Coolant leaking from passenger side firewall

[BroncoBill96]

Hi, I was hoping someone can tell me if this sounds like the heater core on my 1996 Bronco 5.8. I didnt get a chance to completely crawl under the truck yet, it is leaking/running down from the passenger side firewall. I looket at the 2 heater hoses that are near the passenger side compartments corner, but nothing seemed to be leaking. It looks like it is coming from under the big box that is wrapped with factory aluminum foil/padding. Any help would be greatly appreciated. Thanks!

 

[Krafty]

yes that sounds like textbook heater core leak.

 

[BroncoBill96]

Thanks Krafty, thats what I thought but what threw me off is that it doesnt appear to be leaking in the cab. It all seems to be pouring down the firewall on the engines compartment side.

 

[nelbur]

I would also expect a leaking heater core to leak inside the truck. I would check the hose connections to the heater core, which ,if I remember correctly, are right at the firewall.

 

[BroncoBill96]

The hoses are ok, (atleast on the firewall). The coolant/water is leaking down the firewall from under the box besides the 2 heater hoses. I assume there is hose clamps on those 2 hoses under all the mould as shown? And hopefully its the heater core??

 

[Krafty]

I would clean all that gunk up to have a good look at where the hoses run through the firewall, its easier to tighten up a couple clamps then tear apart your heater box, there should be clamps under all that gunk at the firewall unless I am mistaken.

I liked changing the heater core in my 79 t bird, had a cover over it in the engine compartment, take that off pull the core out drop the new one in put the cover on and done. they don't engineer things like that anymore. nowadays you have to pull the intake off a gmc canyon just to get to the starter.

 

[miesk5]

yo,

In case;

Section 12-02: Heating and Defrosting 1996 Bronco Workshop Manual

REMOVAL AND INSTALLATION

Heater Core

Removal

Allow the engine (6007) to cool. Then, observing the safety precautions in Section 03-03, proceed as follows.

Place a thick cloth over the radiator cap.

Turn the cap slowly to its first stop to release system pressure.

When the pressure has been released, tighten the radiator cap.

Disconnect the heater water hoses (18472) from the heater core (18476), and plug the heater water hoses.

For easier access, remove the glove compartment.

From inside the passenger compartment, remove the seven screws that attach the heater core cover (18B300) to the heater air plenum chamber (18471).

Disconnect the vacuum source. Leave the vacuum hose harness (19C827) attached to the cover. Remove the cover.

Remove the heater core from the heater air plenum chamber.

Installation

Position the heater core and seal in the plenum heater air plenum chamber.

Install the heater core cover on the heater air plenum chamber and secure it with its seven attaching screws. Be certain that the vacuum hose harness is not trapped or pinched during the cover installation. Reinstall RABS module if applicable.

Connect the vacuum hose harness to its source connection.

Install heater water hoses on the heater core at dash panel in engine compartment. Do not overtighten the clamps.

Check coolant level and add coolant as required. Refer to Section 03-03.

Check system for proper operation and coolant leaks.



Item Part Number Description

1 18B300 Heater Core Cover

2 18476 Heater Core

3 � Heater Core Tubes (Part of 18476)

4 18658 Heater Core Case Seal

5 18471 Heater Air Plenum Chamber

6 18A318 Vacuum Control Motor

--------------------------------------------------------------------------------

TSB 06-21-19 Heater Core Leakage and Electrolysis

The majority of repeat heater core leaks are due to high flow rate or use of poor quality coolant. However, electrolysis should also be checked, especially when repeat repairs have occurred.

If the heater core is leaking, review the location of the leakage and check the condition of the coolant.

1. If leaks are found on the inlet (or outlet) tubes entering / exiting the heater core, it is most likely due to due to high flow rate. Replace the heater core and install a restrictor in the heater hose closest to the engine block, reference Workshop Manual, Section 412.

2. lf leaks are found in the body of the heater core itself, and they do not appear to be the result of physical damage like contact or puncture, check the coolant for possible electrolysis.

Check for voltage in the cooling system by touching the negative contact of a voltmeter to the battery ground or a known good ground and suspend the positive lead in the coolant, making sure it is in contact with the coolant, but not touching any metal part of the radiator or cooling system. Both AC and DC voltages must be checked. Vehicles normally have DC voltages; however, a faulty engine block heater or faulty diode in the alternator can produce AC voltages. It is understood that coolant is lost due to heater core failure but try to obtain a voltage reading on the old coolant in the engine block before addition or replacement. To keep more coolant from exiting the heater core, clamp off heater core lines and measure coolant in the engine block. Try not to

dilute the original coolant with new coolant during testing if possible.

1. Determine whether coolant condition is acceptable.

a. Remove both cables from the battery and ensure they do not contact each other or the vehicle.

b. Touch negative lead of DC voltmeter to engine ground and positive lead in the coolant.

NOTE: POSITIVE TEST PROBE IS IN THE COOLANT FOR TESTING.

c. Check the voltage in the cooling system. If less than or equal to 0.4 volts (VDC) OK, reconnect battery cables and proceed to Step 2.

d. lf greater than 0.4 V, flush cooling system thoroughly.

e. Recheck voltage less than or equal to 0.4 V.

f. Reconnect battery cables.

g. Refill the system with appropriate Motorcraft® engine coolant.

2. Check for loose or missing grounds at static conditions.

a. Turn off all accessories. Turn ignition on but do not start engine.

b. Test with ground probe to battery ground, engine ground, and vehicle ground sequentially.

c. Voltage less than or equal to 0.4 V on all grounds OK.

d. Any one greater than 0.4 V, check and clean ground cable connections.

e. Check accessories without using the on/off switch on the vehicle instrument panel; use a jumper wire to ground.

f. Plug in engine block heater, if equipped, and test.

g. Recheck voltage less than or equal to 0.4 V.

h. Unplug engine block heater, if equipped.

3. Check for loose, missing, or inadequate grounds.

a. Test with ground probe to battery ground, engine ground, and vehicle ground sequentially.

b. Crank engine but do not start.

c. Monitor voltage while cranking. Less than or equal to 0.4V OK

d. If greater than 0.4 V, ground or repair starter.

e. Start engine and run at about 2000 rpm.

f. Turn on all accessories including those customer only uses occasionally such as CB radio, cell phone, etc.

g. Test with ground probe to battery ground, engine ground, and vehicle ground sequentially.

h. Voltage less than or equal to 0.4 V OK

i. If greater than 0.4 V, turn off one item at a time until voltage drops to less than or equal to 0.4 V. Repair ground to the accessory just identified.

j. Recheck voltage less than or equal to 0.4 VDC

k. Turn the DVOM to AC volts.

l. Check for ANY AC voltage greater than 0.4.

m. If any AC voltage is present, try turning off each accessory one at a time including blower motor and any fan motors.

n. If AC voltage is still present, shut engine off and remove B+ from the alternator and tape it up, then retest.

o. If voltage drops gradually to less than or equal to 0.4 VAC, the ground straps may simply be overloaded by added accessories. Test by using a heavy gauge jumper to ground. If indicated, install heavier gauge ground strap(s) and recheck.

NOTE If vehicle is equipped with electric cooling fans, be sure they cycle during this testing and monitor voltage when they are on, and off.

CAUTION: DO NOT GROUND HEATER CORE. IF THE HEATER CORE IS GROUNDED, YOU HAVE PROVIDED THE ELECTROLYSIS A PATH THROUGH THE HEATER CORE. THIS WOULD CAUSE THE HEATER CORE TO BECOME AN ANODE OR RECEIVER AND IT WOULD PROMOTE THE ELECTROLYSIS, OR ANY STRAY VOLTAGE TO USE THE COOLANT AS THE GROUND PATH.

4. Refill the engine cooling system, reference Workshop Manual, Section 303-03.

NOTE IF THE HEAT OUTPUT IS INSUFFICIENT, OR IF THE ENGINE DOES NOT REACH NORMAL OPERATING TEMPERATURES, VERIFY PROPER THERMOSTAT OPERATION AND REPEAT

PROCEDURE IF REQUIRED.

=========

More info LINKs in my site @ http://www.broncolinks.com/index.php?index=86

 

[BroncoBill96]

Thanks Krafty and Miesk5, assuming I do my heater core here real soon I will definatley re-read that post u put up. Today I was driving to work and inside the truck it started to smoke from under the dash where the heater core would be. I pulled over for a sec. and lifted the carpet up on the passenger side near the firewall and was looking under the dash and everything looks dry, thats why I am abit puzzled. The only real way of course is to pull the glovebox door out and start taiking things apart on my way to the heater core, with the truck running I will pin-point the leak as it leaks. Fortunately it seems to be like a easy and not to expensive project at all. /emoticons/[email protected] 2x" width="20" height="20" />

 

[BroncoBill96]

Thanks for all your help, last night I replaced the heater core, nside the box the heater core sits in was all wet. Strange how nothing leaked in the cab and was leaking down the firewall on the engine compartment side. I assume maybe the 96' Bronco has a drain port in case the heater core starts to leak?

 

[DNBELOWBRONCO]

I hope so.... haven't had to do mine yet! > -Kevin-