Detroit Diesel Overheating on Mountain Grades

[Newell Attack]

My immediate issue is a tendency for our engine in the classic newell coach(6V92T) to overheat in a hard climb. About 4 months ago it started and it seems to be getting worse. I have had the radiator power washed twice. Still, towing the car on a steep or long climb, it will heat up. I have always been able to nurse it along and keep it within the operating temperature. I don't think I could do a mountain climb now without letting it cool. Before, it would climb a grade and barely move the gauge. What would you check first? Thought I might get a little education first before I take it in for a checkup. Thanks, ..Jeff

[prairieschooner]

As long as the radiator is clean then I would suggest pulling the Thermostats and checking them. I think that they are marked for the temperature and you can check them by.
I like to put it in a pan with hot water and while open use a piece of string and let it close on the string. Now put a pan on the stove with cool water and begin to heat the water with the Thermostats suspended in the water and a Thermometer in the water. When the Thermostat opens it will fall off of the string and you can look at the temperature of the water. They should open relatively at the marked temperature.

Some like to remove the Thermostats but that could allow the water to flow too fast through the radiator and not long enough to cool.

Also make sure that you have the correct Coolant at the correct Ratio.

[NewellCrazy]

Replace the thermostat and see what happens, its the cheapest repair.

[folivier]

If you have an infrared thermometer "gun" you can shoot the different areas of your radiator to see if any areas of the fins are clogged. Alternatively you can use a good flashlight to see if they are clogged. Usually the outer perimeter of the radiator gets clogged pretty quickly.
What engine? What temperatures are you seeing?

[Viva Las Vegas JDR]

Check thermostat first and If its still is running warm it could possibly be the radiator. Since you state it has been pressure washed twice it is entirely possible that you have separated the fins from the tubes enough to effect heat transfer. My guess it your radiator. Check it for cold spots to determine if it has any restrictions through the core and check to make sure the fan is working correctly.

JDR

[GringoPhil]

Maybe pressure loss on radiator. Bad pressure cap?

Phil

[prairieschooner]

Thermostats aren't cheap, test them 1st before you just start changing parts. They are basic and should open by about 180 Degrees (newer Engines open at higher temps). Check them a few times but check them non the less, this will help troubleshoot the problem. Being a mechanic I want to know why I am replacing a part but....replace both if one is bad. If your replaced the Coolant doesn't have enough water this could also be a problem.
Climbing a grade I always gear down to stay within the power band.

PS just read Gringo's post and that is another potential issue. Water Boils at a higher temperature when under about 15 Lbs. of pressure. Good call Gringo!

Good Luck

[express1]

Maybe gauge?

[David Carrol]

have you done a radiator flush and replace coolant ?

[Chester B. Stone, Jr.]

If the radiator is in the rear, rather than the side, it may have been clogged with oil and dirt. If so, power wash will not help much, but steam cleaning will attack the oil-dirt mixture and the lower pressure will not bend the fins. Also, are you keeping the RPMs up when climbing a hill? This is especially important if you have a direct drive fan rather than a hydraulic one.

[Newell Attack]

Thanks for your help, My radiator is in the rear and I located a thermostat in case I need to swap that out for 28.00 online. Steam Cleaning is a great idea I could grab a steam cleaner and start there and work my way down the list of ideas until I find the culprit.

Jeff

[ccjohnson]

You may have internal clogging in the tubes. If so, a good radiator shop can hot tank it. We had to get ours done. They found some damaged leaking tubes so we opted for a complete re-core of the radiator. It was +/-2700 with a year warranty. If you have a 6V92, Newell may still have 1 or 2 laying around. They didn't have any 8V92 radiators when we got ours done. I think Atlas Radiator in Dallas has drawing for 8V92 radiators if my memory serves me right. I'm fairly sure that is where they got our re-core from.

[prairieschooner]

There was some discussion about cleaning radiators in the past. Make sure that whatever you use isn't acidic. As I remember Dawn Dishwashing Liquid was a good choice. Mix up a solution, spray it on from both sides but Rinse it off from the outside to the inside. The Oils and Dirt come from the inside on ours typically from the Fan, if you do a quick inspection you may find gunk on the outer perimeter of the radiator.
This reminds me to check mine before I head up to Moro Bay and Monterey in a week, I typically check ours a few times a year.

[Lindsay]

I had a similar issue. It turned out to be the radiator was clogged.

[Chester B. Stone, Jr.]

If you do find that steam cleaning solves the problem, next check to see if the engine oil slobber tube is vented away from the radiator, and if not, relocate it to the side.