Leave engine brake on?

No, my statement was not total bs. What your talking about is intentional slowing down. If you didnt have your jake on you would use your brake more and thus waste the same fuel. My post said "Any unnecessary or unintentional braking hurts mpg." Your talking about intentional braking.

Now use of jake should depend on driving conditions. On a 55 with curves, I leave it on so as oon as i lift off, i get a little braking power helping me slow for the curves. That is intentional braking. On the highway, on cruise I leave mine on because if it gets 3 mph over my set speed the jake will auto engage keeping me from speeding by mistake. Again, this is intentional. If there was no jak i would use the brake.

Where it hurts is going through traffic, coasting up to lights, etc. Every time you take your foot off weather you want to stop or not, it slows you down. Also at slow speeds, the whole idea of a jake is to slow engine. So unless your timing is perfect on shifting, its going to slow the motor more then you want during up shifts and make it harder to accelerate. For every driver I see that can do perfect shifting with jake on, i see 30 that cant. So in general, i'd say for 95% of you, its not advised to leave it on in ALL situations. Alsi if you are not intending to slow down and it sloes you down, you are wasting fuel.

Now there is a difference in safty and fuel economy. Yes it may cause you to slow sometimes when you dont want to but it may make you safer by having the auto brake when you step off throttle. I say a good driver keeps his distance and can react quickly enough to not need it. They way to prevent mpg loss is hold throttle to 1% when you want to coast so the jake wont activate, but you wont really be pushing the engine.

 

Whatever happened to using the jake for what it was designed to be used for....an AID in descending a grade.....

 

And a hair dryer has a warning not to use it in water.

The fuel is shut off when coasting or when the jake engages on the electronic engines. Any increase in fuel usage because of the using the jake is solely related to driver behavior. And any driver having issues with unintentional slowing because the jake comes on has larger problems with vehicle control to overcome.

Should you have it on while shifting? Not normally, unless you cover the clutch pedal to disable it or your truck has enough dead space in the pedal to enable the driver shift without a complete lift off the throttle. The autoshifts use the jakes to make their shifts faster, but they also perfectly match RPM before they move the actuator. It is a help to use the jake when upshifting on severe grades and soft terrain where the truck would otherwise slow to rapidly to shift, but it's hard to be smooth doing so, and the newer transmissions shift much quicker than the old designs, making this mostly unnecessary on the road.


And now I'll turn the thread back over to the two-year terrors!

 

You wont hurt your fuel economy and you will learn to love your Jakebreak.

 

let me know if your truck has any drivetrain problems in a few years. i air on the side of caution since i own my truck.

 

Any do you follow that warning or do you drop the hair dryer in the tub while your in it?

 

I feel dumber after reading this thread.

 

You do realize that those types of warnings are there for liability concerns? They are written to the least common denominator. Try it some time, rev your truck up in neutral, and jump off the throttle with the jake on. On some trucks, some of the time, it might kill the engine some of the time. I didn't say it was wise, my point was that you can't make too broad of assumptions based on a warning in an owner's manual that was written to protect the manufacturer from lawsuits by window lickers.

*holds up mirror for Richter*

Do you see one?


You've learned a lot in the few years you've been trucking, more than most; you'll be much wiser when you realize just how much you don't know. That's not a slam, that's just the advice of years.

 

Nothing happened to that. It's still common practice.

 

Just curious....I drove for quite a while and never seemed to see the need for leaving it on. Never used it on snow or icy roads either...but that's a whole nother thread I suppose.