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jjrowan
07-10-2014, 02:38 PM
I've had my 1998 Gulf Stream Sun Voyager since April. It has the 5.9 liter Cummins turbo Diesel with 4 speed Allison transmission. We took it to Maine in May, had a problem with clogged fuel filter but once the filter changed, it ran 100%. I've taken for several short runs (short being 120 to 150 miles each way) where the water temperature gauge didn't go much above 160. Coming back from Maine yesterday I noticed the gauge approximately at 190 after we'd been driving an hour around 9AM. Later in the day I noticed it go up to 200 and then back down. Later I noticed a red "high coolant temp" light come on, the gauge was already receding and was around 200. Outside temps were in mid to high 80s. Coolant temp would go up on any long hill climb. These aren't the mountains of Vermont or New Hampshire that we were on in late May / early June where the RV would drop to 20 to 30 miles per hour climbing serious hills. These were gradual grades, not sure what the federal standard for grades are (thought 6%). We got home last night. Today I looked at the overflow reservoir bottle and the color is green at "min cool" line. Opened the radiator cap and coolant same green color right at top of cap (actually some came out when I opened cap). So my question is: is this normal behavior? Should I expect high coolant temp when climbing interstate (routes 95, 495, 84) routes? Or is something else going on I should be looking at?

JIMNINA
07-10-2014, 06:25 PM
Going up grade with the outside temp you had shouldn't cause the indicator warning to come on.
We have a 2003 Yellowstone, with 330HP CAT that had a overheating problem. Some of the items we had to look at where:
Does the temp go down at higher RPM's? If so might be a water pump or loose belt problem.
At one point the engine was not pulling enough RPM's to push enough water through the radiator.
Is the air flowing through the radiator well enough to cool the water running through the radiator.
Another of our problems was that the radiator fins were mostly clogged up with stuff and we had to have the radiator cleaned. I tried but couldn't get to the fins good enough.
Hope this helps

jjrowan
07-10-2014, 08:15 PM
No the temperature doesn't go down at higher RPM. I have my cruise control going which does a better job of maintaining speed than I can mashing the pedal. Going up grades the RPMs usually are at 2200 to 2300. Cruising at 70, same 2200 RPM. Fins on radiator look clear, I'll check the fins tomorrow, while in there I'll look at the belts. Previous owner replaced the alternator and "kick down cable", they said fluids and filters changed in October, trans fluid looks new, nice red color, no smell, oil dip stick says full, oil looks relatively new, when I looked at it before May trip it looked like it has just been changed. One of the fuel filters though had NOT been changed in October as previous owner had stated. Shop that changed both fuel filters said the problem one had been on for years.

JIMNINA
07-11-2014, 08:59 PM
Well the RPM's are definitely high enough to push enough water and the coolant appears to be in good shape. We had an issue with the temp gauge almost pegging out right before we went on a trip. The CAT dealer checked the sensor and determined that it was bad so we replaced it. After we left and drove for about 20 miles the gauge started running hot again. When we took it back it showed that the sensor was reading properly, but the gauge was reading incorrectly. The difference for us was at that time no High Temp alarms were sounding off so we know it wasn't running hot. It probably would be worth spending the $100.00 to have someone check the cooling circuit to at least determine what the problem may be. Could be a bad sensor, weak thermostat, or ???