We eas­ily swap out our 1991 Bronco’s heater core and say good­bye to an­tifreeze odor and leak­age

Four Wheeler - - Contents - By Bruce W. Smith ed­i­[email protected]­ Pho­tos: Bruce W. Smith

We eas­ily swap out our 1991 Bronco’s heater core and say good­bye to an­tifreeze odor and leak­age

THE SWEET SMELL OF AN­TIFREEZE WHEN THE heater was turned on, along with tiny pud­dles of coolant on the pas­sen­ger-side floor mat, were ob­vi­ous signs there was an is­sue with the heater core in our ’91 Ford Bronco. Af­ter sev­eral months of wor­ry­ing the lit­tle drips would turn into some­thing more se­ri­ous and ruin the new car­pet, we fi­nally de­cided it was time to ad­dress the is­sue.

Fix­ing a heater core can be a daunt­ing task, and if you are the ve­hi­cle owner, a task that can hit the wal­let pretty hard. In the ma­jor­ity of ve­hi­cles such a job re­quires re­mov­ing part, if not all, of the dash to get to the heart of the heat­ing sys­tem that mea­sures less than a foot square and maybe a cou­ple inches thick. That was our con­cern, and the rea­son we kept putting off the re­pair.

As luck would have it, Ford had a bet­ter idea back in the late 1980s through mid-1990s when they placed the heater core directly be­hind the glove­box in the Bron­cos and F-se­ries, mak­ing re­place­ment easy. From the time the glove­box was opened un­til the time it was closed with the new core in place, we spent about an hour and in­vested less than $30, which was the cost of the core from Ama­zon. An­other up­side of fix­ing our Bronco’s leak­ing heater core is the re­place­ment ver­sion has a much tighter clus­ter of wa­ter pas­sages in it, which in­creases the heat gen­er­ated. That im­proved heat­ing ef­fi­ciency means we’ll be nice and toasty in the win­ter, and the de­froster will be do­ing a bet­ter job clear­ing our view of roads less trav­eled.

1. The plenum con­tain­ing the heater core on our Bronco was lo­cated right be­hind the glove­box, mak­ing ac­cess and re­place­ment very easy. We re­moved the plas­tic pin that held the glove­box limit ca­ble, and then lifted the glove­box from its slots to give us a clear view of the heater core lo­ca­tion.

2. We marked the two hoses run­ning into the heater core “D” for driver side, and “P” for pas­sen­ger side. It’s im­por­tant the hoses aren’t re­versed. The ones on our truck had never been re­placed, so we had to use a ra­zor knife to slit them un­der the clamps to take them off the heater tubes.

3. A pre­vi­ous owner ap­par­ently thought the way to stop the heater core leak and to im­prove heat­ing was to gob clear RTV sealant all around the plenum cover. If they’d spent an­other 15 min­utes ac­tu­ally fix­ing the is­sue we wouldn’t have had to do this lit­tle project.

4. These seven lit­tle screws are all that held the plas­tic cover to the plenum that housed our Ford’s heater core. The only tool re­quired was a nut driver or suit­able socket.

5. The plenum cover was easy to re­move once we got it over the plas­tic lo­cat­ing pins that are part of the plenum hous­ing. A very light out­ward pull on the plas­tic bot­tom cross­brace of the glove­box pro­vided just enough room to pull the cover down and out of the way.

6. Be­fore re­mov­ing the plenum cover it’s nec­es­sary to slide the heater ca­ble from its re­tainer (white). The ca­ble pushes into the re­tainer from the right, and the tab on top of the re­tainer needs to be pulled to­ward the glove­box in or­der to get the red plas­tic end of the ca­ble to slide in or out of the re­tainer.

7. Pool­ing coolant in the bot­tom of the plas­tic plenum hous­ing re­in­forced our de­ci­sion to re­place the old heater core. Our truck’s core had a tiny pin­hole leak some­where on the lower left be­tween the tubes.

8. It’s worth not­ing that there’s noth­ing hold­ing the heater core in place other than the plas­tic plenum cover and the hoses that at­tach to the two tubes that pro­trude through the fire­wall into the en­gine com­part­ment.

9. We re­moved the old heater core by sim­ply pulling it out and away from the plenum and then slid­ing the core straight down past the plas­tic glove­box cross­brace.

10. The Spec­tra Pre­mium heater core we used is more ef­fi­cient in heat gen­er­a­tion than the OEM core. It also comes with a thin foam outer wrap that gives it a tight, rat­tle-free fit into the plenum.

11. Re­place­ment heater cores range in price from less than $30 to more than $100, de­pend­ing on where you buy. We shopped on­line at Ama­ to get ours. To­tal cost was less than $30 in­clud­ing two-day de­liv­ery.

12. We cleaned up the plenum to re­move coolant residue and lightly lubed the di­verter door (left) so it swung freely. We also used a piece of sil­ver duct tape to patch a split in the thin plas­tic duct­ing that runs above the plenum feed­ing the de­froster on the pas­sen­ger side.

13. In­stalling the new core was a re­ver­sal of how the old one was re­moved. It helped to have a sec­ond per­son guide the two coolant tubes through the holes in the fire­wall since we couldn’t see them from in­side the truck.

14. A lit­tle duct seal com­pound, which can be found at just about any hard­ware store, worked great seal­ing around the heater core’s feed tubes. The non-toxic, dough-like ma­te­rial pre­vents wa­ter and fumes that might arise from the en­gine com­part­ment from get­ting into the cab. Af­ter we had that done, the heater hoses were re­con­nected to their proper side. The heater core now works great and it doesn’t emit an­tifreeze odor when the heater is ac­ti­vated. fw


Ama­zon ama­

<- Re­place­ment heater cores are read­ily avail­able on­line. We bought our Spec­tra Pre­mium core (left) on Ama­ for less than $30. The new core is alu­minum and has con­sid­er­ably more heat­ing sur­face area than the OEM Ford unit on the right.















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