Hot raw water pump

[Dr. D]

I spent today on my boat doing this and that. Being a somewhat hot and muggy day I turned on the AC in the morning and let it run. Mid afternoon I pulled up the cabin sole to inspect. I came across the AC raw water intake pump. For some reason I touched it and the body of it was nearly too hot to touch.

Is that normal? Seems rather hot for a water pump.

[a64pilot]

Many if not most of the motors are not water cooled, actually have no direct connection with the pump for the water to cool them.
Not having any real air flow and not having a cooling fan etc., some get pretty darn hot.
I assume this is not a square shaped brick colored March pump, but some kind of pump that you can plainly see a round motor connected to the water pump?

[Dr. D]

Yes, round motor housing with no apparent space for water cooling. Maybe normal, but sure is hot!

[svHyLyte]

Originally Posted by Dr. D

Yes, round motor housing with no apparent space for water cooling. Maybe normal, but sure is hot!

If round, odds are it's a Cal Pump which were actually designed as submersible pumps, to be cooled by the water they are submerged in. Unfortunately, their endurance when not submerged isn't great. That pump may have been used because of the location, on the assumption that if one did get much water in the bilge, the pump would not be destroyed. N'any case, good luck!

[mvmojo]

I had a manufacturer supplied Cal pump running an a/c 17 yrs ago. The motor is in an oil bath and is magnetically coupled to the pump. They definitely run very hot. Mine got so hot that the oil expanded and separated the motor housing from the case, spilling oil in the bilge and destroying the pump. They are definitely meant to be submerged. Not sure why a/c manufacturers supply them with their units... I switched to a Little Giant pump and it's been doing fine for 17 years! It's 20 gpm and runs 3 a/c units (54K BTU's combined). Has a conventional a/c motor, fan cooled. Pump impeller is magnetically coupled.

[Seriously Slow]

We also have a Little Giant round air cooled magnetic pump in our bilge cooling 2 A/C units and it gets very hot and from it's looks it is quite a few years old.
Maybe nothing to worry about. Our boat is in the Florida Keys so it gets plenty of use.

[mvmojo]

Our Little Giant is a TE-5.5-MD-HC. It does not run hot at all. The 1/3 hp motor is air cooled via an internal fan. The motor is warm to the touch, but not hot. My definition of "hot" is the old electronics definition of "if you can't put your finger on it for 4 seconds w/out a blister it's HOT!" You could put your hand on our pump forever and it would only be "warm"...

[Seriously Slow]

To clarify, I am unaware of official levels of " hot" but my fan cooled Little giant is too hot to leave my calloused fingers on it for more than a few seconds. I am not foolish enough to see how long it takes to blister.

[mvmojo]

Originally Posted by Seriously Slow

To clarify, I am unaware of official levels of " hot" but my fan cooled Little giant is too hot to leave my calloused fingers on it for more than a few seconds. I am not foolish enough to see how long it takes to blister.

IMHO, your pump is running very hot! I've been out of the electronics field for quite a while but we used to say that if you couldn't hold your finger on a component for more than 4 seconds it's running too hot. I think that's still a good rule of thumb for most things electrical other than a/c compressors which tend to run pretty hot... but not for motors!