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1973 - 1979 F-100 & Larger F-Series Trucks Discuss the Dentsides Ford Truck
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heater core issues...

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Old Dec 28, 2009 | 06:16 PM
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heater core issues...

Ok guys, i have a 79' f-100 the heater core is leaking. no biggie, bought one from rock and figured it would be an easy install. I start removing the dash since it is right in front of it and figured i could just reach through the hole instead of laying upside down to find all the screws that holds the plastic together. well no screws so i looked into other posts from other people that have done it and all the ones i have seen dealing with a 73-79 have noted ''remove heater core/fan cover screws" mine are factory and look like factory star rivets. If so its still no big deal just a minor inconvenience... and before i go and remove the top dash to drill out the left hand top cove rivets i was going to verify if they started to rivet them? and if so should i rivet it back or go to a self tapping screw when im complete? thanks for the advise/help!
 
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Old Dec 28, 2009 | 07:31 PM
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If you have A/C, the following article should be of some help:

Heater Core Removal and Installation For 1973-1979 Ford F-Series Trucks .: Articles

The access to the heater core is not from the front side (seen from inside the cab). The access door is on the side against the firewall. You'll need to remove the ductwork from under the dash. There are three or four (don't remember exactly) studs protruding through the firewall into the engine compartment. The nuts are removed from the engine compartment side. On a non-A/C truck (which is what I have) disconnect the cables for the blend door and heater control, then wrestle the ductwork out. Once out, you can take off the panel and change the core.
 
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Old Dec 28, 2009 | 08:49 PM
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It is non A/C and there are no nuts/bold in the engine bay on the fire wall... i need to learn how to upload pictures so i can show what i see... it is just 2 tubes coming out of the firewall. No nuts/studs. That's why i need a little help
 
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Old Dec 28, 2009 | 09:21 PM
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There should be three (couldn't remember for sure so I checked the shop manual) studs for the heater housing/ductwork. Two of them are arranged on either side (top/bottom) of the blower motor in the engine compartment. The other stud is hard to see - behind the engine/transmission on the firewall.
 
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Old Dec 30, 2009 | 04:57 PM
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Ok, I found them. They looked like they held the fan motor in that's why i looked over them. I removed the plastic duct from under the dash and removed the heater core. Well the one i ordered was a high output core and its was longer than the factory so some modifying had to be done... so i ended up cutting the holder out with a dremil and jb weilding it back in lower part of the duct. so all is great. Topping off the colant i noticed the t-stat housing leaking.... great.
 
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Old Jan 2, 2010 | 08:31 PM
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did you have to modify the plastic duct or by "holder" did you mean the core mounting bracket? I was thinking of ordering the high output core also.

Does it put out more heat? My heater seems to blow "warm" but not hot.
 
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Old Jan 2, 2010 | 08:46 PM
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If you have had it off and out you will notice a pattern in the steel/metal shim/gasket it is about 2'' longer the plastic holder in the duct needs to be cut. i guess i should have taken pictures... but it was fairly simple. and yes it is a lot hotter. but i don't have a/c so i dont need to worry about the sealing of the core in the duct. if you have a/c then you would need to find a way to re-seal the bottom of the core so the cold air can pass through the duct without coming into contact with the heater core. but like i said no a/c so no worries. all and all it was pretty easy i just removed my glove box and reached through it. The job took about 35 min from start to finish. hope this helped.
 
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Old Jan 2, 2010 | 08:52 PM
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From: where the deer and antelo
Originally Posted by Danny Stroup
did you have to modify the plastic duct or by "holder" did you mean the core mounting bracket? I was thinking of ordering the high output core also.

Does it put out more heat? My heater seems to blow "warm" but not hot.
If he modified his like a heater I had in a parts truck, (the PO had cut the plastic so a HO core would fit) I doubt you will get any more heat.

I would check for a pluged core, bad control valve or too cold of a thermostat. If those are all good, you may have a high output heater that some one has put a regular core in. If you have a high output heater with a regular core, there will be about a 2" gap at the bottom of the core that cold air can blow past.
 
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Old Jan 2, 2010 | 09:06 PM
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Thanks...I'll check t-stat and core hoses for heat; also found how to backflush the existing core. I'll try all that first.

Good to know about the replacement procedure through the glovebox. I don't have A/C either and I don't think I have the HO heater...I only have defrost vents and one vent under the dash...no vents in the dash front at all.
 
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Old Jan 3, 2010 | 08:53 AM
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My 79 is the same way. no dash vents, thats why im making some for it. ill post pics of what i have done,
 
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