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I have a 2008, 780 with the D16 engine and I-Shift. For you experienced HDT'ers, you probably already know about the following.


Ordinarily, I always make sure the engine is up to operating temperature before I drive down the road. Today was an exception. I had a dentist appointment and as I was leaving, I remembered that my dentist wanted to see the HDT. So, at the last minute, I decided to take the HDT.


Due to the water shortage on the West Coast, I have not washed the truck in a while. I was afraid if I did, and got caught, I could spend the rest of my life in water waster's prison. :wacko:


So, I started the engine and then activated the windshield washer and wipers. In my haste (always a bad thing when driving) and unbeknownst to me, I had accidentally bumped the jake brake lever and activated the jake brake.


As I drove down the street, with the engine cold, I got a flashing dash icon that said something to the effect of "too cold for engine brake." I immediately pulled over and noticed that I had inadvertently activated the jake brake. I turned off the jake brake and drove off, without incident.


I am guessing that the computer would not allow the jake brake to be activated because the engine had not fully warmed up. Does that make sense to you experienced "truckers?"


Since I have never towed, with any vehicle, without first warming up the engine, I guess I will never see this warning again. But it is good to know.



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Correct assumption. I'm not sure why you run with the switch off, but...shrug. Mine runs "On" all the time, controlled by my right foot.

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Doesn't make sense to us. We also leave our switch on all the time and in MN you might be waiting a long time for the engine to warm up. We have never seen any indicator even when our thermostats were stuck open in the middle of winter. Oh wait we drive a Freightliner!


Next time wait and see what temp the light goes out at.



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On the advice of a truck driver buddy of mine, I always leave the jake brake off until needed, such as descending long grades. His explanation was that if it is on and I forget that it is on, then it could get scary if I hit water or ice (ICE - NO ICE FOR ME) while I am deadheading. I got the impression that the rear end could lose traction due to the severe engine braking and no weight on the rear tires.


To be honest with you, I just took his word for it. He has a "bazillion" miles of cross country driving. I have noticed that some small towns post "use of engine brakes is prohibited." Although my Volvo with its DPF and muffler is not that loud when it jake brakes.


As a newbie, I am curious as to what every one else does with their Jake and Why.


Mr. Seas sent me an email about Volvo's programming (I think that's what it is). And it appears that the engine has to be above a certain temperature for the Jake to activate.


I have no idea how Mr. Seas finds this stuff, but he is AWESOME!

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3 yrs ago Gregg Shields had me out for a run in his truck, the engine brake was on and he said the engine was too cold. The odd time since, when left on and started the next am, I will get the message about the engine too cold so I just flip the lever up to the top and off until required.

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Even with a warmed up engine, I would not routinely have the jake armed. There is nothing that happens so fast that having it armed would make much difference, conversely, if you ALWAYS drive with it on it will become so much part of the routine that you could get into a situation of ice, as mentioned earlier, or even in severe dry places when it rains for the first time in several months, and wind up in a world of hurt.


For those who may want to get technical, it used to be one of the items that result in a failure in a standard road test for licensing or employment.



All of this is respectfully submitted in my opinion.


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2008 Volvo 780, D13, I-Shift

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Jake or even exhaust brakes and the slick plastic crosswalk material with a bit of rain on it do not mix. Turn across one of them with much braking or throttle and you'll get a double slip that will scare the heck out of you, much more braking/power or a bit more speed and you are gonna move several feet off line.

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I normally run with the Jake on. I shut it off when in cities where it is banned "except in emergency."


I find it interesting that a Jake starts braking as soon as you get off the accelerator which is several milli-seconds before you can be applying the service brakes. That extra braking effort might avoid the "emergency." Flipping on the Jake brakes in an emergency is too late.


Colorado does it right, un-muffled engine brakes are banned.

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On my 06 Volvo the engine brake disengages when the rear wheels slip. I usually run with mine off most of the time to save fuel. Might change that thought now that I have retired.



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Man that was a long time ago when you had to park a truck for the night and remember to use the blue knob or not, get all the lights off, get the windows slid up before you run out of air, and get the Jake switch off so you don't forget it when it is cold in the morning. I think it was like 1990-ish when they came up with the dual spring slaves that helped with valve jacking in thick oil? By habit I still don't turn the switch on until I see the needle cross 100 on the oil temp gauge. But anymore I think I remember about half the time. The MX engine cuts it off below 60 deg of water temp so it remembers when I forget as well. I'm not sure why it goes by water temp when the rest of the world goes by oil temp but it the idea is the same I guess.

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My 780 complains about being too cold but operates normally anyway. Probably an ecm setting. As is Jake aggressiveness.

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Oh for the old-times..........in the 50's and 60's Edward Hines Lumber Company in Easten Oregon provided FREE nightly fuel fill-up service to ALL vehicles that were idling in the logging town of Senica, OR.


Often Senica Oregon and International Falls Minn. were neck-and-neck in the contest who would be the coldest reporting station in the USA with both often -40f as a high for a given day.


Why FREE fuel??.......Simple....... if you shut down a diesel engine at -40f it will likely not start again until the grass greens up........


The real neat trick was that the service crews often changed oil on the heavy equipment while the engines were idling........


Fuel was cheap by the train loads ( Hines owned their own railroad as well) so keeping ALL engines running was the best way to keeping the logging operations running.


Oh the good-old-days........ never had to warm-up your engine.......it never cooled off.......


Drive on..........(keep that engine at the proper temps......)

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