I have a 1996 F350 crew cab 460CI with 104k miles. My heater core has gone bad again! This is the fourth core I have put in it in the last 2 years! What would cause this? I replaced my radiator cap recently and thought that was the problem. Has anyone had this same issue? What can I do to fix this besides replace the core when it happens? Thanks for any help anyone can give.

 

I'm curious about the condition of the coolant....have you flushed and replaced it recently? Sorry but I don't have any suggestions besides replacing. Maybe try a different store and/or brand for the core.

 

Is there a flow restricter in the Intel? If not it may be to much flow blowing out the heater core.

 

Courtesy of Steve 83

ISSUE: Some vehicles may exhibit (repeat) heater core leaks. This may be caused by a chemical reaction called electrolysis. Electrolysis involves an ion exchange between the heater core and engine coolant which can result in a breakdown of the heater core material. This is similar to the operation of a battery.

ACTION: Check for electrolysis on any vehicle with a heater core failure. If electrolysis is verified, flush the coolant and follow additional steps as required. Refer to the following Service Procedure for details.

SERVICE PROCEDURE - Electrolysis Inspection:
If there is a condition of a heater core leaking or repeat heater core leak, check for electrolysis using the following procedure:

1. To check for electrolysis use a DVOM set on DC volts. Place the positive probe of the meter in the engine coolant and the negative probe on the negative battery post.
2. Adjust engine throttle to 2000 RPM to properly get coolant flow and true electrolysis voltages.
3. If more than .4V is recorded, flush the coolant and recheck (follow guidelines in TSB 98-23-16 for Cougar). See Coolant Fill Procedure below to remove trapped air on 4.6/5.4/6.8L modular engines.
NOTE: EXPORT MARKETS, BE SURE THE WATER IS DESALINATED.
4. If there is still excessive voltage present in the coolant, check the engine to body/battery grounds. Also, verify proper grounding of any aftermarket electrical/electronic equipment which has been installed into the vehicle. Improperly grounded electrical devices can cause electrolysis to occur.
5. If the condition is still present after the grounds have been checked, it may be necessary to add extra grounds to the heater core and engine. A hose clamp can be used to secure a 16 AWG stranded copper wire to the heater core inlet tube. The other end should be secured to an EXISTING FASTENER on the body sheet metal. Extra grounds to the engine should be attached between EXISTING FASTENERS on the engine and body sheet metal. Verify continuity of any added grounds to the negative battery terminal.
6. If the condition is still present, add a restrictor (part F1UZ-1406-A) on the inlet hose with the arrow facing the direction of coolant flow (toward heater core). Cut the line and install with 2 hose clamps. It is important that the restrictor be installed in the right direction of flow and as close to the engine block as possible (not near the heater core itself).

 

Thanks for the replies. The condition of the coolant is about 4 years old. However each time I replace the core I’ve had to add about a gallon of new 50/50 coolant. No there is not a flow restrictor. I will have to check the electrolysis, I’ve never heard that before. I am curious why the flow would differ and electrolysis develop now versus the 20 years I drove it with the OEM core. At this point, I’m willing to look at anything!

 

I had never heard of it before either. When I read the last sentence of bullet point four, I felt that just maybe that should be something to look at. Given the age of our trucks, bad grounds have become a regular issue on the forum. Many successful repairs have happened by cleaning corroded grounds or replacing old ground straps. Hope you find the problem.

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That's too old in general for an older truck even using the modern "5-year" replacement anti-freeze stuff. But you're right that adding all that new stuff has probably renewed it to at least a slightly newer quality.
However i would still flush and replace the entire system.

It's been a bigger and bigger issue since more and more heater cores are aluminum now instead of brass (aluminum is more sensitive to reactions like this) and the fact that new aftermarket replacement stuff is mostly JUNK too!!!
Seems hard to mess up a simple heater core, but they've found a way to do it. You're not the first one to experience too-soon failures. Original stuff was simply better in most cases. Heater cores included I'm betting.

Sandymane hit it right on the head. Natural and quite common deterioration of many of the systems in the vehicle.
When was the last time you replaced your battery cables? When was the last time you removed, cleaned and reattached your ground wires?
How old is the water pump? Does the truck live in a moist or salty environment? Age alone will do it, but some of those added conditions just make it worse.

Easy enough to test the electric aspect. Be very interested to hear if yours has much voltage running through the coolant. Since your radiator is also probably aluminum, it's hard to imagine why it would be fine after all these core failures, but the heater cores are biting the dust like flies.
Also easy to check/clean some of the grounds. Including where the alternator is attached to the serpentine setup. Some are attached directly to the engine, while others are mounted to their aluminum carrier brackets. Assuming yours is the latter, but I'm not that familiar with the 460's like I am with other engine setups.

Good luck. Hate changing heater cores myself, even though some of our trucks are quite easy to do. Some are not!

Paul

 

Help with the grounds, Sandymane mentioned
post #3-->Ground Points - Ford Truck Enthusiasts Forums