All,
In previous post my Onan DK 7.5KW diesel generator was running hot last Saturday with an ambient over 100F and running at 220F. This week I cleaned the cooling system with Prestone flush (manual recommended) many distilled water flushes and finally a top off with 25% Orange Stuff (GM Long Life) Coolant, Redline Water Wetter (made about 5%)and 70% Distilled water. From the looks of the cooling I'm not sure it had -ever- been serviced, the drain cock plastic was still painted, paint which I quickly cracked off...
After this service: the temp today was just at 100F ambient and I ran the generator with both airs on and the battery charger. It very slowly ran to 200F and stabilized there. The data from Redline is that with this ratio of coolant/water/Water Wetter I should see about a 20F drop, and that it exactly what I saw.
I drive tomorrow 75 miles to San Angelo (my first triathlon early Sunday AM, pray for me: I'm 49...) I will report if any results change. But first impressions with the generator running over half an hour a 3:30PM under a heat advisory and ambient at 100F: Redline Water does what it says it will. I know the cleaning had to help and the new coolant as well, but certainly not 20F down.
I should be freeze protected down to 10F and thats all I need here in the Heart of Texas.

You would be surprised how much cleaning does help. I think you may have had air in the system, this would explain the very rapid rise in temp. Now that you are completely topped off, it should be much better.

If the system has never been cleaned and the coolant mixture wasn't good, you still may have a partially plugged radiator, which would explain why it is running higher then the thermostat rating.

Good luck on your triathlon and stay safe!

quote:

Originally posted by Stratosurfer:
I drive tomorrow 75 miles to San Angelo (my first triathlon early Sunday AM, pray for me: I'm 49.

Enjoy your triathlon and glad to hear everything worked out great.

Bill,
You may well be correct in the air pocket issue, I observe the radiator is mounted on the side of the coach quite a few inches -below- the topmost radiator hose. I suspect an air bubble hanging around in that 90degreee turn on the hose coming out of the T-stat housing and heading downhill to the top tank of the radiator. Certainly this arrangement deserves a bleeder valve, but alas, we have none...
Possibly after hours of running this buble finally gets blown out of the overflow into the expansion tank, for it has been drawing in coolant. On the ride to San Angelo it was 100F and the temp went to 205F on the generator. Yesterday on the way back it was much cooler, topped at 97F, and the highest temp I saw was about 190F. This after two toppings of the expansion tank post-radiator cleaning.
So is the air bubble blown out?
Anyhow things are better now with my generator- except for the noise... I start another thread.

BTW: Completed Sprint Triathlon in 1hr 5 mins: not bad for a fat old fart. I love it, they tattoo (mark with a fat Sharpie) your age on your left calf on the angle so that when the 22 year old cruise easily past you on the bike and run they can physically see your age and some would cheer you on... There were folks over 70 that completed.