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scooter01922

1986 s1954 dt466 heater issue

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Hey there guys, just did a search and am absolutely amazed nobody has posted up the correct way to connect the heater hoses to get good heat out of a mechanical dt466. Engine in this truck runs great, temp needle stays at 180 once she warms up. The heat from the heater core is however rather unimpressive. It blows plenty of air, its just kinda warm-ish. Really need to get some heat going to keep the windshield snow free since this in a plow truck now. Looking around there is about a dozen plugs you could hook in the hoses, and searching around online yields little info but several pics of the hoses running several spots. Trying to figure out where is going to get me the most flow of the hottest coolant. Sure trial and error works, but who has time for that when i'm positive somebody knows the answer to this one. Someone on here must have a dt466 with toasty defrost temps that can share a pic of where his hoses run. Thanks a bunch, this old gal is soooo nice to run compared to the new stuff with computers on everything, as long as she starts she always keeps on trucking through the storm.

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back of the head and return by the thermostat the problem is usually the little door in the heater itself  is not moving full stroke  so you are not sending all the air through the heater core just blending warm and cold have you verified that the door is sealing off correctly? 

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Try bleeding the air out at the firewall. Had a Loadstar that needed bleeding any time the coolant was drained. I drilled a small hole in the heater tube so the hose covered it. Loosen the hose and pull it off till the hole is exposed and the air comes out with very little coolant loss.

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I'll check the little door thing, and i'll see if its a bit air bound. I know one hose currently attaches down at the lower rad hose, right by the coolant filter. Have to take a peek to remind myself where the other one is.

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2 hours ago, scooter01922 said:

I'll check the little door thing, and i'll see if its a bit air bound. I know one hose currently attaches down at the lower rad hose, right by the coolant filter. Have to take a peek to remind myself where the other one is.

the return could go in by the lower hose that would be suction then the hot should come off the head my dt 466 was plenty warm is this an s series or a newer truck ?

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Its an S series, i put it in the title but not the post, sorry 1986 S1954. Going to go take a look later today, went from highs in the single digits for 3 weeks to 60 and heavy rain yesterday so ALL the snow melted. Seems a good time to go screw around with the plow truck now that its 40 out.

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Bottom if the radiator is as said the suction side, and be the coolest water source. I am with the others in thinking your door isn't closed and your mixing cool/warm air. As long as your other heater hose is connected to a pressure port from the head or before the thermostat and no air lock, you should have good heat. Another option could be that you have a partial blocked heater core. Has anyone ever had a leak,blown head gasket and used that "leak stop" product?  Have worked on many vehicles that people thought that was a fix, only thing it is, is a guarantee you will be replacing your heater core. On today's cars/trucks where you have to pull dashes, and even seats, it's not a cheap alternative to fixing the problem

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Took a look today, door seems to be closing. Removed the actuator wire and moved it manually and it stops right where the wire had it. Truck was a bit low on coolant when i got it, never thought much of it after topping it off but now that i have looked at the routing of the heater hoses i can see how a bubble will go in but never back out of the heater core. One hose hooks up at lower rad hose and the other arches up over the motor to the back of the head. No way there is enough flow to push much air down the several feet to get to the bottom of the rad. Think i'll be installing something in that upper hose right over the top of the motor to be a nice high spot to bleed out the air.

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