Hello to all:

Like so many others, my '97 F-150 has begun to intermittently generate an antifreeze smell/mist/fog into the truck.

During my research of the problem I discovered that the Ford CD manual suggests that sometimes the problem is not with the heater core, but rather with the coolant lines connecting the heater core to the engine.

I have copied that information from the manual and will post it here for future reference for all F-150online members.

Good Luck,

Wilk


From the Ford Manual on CD:

Heater Core

WARNING: CARBON MONOXIDE IS COLORLESS, ODORLESS AND DANGEROUS. IF IT IS NECESSARY TO OPERATE THE ENGINE WITH THE VEHICLE IN A CLOSED AREA SUCH AS A GARAGE, ALWAYS USE AN EXHAUST COLLECTOR TO VENT THE EXHAUST GASES OUTSIDE THE CLOSED AREA.

1. Note: Testing of returned heater cores reveals that a large percentage of heater cores are good and should not have been replaced. If a heater core leak is suspected, the heater core should be tested as outlined in the Plugged Heater Core procedures before pressure testing the heater core. Perform a system inspection by checking the heater system thoroughly as follows:

Inspect for evidence of coolant leakage at the heater water hose to heater core attachments. A coolant leak in the heater water hose could follow the heater core tube to the heater core and appear as a leak in the heater core.

2. Check the integrity of the heater water hose clamps.

3. Spring-type clamps are installed as original equipment. Use of non-specification clamps can cause leakage at the heater water hose connection and damage the heater core.


Plugged Heater Core

WARNING: THE HEATER CORE INLET HOSE WILL BECOME TOO HOT TO HANDLE IF THE SYSTEM IS WORKING CORRECTLY.

Check to see that the engine coolant is at the proper level. Start the engine and turn on the heater. When the engine coolant reaches operating temperature, feel the heater core outlet hose to see if it is hot. If it is not hot, the heater core may have an air pocket or may be plugged, or the thermostat is not working properly.


Pressure Test

Use Radiator/Heater Core Pressure Tester to perform the pressure test. Note: Due to space limitations, a bench test may be necessary for pressure testing.

1. Drain the coolant from the cooling system.

2. Disconnect the heater water hoses from the heater core.

3. Install a short piece of heater water hose, approximately 101mm (4 inches) long on each heater core tube.

4. Fill the heater core and heater water hoses with water and install plug and adapter from Radiator/Heater Core Pressure Tester in the heater water hose ends. Secure the heater water hoses, plug and adapter with hose clamps tightened to specifications.

5. Attach the pump and gauge assembly from Radiator/Heater Core Pressure Tester to the adapter.

6. Close the bleed valve at the base of the gauge and pump 241 kPa (35 psi) of air pressure into the heater core.

7. Observe the pressure gauge for a minimum of three minutes.

8. If the pressure drops, check the heater water hose connections to the core tubes for leaks. If the heater water hoses do not leak, test the heater core as follows:

a. Drain all coolant from the heater core.

b. Remove heater core from the A/C evaporator housing.

c. Connect the 101mm (4 in) test heater water hoses with plug and adapter to the core tubes. Then connect the Radiator/Heater Core Pressure Tester to the adapter.

d. Apply 241 kPa (35 psi) of air pressure to the heater core. Submerge the heater core in water.

e. If a leak is observed, service or replace the heater core (as necessary).


This thread is a revision of a thread I had previously posted under a different title. There was a typo in the title, and was therefore somewhat misleading. I tried, but was unable, to delete the previous thread. Paul Wilkinson

 

Hello to all:

The intermittent problem with the fog, mist and smell of antifreeze in the cab of the truck turned into a constant issue. As a result, I changed the two heater hoses in the engine compartment.

One of the hoses had the wrong type of clamp on it, a screw-type clamp, as opposed to the original spring-type clamp.

The other hose had two rubber o-rings at the end where it connects to the heater core inlet/outlet ports.

I have no idea how these changes occurred, but I have to assume that Tasca Ford made these modifications when I had them flush and fill my coolant.

Regardless, the fog, mist and antifreeze smell have all ceased since the replacement of the hoses, without replacement of the heater core.

Wilk

 

I am having a similar problem with my truck. The only difference is that I have also seen some coolant leaking under the truck, in the back on the right side.

I assumed the heater core was bad, but now I will check the hoses.

I have had some work done (timing cover gasket & intake gaskets), so those hoses were taken off I bet and maybe the wrong clamp used.

 

Ok I was able to get up under the truck this weekend, and the coolant leak is coming from what looks like a weep hole in the fire-wall.

The truck has to running long enough for the thermostat to open before the leak starts. I am pretty sure this is the heater core

Have any of you heard about electrolysis, being a cause for premature heater core failure.

 

F150NKY:

No, I have never heard of electrolysis causing heater core failure, however I am not a Ford mechanic. The information in the first post of this thread was copied and pasted from the Ford CD Repair Manual.

The space for the connection of the hoses to the core is tight, and was very difficult for me to reach. The problem for me was the hoses and/or the connection of the hoses to the core. I would say it is very possible that your hoses were not properly re-attached when you had the service work done on your truck.

I would recommend replacing the heater hoses that connect to the core, before you replace the core. The hoses cost me about forty dollars at the local dealership, and took about 1.5 hours to remove the old hoses and install the new ones. That's short money compared to replacing the heater core, particularly if replacement of the core is not necessary.

Good Luck

Wilk

 

How long after you changed/fixed the hoses did the anti-freeze smell go away? I checked mine and one had an o-ring and the other didn't. I put tow o-rings on each and re-attached. I can't see it leaking from there and the smell is still coming from the vents. I'm hoping it'll take a while to go away

 

Joe, it was a year-and-half ago since I swapped the hoses, but as I recall it took several hours of running to remove the odor.

PdW

 

Thanks for the info. I was hoping it would've been longer, though. I've been running mine for a while now and it's still there. The weird thing is that I can only smell it in the two passenger vents.

What would this hurt in the long-run if I just left it as-is for a while? I've got to drive about 500 miles this weekend and there's no way I'm going to have time to replace the core.

 

Joe,

Check if the antifreeze was leaking inside the truck. I have read of several instances where the fluid collected in the footwell on the passenger side. If the carpet is wet, this may be the case. It would be best to remove as much of the standing fluid as possible if the carpet or floor well is wet or damp.

Provided you are not loosing any more coolant, it should not hurt anything to make your weekend trip. If you are still loosing coolant, than you will have to monitor the fluid level, and add as necessary, to assure that the engine does not overheat. Obviously having antifreeze in the cab is not a good thing.

Good luck.

Paul Wilkinson

 

Electrolosis is a very common cause of heater core failure. There are two ways to check for electrolosis. Using a digital volt meter, put the ground side to a good ground. Preferably the neg battery post. Then put the positive wire in the coolant tank. If it reads more than .2 volts. You have electrolosis. You will have to drain all of the coolant, flush the system really, really well. Then refill with distilled water and coolant. Then check it again. If you still have too much voltage, then you probably have a bad ground somewhere. Most common is any aftermarket add ons. Radio, amps, cb, etc.

The other way to check is to pull a heater hose off of the heater core. Look inside the heater core tube. If it is black inside the tube then you have electrolosis.

I have had customers come in with leaking heater cores just weeks after having them replaced. Electrolosis destroys aluminum very quickly. The heater core is the thinnest aluminum part of the cooling system. That's why they go first.

It is very important to flush the cooling system once a year, and replace the coolant. This will ensure a long life for the heater core.

I have also seen people using copper heater cores to try and combat the electrolosis. This just prolongs it a little bit. I have also replaced leaking copper cores. The only way to fix the problem is to get rid of the electrolosis. That's it.

 

I've become a pretty good believer of copper heater cores. I've been told that adding an extra ground to the heater core itself and making sure the various chassis grounds are clean and tight will help combat electrolysis somewhat.

One oddball heater core killer you might see, a head gasket leak or small crack or some other imperfection that'll allow combustion pressure to get into the cooling system. Not enough usually to show on a combustion leak tester (in my experience), but enough to compromise the weakest part of the cooling system, usually the heater core.

 

Could it be caused from an alarm? My pickup was running perfect until I had an alarm installed. Later that same night was the first instance of the coolant smell through the vents. Would it happen that quick? That's why I figured it was the hoses leaking since it was so soon after teh install. He moved them around a little bit to put the siren in.

I checked the voltage and it is about .33 V. I guess I'll drain all of this out and see if I can get rid of the voltage. Anybody know how much coolant this thing holds??

 

No, it can't happen that quick. If he messed with the hoses, then you answered your own question. It's beyond me though why they would mess with the heater core to install a siren.

 

well he screwed it to the firewall just above the hoses. I figured he nuged them just enough to get 'em to leak. one didn't have any o-rings at all. I guess I'm just lucky it didn't leak before that.

 

I have replaced the OEM heater hoses w/snap on connectors with plain heater hose and clamps. I pushed them on far enough that they are far enough past the lip on the heater core pipes and used a screw clamp. They don't leak. They are a PITA to get on but they don't leak. Electrolysis will destroy the heater core is a short time if it is bad enough. Adding an extra ground will just amplify the problem.
Find what is casuing it and cure it.

JMC