Leaking Heater Core?

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Leaking Heater Core?

LARIAT 85
I think my heater core is leaking...again.  My original one lasted for almost 30 years before it soaked the passenger side floorboard.  This one has only lasted a few years, but it's not leaking inside the cab?  There is a small coolant drip landing on the plastic inner fender on the passenger's side and then on to my garage floor.

I can't seem to find an OEM Motorcraft replacement, which leaves me no choice but to buy aftermarket.  And I hate aftermarket parts.

So what are we using for replacement heater cores for a factory A/C truck?
Lucille:  1985 Ford F150 XLT Lariat

*Colors:  Dark Canyon Red exterior, Canyon Red interior
*Engine: 5.0, CompCams 31-230-3, "Thumper" E7 heads, Edelbrock Performer intake, Autolite 4100 carburetor, DuraSpark II ignition, Thorley Tri-Y headers, Flowmaster dual exhaust, H-pipe.
*Drivetrain:  AOD transmission, 3.55 gears, 2wd.



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Re: Leaking Heater Core?

Gary Lewis
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Spectra Premium.
Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker in front & 10.25 Spicer/Trutrac in back, & EEC-V MAF/SEFI

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Re: Leaking Heater Core?

85lebaront2
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I have had excellent luck with AutoZone Duralast lifetime, they do eventually go bad, but for the time it takes to change one of these, I'll let them keep giving me new ones.
Bill Profile

"Getting old is inevitable, growing up is optional" Darth Vader 1986 F-350 460 converted to MAF/SEFI, E4OD 12X3 1/2 rear brakes, traction loc 3:55 gear, 160 amp 3G alternator Wife's 2011 Flex Limited Daily Driver 1994 Taurus LX Project car 1986 Chrysler LeBaron convertible 2.2L Turbo II, modified A413

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Re: Leaking Heater Core?

ArdWrknTrk
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In reply to this post by LARIAT 85
I'm not sure how a '85's heater core is mounted but unless the neck got rubbed through by the firewall I'd think it's a hose or clamp problem.

All the seams are inside the cab, aren't they?
 Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with an Edelbrock 1826 and Performer intake.
Too much other stuff to mention.
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Re: Leaking Heater Core?

Rembrant
ArdWrknTrk wrote
I'm not sure how a '85's heater core is mounted but unless the neck got rubbed through by the firewall I'd think it's a hose or clamp problem.

All the seams are inside the cab, aren't they?
On my 1984, everything is in the engine bay, but it is a non-AC truck. When my heater core leaked, it too dripped down on the plastic fender liner. The AC equipped trucks are quite a bit different though, and the heater core much easier to change....from what I've read at least.
1984 F150 4X2 Flareside. Mild 302 w/GT40 heads, BBK headers, Holley 4bbl, XE256H Comp Cam, M5R2 5spd swap, Magnaflow full duals. Fresh Medium Blue Metallic in August 2019.
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Re: Leaking Heater Core?

ArdWrknTrk
Administrator
Rick said "Factory AC truck" so I assumed it was like mine.

I still don't understand how you can have a heater core leak without a windshield sauna.
 Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with an Edelbrock 1826 and Performer intake.
Too much other stuff to mention.
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Re: Leaking Heater Core?

Gary Lewis
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ArdWrknTrk wrote
Rick said "Factory AC truck" so I assumed it was like mine.

I still don't understand how you can have a heater core leak without a windshield sauna.
Good point.  Any leak of the core itself would be inside the truck.  I guess it is possible the leak could be where the inlet/outlet tube hits the body and it could run down the tube and drip in the engine compartment.  But that would mean the seal to the cab would have to be bad.  And it would have to be a slooooow leak.

More likely it is the hose/tube seal that is leaking and dripping on the fender.
Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker in front & 10.25 Spicer/Trutrac in back, & EEC-V MAF/SEFI

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Re: Leaking Heater Core?

LARIAT 85
In reply to this post by ArdWrknTrk
ArdWrknTrk wrote
I'm not sure how a '85's heater core is mounted but unless the neck got rubbed through by the firewall I'd think it's a hose or clamp problem.

All the seams are inside the cab, aren't they?
You know, I thought all the seams are inside the cab as well.  But I checked the hoses and connections, and I can't find a leak anywhere.  The only place it is wet is the outside of the plastic heater case, under the hood.  There is a small drip there that lands on the plastic inner fender.

Lucille:  1985 Ford F150 XLT Lariat

*Colors:  Dark Canyon Red exterior, Canyon Red interior
*Engine: 5.0, CompCams 31-230-3, "Thumper" E7 heads, Edelbrock Performer intake, Autolite 4100 carburetor, DuraSpark II ignition, Thorley Tri-Y headers, Flowmaster dual exhaust, H-pipe.
*Drivetrain:  AOD transmission, 3.55 gears, 2wd.



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Re: Leaking Heater Core?

kramttocs
Just installed my core a couple weeks ago and I didn't like the look of how close the tubes were to the firewall (was clearance but not much) so I wrapped the tubes with some of the silicon repair tape to provide a bit of a buffer.

But I agree - I can't think of anywhere else beyond the tubes + firewall or tube + hoses that would be dripping outside the cab.

I don't know how often you drive it but maybe stick some tissues in various locations and monitor?
Scott
Daily driver: 'Camano' 1986 F250 Supercab XLT Lariat 460/C6
Work truck: 'Chanute' 1980 F350 C&C 400/T18 - Gin Pole
Various parts trucks
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Re: Leaking Heater Core?

LARIAT 85
Just to be clear:  if my [A/C equipped] heater core were truly leaking, there should be coolant leaking *inside* the cab on the passenger's side.

Right?

I just checked the box from the inside again, and it is not wet with coolant - at all.


Am I barking up the wrong tree?

 




 
Lucille:  1985 Ford F150 XLT Lariat

*Colors:  Dark Canyon Red exterior, Canyon Red interior
*Engine: 5.0, CompCams 31-230-3, "Thumper" E7 heads, Edelbrock Performer intake, Autolite 4100 carburetor, DuraSpark II ignition, Thorley Tri-Y headers, Flowmaster dual exhaust, H-pipe.
*Drivetrain:  AOD transmission, 3.55 gears, 2wd.



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Re: Leaking Heater Core?

ArdWrknTrk
Administrator
Not only should the box have coolant in it, the windshield should be covered in glycol slime.
You'd likely see steam (even in the desert) but you can't miss the vape film.
 Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with an Edelbrock 1826 and Performer intake.
Too much other stuff to mention.
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Re: Leaking Heater Core?

1986F150Six
Lariat 85, try wrapping each individual hose, as it exits the heater core, with paper towels. Go out as far as you can toward the plastic fender liner. Drive the truck and then check the hoses. One side will have evidence of the leak and possibly the location.
1986 F150 4.9L manual O.D. 3.08 Duraspark MSD ignition w/ no EGR
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Re: Leaking Heater Core?

LARIAT 85
1986F150Six wrote
Lariat 85, try wrapping each individual hose, as it exits the heater core, with paper towels. Go out as far as you can toward the plastic fender liner. Drive the truck and then check the hoses. One side will have evidence of the leak and possibly the location.
I tried your idea, and found the culprit.  It turned out to be a loose clamp on one of the heater hoses.  I tightened it back up, and the leak has stopped.

Thanks for the advice!  
Lucille:  1985 Ford F150 XLT Lariat

*Colors:  Dark Canyon Red exterior, Canyon Red interior
*Engine: 5.0, CompCams 31-230-3, "Thumper" E7 heads, Edelbrock Performer intake, Autolite 4100 carburetor, DuraSpark II ignition, Thorley Tri-Y headers, Flowmaster dual exhaust, H-pipe.
*Drivetrain:  AOD transmission, 3.55 gears, 2wd.



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Re: Leaking Heater Core?

85lebaront2
Administrator
I started salvaging the flat spring clamps in junkyards, they may be a royal PITA to R&R, but they don't loosen with the heating and cooling cycles.
Bill Profile

"Getting old is inevitable, growing up is optional" Darth Vader 1986 F-350 460 converted to MAF/SEFI, E4OD 12X3 1/2 rear brakes, traction loc 3:55 gear, 160 amp 3G alternator Wife's 2011 Flex Limited Daily Driver 1994 Taurus LX Project car 1986 Chrysler LeBaron convertible 2.2L Turbo II, modified A413

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Re: Leaking Heater Core?

grumpin
Glad you found it!

Bill, I have replaced a lot of those clamps, but kept them. Always hoping to find a good tool for them.

Any suggestions?
Dane
1986 F250HD SC XLT Lariat 4x4 460 C6
1992 Bronco XLT 4x4 351W E4OD
1998 Suburban LT K2500 454 4L80E
2000 Nissan Xterra XE 4WD 3.3 RE4R01A
Oregon
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Re: Leaking Heater Core?

FuzzFace2
grumpin wrote
Glad you found it!

Bill, I have replaced a lot of those clamps, but kept them. Always hoping to find a good tool for them.

Any suggestions?
There is a slip joint plier type tool just for them clamps.
They have little indents for the clamp ends to fit in and not slip out.
https://www.geniustoolsusa.com/550810.html?gclid=EAIaIQobChMI-YDG89q85gIVAtbACh2IBwMaEAQYDiABEgJRfPD_BwE
Google will post up a bunch of others - "hose clamp pliers"
Dave ----
Dave G.
81 F100 flare side 300 six/T18 project
http://cars.grantskingdom1.com/index.php/1980-Ford-F100?page=1
81 F100 style side 300 six/SROD parts truck -RIP
http://cars.grantskingdom1.com/index.php/1981-Ford-F100
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Re: Leaking Heater Core?

85lebaront2
Administrator
In reply to this post by grumpin
I have an entire kit of strange pliers I bought years ago, label on the case they are in has come off, I don't think they were Harbor Freight. I will try to get a picture of them. There is a pair specifically for separating the hose from the fitting too.
Bill Profile

"Getting old is inevitable, growing up is optional" Darth Vader 1986 F-350 460 converted to MAF/SEFI, E4OD 12X3 1/2 rear brakes, traction loc 3:55 gear, 160 amp 3G alternator Wife's 2011 Flex Limited Daily Driver 1994 Taurus LX Project car 1986 Chrysler LeBaron convertible 2.2L Turbo II, modified A413

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Re: Leaking Heater Core?

grumpin
Thanks guys, Dave I think I have a pair of those.

The flat square type is what I have more of.

I’ve used 90° needle nose with success, if there is room.
Dane
1986 F250HD SC XLT Lariat 4x4 460 C6
1992 Bronco XLT 4x4 351W E4OD
1998 Suburban LT K2500 454 4L80E
2000 Nissan Xterra XE 4WD 3.3 RE4R01A
Oregon