What is this and should it be hot?

[Thonas]

the smaller cylinder is hot enough to burn you. My car has not been driven in over a week. Should this be scalding hot just sitting?

[heinzboehmer]

One of those cylinders is the auxiliary coolant pump, which works to circulate coolant to the heater core when the engine is off or the mechanical water pump isn't flowing enough (idle). The other is the heater core valve, which opens when coolant needs to circulate to the heater core (when you turn on the heat). I forget which is which, but the point is that both have hot coolant flowing through them, so I would expect them to be hot after a drive.

Hot from just sitting with the ignition off? Sounds like an issue. I would first check to see if there's any current draw with a multimeter and go from there.

[old///MFanatic]

Yeah HCV, the little cylinder is the heater valve that has a magnetically controlled plunger. The taller one is the pump. The M3 has the added pump while other E46s don't(excluding diesels iirc).
Yep that bugger gets hot.

[Thonas]

Yeah HCV, the little cylinder is the heater valve that has a magnetically controlled plunger. The taller one is the pump. The M3 has the added pump while other E46s don't(excluding diesels iirc).
Yep that bugger gets hot.

I would understand it getting hot when in use, but my car had been sitting for a week. It was scalding hot, I unplugged it cooled off. Plugged it in and it started getting hot. Very strange and a new unit is 300. Anyone know if we can swap over to the single cylinder version like on the CSL?

[bigjae46]

It’s a valve and a pump. It shouldn’t be hot when off. Probably needs to be replaced.


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[heinzboehmer]

I would understand it getting hot when in use, but my car had been sitting for a week. It was scalding hot, I unplugged it cooled off. Plugged it in and it started getting hot. Very strange and a new unit is 300. Anyone know if we can swap over to the single cylinder version like on the CSL?

Just go to a junkyard and pull off the single cylinder one off a regular e46. Then use ncs expert to code out the thing in the IHKA module.

[Thonas]

Just go to a junkyard and pull off the single cylinder one off a regular e46. Then use ncs expert to code out the thing in the IHKA module.

Thanks for the suggestion. I assume you can’t use this to code out the second valve, Schwaben Multi-System Elite Scanner ?

[Thonas]

If you swap to the single valve and do not code it what will happen? Just throw a code?

[Titaniu//M]

I swapped mine to the single valve non-M/CSL version and haven't coded it. No issues but I don't drive my M3 in the winter so I'm not 100% sure if the heat works effectively.

[Thonas]

I swapped mine to the single valve non-M/CSL version and haven't coded it. No issues but I don't drive my M3 in the winter so I'm not 100% sure if the heat works effectively.

Excellent. I don’t drive mine in the winter either. Do you happen to have the part number for the one you used? Or did you pick up a used one?

[Titaniu//M]

Excellent. I don’t drive mine in the winter either. Do you happen to have the part number for the one you used? Or did you pick up a used one?

I am running the Febi brand version of part 64118369805. Used ones are plentiful but a new non-OEM one is only a few bucks more so I bought one of those.

[old///MFanatic]

I would understand it getting hot when in use, but my car had been sitting for a week. It was scalding hot, I unplugged it cooled off. Plugged it in and it started getting hot.

You didn’t drive it but did you have the key on or take it out of sleep mode? Iirc it’s pwm powered to activate the solenoid to close. You don’t have to run the engine to get the solenoid hot. We’d bet against another if could last over 30 seconds with forearm against it. Bugger gets hot. This with key on and HVAC activated.

Now if your car is completely untouched then that would be an issue. There is a seal inside that can go out and cause a short. They can also get jammed. I’ve rebuilt them before, they sell a kit. But that’s not for the coils. That’s internal seals, plunger.

[Thonas]

You didn’t drive it but did you have the key on or take it out of sleep mode? Iirc it’s pwm powered to activate the solenoid to close. You don’t have to run the engine to get the solenoid hot. We’d bet against another if could last over 30 seconds with forearm against it. Bugger gets hot. This with key on and HVAC activated.

Now if your car is completely untouched then that would be an issue. There is a seal inside that can go out and cause a short. They can also get jammed. I’ve rebuilt them before, they sell a kit. But that’s not for the coils. That’s internal seals, plunger.

My car had been sitting for a week, no key or even opened door. I was performing a spark plug change and removing a defective Turner CSL air box to ship back. I was moving around the oil dipstick and my hand touched the smaller of the cylinders and it was as hot as you would expect it to be if the car was running. Since I don’t drive this car if the temps are below 40, I think I will swap to the single unit.

[Thonas]

I am running the Febi brand version of part 64118369805. Used ones are plentiful but a new non-OEM one is only a few bucks more so I bought one of those.

Thanks! I think I will go this route. I assume the wire we connect to the single unit is the one attached to the larger cylinder? Thanks again

[jbfrancis3]

You may want to put a battery tender or charger on your battery so you’d don’t have a surprise when you’re ready to fire up.