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Old 08-10-2022, 07:00 AM   #1
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Eliminate dash heat loop

2005 Newmar Mountain Aire 4042 with 2004 Cummins 400 hp ISL.

For a variety of reasons, I want to eliminate the 80ft round trip 3/4 in heater hose run to the front dash. I have already fixed two leaks. The dash air does not work. If I need heat or cool I run the house heat pumps or the Hydrohot.

I will leave the lines in place incase I change my mind later.

Do I have to retain a short loop at the engine or can I just plug both ports at the engine block?
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Old 08-10-2022, 07:10 AM   #2
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Quote:
Originally Posted by bentjm View Post
2005 Newmar Mountain Aire 4042 with 2004 Cummins 400 hp ISL.

For a variety of reasons, I want to eliminate the 80ft round trip 3/4 in heater hose run to the front dash. I have already fixed two leaks. The dash air does not work. If I need heat or cool I run the house heat pumps or the Hydrohot.

I will leave the lines in place incase I change my mind later.

Do I have to retain a short loop at the engine or can I just plug both ports at the engine block?
Cut the heater hose by the outlet/inlet of the engine and install 2 barbed ball valve's....... do you have hot water motor aid for heating your water during travel?
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Old 08-10-2022, 07:14 AM   #3
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You can install the valves, which i would also recommend or you can cap them. The valves allow you to open it back up should you change your mind. They use a ball valve on the new coaches.
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Old 08-10-2022, 09:17 AM   #4
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There is a frozen ball valve on the port towards the front of the coach (back of the engine).

The port towards the back of the coach (front of the engine) is buried right behind the alternator. I have to remove the air filter and alternator to get to it. There is no room there for a valve. I could hard line it from that port towards the bottom of the motor where I could install a valve.

I assume that brass fittings and pipe would be the type to use.
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Old 08-10-2022, 09:44 AM   #5
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Both heater hoses were stepped down from 3/4 to 5/8 at shut off valves (2) at the drivers side of the transmission on my Freightliner chassis .
I replaced 10' of 3/4" and 78' of 5/8" last summer .

Your hose being 18 years old should be replaced , if you decide to loop from the back of the water pump to the other engine fitting ( mine was the back of the cylinder head ) or down to new shut off valves and abandon the run to the front of the coach with the valves shut off is your choice.

I'd say , loop the engine hose connectors together , rather than block them off ; blocking may result in an air pocket in the engine that won't clear.
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Old 08-10-2022, 11:05 AM   #6
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Both heater hoses were stepped down from 3/4 to 5/8 at shut off valves (2) at the drivers side of the transmission on my Freightliner chassis .
That is the root of the problem. The previous owner had the hoses replaced.

What the shop did was replace what he could see. Also, they did not reduce the hose to 5/8 at the block.
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Old 08-10-2022, 05:13 PM   #7
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Heater hose replacement

Just a thought - if you deal with a fair amount of mountain driving, especially in the summer, I would recommend completely replacing your heater hose loop since you know that the previous owner/shop cut corners and NOT eliminating it... Living in Oregon, I drive a lot of mountain roads (some long climbs) and when I switch the dash heat on, it really helps bring the engine temps down quickly - it's a long run of hosing to dissipate heat and with the fan blowing even more heat from the coolant...
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Old 08-10-2022, 05:27 PM   #8
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Just install and shut one valve, no flow.

Keep in mind that 80 feet of coolant flow is helping the cooling system keep temps down.
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Old 08-10-2022, 09:18 PM   #9
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Yes , you can cap them at the motor. Off is off. But remember that you lose your defrost. Not that they work all that great on a 40 square foot windshield anyway. A fan will probably do a better job with house heat on. I don't see much cooling for the engine. I can tell when the engine loop warms up the aquahot from cold but the heater is tiny , it has to help, but I can't perceive it on my temp gauges. Monaco ran a heavy pex through the bays so hoses at each end. The aquahot used another good amount for the engine loop. About 65 ft of gates green in all. The parker was 200 psi hose , the gates is 100. Just some of the ends were getting hard on my 2004. Could have gone years on the old ones but might have had problems if I needed to r@i one. I used the original spring clamps as they provide the truest round seal and self adjust. I did have one leak rt at the motor , lower left rear. Always the hardest one to get to, lol. So it got a band clamp. Seems I cut that hose a little long so it came in at a slight angle onto the bib. I'll fix it at the next coolant drain. It's all 5/8 on mine
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Old 08-10-2022, 09:32 PM   #10
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Just install and shut one valve, no flow.

Keep in mind that 80 feet of coolant flow is helping the cooling system keep temps down.
He's trying to stop any leaks, needs caps on both hoses, or valves.
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Old 08-10-2022, 09:46 PM   #11
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The port towards the back of the coach (front of the engine) is buried right behind the alternator. I have to remove the air filter and alternator to get to it. There is no room there for a valve. I could hard line it from that port towards the bottom of the motor where I could install a valve.
I don't know how many changes were made to ISL cooling systems over the years ; but from this picture , posted by a member to show the block coolant drain ; it would appear that the best access to one heater hose connection is from underneath just in front of the oil filter , removal of alternator not required.
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Old 08-11-2022, 04:21 AM   #12
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I don't know how many changes were made to ISL cooling systems over the years ; but from this picture , posted by a member to show the block coolant drain ; it would appear that the best access to one heater hose connection is from underneath just in front of the oil filter , removal of alternator not required.
Mine is slightly different than that. The hose bib comes out at a 45 degree angle from the block and is right up against the frame rail of the Spartan chassis. I can feel it from the bottom, but cannot see it.

I have parts coming to cap/loop it off.
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Old 08-11-2022, 10:14 AM   #13
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I'd recommend a three port heater control valve system. When closed it blocks flow to the heater core yet allows a coolant loop back to the engine.
This allows for a little cooler engine temperature, while keeping the heater core cool.
Or, as others have suggested, an inline ball valve on the supply hose.
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