Tried a homebrew coolant flush on my F-150 and got a nasty surprise

I followed a YouTube video from some guy in Ohio that said using dishwasher detergent would clean out my radiator, so I dumped a cup in and ran it for 20 minutes. Next morning I had a brown sludge coating everything in the overflow tank and a coolant leak at the water pump gasket that was fine before. Anyone else ever chase down a DIY tip that turned your engine bay into a chemistry experiment gone wrong?

2 comments

2 Comments

gracecarr8d ago

Did you try to flush it out with water after the detergent run? Because that dish soap leaves a film. It sticks to everything. Then the heat bakes it into sludge. You basically made your cooling system into a slow cooker full of grease. The water pump gasket probably swelled up from the chemicals and then cracked when it dried out. Only fix now is to pull the radiator and flush the block with a real chemical cleaner.

riverwhite8d ago

Honestly I read somewhere that standard dish soap has way more surfactants than people think, and those things aren't meant to handle high heat in a closed system. They break down into this sticky goo once the coolant temps hit above 190. I think I saw a thread where a guy used Dawn and ended up with this weird foamy sludge that clogged his heater core halfway through winter. That part about the water pump gasket swelling makes total sense too. Dish soap can wreck rubber seals way faster than any proper coolant or flush chemical would. You're probably right, the only real fix now is to tear it all apart and start fresh with the right stuff.