I am new to the board, having traded my 2004 F250 CrewCab 6.0 Ford experimental diesel for a 2004 Cummin Quadcab 2500. I am aware of the Cummin recommendations for Breakin and have read some of the past threads.

I am using a breakin procedure that made sense to me and I wanted to get the comments of other members after they reviewed it.

It involves gentle driving the first 100 miles, then "heating up" the rings using controlled deceleration. For instance either using tow or locking the automatic in 1st or 2nd, you roll up to 3000-3200 RPM and back off using the engine to slow down the vehicle. You do this intermittently to alternately heat and cool the rings for better/faster seating and properly surfacing the cylinder walls.

On a couple of runs, I went up to 3500 RPM and backed off. Anyway read the material and give my your opinions.

http://www.thedieselstop.com/content...iesel%20Engine

 

It's interesting that the break-in recommendations are different between the pickups and the medium duty trucks. The manual for my work truck (listed in my sig, also available with a Cummins) says that the Cummins engine requires NO break in period, just let the coolant temp get to 160 and drive as normal. For a medium duty truck, that means "Flog the wee out of it!"

 

I agree. I am somewhat confused but perhaps the manual transmissions do break in better than the automatics because may people with autos never compression break their engines.

I am also uncertain about the redline on my 2004 (305 HP version). I have taken it up to about 3600 RPM and it is still accelerating strongly. I backed off because the redline on the Tach starts at 3200. It runs up to 5000. Why have a tach that goes 1800 RPM above the redline.

Rather than start a new thread. I would appreciate any comments on RPM and engine damage. How high are members here taking their engines?

 

I've read that when you go over 4300 RPM the crank snaps. There's bunches of 12 valve guys with 4000 RPM springs in the governor, they have the same rotating assembly and it holds together. 3600 would not concern me at all.

 

GeorgiaCracker the fuel cutoff is by 3600 RPM, when I hold my foot to the floor it won't rev past about 3600.

Destructive harmonics begin around 4300 like wannadiesel says but I don't believe the crank will snap, I've never heard of it, it's just murder on the bearings.

The only way to really overrev is downshift to far and force it past.

Vaughn

 

Wow, you guys are talking high rpm's, at least way too high for my comfort level. I personally won't ever take my engine over 3000. I don't see the need unless I'm on a dragstrip. That'll never happen. I use my rig for regular driving and towing, so I tend to keep it as much in the optimum powerband as possible.

 

I kicked mine on the Xway and the transmission/engine programming shifted at 3100-3200 RPM. I assume that Cummin must feel pretty comfortable with that level on a routing basis.

As I stated earlier, I guage the functional range of the engine by whether or not it is continuing to accelerate of is bogging down. I had a Mercedes 350 diesel that would just flatten out when it hit redline. My sense is that the Cummin would do the same.

I dont blame you for being conservative, but I think engine was bred to work hard and high.

 

Yep, the manufacturers lie to us because they want to pay for warranty work due to leaking oil and poor efficiency. Makes sense to me.


I'm sure this guy is more knowledgable then the engineers at Cummins who design our engines. Or the ones at Navistar, though with their recent contribution, maybe he is.

Sounds to me like something he "learned" a long time ago and still holds it as the gospel. Same as "change your oil every 3000 miles." It's an extra margin of safety, but from everything I've read about modern oils, totally unnecessary. (Not to mention, again, the guys who design these engines put a 7500/15000 mile interval on them).

I'll follow my manual and work the truck hard from the get go. Did that on my last one and didn't have any oil comsumption on it at all.

Now, maybe if this guy was talking about airplane engines, which haven't changed much in the last 50 years, he'd be on the mark....

 

The only time I run mine up on the red line is like going up Afton mountain loaded. I'll drop down to fourth and run it right up on the line and it will do about 74 mph at about 32 or 3300. It did go to 35 on me one time. Other than that, mine rarely sees 3000.
The whole concept of a diesel, for normal people, is lower rpm's for longevity. Some people, one fellow in particulat that I know that owns two red diesel trucks, may disagree however.

I didn't mention any names John.... DOH.....

 

If you want to break the motor in, after 1000 miles hitch up a trailer and put it to work!

 

Yep, that's what we did. A nice 600 mile trip broke it in quite nicely. I can say that after 6000 miles, the 6spd shifts much smoother and easier then when new.

 

Hey Jack, when are we putting a pusher on your new ride?

 

Never! I'm not toucing this ride. No way, no how.

 

Figured that.

 

Jack, you know he's saving that quote for his signature for when the EZ goes on.