Coolant Loop / Recirc Pump Question - LotusTalk - The Lotus Cars Community
 
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post #1 of 11 (permalink) Old 10-20-2017, 04:17 AM Thread Starter
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Coolant Loop / Recirc Pump Question

Alright, so I recently had my blower resistor pack go out and took care of all of that, but now I am having a beast of a time with an air pocket. I should've pre-filled the heater core with coolant but didn't. I have bled everything many times before, and I finally have it such that the radiator is certainly working. However, the heater still blows cold.

My question then is regarding the coolant pathways. The service manual shows coolant pumping to the heater core at all times (thermostat open or closed), but this diagram shows it also passing through the recirc (heatsoak) pump in order to do so. Is this pump active during this phase or just passively allowing fluid through?With the thermostat closed, this pump seems to be stalled and draws 3-3.5 amps, but it only draws 1A and actually runs when the thermostat is open. This doesn't jive with the service manual, so I'd like to know what's going on here.
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post #2 of 11 (permalink) Old 10-20-2017, 04:46 AM
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I 'thought' it didn't run with the car on, but I suppose it really only says it runs after the car is shutoff when it is very hot, not specifically that it doesn't run when the car is running, so perhaps this is normal.

Have you used a vacuum bleeder?

Are you sure your heater flap is operating?

I suppose you could get a quart of coolant, a turkey baster and some towels and try to fill the heater core..........
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post #3 of 11 (permalink) Old 10-20-2017, 04:58 AM Thread Starter
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I 'thought' it didn't run with the car on, but I suppose it really only says it runs after the car is shutoff when it is very hot, not specifically that it doesn't run when the car is running, so perhaps this is normal.

Have you used a vacuum bleeder?

Are you sure your heater flap is operating?

I suppose you could get a quart of coolant, a turkey baster and some towels and try to fill the heater core..........
I have a long-neck funnel that could work, too...

I had checked the heater flap a few times at different stages during reassembly, but not since then. Since we all know what it means to assume, I should probably check again.

I have used a vacuum bleeder on it before with subpar results. I made sure to follow directions to a T and pull the full vacuum, but I think the heater core bypass mod makes that tricky. I have to cycle the bypass a couple times, and that kills the vacuum. Without cycling though, it seems to leave air pockets.

And yeah, the service manually is empty with regard to when the pump kicks on, as you say. Sir Lotus has a post where he stated it kicks on at 230F, but that is so far outside of the normal operating region that I find it hard to believe the pump was worth having if that is the case.

I also want to force run the pump again. It made a sound like it was stuck when I ran it cold last time, and it only whirred when the thermostat was open. Either the diagram above is wrong then and there is no circulation through the pump with the thermostat closed, or I had a blockage that moved. Really hoping the diagram is wrong...

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post #4 of 11 (permalink) Old 10-20-2017, 05:08 AM
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The bypass of course adds a complexity, hoses can get crimped in tight space, actuator can be defective or vacuum hose crimped. I used an electronic one, which I hope stays working cause its a bitch to get at in the Exige and you have no external evidence of it moving....
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post #5 of 11 (permalink) Old 10-20-2017, 05:14 AM Thread Starter
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The bypass of course adds a complexity, hoses can get crimped in tight space, actuator can be defective or vacuum hose crimped. I used an electronic one, which I hope stays working cause its a bitch to get at in the Exige and you have no external evidence of it moving....
Do you recall the part number? My car came with one of Tony Wa's original installs, but the valve had a crack in the plastic. Took forever to find the pinhole leak, but then I replaced it with a drop-in replacement. That one is also starting to fail, it seems, so I want to go to an electrical one. The nice thing with the vacuum ones though is that they do have external evidence, so I can tell it is all working fine.

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post #6 of 11 (permalink) Old 10-20-2017, 05:30 AM
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Its in my heater rework thread Old Air Products, I think they have them on amazon




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post #7 of 11 (permalink) Old 10-20-2017, 05:32 AM
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there is also a common i think ford part that is 'wicked cheap' but I don't know how it would install. figured I would look into it if mine ever died

saw it on SELOC

https://www.ebay.com/sch/?_nkw=Heate...0Ford%20Fiesta

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post #8 of 11 (permalink) Old 10-20-2017, 06:18 AM Thread Starter
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The vacuum operated one I have now is also ford, so I'd suspect those would drop right in. Might as well try and pre-fill the heater core while I am at it if the heater flap truly is moving.

I still don't know the operation of there recirc pump though, and that really bothers me out of principle, haha

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post #9 of 11 (permalink) Old 10-20-2017, 08:25 AM
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SO the deal with the cheap for one is that it is designed for a PWM so I 'think' it will work the same as the Tony Wa mod, 12 volts should open it full. The Old Air one opens progressively with the door and requires no extra wire, the knob that comes with it is discarded and you twin it with the the output of the dash knob, and stuff the little control box out of the way somewhere

I think the PWM is for climate control so it can electronically vary the heater temp, which we dfon't really care about
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post #10 of 11 (permalink) Old 10-20-2017, 01:59 PM
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I still don't know the operation of there recirc pump
It rarely runs. The tech manual covers this on page 292. Guessing you have an air pocket or faulty flap in the HVAC chamber.

Heat Soak
The (recirculation) pump functions only with ignition off in conditions where the ECU remains live. The pump is then activated at coolant temperatures over 110C (230F), switching off at 100C on fall. If temperature should rise to 115C, the pump will be supplemented by the two cooling fans running at half speed, switching off at 110C on fall.
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post #11 of 11 (permalink) Old 10-20-2017, 05:53 PM Thread Starter
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Turns out it was a loose connection for the flap. Must?ve come loose when I connected the corrugated hose. Thanks!

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