Reduced Cooling Flow

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MarbleMark
Posts: 2
Joined: Sat Jan 12, 2019 1:26 am

Reduced Cooling Flow

Post by MarbleMark »

We have a water cooled HD4 with a flow meter that has been turning slower and slower. I wasn't too worried because the spindle never gets warm. But it was so slow today that we replaced the pump, with no change. So there must be a blockage. We removed the input hose from the spindle and the flow meter spins like it should. In fact, we put on a new flow meter this morning. So the supply to the spindle is good. We put the input hose on again, and it just spurts a little as the pressure builds, then stops.

We checked the output hose and there are no kinks or apparent blockages. Thinking the blockage must be in the spindle, we reversed the hoses and ran the pump, thinking we might remove the blockage with a reverse flow. Coolant came out the spindle immediately, but when we hooked up the output hose again, it stopped.

We're using antifreeze in a 5-gallon pail. The lid is closed, but there's a small hole in it where the hoses and the power cord for the pump run through. I see no signs of any debris in the bucket, though I suppose if a small amount of dust was dissolved in the antifreeze, we'd never notice it.

I don't see any other discussion about this on the forum. Anyone have any ideas what's going on?

cromag27
Posts: 29
Joined: Fri Apr 20, 2018 10:13 am

Re: Reduced Cooling Flow

Post by cromag27 »

i’ve shot air through mine via a compressor without an adverse effects. just take it easy. i live in az where it gets 100+ during the summer and sometimes i get crud built up in the hoses or the spindle.

Rando
Posts: 757
Joined: Tue Jan 06, 2015 3:24 pm
Location: Boise, ID
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Re: Reduced Cooling Flow

Post by Rando »

The internal construction is not very complex: Turn OFF power the the VFD! Put an alignment mark on the top cap and body so you can realign them in re-assembly. Clamp off the water tubes (have a towel/rag handy) and pull the three (four?) screws that hold on the cap. It should lift right off with only a little encouragement. It's also how you get to the top bearing(s). If yours is like mine, there are only two o-rings that connect the top cap and fittings to the main body and the coolant passageways. Make sure those o-rings are okay, and clean things out from there. Re-assemble to the alignment marks, putting a little grease on the o-rings, make sure they aren't pinched, and re-seat the top cap. Hopefully it's not something odd going on with corrosion from the coolant, but that's very unlikely. When I originally searched it, there were warnings that the antifreeze would eat the o-rings, but at least with mine I haven't seen any degradation at all, and they've been in there five years now.....
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MarbleMark
Posts: 2
Joined: Sat Jan 12, 2019 1:26 am

Re: Reduced Cooling Flow

Post by MarbleMark »

I tried the compressed air approach in the opposite direction of the pump and nothing but clean antifreeze came out of it. Then I shot air through in the same direction as the pump and something very small and light hit the palm of my hand. I believe that must have been the little piece of debris that was cutting the coolant flow.

Next time I'll try that before buying a new pump.

Thanks, guys!

cromag27
Posts: 29
Joined: Fri Apr 20, 2018 10:13 am

Re: Reduced Cooling Flow

Post by cromag27 »

good deal!

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