Lugging a 325/600 (with a 6 speed)

[Takomax]

About 25 years ago I was told that lugging a diesel engine was very harmful to the engine. As a result, I have always been careful to keep the rpms up above 1500 when rolling even when running empty. Of course, this doesn't include putting around in 1st or 2nd gear when empty.



My question: What effect does lugging have on the engine?



Lugging, to me, would be less that 1500 rpms under most conditions. Specifcally, if one were in 6th gear and running 35 mph I would consider this lugging. Or if after a shift, the rpms fall to around 1000 I would consider that to be lugging the engine. Does this hurt the engine?

If so how?



-Carl

 

[JLovas]

I wouldn't worry about dropping your rpm's below 1500 for fear of lugging the engine. Heck, peak torque occurs at 1400 RPM's for these engines.



In daily driving, with no trailer, should be no big deal. If I'm driving through town and I come up to a light that has just turned green, I don't hesistate to accelerate through the intersection as long as I'm above 900-1000 RPM's. But when I'm pulling heavy, then I like to keep her above 1400 for any hard acceleration or climb up a hill.

 

[MCornwell]

These trucks fuel according to how much boost the ECM sees... so lugging



the engine isn't goin to hurt it, its just not the quickest way to get



around. NO lugging when cold though.



-Mitch

 

[B.G. Smith]

Some good reference material on the subject. bg http://dodgeram.org/tech/dsl/FAQ/engine_op.htm

 

[Prairie Dog]

It's better to keep it above 1400 RPM for the sake of transmission lubrication.

 

[BHolm]

"Lugging" as I understand it is using full throttle with a heavy load below the engines torque peak. Doing so increases stress on the crank, rods and creates undue strain on components. It is pretty unlikely that flooring the truck at 1000 rpm empty or even moderately loaded is going to hurt anything. The Cummins is a very durable design. I have noticed that the D-max trucks do not take well to lower rpm operation though. The Allison it very quick to drop a gear and run 2500+ rpms. The Dodge doesn't do this. My 48re's lock the convertor and allow the engine to pull hard from as low as 1200 rpm.

 

[DPelletier]

I agree,

I don't think low RPM operation is a problem unless combined with heavy or full throttle application and even then (although it isn't ideal), the Cummins will likely put up with it for a looooong time.

My transmission never downshifts, unless I tell it to!



Dave

 

[DarkRAM]

Torque rating

Peak torque for the "600" occurs @ 1600 rpm. Per DC.

 

[Patriot_RAM]

I keep my RPM's above 1100. And that's only becuase the TST occasional miss only happens right at 1100 RPM on my truck. Keeps the check engine light off.

 

[opjohnny]

I read here somewhere that if you can accelerate you are not lugging the engine.

 

[nickleinonen]

i'll cruse in the city at between 1000 - 1400 rpm with no issues... in 5th and 6th gears...

 

[dtygart]

Lugging a diesel enginge is when you add more fuel and don't get an rpm increase--just makes black smoke. In older big rig engines you could pull a liner down if you lugged the engine hard. With our smaller size diesels and high torque output not too much chance of hurting the engine, especially with all the computer control added on. (IMHO)

 

[Dick Garcia]

Transmission

Has anyone experienced any problems with the "out put seal" drying up and making high pitch sceeching sounds in for the first 15 min. of driving. Usually occurs between 5 to 35 mph, then the sound goes away. Dealer says the out put seal was dry and there was rust on the slip yoke. 04 Dodge 3500 HO diesel engine with 6 spd. SWD.

Thanks

Dick