Engine Retarder

[ccmsm]

I"m new to the diesel world. We've only had one since January.  My question is does it cause a problem if I leave the engine retarder on. I forgot and left it own a couple times and drove about a hundred miles each time with it on.   Thanks,  ccmsm

[larryanelson]

If you are referring to a Jake or exhaust brake, I leave mine on all of the time, except in rolling country with the cruise control on.  Driving in Californa 55 MPH speed limit it is on all of the time $400.00 plus ticket for 62.

[dickandlois]

CCMSM!

Not really an issue, when the cruise is set and you are going down hill you need turn off the cruise (just need to tap the brakes and it will engage. ON a steep down hill grade, the CAC(intercooler) temperature can go up and you might get a yellow check engine light so keep applying enough braking so retarder is not doing all the work keeping ones speed down.  

Rich.

[rossboyer]

Mine is on all the time unless there is a sign that says NO EXHAUST BRAKES.  Some towns post that.

[wolfe10]

1 hour ago, DickandLois said:

CCMSM!

 ON a steep down hill grade, the CAC(intercooler) temperature can go up and you might get a yellow check engine light so keep applying enough braking so retarder is not doing all the work keeping ones speed down.  

Rich.

Rich,

Have you actually observed intake temperatures rising when on the exhaust brake?  I don't have an intake manifold temperature gauge, so just asking.

But, not sure it makes sense.  When throttle closed, there is zero boost. So no compression of air by the turbo and only a small amount of intake air of any kind (as the exhaust brake limits air movement in/out of the engine.

Interesting to see of that theory translates in real life.

[tbutler]

I get an engine warning light if the engine brake is on for an extended time.  I've replaced several exhaust manifolds and the last time in the shop I asked if use of the engine brake could be causing this.  The answer from the Cummins tech was no.  He said the exhaust temperature would be lower when the engine brake is engaged.

Our brake functions differently than some others.  I can't set the cruise with the engine brake set.  When I use the engine brake it cancels the cruise and it must be manually engaged.  I've driven behind people who have the cruise and the engine brake set and their brake lights come on on every downgrade.  I like to coast downhill until I reach the speed limit (for our toad that is 65 MPH) then if necessary I'll use the engine brake to maintain that speed to the bottom of the hill.  If you can drive without using the brake (safely of course), you'll get better fuel mileage.  Every use of the brake is taking taking energy (inertia) out of the system that you have used the engine (fuel) to put into the system.

[wolfe10]

Tom,

Yes, with exhaust brake or engine compression brake (the ISL is the only engine that could be ordered with either) EGT's will be lower.  With a closed throttle, there is ZERO fuel injected.  No fuel, no fire, less heat.

On LONG grades, you can even notice that coolant temperature drops below thermostatic control, as a few minutes with zero fuel/zero fire WILL cool down the engine.

[dickandlois]

1 hour ago, wolfe10 said:

Rich,

Have you actually observed intake temperatures rising when on the exhaust brake?  I don't have an intake manifold temperature gauge, so just asking.

But, not sure it makes sense.  When throttle closed, there is zero boost. So no compression of air by the turbo and only a small amount of intake air of any kind (as the exhaust brake limits air movement in/out of the engine.

Interesting to see of that theory translates in real life.

With the Silverleaf running the the intake temperatures jump from 125deg. on top of the mountain to 195 real fast to over 225 if I do not give the exhaust  the off signal. Then things cool down fast into the 120deg. range 

Now, if you have any thoughts, please pass them on. Engine has a Mechanical Bosh 44 injector pump, it just might be allowing a small amount of fuel into the engine. The thing never stops running.

Rich.

[wolfe10]

Just speculating, but wonder if your intake manifold temperature sensor is "heat soaking". That is, with significantly reduced air flow through the intake manifold, it may be picking up heat from other (hotter) metal parts of the engine.

And, fueling will return as the engine approaches idle speed.  There is just zero fueling at higher RPM's with throttle closed.

[dickandlois]

Point taken, Yes that area of the doghouse is HOT! That is why I added the Outside Air duct work to cool the Alternator. There is always something to add to the pot !

Thanks Brett, Fair winds !

Rich. 

[obedb]

CAT 330, exhaust brake, love mountains, Monarch Pass Colorado11312 ' above, a favorite of ours, absolutely beautiful and legendary, coolant temp stays normal on the pull, coolant temp  cools when dropping off the other side with the exhaust brake on but low normal with rpm about 2200. I don't get it folks that is the way it is supposed to be. Jake brake the same results . Now if you have  a CAT Brake Saver the oil temp will rise on a descent. Anybody have one? I doubt it. Not on a motorhome. They are expensive.

[jleamont]

I believe a transmission retarder is not common on an RV, I have only ever seen them on Fire apparatus used in conjunction with a compression engine brake for extreme stopping power.

i am suprised how different these operate, I have to be honest my compression brake operation is pretty annoying and little to no thought was given in its set up. My high/low switch does not work (programmed that way per the original owners request) I have to get that fixed, I also have no braking in 1st gear, which is scary when you are approaching stopped traffic, when the transmission down shifts into 1st gear the coach jumps forward, if you are not expecting it it's like an amusement park ride. While the cruise is on if the brake power switch is on it will come on everytime the cruise is not throttling the engine, this works the same way when the cruise is off so you basically have two choices, speed up or eat seat belt, when it engauges your face will go pale if you forgot it was on. 

From driving other large vehicles with compression brakes they are programmed with several parameters to avoid the issues I have, some are set to only turn on when the driver steps on the brake pedal, I have driven some that will come on automatically with no brake pedal interaction but only if you coast over a pre programmed speed which would be nice if my low setting was set to operate. My plan is to bring the lone lap top home that has Cummins Insight on it and see what setting options I have to correct the current settings.

i drive with it off unless I need it, I will turn it on, come to a stop and immediately flip it off once stopped. It will not hurt to leave it on while driving, in my case you will just loose your sanity.

my boost gauge rises with the engine brake on, my thought was all of the compression from the compression brake is spooling up the turbo it will rise to 10 psi when in operation while the engine is at 2200 RPM. 

[ccmsm]

Thanks for all the replies to my question. The only word on the switch is retarder. It works well and it gives me peace of mind knowing its there. I have lots of other questions but I'm scheduled for Frieghtliner Camp at the factory in July. Its a 2 day class and I've been told it is very informative.  Thanks again,   ccmsm

 

 

 

[dickandlois]

3 hours ago, jleamont said:

I also have no braking in 1st gear

Think that is due to the fact that the transmissions Torque converters are not locked up in Low gear.

Rich.

[jleamont]

8 hours ago, DickandLois said:

Think that is due to the fact that the transmissions Torque converters are not locked up in Low gear.

Rich.

That makes sense, hadn't given that much thought to it. 

[wildebill308]

2 hours ago, jleamont said:

That makes sense, hadn't given that much thought to it. 

The first time it happend to me I tested the brakes right then. 

Bill