Coolant pipe coating

[tjs82]

The picture below is the inside of my upper radiator pipe. The pipe from the pump to the oil cooler looks pretty similar, and the bypass pipe has almost no coating left in it. Has anyone on here ever encountered this before? I've always ran dex-cool, and the thing has never overheated as long as I've owned it. The truck had 130k on the clock (it's at 160k now) when I bought it though, so who knows what the previous owner put it through. My thoughts are either the previous owner ran coolant that wasn't compatible with the coating, or severely overheated it. Those are guesses though, as I've got no factual information to back that statement up.

 

[Ron Nielson]

Looks like scale from hard water to me. I grew up in AZ and our water was very hard and everyone's radiator and hoses looked like that. Use a heavy duty cleaner in the cooling system to remove the scale, flush 3 to 5 times with Distilled water only, then fill with coolant and distilled water ONLY. I run a coolant filter on mine and the coolant in the cooling system looks like orange Koolaid, like you want a drink of it.

 

[tjs82]

Sorry for taking so long to follow up on this. I've had some other issues to address, so this got put on the back burner. Anyway, I'm not completely ruling out scale from hard water, but it doesn't seem like scale to me, and here's why. Everywhere else in the cooling system is clean of this stuff (hoses, radiator inlet/outlet, overflow tank, etc.) This stuff is black in color, unlike any other cooling system scale I've seen. It looks identical to the black coating on the outside of the pipes, except it's bubbling/flaking off. I've dumped the coolant several times since I bought the truck (for various reasons) and have only ever used Dex Cool and distilled water. Again, not completely ruling out your idea Ron, it just seems like a bit of a stretch to me.

 

[ChrisPerry]

Dexcool is an organic acid coolant, the coating applied to the pipes might not be 100% immune from it over long term. The metal of the pipe shouldn't be affected.

 

[Ron Nielson]

This stuff is black in color, unlike any other cooling system scale I've seen. It looks identical to the black coating on the outside of the pipes, except it's bubbling/flaking off.

From your picture, I thought the WHITE stuff is what you were concerned with. I have no idea what the black stuff might be. Only thing I can think of being black is from a head gasket leak.

 

[Chevy1925]

doubt its from overheating or wrong coolant used. probably just wasnt cleaned well enough prior to the coating being put on from factory. i would try to scrape out what you can though or use a long buffing/sanding wheel on a dremel extension to get what you can out of it. i wouldnt want that blocking up the radiator cores. could even cap one end and fill it with brake fluid. that would take that crap off in a hurry

 

[tjs82]

Thanks for the quick replies guys! I was planning on either stripping the coating or worst case, replacing the pipes. I just don't want that stuff floating around my cooling system (especially the radiator). Considering getting a filter setup too, as a decent amount of coating is already missing from both the upper pipe and t-stat bypass pipe. As far as removing the coating, I'll try a few things to chemically strip the coating. The bypass pipe has some pretty serious bends in it, so it'll be difficult to get any sort of tool in there.
That being said, I'm in the process of re-routing the turbo lines and a few other things to clean up the engine bay, and make the thing easier to work on without having to fight all of the factory hard lines on these engines. Does anyone know of an aftermarket bypass pipe without the barb for a turbo coolant line? All I've been able to find is the original GM one.

 

[Chevy1925]

No, I’ve always welded the hole up for buddies that ran different turbos

 

[tjs82]

That's likely the route I'll be taking. I figured if there was an alternative to the OEM part, I'd be able to kill two birds with one pipe. Thanks James