Originally Posted By: Leo99
I've never heard of such a thing. What needs to be filtered out of coolant?
Unless an engine was manufactured and maintained 100% correctly, there is a lot that might need to be filtered out of coolant.
In my case, rust flakes, stop leak flakes, and whatever the heck else I have seen that I can't identify.
My case was also one of a poorly maintained cooling system. Florida has a lot of vehicle owners who subscribe to the "you don't need antifreeze in Florida" mentality, not realizing they are inviting electrolytic corrosion.
I flushed all of the offending engines "until clear" many times, and the scum always came back.
Friend of mine had it so bad, that he could count of his heater core blocking after 6 months, even after doing CLR and citric acid flushes. Coolant filter saved him from ever having to do that again. We poked out the rubber "orifice" limiter, and ran it as a full flow filter leading into his heater core. The filter would plug about every 2 months instead, until it finally stopped after 4 filter changes.
Casting sand escaping from the casting after manufacture is another problem that can occur. Chrysler and Ford have had their own adventures with this. Lot of Jeep owners install coolant filters to prevent this from blocking their heater cores.
Some cars (Honda) get blocked cores for no good reason at all, and have TSBs advising CLR flush to fix this problem. Coolant filter stops that from ever happening.
Basically, a coolant filter is something for the trash to clog, rather than your heater core, if there is indeed trash in your system. Apparently, even though most vehicles will never need such a thing, no vehicle is automatically excluded from this, mostly due to casting sand issues.