Heater core!!! Help!!!
 

I have a 98 f-150 and ive ben having problems with the heater core going out and gushing fluid. this is the 5th or sixth time this has happend so ive gone through 5 or six heater cores in the last year. its getting ridiculous:censored:. has this happend to anyone else? and does any one have suggestions on what to do about this problem?

Maybe you have poor grounds somewhere. Check for voltage in the coolant. Connect the negative lead of your multimeter to the battery ground and the positive in the coolant. If you get .3v or more there's a problem.

Every heater core thread I have seen every one goes to the electrolysis issue.

I have had issues with excess flow through the heater core on 2 different Ford vehicles. (84 Mustang GT and 90 T-Bird)

My 97 F-150 has a restrictor inside the heater core inlet hose, check your hose and make sure you still have the restrictor.

Electrolysis can still be an issue with these vehicles, and keeping your coolant in good condition is a major factor in reducing the electrolysis.
Electrolysis, however takes time to happen, I doubt that it would happen so fast you'd go through 5 or 6 cores in a year, so I would check into the flow issue.

Search the Ford TSB's, I did find one where the flow issue was acknowledged.