What could this be?

[simon_o]

So my water pump was leaking and I changed it and when I was doing a coolant flush I noticed some white film inside the radiator does anyone know what that is?

 

[Jeepwalker]

I don't know for sure. Sniff inside the radiator ...see if it smells like combustion gasses. What's the underside of your engine's oil cap look like ..also milky? Have you been hearing any heater core 'girgling' in the morning? Was the truck using coolant in the last month or two?

Did you have any reason to believe the system was becoming over-pressurized? Over-pressurization is usually a symptom of a leaking head gasket (or cracked ...something). Head gasket leaks can be a result of the breakdown of the gasket itself. They can start slow and barely noticeable & persist (sometimes) for years, till they fail and blow white out the tailpipe. But the telletale signs are as I listed above. They can also cause water pumps to fail as it can push coolant past the water pump seal and wash the bearing grease with coolant losing bearing lubricity. That's why I'm asking.

You might pull one spark plug from each cylinder and put them in order how you removed them. If one spark plug looks super-clean on the end, that would be the leaking cylinder/s. That's a good way to possibly rule it out.

Otherwise, just finish the job and afterwards, sniff inside the radiator (engine running -- obviously don't burn yourself!), and feel for abnormally high pressure in the radiator hoses. They make combustion sniffer machines, but the nose is pretty sensitive enough.

Maybe it's something else completely unrelated, and it was normal pump age-related failure. But it doesn't hurt to check. Keep us up to speed what you uncover. Cheers!
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[simon_o]

Thanks for the help, Firstly oil cap looks normal not milky when i started the truck the inside of the rad smelled like coolant. Cant check the sparks plug at this moment i did hear the heater core gurgling but i think thats from the coolant flush might have a bit of air in the system?

 

[Jeepwalker]

I meant ...does the heater core gurgle on a regular basis in the AM when you start the tk and take off to go to work/run errands?

It might just be a failed water pump...and that's it. They don't last forever. Hard to say what that substance is. Maybe someone else will chime in who has an idea. I don't want to scare you, just asking questions that a good mechanic ought to ask when something in the cooling system fails. It takes very little time to ask the questions and rule something larger out. But as it is, just put it back together and keep your eyes and ears open like per normal. Cheers!