[folivier]

If you want to test your radiator fix then take I-15 south from Great Falls to below Butte, MT.
Lots of 6% long climbs, with 45mph curves at the bottom of the descents.
I found out that my check engine light will come on at exactly 219 F. Once I pulled over the light went out, engine cooled right down, and continued on.
So what rpm should I run the series 60 on hard uphills? On my 8v92 at 2000 rpm the temp would stay steady, but this had the direct drive radiator fan.

[ccjohnson]

Forest, I have 8V92. My rule of thumb on hills is drop a gear when temp rises. If it keeps rising, keep dropping gears.

[Chester Stone]

Forest, I recently experienced significant mountains on I-5 in Southern Oregon and Northern California with long and extended grades. I decided to ignore the RPM and speed gauges and focus on the boost gauge. The transmission did a good job of downshifting and I tried to keep the boost below the maximum which is 27.5 to 28 lbs. The boost air is the cause of most of the engine heat buildup, and keeping the boost at about 20 lbs. resulted in the engine never having excessive temperature. Speed and RPM were of no concern going up, but came into play going down the mountains. The transmission increased its heat going down hill using the Jake, and reached 135 degrees. I was relieved when I discovered that the transmission top temperature should not exceed 150 degrees. So in answer to your RPM question, I suggest the boost gauge is more important the RPMs.

[folivier]

Interesting Chester. When we leave here I'll try that. My boost was running 25+ lbs and the rpm didn't seem to matter much on the engine temp.
Your transmission temperatures were 135? Do you mean 235? Mine runs about 215 to 230.
Thanks!

[Chester Stone]

Yes Forest, a typo. I meant 235.

[Richard]

I agree those techniques will hold the temp down. Not to be an alarmist, but the thermostats should be fully open at 206, and the hydraulic fan on high speed. It's a two speed fan and on high blows a lot of air. In my opinion the ddec and Allison controller should work in conjunction to keep the temp in normal range. Assuming the fan came on high, I am wondering if you have a dirty radiator, outside or inside, or if one of the thermostats is not opening.

On flat ground, do you normally run 196 to 204? If so, I would say the thermostats are probably fine.

Simple green the radiator next. If that doesn't help, I would go for a radiator flush.

Just my two cents, and worth less than that.

My coach weighs less, so the guys with slides may say that the added weight makes that much difference and they have to do manuevers to keep from hitting the high temp alarm

[encantotom]

ok, cooling system essentially still holding pressure. it goes up during the day and down at nite a few pounds either way. and the pressure tester i have i think leaks a little as well. oh, by the way i own a pressure tester now. i put a deposit on a loaner at a local parts house and i kept needing it longer and longer so now i just own it. oh well,

i bought new silicone 2.5" radiator hose today. i have been in the peterbuilt shop so much the parts manager gave it to me at a significant discount.

we will replace all the hoses on saturday. i will try to reclaim as much of the coolant as possible.

does anyone have any opinions on coolant if i change it?

tom

[whatsnewell]

Super Cool by DD? That's what I use....

[rheavn]

I also use the DD Super Cool. Just bought some for $11.42 a gallon.

[encantotom]

i had the coolant changed when i bought it, so 18 months ago. andy reason i cant reuse it if i filter it before putting it back in?

tom