Turbo Coolant Pump Flow

[Spaceman]

Has anyone had problems with the spec'd coolant pump for the turbo cooler system? I finally filled up my coolant today so I could test the pump, and the pump spins but doesn't appear to create any flow at all!

All the hoses are connected to the right things, and the pump is wired the right way (I tried swapping the wires thinking I had it backwards, but that just pops the fuse). I removed the inlet hose and looked inside the pump, and it spins the right direction when I turn it on. I even connected a long hose to the pump inlet to supply water to it from like 5' above the pump, to make sure it was actually getting a good supply, and even then there's no flow at the pump exit.

So the pump is getting coolant, and it spins, but nothing else happens. Anyone have any other ideas? I feel like I'm either missing something really obvious, or there's something wrong with the pump!

[Rynoth]

It's hard to try and diagnose your setup without a photo(s) of it. I think all our Turbo cooling installs end up being a bit different than others. Based on your description I suppose my first question would be to verify that you have the inlet>exit ports of the pump correct. It's a centrifugal pump, so the side port is the exit.

That said, it took me 30min-1hr to fully purge all of the air from my cooling system. Question: are you filling the reservoir all the way to the top, and is the fluid level dropping after having run the pump for 10-15 seconds? If the answer is yes, and you're refilling it each time, you're purging air from the system and just need to keep repeating. My theory is(was) that if you fill it to the top each time, when you fire up the pump (which presumably is fully immersed in fluid at this point) it will initially push fluid into the tank, which pushes fluid from the tank and into your lines. After, even if the pump starts to catch air and stop flow, you've still pushed more fluid in (and more air out) of the system. In any case, I think the most likely spot for trapped air is in the heat exchanger.

Another thing to try is let the reservoir be half full, leave the cap off, and watch the flow into the reservoir from the pump when you start it. If it's strong for a few seconds then sputters, you're still pulling air through your system and need to just keep repeating.

One other thing I've noticed about my system after having run it after a few dozen hours on the engine is that it likes the fluid level to be about 1 inch below the top of the reservoir. I think if it's fuller, as the fluid heats up and expands during flight it will purge some out the drain tube. Otherwise, I don't have leaks and the fluid level stays pretty steady at that mark.

[Spaceman]

Ryan,

Thanks for the info! 30-60 minutes is way longer than I thought it would take so maybe I just need to be more patient.

I tried to copy the factory example as much as I could, so I think my system looks pretty much like that. I'll get some pictures. I think part of the problem is that the filler cap is barely higher than the radiator, so there's not much pressure there to push air out of the radiator. I initially tried what you said, filling the reservoir like half way and seeing what comes out of the return port into the can, but then the fluid level is lower than the radiator so not much happens. To have the fluid higher than the radiator, it has to be higher than the return port too, and then I can't really see what's happening!

See if this link works. This is the very unimpressive flow I'm getting into the reservoir so far haha: https://photos.app.goo.gl/gaBD4eCenVrbYKnV8

I think what would make this go a lot faster is one of those filling devices that screw onto the filler neck and then force coolant in under pressure; I'm pretty sure that exists...

[Spaceman]

OK here are some pictures of my setup. Disregard the various missing hose clamps, I've been removing and installing hoses here and there to try and understand what's going on!

I think the only difference between mine and what the instructions show is that my reservoir exit connects to the forward rather than aft radiator port. I can't imagine that makes much difference, although the aft side is a little bit higher. So the forward radiator port comes from the reservoir, and the aft port goes down the engine mount to the pump inlet.

The blue hose on the right in this pic comes from the front of the turbo and goes to the reservoir return port.

Here's a better view of how the filler is barely higher than the radiator.

Here's the pump. The inlet comes from the aftr radiator port, and the outlet goes to the back side of the turbo!

[Rynoth]

Good pictures, and your setup looks good as well! So, any air in your system is going to either end up in your reservoir or your radiator, which is pretty much the best you can do with a top-mounted radiator due to the way the ports on the reservoir are designed. I think your reservoir height is sufficient and can't really be helped. No air would flow back into the reservoir from the radiator anyway because of the way the exit port comes up from the reservoir. Even if your reservoir was a foot higher, air would still be trapped in the line that loops up and back down from the reservoir exit port. Can't really be helped, but once most of the air is gone it'll work a lot better.

So, the air in your radiator has about 1.5ft to travel down before it reaches your pump. Once your pump moves 1.5ft of fluid it starts eating air and slows/stops flow. I think you just need to keep at it, once most of the air is out of the radiator you should be good to go, the pump can handle SOME bubbles and those will go straight back up to the reservoir (via the turbo) and be trapped where they need to be.

Run the pump for 10-15 seconds, stop and wait a minute for the bubbles to rise in the thick fluid. Repeat (in my case) a few dozen times. Keep topping off/capping the reservoir to maximize the fluid flow through the whole closed-loop system those first few seconds you run the pump. You can hear when the pump stalls on air, that's a good time to stop it and let the bubbles rise from it to the reservoir. At some point your pump will start chugging nicely and the fluid in your reservoir will disappear into your lines replacing all that air.

P.S. I think ideally your input/output ports on the radiator would be reversed simply so the air has to travel farther before reaching the pump but I don't think that's a deal breaker.

[Spaceman]

Thanks! I'll try it again tomorrow. I got to the point today that so little was happening I was sure something had to be wrong with the pump; I need to lower my expectations!

[tx_swordguy]

I know nothing about aerovee or the turbo setup. That said do you have a fully charged battery and are you getting full voltage to the pump. Some motors will run on a greatly reduced voltage but also at a greatly reduced output. It would be easily checked with a $5 multimeter.
Mark

[Rynoth]

I know nothing about aerovee or the turbo setup. That said do you have a fully charged battery and are you getting full voltage to the pump. Some motors will run on a greatly reduced voltage but also at a greatly reduced output. It would be easily checked with a $5 multimeter.
Mark

This is actually a really good point. In my cooler setup I have 2 separate circuits that can power the pump/fan, and both circuits are of less than ideal length since my cooler install was a bit of a shoe-horn and I basically branched off of some existing circuits. The first circuit is full ON and has a relatively short wire run, the other is AUTO and runs through the thermo-switch and has a few more ft of wire. When I flip the switch from one to the other there is a noticeable change in the tone of the pump/fan. The AUTO one that runs through the thermo-switch has a distinctly lower tone. Definitely a bit of voltage drop happening though I've never measured it and my flow is sufficient either way. That said, it surprised me and is worth considering as Mark mentioned.

[Spaceman]

Hmmm that is a good point. I have been doing all this with all my avionics turned off so I haven't been keeping an eye on battery voltage at all. I checked at it was at like 12.8v... I plugged in the battery tender and now it's more like 13.5v (bus voltage). I'm not sure if I can tell a difference in how the pump sounds.

Anyway good idea checking voltage at the pump. It has a sealed connector so I can't really get a multimeter on it; if I had a spare connector I'd make a test one that I could check, but I don't think I'm at the point of hacking up my wiring yet!!

The pump appears to draw about 2 amps. I can't tell exactly but my EFIS ammeter goes from 2 to 4 amps discharging when I turn the pump on (it only reads in 1A increments I guess). If I round up to 3A, my little reference table of wire lengths versus load versus gauge says that for <5% voltage drop at 3A over 18awg wires, it takes 36 feet. I think I'm well below that; my "ON" circuit goes from the main bus, to the switch, to the fan (unplugged for now), to the pump, and then grounds like a foot away from that. In fact, now that I look at it I made everything up to the switch 14awg for whatever reason, so there's no way I'm losing out on voltage due to wiring!

Anyhow, I've been working on it on and off most of the day. I hooked up one of those coolant funnels to the filler neck so I could make sure the fluid level was well above the radiator all the time. Seems like I can run the pump about 30 seconds, turn it off, and then get like one bubble to appear shortly after. After doing this a bunch of times I don't think I'm getting bubbles anymore. I'm just not sure how to determine I'm actually done. I can't really tell by sound if the pump is sucking air or not, so maybe based on that it is not. I can leave it running for a couple minutes and not really notice a change in the pump noise. I think I'm going to call it done for now, and maybe when I have a running engine that'll vibrate a little more air out of the system and I'll see the level in the reservoir drop!

[Spaceman]

I just revisited my coolant flow concerns after looking at this thread: http://www.sonexbuilders.net/viewtopic.php?f=7&t=6031 , and the Sonex revision that addressed the same thing. I got the appropriate parts and installed them, but when I removed the original thermostat adapter fitting I found that it wasn't blocking the flow at all with the parts I had on there to begin with. So that wasn't my problem!

I tried connecting a piece of clear tubing to the outlet at the turbo, right after the t-stat, to see what the flow looked like, and I found that the pump could not even push the coolant up to the level of the catch can! It would travel up the clear tube about 3" and then just hold it there. So that would explain why almost nothing seems to happen when I run the pump.

I wasn't sure if there was some kind of obstruction inside the turbo that could be blocking the coolant, so I pulled the hose off the pump outlet and connected a clear tube there, and again it could barely push the fluid even a few inches higher than the turbo.

So, I don't think it's a blockage issue I'm having, I think there's still so much air in the lines that the pump can't even circulate the coolant all the way through to bleed itself. I think I'm going to rig up some kind of positive pressure filler with a garden sprayer or something, and try to force all the air through the radiator and pump and see if that helps it.