We're on a trip to Yellowstone and in the last two days, we've climbed over 6000 feet. The 5.9 Cummins has heated up to 212 at times. Is this too hot or am I worrying over nothing? The oil pressure has been 40 pounds or better.

212 is not to hot. Just not ideal. If you have a 50/50 mixture of water to anti-freeze I believe the boiling point of that mixture is around 240F. Now you add a pressure cap and the boiling point rises again.

Ok now back to my Detroit two stroke days. Over heating those babies could crack a head. But! in conversation with DD engineers I was given this information. "As long as you are not creating vapor, your are not to hot." If you create vapor you can generate serioud hot spots and that is where the problem comes in.

In summary, no vapor no problem.

Thanks for the feedback Gary but how do I know if I create vapor?

You're still good - 212°F isn't too "hot" for hill climbing. Find your radiator pressure (it'll be in the manual or on the cap). Add that amount to 14.7 psi, then go to this chart (the second one down) and it'll tell you the boiling point at sea level. At 6,000', the atmospheric pressure mean is 12.59 psi. Add that to the radiator pressure, and that'll give you the boiling point from the chart.

For example, at sea level with a 10 psi cap, the radiator boils at around 239°F. At 6,000 ft, 233°F.

Note that at the boiling point, the entire system doesn't turn to steam; additional heat (heat of vaporization) has to be added before it all flashes off. Some saturated steam may be produced at the boiling point, but very little, and in flashing to steam, heat is carried away, just as it is with liquid coolant.

Before I did some of the mods to my exhaust and turbo plumbing, I would regularly see 220 at 4000 feet and above and this would be on the flats going 70+ MPH if the outside ambient was 85 + degrees.

Now I see only 200 but still I have been told that 220 at 6000 feet isn't that bad as long as you have a good rad cap and can hold 14 to 16 PSI radiator pressure.

You have probably noticed that oil pressure drops almost linearly with increase in water temps. Again normal.

Cooling effectiveness/efficiency really goes down as you go up in density altitude!

Ed brings up a good point - the air is less dense at altitude, so airflow across the radiator is less effective carrying away heat.

If one is concerned, manually downshifting lessens the load on the engine while speeding it (and the fan) up.

I can run the northbound 7% grade on I-77 south of Fancy Gap at 45 mph in 4th with coolant, tranny, and EGT temps within limits, but in 3rd or 2nd, everything is much calmer.

Rusty the chart is interesting. The one thing missing is anti-freeze. It assumes pure water. If I remember right there is something about 1 lb of atmospheric drop every 1000 ft of altitude.

If overheating is a major problem, you can always install a mister in front of the radiator and turn it on when needed. I did this on our Newell and it worked. Only used it a few times. The 500HP 8V-92TA pushing 48,000 pounds up a mountain will generate a lot of heat!

+1 on the mister. An RV is an ideal candidate, since it carries a fair amount of water. I don't use it now, but a number of my tow vehicles ended up with misters. Once, on a really hot tow up Sherwin Grade, I stopped and cobbled up a system using the washer pump. It was incredibly crude, but there was no hardware store near where overheating stopped me.

Another help is Red Line Water Wetter. I haven't done any recent tests, but when I towed a ski boat up Chiriaco Summit every weekend, I, and some of my companions, found WW to really help. Towing up that grade weekly at over 100 degrees was sort of a test lab for cooling and vapor lock.

wet water will help get it at auto zone.
lenny

quote:

Originally posted by lenny and judy:
wet water will help.
lenny

I have had good results with a similar product, Water Wetter, from Red Line.

This is preaching to the choir, but at the final leg of a 3,000 mile trip in April, temps got warmer than usual (but nowhere near overheat) up and down hills in AL.

Most of that trip was in rain, and I discovered the radiator was munged up from the road crud the spray delivered to it. Thoroughly cleaned, in a trip to GA last month, the radiator worked normally.

I wash the radiator and (external) oil cooler before every trip, and even on 7% grades at 95°F ambient, the coolant temp doesn't get above 205°F.

With the new water pump in, I'm putting in NAPA's water wetter before I leave Saturday.

quote:

Originally posted by Rusty:
I wash the radiator and (external) oil cooler before every trip...

To others who may read this, and then get out their pressure washers, don't do it!!!

It is always best to use a garden hose and a moderate stream of water pressure for this. Using a "Pressure Washer" will get most people into $erious trouble.

You can also go to an air conditioning supply house and purchase aerosol cans of coil cleaner. Spray on, let sit and hose off. Removes grime and dirt and is easy to use.

quote:

Originally posted by Bill N.Y.:
To others who may read this, and then get out their pressure washers, don't do it!!!

It is always best to use a garden hose and a moderate stream of water pressure for this. Using a "Pressure Washer" will get most people into $erious trouble.

I am one that can relate to that!! Although I didn't use a pressure washer, I used a nozzle at the end of the hose, our water pressure here is about 80 psi on the "street side" and that is what I used to mess up the old rad!! I didn't get the mozzle pointed exactly straight into the fins and the pressure was enough to bend over a couple of fins and one pulled a hole in the core. it was a pin hole but non the less, a new radiator was needed. The old rad would have gone longer, was a little blocked inside but not terribly bad!

Aside from the cost of a rebuilt rad, it was a ROYAL PAIN IN THE A$$$ to get out and back in!

Being a pusher, the rad really get dirty fast!! A lot of junk gets kicked up by the wheels and is literally force blown into the rad. One of the biggest problems is the first rad is the turbo intercooler, followed by the transmission cooler and then the engine rad. So, a lot of junk is still in the intercooler and transmission cooler that will not get washed out by reverse water flow thru the engine rad from the outside. I carefully wash out from the engine side and then wash again from the outside in.

I wish there was a better way!

Amen to no pressure washer. I spray the radiator with Purple Cleaner, let it set for a few minutes, then use the "shower" head on the hose mozzle, which cleans several sq. inches at once, and is low pressure. I have a well, and the pressure is set to 30-50 psi.