98 f150

[crank.it]

hi guys -gotta question 4.2 f150 no 4wheel....not getting heat at the vents cold as can be...blocked heater core...blow air thru one heater hose and it comes out the thermostate housing...but the bottom rad hose is cold like the fluid is not circulating thru the rad???? but vehicle doesnt overheat????any thoughts on what to check next...its coming in today for a water pump maybe the problem????crank.it... also put a new thermo in it last week still no heat

[FIREDOG]

Hey Cranky, I'm thinking you ought to be able to disconnect the heater hoses and blow thru the core to verify it's not plugged.
As fas as the bottom radiator hose, gee, that ought to get warm after a while; after the t-stat opens and starts circulating coolant. Might take 20-30 minutes, though.

Things I've ran into or tried: disconnect heater hose at return to water jacket and verfiy flow thru core from water pump. If so, suspect dampner not working.

hmmm, maybe a 12v electric blanket.

[gacyota]

It may not be a cooling system issue. Check to make sure the heater blend door actuator is working.

[crank.it]

thanks guys,well put a new pump in after checking core and tstat...after pump went in it still was acting up so i suspected an air pocket so I ran truck at 2500 rpm for a few mins and bango!!!heat was excellent also put card board in front of rad cause i suspect the clutch fan isnt up to snuff....the blend door module sounded like it was working so weak pump was my opption..although I thoughht they either pumped or didnt...so far no come back from the cust.....thanks gac..fire dog...crank.it