Question for Little Giant pump users

[Delphinus]

I'm running a 4MDQ ... the pressure rated version not the flow rated version.

After a few hours of having it cycle water in my sump, there is a definite electrical smell in the air, and the pump is quite hot to the touch. Hot enough that I can't keep my hand on the motor for more than a second or two.

Is this normal? I don't like this, I don't want to leave this pump unattended at all.

This is a new pump, although, it has been sitting for about two months unused. Should I oil it maybe? (I had oiled it when I first bought it, but I didn't run it for more than a few hours back then. I figured as such I didn't need to oil it right now.)

[Canadian Man]

Well Tony, you know that my pump does not have this problem but i did oil it quite a bit when i got it used from Alan. What type of oil did you use?

Do you want me to stop by on my way home and give you a hands on opinion?

[UnderWorldAquatics]

You might have this one covered already but anyway... is the input restricted at all??? you cannot restrict the inlet in any way, you can choke down the output but not the input...
just incase..

[Delphinus]

Well ... that is a good question. The inlet DOES go through two 90 degree bends. I asked in here about whether this was advisable; the advice I got was to step up the pipe diameter -- so the 90 degree bends are both 1.5" whereas the sump bulkhead is 1" as is the pump input.

Hmmm. If that is not going to work, I am going to have a real headache on my hands. %$#%$#!!!!! Back the @#$!!! drawing board.

Jon -- yes I think I would like a second opinion. Can't be tonight unfortunately. How is your time on the weekend?

[Doug]

Tony I have to 3MD pumps. One is fan cooled, so stays cool. The other is like yours, just air cooled. It gets very hot. My Iwaki,s do the same. Thats how they expell the heat. I have a small fan blowing on the pumps to keep them cool. Dont know what everyone else does.

Fudgey has 2 4MD,s running. He would be the guy to ask. There is no smell from mine.

[Canadian Man]

Tony, I dont think your 90"s are the problem,
I have 1 90 and quite a length of pipe before the pump. But then again i have a 1.5" bulk head in the tank i got from you.
could be it.
yes
now that i think of it the pump may be stressing to try to pull that much through the 1" bulk head.

cut back the output of the pump for a few hours/minutes and see if the slower flow helps with that problem.

[Bryan]

If the little giant is fanless it will get quite hot to the touch, if not the fan should keep it warm to very warm. I wouldn't worry about it getting so hot it catches on fire. They are all internally protected and will shut off it gets too hot.

[stephane]

dont worry mine are hot like your for more than 4 years and never fail

[Delphinus]

This seems a little goofy, but I have both the flow rated version of the 4 and the pressure rated version of the 4. The flow rated has an internal fan, whereas the pressure rated one does not. You'd think it would be the other way around, I would have guessed the pressure rated version is the one who works harder.

So anyways. Yes. We are talking about the non-fan-cooled pump here. So it is normal for it be a hot coal? Like I said, I can -touch- it, so it can't be hugely hot; but the flip side is that I can't touch it for more than a second, it is hot enough that you can't touch it for long without discomfort.

I'm used to using all my pumps submerged, my new tank is my first foray into inlines. It's been a long battle, of trying to get the plumbing "just right" -- been plagued with microbubbles from the get-go.

I mean I guess I could throw a fan to blow air on it, that'll deal with the heat. But the other weird thing is the smell. That's the one that really kind throws me off here.

[ 06 July 2002, 10:24: Message edited by: delphinus ]

[ldzielak]

Delphinus,
I have the Flow rated version of the 4MDQ with the fan, it runs almost as hot as you decrib with no fan on your, must be much quieter. They do have an over temp protection (on mine I know). So I would not be worried about the heat. But after all my learning about 90 elbows and stuff on my overflows, I would not be suprised if you are starving the input. I have a 2" bulkhead, then 2" 90, then goes down to 1" line for 12" and then the 1" ball valve and union on the inlet. I have contemplated re-doing mine to give more smooth flow. If your using a 1" bulk head, with screens, you have a problem.

Lee

[ldzielak]

Also forgot to mention I have my pump seize on me once, when I turned it off for a water change. On start-up 10 min later, is started really slow then stoped. When I unpluged it and pluge back in you could see some movement, but then nothing.

I was going to get the motor re-wound locally then after opening it up, found out the motors are not serviceable. The local LG rep does stock them and parts too.

But I found out if you remove the impeller there is no problem runing the pump dry. I removed everthing I could, mag drive assembly and all. I could not even turn the motor with a large pair of chanel locks. So as a last resort, I used WD40 down the oil holes. Tried the pump and then it started to turn. Left it on and dosed heavily with WD40 and it just go better. Then followed with contact cleaner then used the recomended weight oil. Guess the dust and dirt over the years turned the oil into grease and then glued it closed. Was fine when the pump was hot, but after it cooled, it was screwed.

I will do this on a yearly maintenance, since my pump is exposed to dust right now. Did not notice a temperature difference with the fresh cleaned motor compared to before.

Lee

[ 06 July 2002, 11:04: Message edited by: Lee ]

[Delphinus]

No screens on the bulkhead.

Hmmm. Conceivably, I could, with very little effort, switch to a 1.5" bulkhead on the sump, then go 1.5" pipe through the two 90 degree bends, and then step the pipe down to 1" just before the pump intake. I wouldn't have to rethink where I've placed my pump (which to me right now is the priority; which I am trying to work around).

How can a person tell if they are starving the pump input? Are there any signs a person can watch for? The flow this pump is putting out is substantial. I have no frame of reference to which I could compare.

[Canadian Man]

Tony,
I dont believe there is any obvious sighns of staving your pump other than the obvious.
1.Excess heat
2.I believe a 1' bulk head flows something like 900gph or something close to that and your pump pulls more than that, right?

That's how i came to that conclusion.

[JimE]

The 4mdq max is 850usgph@1'tdh and flow decreases from there as head increases. Obvious signs of starvation are excessive pump noise due to cavitation (gravel/marbles going through pump) & *not* motor overheating. IME they do run hot and if the pump is new it will smell for a bit while "breaking in". Sure way to tell whats going on is see if you can get a hold of a meter and check the amp draw. If thats below motor specs you are fine. If not.... smile.gif

Jim

[ldzielak]

Delphinus,
You may pump localtion will hopefully not change, if you have some straight pipe run. 1.5 90's take up more "room" than the 1" by a large factor. Rules would be most direct path and if it's not, there is no harm in oversizing. Personaly I would like to have 2x the flow capacity for my piping all the way directly up to my pump.

In my case, I will be re-doing mine, not for more flow, I already have too much, but to see if I can make the system quiet.

[Delphinus]

Ok, this is helping my paranoia. Thanks very much for all the great info, guys.

Any suggestions where to get an appropriate amp meter? How expensive are they? I don't think my little $10 0.5amp multimeter is going to cut it... if I do a measurement on the pump draw.. :rolleyes: smile.gif

PS. Cavitation. DUH. I can't beleive that didn't occur to me. And I work for a oil and gas, water and wastewater pipeline SCADA vendor!! http://jabot2000.homestead.com/files/emoticons/loser.gif Frightening. Well, no, I'm not at work now, so I'm allowed to be dumb. :D Well, the good news is that the pump is not cavitating...

[ 07 July 2002, 11:37: Message edited by: delphinus ]