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hawgguy · 10-31-2014, 09:26 PM

During the process of performing the AquaHot TSB fix for the Cornerstone today, installing constant tension worm gear hose clamps, I noticed something funny about the hoses.

The Engine PreHeat hose from the engine has red tape around it and goes to an AquaHot port with a blue label. and the engine PreHeat hose to the engine has blue tape around it and goes to a port with a red label. I would expect just the opposite.

Seems counterintuitive. Appears to work though. The blue hose does get warm. I ran the preheat for 30 minutes with the engine off and it raised the engine coolant temp from 64 to 97 degrees. I'd be interested to know if other's are labeled similarly.

1mainiac · 10-31-2014, 09:32 PM

That is the correct plumbing for motor assist the hot water from the engine goes into the cold side to heat the boiler tank while driving. When using engine pre heat the circulation pump sends heated water to the engine from the hot side to the return line on the engine. The reason is simple the flow must always be in the same direction in case you start the engine with the preheat on.

hawgguy · 10-31-2014, 09:37 PM

Thank you. I considered that explanation. I guess I was just confused by the colors of the tape and labels not matching. The motor-aid works, and the engine pre-heat works as well.

1mainiac · 10-31-2014, 09:41 PM

no problem it does look confusing since they went to the trouble of color coding the plumbing you would think they would match the colors but the issue is one guy hooks up one end of the hose another hooks up the other so each knows where he is supposed to put it the hoses are marked the same at each end so they don't get mixed up in the process.

brobox · 11-01-2014, 05:37 AM

I guess it was too cold for tape to stick that day on mine.

There is no colored tape on my hoses.

What size constant tension clamps fit the hoses? I also need to change my screw clamps to the constant tension.

hawgguy · 11-01-2014, 08:39 AM

I used 9/16(w) x 1 1/16 (max) (SAE 10) clamps and they fit perfectly. Had to buy a box of 10, I will probably wind up using around 6 total when I'm done. So far I have only done the engine preheat input (which was leaking) & output ports on the Aquahot.

I bought a box of 10, they weren't cheap, but I'll have some spares.