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Low (or no) RPM Heat from a cheapo recirc pump


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So I know there's a Y fitting that some folks will install in their raw water lines to improve the water flow through the heat circuit at idle, but I have heard mixed results on that. A few folks on the Malibu Crew have gone to cheapie solar recirculation pumps to combat the loss of heat at idle instead, but I've seen very few reviews on this.


So I decided to give it a go.


I ended up using this pump.




With these fittings.




I ordered everything on Monday and had it all by Thursday. Prime shipping on the Amazon order, but I picked the slowest USPS option on the fittings. Was surprised when they arrived so quickly.


I stuck this in the return line up by the driver's feet and wired it to a spare "Acc" switch I have right next to my existing heater switch.


When underway, the pump doesn't make any difference, which is good. Even if you switch it off. The existing circuit has enough oomph to push water right past the pump with no issues when underway. At idle, however, the pump definitely increases the heat of the air coming out of the heater tubes. With the pump on, there is no discernible difference in heat output as RPM varies.


The really cool trick though is that if you leave it on after you shut the engine off, it will continue to blow hot until you've sucked all the heat out of the engine block. I don't know how long it would keep blowing hot air, but I imagine it'd take a while to cool off a 5.7L block just using the heater core. This is with the return connected to the recirculation pump, not the Y fitting on the raw water intake.


Not bad for $30.

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