Overheating issues

[jwilliams435]

no idea the hp it was turned up to, ill ask my buddy. I know it barely pulled West va mountains at 20 mph. the heat might have caused power loss tho

[chuckftboy]

If you pulled those mountains in high gear, you may have caused some of the over heating issues. Need to keep the RPM's up to move air over the radiator.

[jwilliams435]

that may have not helped. I couldn't figure how to hold it down a gear (Allison 6 speed). but the radiator and cac are at least 75% stopped up so i think that's the main reason obviously.

[wolfe10]

Originally Posted by jwilliams435

that may have not helped. I couldn't figure how to hold it down a gear (Allison 6 speed). but the radiator and cac are at least 75% stopped up so i think that's the main reason obviously.

First, the Cummins B in either 230 (more likely) or 275 HP version with the Allison 3060 transmission is a very good combination.


My ouji board isn't good enough to tell you the risk of killer dowel pin. Were it my coach and weren't pulling the CAC and radiator, I would risk it.


If the cooling package is out, absolutely, I would do the killer dowel pin remedy and likely replace other "front of the engine components like water pump while they are easily accessible.


I am also a big fan of running it like it was built. Overfueling can get you more HP, but anytime you burn more fuel you PRODUCE MORE HEAT LOAD for the cooling system.


Stressing an engine that age-- sorry, not for me.

[jwilliams435]

yea i shouldn't have let my buddy talk me into letting him turn the fuel up. He said he turned it up half as much as he usually does these because he knew we wanted reliability for long west coast trips. still tho, stock setting sounds like the thing to return to

[RightUR]

Originally Posted by Skip426

After sitting for 20 years , I hope the first thing you replaced was tires.

LOL. Nice. Absolutely.
x2

[RightUR]

Originally Posted by jwilliams435

yes tires were replaced, oil changed, coolant/hoses changed. airbags on chassis/suspension changed. that's about it, everything else seems to work, but could be hidden issues i hadn't thought of like the overheating thing

Without a doubt your being very diligent. I see you already put in new oil, I would have done a motor flush 1st, but that's just me, I'm overkill on all I do. For the Radiator, I'd do the same thing, While cleaning it, do a Radiator flush. Did you change out the Air Filter? I'd hate for any particulate matter to go into that engine and mess it up, after all 20 yrs is 20 yrs. But I think you're doing great, changing things out, fixing whatever you can and cleaning things, Basically using "process of Elimination" as you go.

[DeborahWFO]

Originally Posted by jwilliams435

that may have not helped. I couldn't figure how to hold it down a gear (Allison 6 speed). but the radiator and cac are at least 75% stopped up so i think that's the main reason obviously.

We learned the downshifting lesson in our 99 Beaver Patriot Thunder. If you are under 2k, you are lugging it. The temp will rise as a result. It has a hydraulic cooling fan set up. I agree though on the dirty radiator.

[Ray,IN]

Originally Posted by DeborahWFO

We learned the downshifting lesson in our 99 Beaver Patriot Thunder. If you are under 2k, you are lugging it. The temp will rise as a result. It has a hydraulic cooling fan set up. I agree though on the dirty radiator.

I disagree about your lugging comment. The Allison automatic transmission WILL downshift when engine RPM begin to drop below peak torque range, thus preventing lugging the engine.
The reason for pulling a grade at higher RPM is to keep the water pump spinning faster, thus moving moving coolant through the engine faster.
A hydraulically-driven fan is not normally RPM dependent.

[RV Driver]

Originally Posted by Ray,IN

I disagree about your lugging comment. The Allison automatic transmission WILL downshift when engine RPM begin to drop below peak torque range, thus preventing lugging the engine.
The reason for pulling a grade at higher RPM is to keep the water pump spinning faster, thus moving moving coolant through the engine faster.
A hydraulically-driven fan is not normally RPM dependent.

Ray, I'm sorry but what you have posted here is just not correct.

Yes, the Allison transmission will eventually downshift by itself on a grade, but that approach has a fatal flaw. The transmission cannot anticipate anything, it can only react to something that has already happened. By anticipating a grade ahead, I can manually downshift to fifth gear at 65 mph just as I get into the bottom of the grade. That puts my engine right around 1,950 RPM, just approaching the peak of its horsepower curve. If I wait and let the transmission shift by itself, I end up way behind the power curve, lugging at a lower RPM. It is horsepower that gets you up a grade at a good speed, not torque.

And you certainly do not want your engine lugging down at the peak torque RPM on a long grade. In my engine (400 HP Cummins ISL) that is only 1,400 RPM. Lugging the engine that slowly is a sure-fire recipe for an overheat condition.

With regard to the hydraulically-driven engine cooling fan speed, it is directly related to the engine speed. That fan is driven by the power steering pump. Run the pump faster and the fan RPM is faster. To demonstrate this, here are the target high fan speeds from Freightliner for the side-radiator, hydraulic fan setup:

• Engine at idle - Fan Speed 640 RPM
• 1,400 Engine RPM - Fan Speed 1,340 RPM
• 2,100 Engine RPM - Fan Speed 2,030 RPM
• 2,380 Engine RPM (WOT) - Fan Speed 2,240 RPM

In addition to running the fan faster, there are other benefits to running at a higher RPM on a long grade.

• Better Cooling - Water pump runs faster
• Better Cooling - Cooling fan runs faster
• Better Cooling - Engine not lugging at a low RPM
• Better Performance - Engine RPM is up near the peak of it's HP curve

Believe me, I have studied this at length as I dealt the a lot of overheating issues in our Mandalay. I've consulted with industry experts, both at Freightliner and at Source Engineering out in Oregon. I installed the Source Engineering Thermal Valve Conversion (the wax valve) on our coach because the Sauer-Danfoss electronic fan control was a constant source of trouble. That conversion fixed most of our overheating issues. A new Source Engineering High Performance radiator later this fall will fix it completely.

[Ray,IN]

RV Driver, therein lies the difference. I have a Spartan MM GT chassis, you have a Freightliner chassis. Different designs work differently, I've never had a overheating issue.
BTW 1,400RPM is not lugging a Cummins diesel engine, 1,200-1,400 RPM is peak torque.

[RV Driver]

Originally Posted by Ray,IN

...1,400RPM is not lugging a Cummins diesel engine, 1,200-1,400 RPM is peak torque.

Peak torque means nothing in the context of actual driving. It's just a statistic on that particular engine that tells you at what RPM the engine develops its maximum TORQUE. It is not TORQUE that gets you up a hill at speed. It is HORSEPOWER, and you don't get peak HORSEPOWER out of any engine lugging along down at the peak torque RPM.

You may be fortunate enough not to have overheating issue on your chassis. But thousands of us with Freightliner side radiator chassis DO have this problem. And lugging the engine at 1,200 to 1,400 RPM is a sure-fire recipe for an overheat situation.

[PaulMears]

My Cat 350 overheated in OK, right after I bought my motorhome, at 23000 RV miles. The radiator(s) were cleaned out - with great difficulty - by a truck stop mechanic, using a pressure washer and hand crafted hook wire to pull out plastic bags!!! A deal at $300.

At 50,000 miles I experienced some overheating going up the mountains in WV in the summer, so, I "carefully" drilled a 2" hole on the side of the engine fan shroud, behind the fan and in front of the radiator. I used a fiber optic viewer - from amazon - that displays on my iphone to inspect the entire radiator. It was completely plugged.
I used a pressure washer on medium pressure and a 45 degree spray head - never closer than 3-4" from the radiator - to clean the radiator, using Simple Green Detergent - then lots of clear water to rinse.
Came out sparkling clean.
Cut a piece of aluminum 3/4" larger than the hole and covered the hole using 6 screws.
Will clean out again around 70,000 miles.
Also, put a "white Nike sock" over the oil pan pressure release hose using a hose clamp to catch the oily fumes expelled when mechanics put too much oil in the engine at oil change and occasionally at other times. This is where the worst of the gunk on the radiator comes from. The oily fumes attract and enable adherence of lots of material as it is pulled from under the RV and blown to the radiator(s) by the engine fan.