All,
Drove the Barth in 100F+ heat yesterday about 150 miles. Ran 7.5KW Onan Diesel genset all day and noticed when heading home the H2O temp was steady at 220F. Went to park dump station and cooled the generator's radiator w/water down to 175F and headed home in 105F ambient temp heat. On the road temp quickly ran back up to 220F on the generator. Is this an acceptable temp for a very hot day? The highest operating temps I had seen to date were 190-200F so I was a little concerned?

I am considering adding in some water and Redline Water wetter as the over flow tank is dry (it had some in the bottom while hot) to see if that helps. Any thoughts appreciated.
Thanks

"I am considering adding in some water and Redline Water wetter as the over flow tank is dry (it had some in the bottom while hot) to see if that helps.

The over flow tank should have coolant in it all the time. There should be marks where the coolant level should be when cold. If it is dry, the system will draw in air as it cools and generally will cause hot spots until all the air is expelled during warm up. This should be inspected before each trip.

I don't think water wetter will reduce the temperature in hot weather conditions. I have done extensive work to reduce the temperature that I see during my runs in the high desert. I have found that over 90 degrees ambient, it is difficult to keep the temps below 190-195, at 100 degrees ambient I run 200. As mentioned in earlier posts, at elevations over 3000 feet, I will see 200+ if the outside temps are above 85 degrees.

Before I made changes I would approach 220 degrees in similar conditions. At 215 degrees I would slow down or shift into fifth to get the RPMs up, fan speed increases and has direct effect on cooling.

Rear engine pushers generally draw air in from either the side of the coach, under the coach or both. If air is being drawn in from under the coach, it may go by the exhaust system and that will preheat the air alot. Air just above the road will also be very hot in high ambient conditions. Reducing speed and/or shifting down a gear will generally reduce the operating temperatures a bit.

Personally, I consider 220 degrees to be the upper limit of operation and try to keep it at or below 215 degrees.

Still working on further changes to reduce my temps further, more on that later.

Sorry if I wasn't clear in my post describing my situation: it is my Onan diesel generator that is running at 220F, -not- my diesel main engine. I have added edits to original post to clarify.

I'd check the air filter and the coolant hoses, and blow out the radiator. Last candidate would be the thermostat.

OK, have to bring you guys the final (I believe) issue here. Belt was slipping...
Soooooo, I am in the process of permanently removing the fan belt guard and replacing the belt that is shot and slipping -massively- and of course the waterpump spinning much slower than designed.
So the Water Wetter does work, but my primary problem is a bad fan belt. Oops.

3 liter diesel genny onan most have the themosython system.. no pump or thermostat...kubota!

quote:

Originally posted by robert and kimberly delucia:
3 liter diesel genny onan most have the themosython system.. no pump or thermostat...kubota!

Interesting. My manual shows both a water pump and a thermostat. I would much prefer the thermosiphon methodology. I guess mine is a different derivative of the 3l.
I thought I saw a waterpump when I pulled the belt today, but after your post I had to review the manual.

All,
Just to finish with this thread on my part. I found the belt on the genset slipping and replaced it. In the interim I flushed the radiator, installed Water Wetter and now I am running about 180 to 195 range on days of 95 to 100F ambient.
The belt slipping was the biggest factor I suppose.