Originally Posted by
Dr_Snooz
When I did my rebuild 9 years ago, I filled the cooling system with Evans NPG Waterless coolant. It's a racing coolant that Evans insists is a "lifetime" coolant (and charges accordingly). I bought it mostly because disposing of old coolant was impossible here in California at the time. If it saved me having to dump old coolant on the side of the road in the middle of the night, then it was worth the price. Since then, the cooling system has been completely trouble-free with no hint of any problem. The car has never gotten hot or had a water pump go bad or burst a hose or even lost an ounce of coolant. I'd like to recommend Evans, but I can't.
A couple years into my experiment, I opened the radiator cap to check on things and found that the lovely clear coolant I put in had turned jet black and oily. I thought I had a bad head gasket, but I was broke and the car ran, so I ignored it and kept driving. When I replaced the timing belt this weekend, I had to drain the coolant to remove the water pump. It looks exactly like the worst oil change you've ever done. Jet black and totally nasty looking. Some of it spilled on the shop floor, then dried completely by the next day, so it definitely is not oil. That means the head gasket is good, hooray!!!, but the black coolant mystery remains.
Here's my hypothesis. Evans is very explicit that every last drop of water must be purged from the system before you put their coolant in. I drained my system as best I could, but with no block drain, it's pretty hard and a lot of water remained. My guess is that the residual water turned the Evans black. It's been very nice to have a completely trouble-free cooling system for 9 years, so I might give the Evans another try, but call them first for guidance.
I'd say Evans would be best used after an engine rebuild when there is absolutely no water in the block. The hoses and radiator are relatively easy to drain at that point.
As for the black coolant ...I dumped it back in.