Coolant System Green Goo

[davidbrady]

Seems I have a green film inside my coolant system. Three years ago I had Prevost replace the coolant with ELC. I also had them renew the filter. Just to make sure I'm running as close to pure ELC as is reasonable this weekend I flushed many gallons of DD PowerCool ELC thru the system. The last thing I did was replace the coolant filter. When I took the old filter off and held it upside down some deposit fell out. When I cut the old filter apart I found a significant coating of green goo on the paper element to the point where the filter was clogged. I removed the sight glass from the deaeration tank and ran my finger along the inside of the tank, a green film transfered. I have a multi-thousand mile trip planned for this summer and I'm reluctant to run a caustic alkaline cleaner such as Fleetguard Restore through the system. I'm worried that this type of cleaner may cause problems during the trip; i.e., from loosening debris to eating away at seals and hoses. The manual has a lengthy description on what to do if coolant system contamination occurs resulting in engine overheating. Their remedy includes a fairly involved process of backflushing the radiators and the engine. In fact, any coolant system flush includes the recommendation of removing the transmission cooler for inspection, which I didn't do, and which I may do before the trip. My engine doesn't overheat. It runs beautifully just the way I would expect. On a 90 deg F day the coolant temperature runs around 190 to 195 deg F as does the oil temperature. The transmission temperature settles in around 205 to 210 degrees with occasional retarder use. Heavy retarder use on 6% grades sees transmission temps climb steadily to 230 where it stays for a duration as the fan kicks in full speed - the rate of temp climb from that point on is slower. Pulling long 6% grades out west in the summer sees the water temps climb to 200 to 205 deg F. I don't see any evidence of overheating, so according to the manual there are no grounds for backflushing. Any thoughts on what you would do knowing that a trip is planned in the near future?