Author Topic: Closing Engine Coolant Loop  (Read 259 times)

Offline GnarlyBus

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Closing Engine Coolant Loop
« on: May 17, 2019, 01:10:37 PM »
My OTR Heat and A/C are gone. I'm wondering if it would be advantageous to close the coolant loop in the engine compartment. I could connect the gate valves on each side. Would it make a difference? More flow?

I thought I read something about this somewhere at some point. :)
1984 MC-9 w/ 6v92TA & Allison 740
Oregon Summers & Arizona Winters
Full-Time since 2015

Offline buswarrior

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Re: Closing Engine Coolant Loop
« Reply #1 on: May 17, 2019, 02:02:53 PM »
Instant feedback loop and overheat.

No where for the heat to go, but back into the engine.

Leave 'em capped and closed.

Good for you to ask!

Happy coaching!
Buswarrior
Frozen North, Greater Toronto Area

Offline richard5933

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Re: Closing Engine Coolant Loop
« Reply #2 on: May 17, 2019, 02:11:52 PM »
Curious what you'll do for defrost? Even in the south there are cold nights and windshield icing, as well as condensation and such.
Richard
1974 GMC P8M4108a-125 (Custom Coach "Land Cruiser")
1964 GM PD4106-2412 (Former Bus)
Located in beautiful Wisconsin
KD9GRB

Offline GnarlyBus

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Re: Closing Engine Coolant Loop
« Reply #3 on: May 17, 2019, 02:59:00 PM »
Thanks buswarrior! Glad I asked! Maybe I'll just cap them after the gate valve in the engine bay.

I really thought no defroster would be a bigger issue but we haven't had any problems. We stick to the west and travel fall and spring. I does get below freezing usually when we make our pilgrimage. No condensation problems. When going through the Midwest one time in high humidity I had a towel to wipe the windshield down from my breath. :)

At some point I'll add an electric heater for the driver and route it for defrost as well. I just kinda tough it out for a couple days with double sweatpants and gloves if needed.
1984 MC-9 w/ 6v92TA & Allison 740
Oregon Summers & Arizona Winters
Full-Time since 2015

Offline Geoff

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Re: Closing Engine Coolant Loop
« Reply #4 on: May 17, 2019, 03:48:45 PM »
Actually, you are required by law to have a defroster for the windshield.  I know MCI's have the big gate valves for passenger heat, but I'm not sure if you have separate lines going up to the driver's area driven by a pump for the defroster and driver's heat.

That's what I kept intact.
Geoff
'82 RTS AZ

Offline buswarrior

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Re: Closing Engine Coolant Loop
« Reply #5 on: May 17, 2019, 07:08:02 PM »
If the stock system is capped at the heat exchanger feeds in the HVAC compartment, then the smaller lines that tee off and head to the defroster can be left to circulate, controlled by the valve to the driver's left ankle.

There's a bunch of BTU in that dashboard heat exchanger that is nice to have, if you haven't gone down a one way path yet.

Happy coaching!
Buswarrior
Frozen North, Greater Toronto Area

Offline Ed Hackenbruch

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Re: Closing Engine Coolant Loop
« Reply #6 on: May 18, 2019, 07:28:25 AM »
Besides having it for heat and defrost, i used it a time or two climbing steep grades on 107 degree days to get rid of engine heat. Opened windows and turned it and the other heater on. Sweated some but at least i kept the engine temp down.  :) 
Used to own a 1968 MCI 5A with 8V71 and Allison MT644 transmission.