1992 Magna overheats on climb. WHY?

[benford]

All the other big rigs climb steep hills . My rig overheats, trans and engine .
Has anyone ever had a problem with this?
radiator looks clean trans cooler looks clean,
could
the fan not be doing the job? do they ever have issues with blowing correctly?
She runs fine on flat ground, but put her on a 6 degree grade and she don't like it, trans temp goes over 200, engine temp nears 220

[benford]

Followup question , My book says there is a air bleed on radiator inlet hose does anyone know what this looks like?
Wanted to make sure there is no air pockets in my cooling lines,
I found a small "plug" thing on the inlet line right behind the coolant fill reservoir, but not sure if this is it, We are on the road and I don't want to strip or break something,

[benford]

OK, I should have searched this topic before posting, I learned about keeping rpm up during climb, and not to let the trans "hunt"
So we will see today when I try to get out of this place....
Blew a radiator hose yesterday right after turning around to avoid a steep climb...boy am I glad I turned around...
Actually it was a heater hose, looked like an old splice job going into the "school bus pump" hose was only 8 inches long, it was clamped on a 3/4 inch copper line then clamped to the 1 inch pump,
everthing was closed (Sunday) found a farm store with a box of 3/4 inch car heater hose, thin stuff but boy was it hard to stretch over that 1 inch pump inlet,
NAPA is 30 miles from our location just hope it holds long enough to get there,
lost all my coolant and no alarms, nothing, just hot temp guage,
this old girl is about to get me down...hahaha

[smlranger]

I'm no expert but have had two DP's. Things I would want to check:

1. water pump

2. radiator/intercooler clean

3. engine thermostat

4. is the radiator stopped up? When is last time you had a complete system flush and refill with new coolant?

5. is your's a side radiator or rear radiator? If side radiator, is the hydraulic fan pump controller working properly? If rear radiator, need to clean it thoroughly and yes, keep rpm's up when climbing.

[deandec]

On my rig alarms and shut down occur at 220 and 225 degrees on the water temp.

I can reach 220 degrees on a hot day and a 6 degree grade depending on the length. Do shift down to keep rpms over 2000 for maximum water cooling.

I have removed the rear school bus pump as it was a problem two different times enroute. No noticeable effect since we do not travel in freezing weather and need max heat from the dash heater.

Have you had the engine thermostats tested or replaced? My Gillig manual indicates it is a 181 degree thermostat that opens fully at 205 degrees.

My rig has an air bleed just behind the surge tank. It is most easily purged from the bedroom access under the bed. If the purge is not done, you will likely loose coolant through the overflow. Low coolant can cause engine shutdowns on long entrance ramp curves as coolant splashes in the surge tank on my rig and uncovers the sensor.

There is a long list of overheating causes in the trouble shooting section of the Cummins Engine manual if you have one.

[benford]

Originally Posted by deandec

On my rig alarms and shut down occur at 220 and 225 degrees on the water temp.

I can reach 220 degrees on a hot day and a 6 degree grade depending on the length. Do shift down to keep rpms over 2000 for maximum water cooling.

I have removed the rear school bus pump as it was a problem two different times enroute. No noticeable effect since we do not travel in freezing weather and need max heat from the dash heater.

Have you had the engine thermostats tested or replaced? My Gillig manual indicates it is a 181 degree thermostat that opens fully at 205 degrees.

My rig has an air bleed just behind the surge tank. It is most easily purged from the bedroom access under the bed. If the purge is not done, you will likely loose coolant through the overflow. Low coolant can cause engine shutdowns on long entrance ramp curves as coolant splashes in the surge tank on my rig and uncovers the sensor.

There is a long list of overheating causes in the trouble shooting section of the Cummins Engine manual if you have one.

Thanks for the reply,

How does the air bleed work? does it have a plug that unscrews or does it pop open somehow?
I am on the road and far from home I would hate to break something off

also when you removed the school bus pump what did you do with the wiring just cut and tape it up?

Thanks,
Benny


oh and down shifting on climbs really works, I love the internet.......never too old to learn something new,

[B Bob]

Recently had my radiator cleaned - flushed out. Air intercooler replaced. Valves adjusted. Now my motor is producing full rated power. And it is 15-16 degrees cooler on grades. Went up the very steep grapevine on a 100 degree day a few weeks ago and coolant temp only reached 199. Don't know if these things would help you, but you should check to see if your motor is actually making 300 hp, get radiator flushed, check fan to see it is working correctly. I think Cummins vales don't adjust like my Cat. But if they do get them checked.

[deandec]

Originally Posted by benford

Thanks for the reply,

How does the air bleed work? does it have a plug that unscrews or does it pop open somehow?
I am on the road and far from home I would hate to break something off

also when you removed the school bus pump what did you do with the wiring just cut and tape it up?

Thanks,
Benny


oh and down shifting on climbs really works, I love the internet.......never too old to learn something new,

Air bleed is just a small screw type device that lets the air out while the engine is running. When the coolant flows steadily, close the screw.

The pump wires are still hanging around taped off. I used a hose splice from NAPA to join the hose about 5 years ago. Still good today.

[Peralko]

Are you getting enough air flow through the radiator? Old mechanics' trick is to throw a rag on the outside of the radiator. If it sticks with fans running, you have good air flow.