changed to a much smaller OD water pump pulley to increase circulation at idle. With my more efficient LH-Jetronic, idle control is a more stable event than it ever was with L-Jet, however that does also mean it is lower, which of course decreases flow...

I went back to the orignal model t/stat on mine to verify that that was not a factor. I was otherwise happy with the SuperStant Tony had recommended years ago. I'm using the stock temp cooling fan switch. The fans kick on as they should, right when the needle ticks over the 190º mark. I had tried a lower temp (VW?) thermoswitch.

Again, the issue here is not overheating per se, it is the deviation that can occur when sitting after a highway run. That specifically is what I am looking to address. It may be impossible, given the inherent flaws in the cooling system, I dunno.

Of all the add-ons I tried over the years, the large extraction fan made the most difference. On that basis, I built a fan into the engine cover. I want the control to be fully automated, and getting the thermoswitch engagement right is the bear. Since I added the exhaust heat shields, the sensor is not responding rapidly enough in the stock (injector fan sensor) location. I need to move it closer to the base of the head, and resolve the trigger signal for the relay to operate correctly. The sensor engages at 194ºf, and disengages at 203ºf. Don't recall if it is the stock EFI sensor.

Some of the mods I experimented with:

Internally baffled expansion tank to prevent aeration that can occur with returning coolant

Revised branch pipe (due to header proximity)

auxilary water pump (removed)

Various T/stats

Impeller offset

Large extraction fan (removed)

Oversize Rad

Reduced OD water pump pulley

Where did you get the tank? I have been looking for a baffled swirl tank with a pressure cap for a bit. I either find tanks with a cap that are only expansion with one hose connection or ones with 2 (Intake near top and return on bottom) that have a sealed cap on top. No way to relieve pressure if it builds.

Odie

 

[lookforjoe]

Where did you get the tank? I have been looking for a baffled swirl tank with a pressure cap for a bit. I either find tanks with a cap that are only expansion with one hose connection or ones with 2 (Intake near top and return on bottom) that have a sealed cap on top. No way to relieve pressure if it builds.

Odie

I made it I might have time to make another over the summer. Costs around $100 in materials alone though.

Ended up not using AN fittings for the vent/return, as they were too bulky. Lower hose had to be a "U" to allow for engine movement. The 3/4" straight (short) hose was too rigid.

 

[kmead]

Hussein admit it you just want to make a Chapparal sucker car...

 

[kmead]

If you ever want unload that pipe for the auxiliary water pump let me know.

That is a lot of making and experimenting with muliple parts.

So how over driven is the water pump with the smaller pully? Would raising your idle to 850/900+ make a difference? I can’t imagine your car spends much significant time idling so that minor change in speed wouldn’t have much of a deleterious effect on your overal fuel economy.

There are a variety of small grounding temp sensors you might try with various temp ranges. I would imagine you would want to keep it out of the ‘airflow’ to ensure it doesn’t see large temp variance when the actual engine mass is still hot, hot being a relative term in this instance.

So is one of your next steps to consider an electronically controlled variable speed water pump system to manage this or do you see your engine lid fan as the solution to the problem?

 

[Zippy]

Another example, to add to the wide range we experience My cooling system works without fault or concern.

Daily driver.
Autocross in 98 degree weather, pedal to the metal followed waiting in line for the next run, at idle
stock engine cover and rain tray
stock coolant pipes
stock Bayless aluminum radiator (Bob G?)
stock radiator air ducting
2 stock fans
stock Honda pump, K20 swap
charge heat exchanger in place of the A/C condenser

 

[Dr.Jeff]

Bob Brown set his up such that he made a Y in the radiator exit hose which gave the standard path with no impedance and then the electric pump with another Y back into the radiator hose to go back to the engine.

One possible short coming with adding the second pump parallel to the main coolant line (out from the radiator), is the fluid will want to follow the path of least resistance. So there won't likely be a lot that flows through the small tube to the second (add-on) pump. This set-up would require a bit of testing and engineering to maximize its design. It will be interesting to see where it goes though. However I think the development effort is best spent on this....

I do have a Davies Craig pump which could easily take the place of the mechanical unit. Mounting it after the thermostat housing, likely on the back firewall, and having the hose come around to a hose mount on the former waterpump housing and avoid the exhaust manifold.

I changed to a much smaller OD water pump pulley to increase circulation at idle.

Not that it would happen in your example, but one possible outcome of spinning the water pump's impeller too fast is it creates cavitation. In which case fluid flow is dramatically reduced.

stock Honda pump, K20 swap

Kind of apples and oranges here.

 

[lookforjoe]

If you ever want unload that pipe for the auxiliary water pump let me know.

That is a lot of making and experimenting with muliple parts.

So how over driven is the water pump with the smaller pully? Would raising your idle to 850/900+ make a difference? I can’t imagine your car spends much significant time idling so that minor change in speed wouldn’t have much of a deleterious effect on your overal fuel economy.

There are a variety of small grounding temp sensors you might try with various temp ranges. I would imagine you would want to keep it out of the ‘airflow’ to ensure it doesn’t see large temp variance when the actual engine mass is still hot, hot being a relative term in this instance.

So is one of your next steps to consider an electronically controlled variable speed water pump system to manage this or do you see your engine lid fan as the solution to the problem?

I'll look for it. Not sure what I did with it.

I didn't do any computations regarding the pulley resizing. I would expect however that flow through at idle (750-800 rpm) on my setup is at least equivalent to flow at 1500 on a stock setup. Problem with messing with base idle is that LH2.4 will try to compensate if it's too high & is generally not happy. I'll see if I can bump it 50-75rpm, get it in the 850-875 range.

I really don't want to go the route of an external pump & all the re-configuring of the piping, etc... I'm hoping that the extractor fan will provide the small bump needed to take care of the situation. I'll report back on that specifically once the rewiring & sensor placement are settled. I'll try a lower temp sensor if this one doesn't kick the fan on as intended. The motor runs cool enough in any moving situation.

Another example, to add to the wide range we experience
My cooling system works without fault or concern. stock Honda pump, K20 swap

Can't really compare. Engine swaps create entirely different parameters, simply based on newer engine design/efficiency.

 

[lookforjoe]

Not that it would happen in your example, but one possible outcome of spinning the water pump's impeller too fast is it creates cavitation. In which case fluid flow is dramatically reduced.

Indeed. I don't rev the motor over the stock redline, or see any temp issues at speed. If I was running 8K redline or higher I probably would go back to the larger pulley I made.

 

[geekdaddy]

Larry are you running a completely stock engine config? Stock cam and stock exhaust?

I agree with Carl that an off-nominal condition is worth looking into before going into extra engineering. I too experienced some warmer than desirable conditions in 90 degree heat and high speed slow downs. But that was all solved by just a few things. First, a new Stant Superstat and second a new aluminum radiator. Now I can idle all day with the AC running in high ambient temperatures. I now no longer even look at the temperature gauge as it is always just below 190. It was an amazing thing to see an old problem resolved with just a few basic upgrades of the existing equipment.

 

[Dr.Jeff]

Something else to consider when choosing an electric pump for the cooling system. Those smaller pumps (like in Huss's photo earlier) do not offer much flow volume. Not nearly enough to really help the cooling system's circulation. Previously I purchased a 'air to water' intercooler for my turbo project. I researched those pumps for the coolant circulation for that use. After all some of those are used on similar factory boosted applications. I was quite surprised at how low their output is. I guess on a conservative factory system (low boost), in a front engine layout (excellent airflow compared to our mid engine layout), with much more modern cooling systems in general, they are sufficient for the small intercoolers they use. But even the largest capacity pump I could find was not enough for my turbo project. And that is much less than a engine cooling system requires. By comparison, the bilge pumps for boats offer several times the flow ratings; just look at their 1-1/2" fittings compared to the small ones on these pumps. I realize you are not suggesting the use of these small pumps to replace the original water pump. But even as a supplement pump I don't believe they offer enough capacity to help much. Perhaps a pump with a flow capacity and hose sizes that more closely corresponds to the factory water pump's performance would be a much better choice?

Karl and Huss, you might find some useful info in this interesting article. Among other things we've discussed here, it mentions 'heat soak on switching off the engine". Perhaps it will stimulate some ideas:
https://hitthewave.wordpress.com/tag/fiat-x-19-cooling-modifications/

 

[lookforjoe]

Not sure you could use a extra pump with close to stock flow volume - I would expect that would cause issues since the stock pump vanes will interfere if you are pushing coolant at it at a rate that exceeds what it is already pulling. Pretty sure that's the rationale for smaller pumps that just help push the coolant along without creating issues with the existing pump, no?

My bay fan is set with a (constant vBat supply) timer relay, so it will run both with engine on idling after run or during that heat soak period that occurs immediately after shutdown, if the temp exceeds given parameters.