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Ask Ron Your Own Question
Ron, ASE Certified Technician
Category: Ford
Satisfied Customers: 23001
Experience:  23 years with Ford specializing in drivability and electrical and AC. Ford certs and ASE Certs
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Having heater problems. just installed new theormstat, truck

Customer Question

having heater problems. just installed new theormstat, truck runs where its suppose to at 194 ish. heater gets hot but once i go down the road it will have moments of hot and cold, and i cant seem to pin point if im under load when it goes cold or coasting. possible i just don't have enough coolant and it is sloshing in the heater core and not keeping it contstanly full? head gaskets are good, no leaks. ive read about the different heater problems, none seem to be like this, heard of possible problems with the vacuum line that controls the hot/cold for the truck. im stumped.
Submitted: 4 months ago.
Category: Ford
Expert:  Edward replied 4 months ago.

Hello and thanks for your question. My name is ***** ***** I will do all I can to help.

Expert:  Edward replied 4 months ago.

If you just sit and let the truck idle and blast the heat on high, will it get cold? or does the heat stay warm?

Customer: replied 4 months ago.
stays warm, or rather hot like its suppose to
Customer: replied 4 months ago.
is it possible I have a bad cap and its not holding pressure like it should? rather then a headgasket issue?
Expert:  Edward replied 4 months ago.

How does the coolant look in it? Is it nice and green, my first thoughts are the heaters core plugged, pretty common on Fords. Especially if you get one hose hot going into the firewall and one hose is just warm or cold. I suppose one thing to do, is to get it in this "no heat" stage, and then pull over quick as you can and feel both heater hoses going into the firewall. Can you try that and let me know if both of them are the same temp, or if one heater hose is alot hotter than the other one?

Customer: replied 4 months ago.
If it's plugged wouldn't it be cold all thr time? Or would thst explain when I'm not on the gas it goes cold?
Expert:  Edward replied 4 months ago.

No, it wouldn't necessarily be cold all the time if it was plugged, can you check the heater hoses when it acts up and see if one is hot going in and one is cold?

Customer: replied 4 months ago.
Yep I will in the morning for sure, I'm on night shift right now
Expert:  Edward replied 4 months ago.

Alright, sounds good. Let me know what you find there.

Customer: replied 4 months ago.
It end up being a head gasket, coolant system builds pressure til cap pops off, early stages of the typical 6.0 diesel head problems, next is getting everthring new, got it all lined up wiht a good friend who owns a diesel shop, gonna cost a few dollars but no way around it.
Expert:  Edward replied 4 months ago.

Alright, Thank you.