Here is my read on this.
There is a fair chance the you gave it the first flush. Rarly do folks do maintenannce in the first 4 years especially if they are the type that replaces the car at early intervals. Too many people are sold on payments. Since the coolant was as dirty as it was, it was probably acidic which damages the system components internally. (Hopefully there was never any stop-leak added to this system.) So you have a combination of scale build-up and acidic fluid and the possiblility of an electrolysis situation that fords can have. This is a recipe for future headaches, that your now experiencing. Thermostat may have just been ready for replacement but may have been a victim of the environment it was trying to exist in.
You mention:
"the heat in car was not working properly, so I brought it to the mechanic and he told me that it was my thermostat and that the hoses leaked because my system was dirty and had to flushed 2 times"
So, Thermostat was sticking and needed replacement makes sense. Hoses may have been compromised from the condition, may have been an add on sale based on the assumption of the situation. Don't know. May have even been a poor job of thightening the clamps when the water pumps was replaced, (if either of the mentioned hoses were attached to it). This is where the trust factor of the shop is at stake. This is entirely realistic this happened. So since there is a leak, can the system reach full pressure?
So now that the system has been flushed properly, there has been scale removed from the heater core and radiator. The system can now be brought to full capacity and pressure. Only now the radiator and heater core may be less stable with the scale removed exposing weak spots. Also if one of these hypothetical weak spots are boarderline regarding the pressure it can handle, and the system has more pressure, a new leak can pop almost immediatly or shortly there after.
Now here's the scary part. You may be looking at a heater core in the near future as well.
I hope this helps clear things up a little. Autos can make shops look incompetent, albeit the are shops that make all shops look incompetent.
I hope I have done my job anyways.
Thursday, August 23rd, 2018 AT 11:19 AM
(Merged)