This is topic Home built cool suit question/problem in forum Spec Miata Garage at Spec Miata Community.

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Posted by disquek (Member # 1576) on :
I know that lots of you folks have built your own cool suit coolers, so I thought this was a good place to ask.

I built one using this bilge pump:

The issue I'm having is that the pump doesn't pump any water until you shake the cooler. The motor runs, but nothing comes out. After a while it comes out, when you either go out on track or you shake the cooler a bit.

Has anyone else had this issue?

Posted by Kent Carter (Member # 2245) on :
You mounted it on the bottom, I bet.
Posted by Motor City Hamilton (Member # 13046) on :
Mine is mounted to the bottom and works fine. The bilge pump has space under it to pick up from.

Are you starting with some water in the system or just starting with ice? Seems like a silly question, but I have seen it done.
Posted by Muda (Member # 3309) on :
Should be self priming.
Saw a homemade unit that used that pump this past weekend. It was mounted on the bottom.
Posted by disquek (Member # 1576) on :
The pump is mounted to the bottom of the cooler.

I think I figured out what's happening. What Attwell refers to as "air lock". Picture a cup inserted upside down into a bucket of water. This results in air being trapped inside the cup.

I think I'm seeing the same thing. The pump doesn't prime because the outlet is sealed and water can't rise into it. I used dry break style connectors. They seal when they're not connected.

The solution would seem to be to install a connector into the outlet while filling the cooler. This would open the top of the pump allowing the water to fill it.

Are you saying that your solution is to mount the pump to the side of the cooler? I can see that this might eliminate the issue.

Posted by Bad Al Bell (Member # 237) on :
bilge pumps mount to the bottom of boats.
What do the instructions say?
Posted by Kent Carter (Member # 2245) on :
I used to mount them to the bottom but had a number of cases of airlock. Just as Kyle reported, a good shake and the bubble escapes. You can hear the pump just wailing away, but no water moves

Now I mount them on the side and have had zero issues since.
Posted by wheel (Member # 3072) on :
Bilge pumps sit in the bottom of dry boats and start pumping when the water reaches a certain depth. No need to "bleed" the pump, but you might add some more water. There probably a float switch in there that turns it on, when the water is deep enough. That switch may be sticking or not have enough water. Some models have other switching methods.
Posted by disquek (Member # 1576) on :
In a boat the outlet is open to the atmosphere. This allows the air trapped in the pump to escape and for the pump to self prime. In my cool suit I used the dry break style connections on the cooler, so the outlet is capped off. This traps the air in the pump and doesn't allow it to self prime.

After I made this post, I did some googling around and found this. Kent's idea is a very good one. But I think that it will require more water than if it's on the bottom.

I think my solution will be a spare connector for the outlet. I will plug this in after filling the cooler and maybe draw a little water up into it. That will prime the pump. Then I can connect the hoses to the shirt.

Hopefully this will solve the problem.

I also spoke to a friend that built a similar cool suit cooler. He had the same problem and found that cycling the pump on and off quickly a few times primed it for him.

Posted by Ralliboy (Member # 710) on :
Why not modify the pump itself. Can youu open it up and take that float out? Then you don't have to worry about priming issues. 17 bucks for the pump, You're still ahead budget wise if you break it.
Posted by Brandon Bunkley (Member # 13539) on :
I built my own and I had simular issues when I first used it.

I found having the pump on a switch and filling the cooler with ice then adding the water almost full solved the problem of the pump cavitating when you go around turns because the water can pull away from the pump under a lateral G load.
Posted by disquek (Member # 1576) on :

There is no float. This will happen to any pump. It's because air trapped inside the pump due to the sealed outlet hose. If I used the non dry break style ends in the cooler this would not be an issue.

If I unseal the outlet after filling the cooler by inserting a spare end into the outlet side of the cooler, the issue should go away.

Posted by Bellwilliam (Member # 11740) on :
not sure what you guys says about sealed outlet hose, since water travels back into the cooler, how could it be sealed ?
Posted by disquek (Member # 1576) on :
The quick disconnect fittings I used in the cooler have a valve in them that closes when they're not connected. It's called a "dry break"

So when you fill the cooler, the valve is closed and so the pump outlet is sealed. Connecting the shirt doesn't help since the shirt's fitting have the same valve in them.

Using a spare fitting with just an open piece of hose on it to prime the pump before attaching the sift will fix the problem.

Posted by dhois (Member # 6552) on :
If you use cubed ice instead of blocks check that the impeller is not resting on an ice cube that prevents it from turning. Only a problem if the sump pump can bounce up a ways, like mine. Most likely an air bubble, though.
Posted by John Mueller (Member # 2541) on :
Originally posted by dhois:
If you use cubed ice instead of blocks check that the impeller is not resting on an ice cube that prevents it from turning.

Home made Ice Blocks
Posted by Atlasdelta (Member # 3125) on :
Guys just my two cents. To really prime the pump, make sure the water in the chest is up to the outlet. Preferably covers it. Hold the hoses up so that the bubbles inside go to the top- to the dry break fittings. connect the shirt while standing so the the shirt is at the highest point. once the line is purged of air and everything is flowing well, the priming is complete for the day. Since ice occupies more volume than water, as the ice melts the water level goes down. before you race, enough water to keep the pump primed!
Posted by Brian Ghidinelli (Member # 2327) on :
We did a little testing on this over last weekend with my homemade setup. The real systems have the bilge pump slightly on its side which presumably lets the air escape if it's trapped. I did this to my setup and didn't have a single problem all weekend... the initial water level was not fully covering the bilge pump and certainly not up to the level of the outlet. YMMV.
Posted by Simon Tibbett (Member # 15476) on :
Is there a writeup for this? I'd love to make one to comfort myself with this GA heat. haha
Posted by Gatoratty (Member # 15983) on :
Simon...use the search function and you will find plenty of help and part numbers
Posted by Teamfour (Member # 6000) on :
Simon check out:
Posted by Brian Ghidinelli (Member # 2327) on :
Also, - now with FAST-shirt-compatible part numbers listed from McMaster-Carr.
Posted by Sphinx (Member # 161) on :
The commercial systems use drybreaks on both sides of the cooler hose. Has anyone modified Zack's setup to use two sets of dry breaks? Is that desirable/necessary?

I looked at some of the online pics of the commercial systems and it seems that they use dry breaks right at the cooler itself - not sure how they secure them to the cooler or connect them to the pump.

The only major modification that I'm making to Zack's design is to have the two connectors coming out of the cooler in the same horizontal plane - I think it looks a little better, but not for a functional reason.
Posted by Brian Ghidinelli (Member # 2327) on :
I added dry breaks at the cooler but I didn't mount them TO the cooler; I left about 18" of hose coming out. They're plastic and I didn't want to mount them fixed... this worked out well, because I forgot to strap down the cooler one session and it spent 20 minutes thrashing around in the trunk. Still works great since only the flexible hose was bumped around.

Mine has been working great and it's night and day with it running compared to before.
Posted by Steven Holloway (Member # 2306) on :
You can get the dry breaks in a bulkhead fitting from Mcmaster Carr. That is what I used to connect to the cooler.
Everybody has left the cooler loose in the trunk at least once. Mine worked until it unplugged the power lead.
I know a guy here with the cooler on the pass. floorboard, left it loose, it fell over and soaked his databox and ECU.
Posted by Brian Ghidinelli (Member # 2327) on :
Better that than leaving the hood pins undone... twice.
Posted by Greg Kimble (Member # 11362) on :
I used dry breaks on all of my fittings. I used the bulkhead fittings on the side of the cooler. They were a little too short to get the backing nuts on to secure the fitting. So I filled the two holes in the cooler with a silicon sealant/adhesive and have had no problems so far.

Posted by Sphinx (Member # 161) on :
Originally posted by Greg Kimble:
I used dry breaks on all of my fittings. I used the bulkhead fittings on the side of the cooler. They were a little too short to get the backing nuts on to secure the fitting. So I filled the two holes in the cooler with a silicon sealant/adhesive and have had no problems so far.


Did you use the barbed ones or the compression ones on the bulkhead ones? (does it matter?)

How did you step down from the pump to the fitting? LIke Teamfour's design or some other way?
Posted by Greg Kimble (Member # 11362) on :
The fittings on the cooler are the female bulkhead fittings with the barbed ends for the 1/4" tubing. I did the step down like Teamfour, in fact the adapters come in packages of ten each, I needed one each, if you want a pair PM me and I will mail you a pair.
Posted by Sphinx (Member # 161) on :
If anyone wants to buy a set of the McMaster Carr fittings for this project, PM me. I've got 3 males (5923K61) and 2 females (5923K31) that I'll make you a deal on.