nickg

I belive the "tapered" seat of the Stant brand is susposed to re-direct the coolant flow, but like I said the engine was at 190 all the time yet with the fan on high the heater output would get less, so much so that anything higher than 2nd fan speed would be cold air, this was lessened by proping the re-circ door open, The OEM stat does cycle from 179-200F all the time. that is maddening where the Stant was rock steady at 190 +/- 2 degree, but the OEM re-directs more heat thru the heater core

now with the OEM stat, here is what happens (with re-circ door propped open 3/4)
@ 1300rpm ambiant temp -15C, truck not moving
I have 56*C at the vent on fan speed #2
fan speed 4, I have 53*C at the same conditions.

with the re-circ door closed, and same conditions (this means heater is using all outside air, heating it and pushing it thru the vents)
I get 46*C on fan speed 2
Fan speed 4, I get 41*C

I have a NEW heater core and all heat measurement taken at center vent 4inches away with a hand held temp gun.

Propping the door open nets me a gain of 10C that is a huge improvement in heat output,
prior to the OEM stat I would freeze in the cab on the hi-way, I have not been on the hi-way yet, but I'm sure I wont have that issue anymore

nickg

My OEM stat is the 190F for a 2nd gen, it cost me 125$Canadian at a local cummins store.

does the 3rd gen have the "bypass plate"??

CapnRam

I'm not forsure, the guys at the shop said they were exactly the same except for the temp, the ones they had for a 2nd gen were 180 and the 3rd gen was 190... so how are you propping the recirc door open...and yes when im on the highway i freeze, depending on the outside air temp..the warmer it is the hotter the heat is...so this still might be that blend door not closing all the way?? Its starting to get on my nerves though!!!

nickg

remove the glove box, reach in and instal a piece of broom handle between the door actuator and the cab of the truck, this holds the door open so that warm air can be mixed with the cold outside air, thus more warm air makes it to the cab

you can lock wire it as well, Thats what I did the first time

nickg

There should not be any air in your system, but you can remove the temp sender, right beside thermo housing, and if coolant comes out there is no air under the stat, I find it best to remove the sender then fill the rad till coolant runs out of this hole, that ensure no air lock.
you could also remove the heater hose and fill the system thru the heater hose with a funnel. just remove the rad cap when doing this, and plug the block end from where you removed the heater hose, (someones finger would work,) when coolant runs out the cap its full

have you tried back flushing the heater core?

CapnRam

I have not tried back flushing yet.. what is the procedure for that.. also my recirc actuator works, but only when i turn on the AC does it do anything, isnt that correct? why would you want to open that in the heat position? I already have to much cold air coming in, this is why like today when its 40 out i have good heat, but when its 0 i have no heat...its like the outside air is over running the heated air?? Hope that makes sense??

CapnRam

I was wondering if i took the stat out and drove it around for a bit if that would get any air out of it??

nickg

you are looking at it backwards!!!! by opening the re-circ door you add warm cab air with the ice cold air BEFORE it goes thru the heater core. the way you are set up now you have 100% cold outside air, being forced thru the heater core, hence the heater output is colder as it gets cold outside. because it takes sooo much heat from the core to heat up the ice cold outside air.

or another way to look at it is, when you OPEN the re-circ door you get less outside cold air.

a simple test for you is to put your heat selector to MAX AC, then go for a drive on the highway, you will likely find you have a huge heat improvement, but your windows will begin to fog up, because of the moisture in the air, again this will help you see how much difference is avaliable when opening the re-circ door
back flushing the heater core involves removing both heater core hoses and hook up a garden hose to it allowing it to go in one hose and out the other, (this is the simple back yard version)

removing the stat does absolutely nothing for you, except for having an engine that will never warm up, the two methods I mentioned above will eliminate air.

CapnRam

Thanks for the info nick..i'll try the recirc thing..and the back flush... of course it was susposed to be 40 today.. but what do ya know its 25 right now...lol..

Capn

VICIOUS FISHER

start with the backflush as nick g says....It did wonders for me, blew a pile of junk out of the heater core. It worked so well I didn't have to prop the recirc door anymore. but then again I'm not in Edmonton.

CapnRam

Took it out today for about a 45 mile round trip on the highway, well i tried the max ac and it did not get much warmer!! maybe a little but not a big differance, the pass. window did start to fog on the way back...so whats that saying??? i still have the noise above 2200 r's.. ya know when you have your garden hose on and you start to kink it the noise you hear, thats what i'm hearing... thats why i think the core is full of air?? susposed to warm up a bit tomorrow and i have the day off for obama day(thats the only good thing he's done) so i'll try the flushing thing if i have a hose thats not froze!!! lol.. thanks for all the info...

Capn

Joe Diesel

i backflushed the heater core, i got heat for 2 weeks now its back to heat only on defrost. But engine is still not at operating temp. Does the heater core effect engine temp? Both heater core hoses are hot.

VICIOUS FISHER

are you running a cummins thermostat or a jobber part? and do you know the condition of the thermostat? HOWEVER, If you have heat only on defrost ( had this problem) look at the blend door above tranny hump, remove the airbag module on the hump and the plastic shroud on heat vent, look inside as you shift from defrost to heat. and ascertain if the heat/defrost door is moving. the vacuum actuator may move but the blend door may not. in this case I rigged it half open. DO NOT FORGET TO DISCONNECT BATTERIES AND WAIT FOR SYSTEM TO DISCHARGE BEFORE MESSING WITH AIRBAG MODULE. Sounds like you have a combination of problems as I had, which I fixed by:
flushing rad and system
replaced water pump
replaced thermostat (twice the first one was a NAPA and I learned my lesson) use a cummins part, they are different.
flushed heater core both ways
rigged heater/defrost blend door as the blend door shaft was broken

Joe Diesel

I replaced thermostat with a jobber when i flushed my heater core 2 weeks ago, ive used slant thermostats past 4 yrs with no issues but ill a cummins one this time. Ill check the blender door next. But as u said i got a combo of problems. I think water pump is effecting engine temp & blender door is effecting heat distribution. Thx VF. Ill report back what i do.

dieseldork

If you got a broken blend door shaft you can get a replacement metal one at heatertreater