I think my heater core is plugged up. While installing a new radiator I attempted to flush out the core by putting a water hose to one of the heater hoses. I let the other hose hang over the side of the truck. The water slowly drained from the other hose, and I had to hold the water hose tightly against the other one. Is this normal, or should the water have flowed freely? FYI: I did this because I didn't have any heat last year and wanted to check the core. What is involved in replacing the core on this truck? Is it a through the glove box trick, or dash board nightmare?

'91 F150 4.9L, 2WD, A/C

 

Did you turn on the heater when you tried putting water through it? I don['t know for sure but don't think water flows through there unless its on

 

Yes I did, thanks. I didn't notice any improvement in the flow. Seemed like only about half the amount came out that was going in, that there was a lot of resistance.

 

its super easy to replace, and cheap too. take off the glovebox by pressing in on the tab on one side, then undo the little plastic wire thing on the other side and tilt it down and it should pop off. now you can see the little access hatch that the heater core is in. there are a bunch of screws around it, take those off, pop the cover off and there it is! now just undo the hose clamps and it should slide right on out.

 

Dave186,

Thanks, it does sound easy. That's a load off my mind. I had always heard it involved taking out the dash board, but never looked into it because I just figured "big buck$". I really appreciate the tip. Now if I can just figure out why it stalls on cold starts I'd have it made. She runs great when all warmed up.

 

yah, my boss has a 93 Mustang and the heater core started leaking, first thing he did was take to to the dealer and they wanted $500 to replace it. i took a look at it and told him to go pay the $500!

 

It is really that easy (on our trucks). I did mine last winter, and it took about 30min. I paid someone to do my wife's Sable though! :o

Wade

 

Is it just my truck, or are the '87-'91 F-150's notorious for going through heater core's? I've replaced mine three times in 6 years!

 

I wish that's all I had to replace. I had the transmission rebuilt once, had the tranny seal replaced, and helped the same guy rebuild the tranny a second time. '91 F150, Auto, 155K.

 

One of the many reasons I was thinking of retiring my '87;F150;4spd manual;4x4;with a 302 was the heater core. It sprung a leak into my cab near the end of last winter. I ran some stuff through it to fix the leak, and it lasted about a week. I disconnected the core and connected the two hose ends together under the hood. No leak, but no heat either. At that time I thought the fix was going to be 'very' difficult, but after seeing this thread I know otherwise. My wife and I popped the glove box out and checked, yep it's as easy as mentioned above. Now, I'm starting to think I'll just pull the truck in and start fixing it up little by little: leaking front tank (already fixed the back one), 4x4's out, body rust on doors and fenders, horn (bearly works), ignition switch (currently rewired through a special switch), fog lights (removed because of damaged lens), replace bed cover, etc.