Short story , last week i took the Ol' girl out snow relocating . Temps where low 1-2* and wind chill was -18 , pretty much froze my behind off .

Truck never really warmed up much , probably never reached 175* so not much cab heat . Today i stopped by after i made a cover for the grill and saw that the hose that comes from fire wall and leads to radiator the ball valve was open . I take it that's the reason for no cab heat but when i closed it , it started leaking anti freeze . Should i replace it on the lower end of hose or put a more modern T handle ball valve up higher easier to reach ?
Also how much of grill should be covered up ?

Thanks for any and all help .

 

On our 94 model that valve turns the water flow through the heater off for better AC during summer months, look at the other hose coming from the engine to the heater, it should also have a valve to shut off flow to the heater.
Normally I only turned off the valve that was easiest to reach during hot weather and opened it for heat during winter months.
In your case you need both valves open to have heat.
The type of valve you use and it's location doesn't matter

 

So basically both should be opened to let the antifreeze circulate to the heater ? I’ll check it out later this week , no snow in forecast till this weekend . It’s brutally cold all week long . Thanks Destroked

 

I have frozen as well with our 1992 L8000. The temp doesn't hit 175, which made me think the thermostat is out. What is normal operating temp for these old girls? I will check the valve(s) mentioned previously.

 

Thermostats for most of the older engines are 172*
Winter front over the grill makes a big difference on those trucks
Helps keep the engine warmer and takes some of the chill off the firewall which in turn keeps the cab warmer.
I pretty much lived in a 86 LTL9000 for a few years, bucking head winds at -0 temps across Wy proved to me how much a winter front helped.

 

Came to check on the truck, only found one valve coming from heater . I removed the cover on pass side - blower works fine but I could touch the heater core and truck had been running for about an hour . Should I be considering to replace the heater core or is there something else I should check ?

 

So you have one hose coming from the engine to the heater with no valve in line or mounted to the engine.
Then you have a line coming from the heater to the radiator with a valve.
If that's correct then yes you only have the one valve and it needs to be open for heat.
You could disconnect the hoses from the heater and back flush the heater core, sometimes that helps.
How hot as the line coming for the engine to the heater?

 

I didn't check to see how hot/warm either of the lines where . I'll bring the truck home this weekend and i'll check once i get here . I'll do a back flush and replace the thermostat then . I was checking YouTube vids and saw one guy put in CLR in the core while he changed the thermostat then flush backwards and forwards to clear it all out . Ill keep you guys posted .
The hose that has a valve on it is toward the front of engine , the other hose is between the rear of engine and firewall . Im figuring the flow is from back to core then towards the front , correct ?

 

That's correct

 

Update : Brought the truck home this morning , thermostat or thermostats opened and truck reached 175-200* . Once i got home i checked the lines to and from core both where warm/hot - more hot than warm . After everything cooled down i removed the radiator core and back flushed - forward -back foward ..... Core seemed fine not plugged , I still filled it with CLR and left it while i went to look for thermostat - Dude at Napa asked if 1 or 2 thermostats in the Cummins , then i remembered that i replaced both last spring . He suggested they where fine since i reached 175*+ . Came home and continued to flush out the CLR 5-6 times . Then checked everything in and around the heater/AC area , blower fan worked great threw out enormous cold air . I happened to notice a tube about 12-15" down from core hoses , i stuck a car antenna and my nephew saw it in the AC area .We determined its probably a drain for the AC condensation and we had to plug it - that's where we were getting all the cold air from .


So we got heater blowing hot air out but now someone installed an after market heater control lo-med-hi switch and after a while it turns off .

Now to figure out if its the switch or fan .

Anyone ever run into this problem ?

 

Think I found reason of air flow also

 

That could cause a bit of a issue
Are you going to replace it since you have the old one out.

 

No that’s the AC evaporater , the blower vents right threw it then reaches the heater core . I eliminated it for the mean time , since going out tonight to relocate snow . Now I have lots of warm air coming out the heater vents . I took it home and ran it un water then took a toothbrush to remove the rest of mud . I guess that’s why I hardy had cold ac in the summer . I think the previous owner had the truck in a quarry, since I’ve always removed caked on mud from all over , in and under the cab and actually entire truck