Heater hose routing?

carl

carl

True Classic
In the grand scheme of things it probably does not matter which hose goes to the heater core valve and which to the core return pipe, probably 50% of the 124 spiders out there have it wrong but since I have now replaced the leaking valve;

Which heater hose goes to the valve? Logic dictates the one from the water pump but thought I would ask.
 
We had a bit of a debate about this recently. Although I'm not sure we actually arrived at an answer for the X1/9 specifically. Some vehicles have the 'hot' feed going to the valve first, while others have it going to the core before being controlled by the valve. Personally I prefer the water flow going from the head to the valve, and the return from the core to the water pump pipe. How is it on the 124 Spiders?
 
Not that it Matters on our car's but I had a 74 (ish) ford Mavric that was a parts car that I repowered and made a driver again. But I had the hardest time getting the heater to work. Even bought a 12v pump to push the water through the heater core still no heat... Standing there staring at it going. Why can I not get this to work? Heaters (or a car of this age) are about a simple system as you can possibly get.

Being sure this would have zero effect I swapped hoses, and How.. one of the best heaters I have ever had. (at that point I stopped working on it and moved to other projects. Kinda wish I had played with it more.
 
Feed hose is the one off the front of the head. Return goes to the branch pipe, since that is the direction of flow in the cooling system .
 
Thanks guys, logic does seem to apply here. As a side note, since I have both heater hoses running against the side of the shifter tunnel and no carpet I am able to feel the hoses. With the valve closed both hoses are cool so the thought that the valve being on the return line would allow the heater core to get hot even when off is false. This makes sense as there is no flow at all in the system with the valve off.
 
Water is effectively incompressible in our systems and no flow makes the heater system a dead eddy in the river of coolant so no it won’t get hot, unlike my effing Miata which is constant flow and relies on silly foam seals to close off the heated air in the air box. Which means that its always hot in that car, which suits my wife who is always cold at any temperature below 82 degrees.

Generally flow goes from engine to valve to heater core and back to engine.
 
I noted something else after installing the new valve and refilling the cooling system. While letting the car idle to get the car up to temp I noted the heater hoses did not even get warm with the valve open. I then went for a zip around the block and the hoses were hot when I got back. That damn water pump is pretty much useless at idle. Most Fiat owners are used to frozen fee at idle.
 
I've suggested a few times that an improved water pump impeller could be designed as a direct replacement into the stock pump. That would improve the flow capacity (volume) at lower RPM's. The idea of simply changing the pulley sizes to increase the pump's speed might work, but I think it would have issues. At lower RPM's the velocity (rate) of the water will be increased but not necessarily the volume of water. And at higher RPM's it might cavitate and actually reduce the flow. But testing for both approaches would need to be done to get the best solution. I know, some of you don't have these problems, but way too many others do.
 
Ultimately I think the solution is to abandon the existing pump and go to an electric unit as Ulix has on his 1.9l with a pulse width modulated controller. Trying to develop a better impeller is unlikely for most anyone to be honest.
 
True, to design a different impeller requires fluid dynamics engineering knowledge, etc. It is very commonly done for jet pumps (eg. boats), and for turbo compressor wheels, and other applications. But the thought I had was for someone with the right knowledge to design it, and then have them made as replacements, by say one of the vendors...perhaps preinstalled on new pumps. Then this would be a simple direct replacement for the stock pump, and much less expensive than the electric pumps. Maybe the impellers could even be made of stainless? Not really necessary, but would last forever.
 
Is it possible to have an electric pump that was designed to be installed in the Fiat housing so it was just a bolt in and some wires?
 
It might be possible to design an external electric motor that attaches to the stock pump's shaft in place of the stock V-belt pulley. Or to mount the electric motor next to the pump and use it to drive the stock pump's V-belt pulley. For both approaches to work the V-belt drive to the alternator would need to be rearranged. Either of these designs would be similar to some of the offering for American V8's:

Motor directly on pump's shaft -
csi-billet-elecric-water-pump.jpg


Motor with belt drive to pump -
114366-3.jpg
 
I don’t see much value in putting it in the normal position. It would be interesting to see how Ulix plumbed his 1.9l car with an electric pump.

Here are couple of possible scenarios:
The pump could go under the expansion tank with the current rubber elbow turned in the other direction to feed the pump. The pipe to the engine could be the existing one running across the back of the engine. The pump body itself could be capped with a flat plate to take the place of the impeller and its pulley.​

Alternatively as the drive belt no longer needs to run across the face of the pump, you could remove the pump entirely and run from the pump across the back of the engine compartment to a plate placed where the pump was with a pipe mount in the plate pointed directly at the opening in the engine block. A modified upper mount for the alternator would be needed in this scenario. This gets rid of the pump body, the existing cross pipe and as a result multiple failure points along the way.​

I prefer the second scenario, it is much like Mark Allison does on the 124 engines although I don’t much care for where he puts the pump itself.

https://allisonsautomotive.com/coll...and-heating/products/water_pump_block_off_kit

https://allisonsautomotive.com/coll...-and-heating/products/electric_water_pump_kit

7FA9B30E-3DD4-4CF3-987A-64B366FBB6FF.jpeg
 
After having done it, I would actually favor Carl's suggestion of powering the stock pump with a motor and controller.
Also, further testing under high load in high ambient temps show that the pump is still too large in these conditions. The smallest pump would have been the correct one, whic is what Allisons is selling.
Here is what we did.
Pump basically replaces the short elbow from pipe to t-stat housing. Pipe shortened.
2017-11-03-PHOTO-00000838.jpg
IMG_1509.JPG
On the pipe end, an ebay silicone hose with two different diameters is used. On the t-stat end, a 90° of constant ID with a rubber adapter sleeve that comes with the EWP (Craig Davies pump). The instructions actually say that ideally, the pump should just hang from the hoses so it is not damaged by engine vibrations. Ours is resting with the output flange on the trans bellhousing. The flange has a piece of hose over it at the contact point.

On my car, the stock pumps is replaced by a cover.
IMG_5155.JPG
This doesn't really work out though, because the belt then only drives the alternator. The swing of the alternator then no longer allows any real tightening of the belt. I barely got it to work with a belt of just the right size. I have to remove the alternator to install the belt though. On my buddy's car, he chopped off the stock impeller and used the stock pump as an idler for the belt.

The instructions call for removing the thermostat and blocking off the bypass route at the thermostat, so that the water flows through the rad at all times.
So we did that and installed the temp sensor for the pump controller in a convenient spot on the t-stat housing. I am not sure that this spot is there on all housings.
IMG_2867.JPG IMG_2868.JPG

Getting the heater connections correct wasn't so straightforward. The two connections need to be before and after the pump, so that the heater sees a pressure differential and the coolant actually flows through it. My 1974 water pump housing has a heater hose connection. This was for the heater return originally, because it is directly before the pump. Having moved the pump, I now used it as the heater supply since it is now right after the pump. Heater return is a T into the hose from expansion tank to t-stat housing, this is right before the pump.
The pic shows the T and the heater supply in the top right corner of the pic.
IMG_0062.JPG

So after all that, driving the stock by a motor sounds attractive to me.
I would see if the stock t-stat couldn't stay in operation and wouldn't mess with the heater circuit. All I would have to do is mount the temp sensor.
But you would still have to solve the problem of tensioning the v-belt.
 
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Ulix said:
After having done it, I would actually favor Carl's suggestion of powering the stock pump with a motor and controller.
Also, further testing under high load in high ambient temps show that the pump is still too large in these conditions. The smallest pump would have been the correct one, whic is what Allisons is selling.
Here is what we did.
Pump basically replaces the short elbow from pipe to t-stat housing. Pipe shortened.
View attachment 14699
View attachment 14700
On the pipe end, an ebay silicone hose with two different diameters is used. On the t-stat end, a 90° of constant ID with a rubber adapter sleeve that comes with the EWP (Craig Davies pump). The instructions actually say that ideally, the pump should just hang from the hoses so it is not damaged by engine vibrations. Ours is resting with the output flange on the trans bellhousing. The flange has a piece of hose over it at the contact point.

On my car, the stock pumps is replaced by a cover.
View attachment 14702
This doesn't really work out though, because the belt then only drives the alternator. The swing of the alternator then no longer allows any real tightening of the belt. I barely got it to work with a belt of just the right size. I have to remove the alternator to install the belt though. On my buddy's car, he chopped off the stock impeller and used the stock pump as an idler for the belt.

The instructions call for removing the thermostat and blocking off the bypass route at the thermostat, so that the water flows through the rad at all times.
So we did that and installed the temp sensor for the pump controller in a convenient spot on the t-stat housing. I am not sure that this spot is there on all housings.
View attachment 14703 View attachment 14704

Getting the heater connections correct wasn't so straightforward. The two connections need to be before and after the pump, so that the heater sees a pressure differential and the coolant actually flows through it. My 1974 water pump housing has a heater hose connection. This was for the heater return originally, because it is directly before the pump. Having moved the pump, I now used it as the heater supply since it is now right after the pump. Heater return is a T into the hose from expansion tank to t-stat housing, this is right before the pump.
The pic shows the T and the heater supply in the top right corner of the pic.
View attachment 14705

So after all that, driving the stock by a motor sounds attractive to me.
I would see if the stock t-stat couldn't stay in operation and wouldn't mess with the heater circuit. All I would have to do is mount the temp sensor.
But you would still have to solve the problem of tensioning the v-belt.
Click to expand...

Thank you for weighing in with a real life experience and some great pictures. All this stuff is very nice when conceptualized, engineering is a hands on business and one test is worth a million opinions. Thank you for providing that test.

Thanks

Karl
 
Ulix, is the alternator motion limited if there is no water pump housing? It would seem like there would be the opportunity for a greater arc of motion and as a result easier belt installation. In looking at pictures of engines out of the car, it appears this is so but that which appears is not always so.

From a heater efficiency standpoint the supply hose to the heater should come from the head or after the head with the return going before the pump. As you have it now it would appear that you are circulating cooled return coolant as the supply to the heater core and the return isn’t currently clear. On later heads the supply is from an elbow from the front of the head above the existing water pump. As you have a later Tipo head I don’t know what ports are available. I would think adding an adapter after the thermostat housing to be the supply with another adapter on the return line would provide much better heating which I am sure would be of value around Stuttgart.

Another question, which size pump did you choose? DC no longer shows the pump that is in the Allison images, so knowing what pump would be better sized would be worth while. They seem to have a large bump between sizes, 40, 80 and 120 for the ones really intended for car engines.

Thanks
 
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Dr.Jeff said:
I've suggested a few times that an improved water pump impeller could be designed as a direct replacement into the stock pump. That would improve the flow capacity (volume) at lower RPM's. The idea of simply changing the pulley sizes to increase the pump's speed might work, but I think it would have issues. At lower RPM's the velocity (rate) of the water will be increased but not necessarily the volume of water. And at higher RPM's it might cavitate and actually reduce the flow. But testing for both approaches would need to be done to get the best solution. I know, some of you don't have these problems, but way too many others do.
Click to expand...

I had previously stated that increasing water pump speed with a smaller OD (3.25") pulley had no negative impact at higher RPM (say over 5K). I'm not sure of that now. I noticed that under hard acceleration the coolant temp would rise in the upper rpms, when sustained.

I switched back to the stock size some months back (not Fiat pulley, since I have serpentine), however have not driven the car under the conditions required to retest. I can say reverting it did cause the idle temp to bump up a few degrees. In my case, the timing high load/rpm mapping may also be the cause though. I will have to look at that after I check current setup.
 
I was thinking in terms of least intrusive change, keeping the back of the stock pump housing and thus routing circuits untouched. Basically the fan belt just goes from the crank to the alternator and the pump is now in the same spot it was originally but electrically run.
 
Loving the discussion and the show-and-tell, but I am wondering if we are unwitting victims of driving modern cars.

Consider that with cars from the X1/9's era, with direct analog information and no computer control whatsoever, when we look at gauges, we are looking at stark reality.

On the other hand, when behind the wheel of modern cars, when looking at gauges, we are seeing what the car's computers (and of course, those who programmed the computers) want us to see. Yes, there is a pointer and numbers, but the data on the gauge comes from the Body Control Module, not a sending unit. The BCM is programmed to know that swings in temperature during normal operation might be noticed by the driver, and such driver might bring the car back to the dealer thinking there is a problem, which costs the manufacturer money if under warranty.

Also, with recent cars, the Engine Control Module is now supplementing or completely controlling thermostat operation. Look at the chart in this article https://www.motor.com/magazine-summary/electrically-assisted-thermostat/, note that for typical operating conditions (50% or less load at speeds under 75mph) the ideal coolant temp target is between 210 and 220. But also note the wide range of temps that is on that chart. Imaging the temp gage needle swinging up and down thru an arc of 185 thru 215 in the space of a few minutes----service writer phones would be ringing off the hook with calls from drivers who have been conditioned to think that the temp needle should get to a spot and stay dead on that spot.

So if we compare the temp gauge behavior of our modern cars to our X1/9s, I think we should consider whether we are setting our expectations too high.
 
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