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Coolant indicator pop up

26K views 41 replies 21 participants last post by  CarNut 
Same is happening when parked in my sloped driveway.

I have half a bottle of Pentosin G12 (pink stuff, "OA/OAT") left over from my Audi, but that isn't labeled for MB since the formula doesn't have silicates. Since I'm topping off with such a small amount, would it even matter if I just used the stuff I have on hand?
 
Just checked my coolant today on a routine inspection. Level is now ~1" below the full mark inside the expansion tank but the dash light isn't on yet. I had to top it off about a year ago already and I filled it to the mark.


Anyone else have the coolant very slowly dropping like this? Could be a very small leak. I wonder if a pressure leakdown test would find anything at this slow of a rate.
 
Anyone else have coolant leaks and get them fixed? I've needed to top off my coolant just about yearly, but I certainly do have a leak.

I was just on a long road trip and was at least 400 mi from the closest dealer when the low coolant alarm went off :oops:. I had to add ~0.5 L of coolant (Zerex G-40 premix) and I did make it home. There is white coolant residue on top of the radiator (have to remove cover to see) and some of it also was blown across the engine bay by the fan. I drove several rough and bumpy dirt roads before I got the low level alarm, so I'm wondering if something is jostling around and burping coolant. There's an infrequent smell of antifreeze at the front of the vehicle but I never did see residue again. Interestingly, I did see a small amount of coolant residue on engine components a few years ago, but I thought it was spillage from refilling the reservoir. Time to get service...
 
Yeah, it is strange. I don't know why I was using a pint each year since new, but my radiator was certainly bad this time. I forgot to ask the shop what they saw, but it was leaking from the top corner. Pretty sure it was the end-tank gasket burping coolant when it was cold since I'd lose the same amount of coolant each drive I made no matter how far. System would pressurize when at operating temperature and if the radiator wasn't hot itself yet, it would leak.
 
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