Engine Lugging...

[The_Oz]

...how does the oil protect the engine during this situation? In fact, can anyone explain the consequences of prolonged engine lugging? I lug my engine probably around 5 times per week (stupid hydraulic clutch systems

). So, I guess the questions are:

- How does oil protect the engine in this situation?
- Is there a particular additive in the oil that helps?
- What engine internals gets worn down prematurely?
- Does it affect other non-engine related components?
- How in the world do I prevent this!?!?!?

Thanks,

Oz

 

[UncleS2]

Oz, careful there! Lugging an engine is *Very* hard on the bearings. Just downshift sooner. If pronounced enough, it's also hard on driveline U-joints in RWD. My guess that when lugged, the EP additives become very important. Since engine rpm is low, oil pressure is probably on the low side too. Repeat: lugging is very bad for your engine & vehicle.

 

[MolaKule]

I don't think occasional lugging will do much damage. Howver, it should be avoided if possible.

As I understand it, lugging is low engine rpm caused by a mismatch in vehicle/engine speed, and improper gear slection under high loading conditions. Lugging creates "shock" loads to the piston and crankshaft. You also have a momentary heat rise, since the coolant moves slower than normal.

How does oil protect the engine in this situation?

By providing lubricating films and cooling.

- Is there a particular additive in the oil that helps?

Anti-wear and Friction modifiers certainly help here, since your oil pressure is probably too low to keep hydrodynamic lubrication going. A good boundary additve as backup certainly helps.

- What engine internals gets worn down prematurely?

I would say the wrist pin, the connecting rod, and the large bearings in the engine get stressed the most.

- Does it affect other non-engine related components?

The timing chain or timing belt is also seeing these shock loads. And you will get surges in fuel delivery since the computer is attempting to compensate.

- How in the world do I prevent this!?!?!?

Get the clutch adjusted and make sure the rpm's are high enough to produce a sufficient amount of torque to move the vehicle. I had rather burn clutch material than damage internals.

 

[Patman]

quote:

---

Originally posted by The_Oz:

- How in the world do I prevent this!?!?!?

---

Get an automatic!

 

[Al]

Lugging is extremely hard on your bearings. That is because you are creating max horsepower at that given rpm which translates into a very high bearing load on the big end and small end rod bearing. That coupled wwith the fact that you have a very low rpm and you totally violate the classical bearing equuation: (N x V)/L, where L = Load, V= viscosity, and N= RPM. As this value gets lower in magnitude you drift into the mixed film and into the boundary lub conditions. Needless to say a heavier oil (Higher V will help).

 

[widman]

Stuart and Molakule hit it on the head. very bad. Get the adjustments made to eliminate the situation.

 

[The_Oz]

Stuart -> I have a FWD. It's not that I'm downshifting later, I lug engine normally when accelerating, accelerating on a hill, heavy loads from a complete stop OR when the car is around 10km/h and I engage to 2nd instead of rev-matching to 1st.

MolaKule -> Once again,

Patman -> Automatics are boring!

Al -> Based on your statements, I guess this is another plus for the Delvac 1 5W40 that I'm using instead of 5W30. Woohoo!

Widman -> I think the adjustments required is not in the car, but me

Thanks Guys,

Oz