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    Guest Message by DevFuse
     

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    Engine Brake



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    22 replies to this topic

    #1 OFFLINE   bigen

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    Posted 26 June 2010 - 12:19 PM

    i don't think my engine brake is what it should be????????????
    on a 6% grade grossing 72,000 if im run in 6th gear thats about 25mph i still have to touch the brakes now and then to keep it from over reving, in 7th about 30mph i have to use brake quite a bit, in 8th gear around 40mph i have to hold constant preasure, to keep it off the rev.
    i know some engine brakes are not as good as other, same make, modle, year, miles,and so on
    i don't have a lot of experriance out west, so im not sure if this is normal, or is something wrong with my E.B.
    GRANDDAD, taught me get in low enough gear you run just below the rev limit and never touch the brake, but granddad never went west.

    #2 OFFLINE   Lmackattack

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    Posted 26 June 2010 - 12:39 PM

    On the 3406E Cat / 18 speed trans I drive, Grossing 72K, I can decend most hills in 14th-15th gear(6th or 7th hole in hi range) and maintain about 40-45 MPH without out the need to use the brake pedal. if I do hit the pedal its just to get it one gear lower and then never touch it again.

    I know Macks engine brakes always seamed weak to me?

    Trent

    #3 OFFLINE   Gambi80

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    Posted 26 June 2010 - 12:40 PM

    Gotta git a BIG motor for a good jake brake...
    Ever wonder how a blind person knows when to stop wiping?

    Posted Image

    #4 OFFLINE   speedy

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    Posted 26 June 2010 - 01:08 PM

    The Mack engine is short on displacement, 12 litres, compared to 15 litres for other engines, so your at a 25% disadvantage right off the start.

    #5 OFFLINE   JerryB

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    Posted 26 June 2010 - 01:18 PM

    i don't think my engine brake is what it should be????????????
    on a 6% grade grossing 72,000 if im run in 6th gear thats about 25mph i still have to touch the brakes now and then to keep it from over reving, in 7th about 30mph i have to use brake quite a bit, in 8th gear around 40mph i have to hold constant preasure, to keep it off the rev.
    i know some engine brakes are not as good as other, same make, modle, year, miles,and so on
    i don't have a lot of experriance out west, so im not sure if this is normal, or is something wrong with my E.B.
    GRANDDAD, taught me get in low enough gear you run just below the rev limit and never touch the brake, but granddad never went west.


    you don't have any problem bigen that's normal for a Mack.. Speedy is right.

    #6 OFFLINE   rhasler

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    Posted 26 June 2010 - 01:22 PM

    According to Mack the retarding power for your engine brake (AC460P with Mack Powerleash engine brake) should be 420 HP at 2100 rpm
    "Mebbe I'm too ugly and stupid to give up!"

    #7 OFFLINE   bigen

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    Posted 26 June 2010 - 01:57 PM

    you say 2100 rpm's
    should i let it twist up that high?
    i try to keep mine between 1800 and 2000, ussually closer to 1800.
    i had a 2001 460 with a jackob engine brake not power leash, grossing 100,000 lbs in 6th gear it would throw your ass on the dash

    #8 OFFLINE   Mackpro68

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    Posted 26 June 2010 - 02:07 PM

    i don't think my engine brake is what it should be????????????
    on a 6% grade grossing 72,000 if im run in 6th gear thats about 25mph i still have to touch the brakes now and then to keep it from over reving, in 7th about 30mph i have to use brake quite a bit, in 8th gear around 40mph i have to hold constant preasure, to keep it off the rev.
    i know some engine brakes are not as good as other, same make, modle, year, miles,and so on
    i don't have a lot of experriance out west, so im not sure if this is normal, or is something wrong with my E.B.
    GRANDDAD, taught me get in low enough gear you run just below the rev limit and never touch the brake, but granddad never went west.

    While I was adjusting your valves the other day, I did take out your engine brake solinoids and replace the o-rings and all looked good. How's the fridge working?
    Havent heard from ya?

    #9 OFFLINE   rhasler

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    Posted 26 June 2010 - 02:09 PM

    Bigen, the owner's manual has several pages of information on the engine brake. It should be pages 2-31
    "Mebbe I'm too ugly and stupid to give up!"

    #10 OFFLINE   bigen

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    Posted 26 June 2010 - 02:18 PM

    While I was adjusting your valves the other day, I did take out your engine brake solinoids and replace the o-rings and all looked good. How's the fridge working?
    Havent heard from ya?

    fridge is doin good, that's a big thing here in phoenix. 106 2day
    i feel kinda like a goofball rolling off these hills at 25mph, but it is what it is, im not gona burn the brakes off it.....

    #11 OFFLINE   bigen

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    Posted 26 June 2010 - 02:22 PM

    Bigen, the owner's manual has several pages of information on the engine brake. It should be pages 2-31

    i didn't get manualls with this truck.
    will have to try to get one.

    #12 OFFLINE   Lmackattack

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    Posted 26 June 2010 - 02:30 PM

    Displacement is likely the issue. I rember the engine brake on the maxidynes. you had 3rd gear and that was pretty much it for your engine braking, if it could hold it back.... LOL. No replacement for displacent.

    I run my 3406 to 2000RPM on the engine brake and sometimes to 2100.Its a big diffrence in stoping power from 1800-2100. I never let it go past 2100 tho but do know other drivers that let them spin to 2200..

    Trent

    #13 OFFLINE   bigen

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    Posted 26 June 2010 - 02:35 PM

    Displacement is likely the issue. I rember the engine brake on the maxidynes. you had 3rd gear and that was pretty much it for your engine braking, if it could hold it back.... LOL. No replacement for displacent.

    I run my 3406 to 2000RPM on the engine brake and sometimes to 2100.Its a big diffrence in stoping power from 1800-2100. I never let it go past 2100 tho but do know other drivers that let them spin to 2200..

    Trent

    it would be a lot easier turning it that high, if it belonged to someone else

    #14 OFFLINE   Mackpro68

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    Posted 26 June 2010 - 02:41 PM

    fridge is doin good, that's a big thing here in phoenix. 106 2day
    i feel kinda like a goofball rolling off these hills at 25mph, but it is what it is, im not gona burn the brakes off it.....

    I dont blame ya for saving your brakes!

    #15 OFFLINE   rhasler

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    Posted 26 June 2010 - 07:06 PM

    i didn't get manualls with this truck.
    will have to try to get one.

    Bigen, the manual you should be looking for is TS49407 Lubrication and Maintenance. I don't know who steals those things out of trucks but their always missing. The manual says maximum allowable engine speed is 2300 rpm in brake mode or normal power mode. I did some research on the Jake Brake's retarding power. Here's the link to the specification sheet on the model 690 that would have been on your E-tech: http://www.jakebrake...df2/024321.pdf. Basically it shows your retarding power vs. rpm. At 2100 rpm the Jake is retarding about 360-375 HP.
    "Mebbe I'm too ugly and stupid to give up!"

    #16 OFFLINE   fjh

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    Posted 26 June 2010 - 08:00 PM

    i don't think my engine brake is what it should be????????????
    on a 6% grade grossing 72,000 if im run in 6th gear thats about 25mph i still have to touch the brakes now and then to keep it from over reving, in 7th about 30mph i have to use brake quite a bit, in 8th gear around 40mph i have to hold constant preasure, to keep it off the rev.
    i know some engine brakes are not as good as other, same make, modle, year, miles,and so on
    i don't have a lot of experriance out west, so im not sure if this is normal, or is something wrong with my E.B.
    GRANDDAD, taught me get in low enough gear you run just below the rev limit and never touch the brake, but granddad never went west.

    Do you got p leash or jake!??? I aint never seen no jake on any thing newer than maybe 05 ,when the power leash came out we droped the jake and used the power leash around here!
    The p leash is good!Ya need to keep the rums up to have good hold back!

    #17 OFFLINE   Vision 386

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    Posted 26 June 2010 - 09:38 PM

    fridge is doin good, that's a big thing here in phoenix. 106 2day
    i feel kinda like a goofball rolling off these hills at 25mph, but it is what it is, im not gona burn the brakes off it.....

    Nah, don't worry about that! you've heard the old saying about comin off a grade too fast right? you can come down too slow a whole lotta' times,but you're only gonna' come down too fast once! now my 460 is equipped with a jacobs retarder,and like you said,it will put you up against the dash! but granted i don't pull the kind of weight you do,not westbound anyway. biggest majority of my outbound freight is less than 15,000lbs. but i do backhaul some heavy shit sometimes, and i take it real easy on the grades myself! nothing at all to feel goofy about! i drive at the speed I'M comfortable at, and try to avoid western COLO. if at all poss!............Mark
    Mack Truck literate. Computer illiterate.

    #18 OFFLINE   theakerstwo

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    Posted 26 June 2010 - 09:44 PM

    The Mack engine is short on displacement, 12 litres, compared to 15 litres for other engines, so your at a 25% disadvantage right off the start.

    This is so true. Macks dont make much power with the jake or dnyotard compared to any of the big bores.
    glenn akers

    #19 OFFLINE   Gambi80

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    Posted 26 June 2010 - 10:36 PM

    fridge is doin good, that's a big thing here in phoenix. 106 2day
    i feel kinda like a goofball rolling off these hills at 25mph, but it is what it is, im not gona burn the brakes off it.....


    Better safe than sorry really. If you have a manual engine fan switch, try turning it on for the extra drag on the motor... I drove an IH (piece of crap) with a Cummins ISM motor...ran good for what it was...and after so long on the jake the brain would kick on the engine fan.
    Ever wonder how a blind person knows when to stop wiping?

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    #20 OFFLINE   rhasler

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    Posted 26 June 2010 - 10:39 PM

    Better safe than sorry really. If you have a manual engine fan switch, try turning it on for the extra drag on the motor...

    Something I meant to say earlier is that the fan can be set to engage with the engine brake in VMAC III programmable parameters.
    "Mebbe I'm too ugly and stupid to give up!"




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