How's this for a plan?

94 Ranger 4.0, 5-speed, 158000 mi.

My cooling system is full of really bad looking water/coolant. Probably from the stop leak crap that I had to use once, that has never gotten completely out of the system... anyways, I need to get it all flushed out and clean. And just draining the radiator, filling it up with water and cleaner, letting it run, draining, etc. ain't gonna get the job done because it's too bad.

So I was thinking of removing the thermostat, breaking into a heater hose with a "t", attaching a water hose and let the pressure from the hose clean out the entire engine and radiator. Good plan? Or is there a better way to get it all cleaned out?

 

Honeslty, for a complete flush I let the shop do it. I had mine done and it ran like $50-$60 or so..no mess or hassle for me..
just my .02

 

When you fush it with a garden hose through the thermostat you don't completely flush the whole block out. If you want to do it thoroughly take it to a shop. I done my truck at school myself because I was lucky enough to have a flushing machine there.

 

I had to do a similar cooling system cleaning on a neglected system last fall.

I opted to pull the heater hoses, install a garden hose inlet fitting to the heater's outlet hose, route the heaters inlet hose into a 5 gallon bucket, so I could catch & watch it, to see when it cleared up.

I used hot tap water from the garden hose & let the engine idle while I slowly added the hot tap water, controlling the water pressure & feed rate with a inline ball valve.

Just back flushing with the "T" & the engine off, was really slow in cleaning it out. Doing it with the engine running at idle was much faster & did a much better job. It cleared completely up in 10 gallons.

Then I opened the radiator drain & allowed the system to drain as much of the tap water as it would, then I added another two gallons of distilled water, via the heater outlet hose, to back flush the engine block of the trapped tap water & let as much of that drain out as would.

Then back flushed the heater core separately. Removed, cleaned & reinstalled the recovery tank & refilled it with a 50/50 coolant mix.

Then buttoned everything up, added straight antifreeze to the radiator, equal to 1/2 the cooling system capacity, started the engine & let it idle on a incline, with the engine facing uphill, so the thermostat air bleed valve could help the system burp any trapped air.

Some folks like to leave the outlet heater hose loose on the refill, so it'll allow most of the trapped air to be removed as the system fills when your pouring the straight coolant into the radiator.

Leave the vehicle on the incline to cool, then recheck the recovery tank level, to see if it's burped some more.

If so, I like to continue to park it on the incline several days & check the recovery tank after each cool down, until it doesn't drop anymore, THEN I consider the system purged of air.