I bought a 2006 f350 6.0 used as far as I can tell no radiator flush has been done it has 161 thousand on it . My question is am I asking for trouble trying to flush it or should I leave it alone ?

 

Best to post in the 6.0L section because the original Ford Gold coolant has caused so many problems. IMO the most important thing for a new owner of a used 6.0L is to evaluate the health of the coolant system and to get rid of the Ford Gold coolant if it still has it.

The way you need to approach this is to first see if the oil cooler has plugged up on the coolant side. It is common to see with the Ford Gold coolant or with a coolant system that has been neglected. The oil cooler (coolant side) has very small passages and needs a clean system.

You need to buy an engine scan tool. The best thing to buy (money wise) is to download an app for your smartphone. The two most common ones are ForScan Lite and Torque Pro. With these apps, you will need an ELM327 OBDII adapter. I like the BAFX brand. The i-phones require a WiFi adapter and the Android phones use the Bluetooth adapter.

ForScan Lite is a better code reader, so I usually recommend it. I like the Torque pro interface better though.

Once you can retrieve engine parameters, you will want to monitor oil and coolant temperatures (EOT and ECT) or PIDs. Then you need to drive for 20 minutes and get the engine fully warmed up. That is the point at which the oil temperature finally stabilizes. Driving at constant highway speeds, read the oil and coolant temperatures, A healthy cooling system will maintain an oil temperature that is 10 degrees or less than the coolant temperature at these conditions. If the oil temperature is 15 degrees or hotter than the coolant, then the oil cooler is plugged up.

If the oil cooler isn't plugged up, then just do a series of 3 or so distilled water flushes. It is best to open the block drain plugs to get the coolant that hods up there drained out. A lot of people put "Fumoto" valves in place of the plugs to make it easier to drain. Be careful if you do remove the plugs, if they are old, they might strip out easily. There are many posts in the 6.0L forum on this.

If the oil cooler is plugged, the first thing to try is backflushing the oil cooler. Again - there are a lot of threads on this in the 6.0L forum. It may take several backfluhing attempts and people that have used a setup that also introduces compressed air with the water have had the best success. Even with all this you may need to chemically clean the system. When you drain the system, the contaminants you see might dictate the use of cleaning chemicals.

If iron and scale have plugged things up and you can't get it all out of the oil cooler, then you may need to try FleetGuard Restore Plus. If it is gelled or congealed coolant, then you would use FleetGuard Restore.

In summary, you really need to evaluate the cooling system and the oil cooler health before flushing. What you find will (or should) dictate how you flush the system.

My system was completely clean when I switched to the HIGHLY recommended EC-1 rated ELC coolant. I only needed to do distilled water flushes, but there is a LOT of coolant that won;t drain out. The entire system holds 7 gallons and EVEN with opening the block drains, all you get out is half that.