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water radiater hoses

  • Ken Ryan
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3 weeks 1 day ago #17391 by Ken Ryan
Ken Ryan created the topic: water radiater hoses
Page 54 of the 914 installation manual shows that the water pump is to be connected to the lower port of the radiator and the expansion tank is to be connected to the upper port of the radiator.

The FWF kit that I got from Just Aircraft has it opposite, with the water pump connected to the upper port and the expansion tank to the lower port.

Is there any problem doing it this way?

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3 weeks 21 hours ago #17392 by Roger Lee
Roger Lee replied the topic: water radiater hoses
Your page 54 is correct. Coolant goes through the radiator before the pump and then up through each head then into the expansion tank which then goes back down through the cooler.

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-574-1080 Home (TRY HOME FIRST)
520-349-7056 Cell

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3 weeks 18 hours ago #17393 by Peter Kl.
Peter Kl. replied the topic: water radiater hoses
With the eye-opening explanation of another thread how fast the water flows I recon it does not really make big difference, temperature wise. However, having the curcuit absolutely air free becomes even more important.
The way the radiator is installed in my baby there is no "upper" port and it all has worked for years.
Regards
Peter

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3 weeks 10 hours ago #17402 by Ken Ryan
Ken Ryan replied the topic: water radiater hoses
Roger: Sorry for the confusion. Yes, I understand all that but that does not address my question. A less confusing way of asking might be:

"Is it important that the water pump connects to the lower radiator outlet (as shown in the Installation Manual) or would it be okay to connect the pump to the upper radiator outlet.

Peter: Thanks. That's what I'm thinking too. Any other opinions either agreeing or disagreeing that it doesn't really matter?

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3 weeks 8 hours ago #17404 by Roger Lee
Roger Lee replied the topic: water radiater hoses
The radiator itself doesn't care which way the flow is.

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-574-1080 Home (TRY HOME FIRST)
520-349-7056 Cell

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3 weeks 6 hours ago #17406 by Ken Ryan
Ken Ryan replied the topic: water radiater hoses
Thanks everyone. I figured it would be okay, but before blatantly contradicting the "official" Installation Manual I needed supporting opinions.

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2 weeks 6 days ago - 2 weeks 6 days ago #17411 by Bill Hertzel
Bill Hertzel replied the topic: water radiater hoses
Ken, I feel your pain,

During operation, the Radiator does not care which way the coolant flow, Up or Down is OK.
The coolant passes through the radiator at Fire Hose Speeds and will flush any air bubbles in the system with it.
The important thing is that the expansion tank is at the high point of the system.
When the coolant system is new, it will have a small number of trapped air pockets.
It will also have dissolved air in the water portion of the coolant.
You can see these bubbles appear in a pan of water as it approaches a boil.

After a few Heat/cool cycles of the coolant, the water will become de-aerated
The radiator cap has a small valve that opens to vent the air and to allow coolant from the overflow bottle to be sucked into the radiator each time it cools.
Eventually, the coolant system become 100% filled with coolant with no air whatsoever.

I said all that to explain this...

If your radiator has both ports on the same level it makes no difference.
If your radiator has one port above the other, when the engine stops, any air in the coolant in the radiator is going to rise to the top.

If the upper radiator hose is attached to the water pump and assuming the water pump is above the radiator,
The air bubble is going to have to pass through the water pump and the all the cylinder plumbing to reach the expansion tank. This may never happen.
If the Radiator is above the Water pump, the air will remain trapped in the radiator.

If the upper hose is attached to the expansion tank, the air will have an easy path to the expansion tank and out of the system.

So YES, it makes a difference!
The UPPER-MOST Radiator Hose should be attached to the expansion tank to make the elimination of the air from the system most efficient when the engine is stopped.

Will it work the other way around? Probably!
It will just take much longer to clear all the air.
Last Edit: 2 weeks 6 days ago by Bill Hertzel.
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2 weeks 6 days ago #17412 by Ken Ryan
Ken Ryan replied the topic: water radiater hoses
Thanks everybody. Bill, your explanation of the theory makes sense. I'm going to count on the fact that there are a lot of SuperSTOLS and Highlanders with 914s so I will do it their way. I do wish they had followed the manual, though.

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