2015 Silverado 3500 dually, Exhuast Brake

[Big Dave]

Maybe someone out here can help with this question, because I am getting mixed answers from my dealer!

Can I leave the exhaust brake on all the time, whether towing or not, I think it would save on the brakes, But I don't want to cause engine problems???????

Thank you for any and all help!
Big Dave

[bsmith0404]

I wouldn't say it will hurt the engine, but I don't think you would want to leave it on. When the engine brake kicks in, the transmission will down shift to raise the engine RPMs in order to get enough exhaust pressure. There are times with light towing that I turn mine off to keep the revs down. I'll replace the brakes.

[Drew Waller]

I only use mine when I get into those 5-8 degree hills in West Virginia. It holds the load back but it revs up to 4K. I think when it revs like that it has to be using fuel so the fuel mileage might suffer a little bit. But it sure is nice going down those hills without applying the brakes on a run. I like it and turn it off when I don't need it.

[JohnD]

I only use mine when I get into those 5-8 degree hills in West Virginia. It holds the load back but it revs up to 4K. I think when it revs like that it has to be using fuel so the fuel mileage might suffer a little bit. But it sure is nice going down those hills without applying the brakes on a run. I like it and turn it off when I don't need it.

I saw a piece on you tube that stated when in tow mode with the exhaust brake on on a downgrade the fuel actually shuts off in the chevy and the motor compression acts more like an air compressor. As far as running it full time, Don't see a need, jmo

[mikebrls]

also when empty and in rain or snow it could lock up tire's briefly and cause you to loose control , and when empty and you take your foot off pedal to coast to stop sign or light it will slow you down to much and cause you to keep your foot on the gas and use more fuel

[bobbecky]

First, you need to turn the exhaust brake on when needed, it will default to off every time you turn the engine off. I will use the brake when in the mountains and not towing. When towing, the tow/haul is on as well as the exhaust brake, always. Better to use a little extra fuel, if the system causes that, than burning up the brakes. Just like on the big rigs, if you lose your brakes, you have nothing else to do but find a place to ditch it. If the manufacturer didn't think the exhaust brake should be used when unloaded, it would say so in the manual.

[bsmith0404]

Okay, to get more technical, diesels are not like gas engines in the fact that they do not have a natural engine braking when you let off the gas. The exhaust brake creates this by partially closing off the exhaust in order to build back pressure in the cylinder. Damage can occur if back pressures thresholds are exceeded. The e-brake is designed to stay below those parameters, so in theory, using the e-brake loaded or unloaded will not cause damage to the engine.

BTW, damage to the engine would occur if the parameters were exceeded because the pressures coming from the down side of the exhaust would exceed the valve spring's ability to close the valve causing piston to valve contact. So it's not from the pressures built up in the cylinder. Hope this helps.

[dm1401]

The engine brake in my ram 3500 cummins and your duramax are basically identical in design, with the ram it is recommended to run it all the time or at least once in a while. When engaged and being used it causes the veins in the variable vain turbo to slide back and forth which regulates the pressure in the cylinder which in turn causes engine breaking , the sliding back and forth helps keep the turbo internals clean and working properly. I assume it would be the same for your duramax, and i did a quick search and it seems lot of owners are running it all the time. I found slightly less MPG when using, but only because you can't coast as much.

[hankaye]

Big Dave, Howdy;

Maybe someone out here can help with this question, because I am getting mixed answers from my dealer!

Can I leave the exhaust brake on all the time, whether towing or not, I think it would save on the brakes, But I don't want to cause engine problems???????

Thank you for any and all help!
Big Dave

You might want to take notice of the signs that some locals post at the
edge of town that state "Engine Brakes are Prohibited", that does not
just apply to commercial trucks.
I don't think it would hurt your engine ... but it may hurt your wallet.

hankaye

[Javi]

I can see no earthly reason to drive around with the Jake switched on.. Use it when you need it, turn it off when you don't. You ain't gonna save the brakes that-a-way.. The Jake is to provide extra braking when needed, not to be your brake.

[bsmith0404]

Javi, too much time in the big rigs :p

Just so people don't get confused, there is a difference between a jake and an exhaust brake, although many people refer to them as the same. A true jake brake on a big rig uses hydraulic pressure to change the valve opening timing essentially turning the engine into an air compressor with no power stroke (exhaust valve opens before TDC on the compression stroke). An exhaust brake simply closes off part of the exhaust pipe or turbo, creating pressure down line from the engine. When the exhaust valve opens under normal timing the pressure is forced back into the cylinder.

Most city ordinances will say you cannot use a compression brake which is a jake brake. Not sure if they would write a ticket for using an exhaust brake. Technically, it's not a compression/jake brake, but that is splitting hairs. I don't know if I'd want to try to argue that case with a judge.

[Javi]

Its the noise they don't want, if the exhaust goes to popping, the law will go to writting..

[bsmith0404]

Its the noise they don't want, if the exhaust goes to popping, the law will go to writting..

Exactly, but these trucks aren't loud when the exhaust brake kicks in. A little louder than normal, but nothing like the popping of the jake brakes that you can hear for blocks. At least with the duramax, I don't know that I've ever heard a ford or dodge.

[Desert185]

I use the EB at will in my mountain environment...empty or loaded. It doesn't hurt a thing. You will adapt its use to your style of driving. Its a great energy management tool that will save your brakes, if used properly. It also quickens warmup in the mornings.

I have a stick, so downshifts aren't an issue for me, unless I want one.

[2014301ktmhauler]

Just so people don't get confused, there is a difference between a jake and an exhaust brake, although many people refer to them as the same. A true jake brake on a big rig uses hydraulic pressure to change the valve opening timing essentially turning the engine into an air compressor with no power stroke (exhaust valve opens before TDC on the compression stroke). An exhaust brake simply closes off part of the exhaust pipe or turbo, creating pressure down line from the engine. When the exhaust valve opens under normal timing the pressure is forced back into the cylinder.

Very well explained by Mr. Smith.

[danisr1]

I only run mine when towing. I also don't live in hill or mountain country by any means.

Running with it on while not towing doesn't make for the smoothest ride either.

[LittleJoe]

Run the exhaust brake all the time except of on slippery or wet roads. It is not lould and the difference is barely audible outside the truck. Keeping it excercised is the key to not having turbo issues.
The "brake" is a variable vane turbo that chokes down to create backpressure, not the old style butterfly valve in the exhaust after the turbo.

The Dmax brake will not hold a candle to the Ram brake(have used both) in holding back a heavy load. Both are a large step forward from not having one.

[bsmith0404]

The Dmax brake will not hold a candle to the Ram brake(have used both) in holding back a heavy load. Both are a large step forward from not having one.

Interesting that you say that, mine holds back 15k lbs without any problem on some pretty steep grades out in Colorado and Wyoming. I also saw comparison tests somewhere and the dmax held constant speed better than Ford and Dodge.

[danisr1]

http://truckyeah.jalopnik.com/2015-silverado-sierra-2500-hd-4wd-crew-cab-the-truck-1515047393

The part on the exhaust brake:

But I'll move it along... it's a heavy duty truck, and you want to know what it can tow.

GM took us out to mountain they call "Rye Grade," where they claimed they do development work on their big trucks. They had a base 2014 F-250 6.7 Power Stroke, an equally spartan Ram 6.7 Cummins and a range-topping 2015 Silverado 2500 LTZ 6.6 Duramax for us to run up and down the hill with 10,000 pounds of trailer behind each.

GM told us everything was as spec'ed out as possible for towing, though obviously the experience in the leather-soaked Silverado was more pleasant than the work rigs.

Our first test was down the hill; each truck had exhaust brakes active and cruise control set to the 55 MPH speed limit. I drove both the F-250 and the Silverado myself, and I can confirm that the Blue Oval was running away on me all the way down the hill. The Ram was a little easier to manage, but only The General's Silverado required zero pedal input whatsoever.

Chevy cleaned up on the climb too — from a rolling start at about 25 MPH, the bowtie buried both of the other two trucks over and over again.

[Desert185]

Within the story was this:

"It's an exciting time to be talking about trucks— every automaker is bending the throttle on innovation in the utility segment and it's all-out war to be king of every comparison. GM impressed me with their intelligent cruise control, but Ram's Nick Cappa wanted to address some things I might have missed.

One of my favorite features about the Silverado 2500 was its ability to lock speed at the 55 MPH posted limit up and down some serious grading. The Ford and Ram ran away, but Cappa explained that Ram's "smart exhaust brake," which modulates itself based on towing weight and vehicle speed, would have been effective at the higher speeds drivers would be more likely to travel. He also mentioned the smart-brake might not have been active in the test vehicle we were driving. Unfortunately, I was ignorant of such a feature's existence when I rode in the Ram so that's a mystery for another day.

As for the results of the drag race, Cappa naturally cited the difference in gearing across the three trucks. True, but the trucks were set up as equally as they could be based on what's available in the market. Granted, GM selected the size they'd perform best at. But wouldn't you?

The last, and maybe most significant, issue he wanted to discuss were the claims GM made about the Ram and Ford heavy-duties limiting the torque output in 1st and 2nd gear.

"Well, what does that say about their engines?"

Cappa was keen to suggest he reckoned that the Ram 2500 applied more power in first even with limited output. Now that's a stat I want to investigate... hopefully someone will lend us a dyno soon."

End...

There might be more to the article that wasn't disclosed, in all fairness. I will also add that the Chev/GMC is a great truck. It would just be nice to know ALL the details...like rear end ratios, etc.

To relate a personal experience, I rolled down an 8% grade from 10,000' in Colorado with the SRX at ~11,000# a few months back. The radar enforced (and it was) speed limit was 45 MPH. With exhaust brake armed, I started down after the climb up in fourth gear. Fifth wouldn't hold the speed, but 4th held 45 MPH all the way down without adding power or touching the brakes. Every diesel, regardless of make needs an exhaust brake in the mountains. I can't imagine having to join the "brakelight brigade" going downhill in the mountains with a trailer that grosses at 12,650#, or even higher as some are.

[bsmith0404]

I saw another comparison a few years back (2012ish) that showed the same results as the write-up listed for the exhaust brake. More recently I saw a test for 2014s that compared them on level ground towing 10k lbs in a 60 to 30 mph test. It took GM and Dodge an identical 19 seconds to slow the load down, Ford was 28 seconds. One thing I noticed was the Dodge slowed quicker initially, but then evened out with the GM. How valid is an exhaust brake test on a level road vs in the mountains??? That's up to everyone to decide for themselves.

Back to the OPs original question, I've seen where Dodge recommends using the brake to work the turbo veins. Others have mentioned that as well. Personally, when I watch the vein movement on my Edge CTS they are working/changing constantly, not sure how using the brake to "work" them is any different. With the design of these, I think it's obvious that it's not going to hurt anything, but as some have pointed out, it does have some side affects that may make you want to turn it off from time to time.

[Ram189]

I only run the engine brake when I tow in the hilly/moutainous terrain.

Around town and daily driving it gets turned off. I asked one of the Chrysler engineers about it when I was a Dodge/Ram service director and they said that would be the way to run it if they owned it.

[LittleJoe]

Interesting that you say that, mine holds back 15k lbs without any problem on some pretty steep grades out in Colorado and Wyoming. I also saw comparison tests somewhere and the dmax held constant speed better than Ford and Dodge.

I have towed to Florida and return with a 11 3500 DMax 4x4 DRW towing a triaxle 5th at 16K. Did same trip with same trailer with 13 3500 Ram DRW 4x4. I stand by my comments that the Dmax is a big step below the Ram in the ability of the ex brake , not just in long down hill grades but in normal speed reduction at lights etc.

The Dmax is not bad, it is just not as strong as the RAM. It is far and away better than not having one though.

[bsmith0404]

I have towed to Florida and return with a 11 3500 DMax 4x4 DRW towing a triaxle 5th at 16K. Did same trip with same trailer with 13 3500 Ram DRW 4x4. I stand by my comments that the Dmax is a big step below the Ram in the ability of the ex brake , not just in long down hill grades but in normal speed reduction at lights etc.

The Dmax is not bad, it is just not as strong as the RAM. It is far and away better than not having one though.

Not disputing your experience, just find it interesting. I have run through the mountains/hills in CO, SD, WY, and now southern MO with mine towing 15k. When I set the cruise and the exhaust brake, it holds the cruise control speed within 2-3 mph. Doesn't get much better than that. I've had the same experience on both my 2500 and 3500 dmax, only difference is the 2500 was only towing 12k. Older comparison tests showed the GM was better, recent comparison tests show them about equal which goes along with everything I can find that they are similar designs. Of course, these systems advance each year just like everything else. Maybe your experience has to do with a 2011 GM and a 2013 Dodge.

[LittleJoe]

Maybe the 15 Dmax has been improved. The 13 Ram was the 1st of the new trucks with the Aisin. A lot of these things can somewhat be addressed in manipulation of ECU programming. I also read that both performed better than the Ford version but have never been in one with brake engaged under heavy load.

I am speaking more to the ability to hold the road speed from increasing on substantial down grade and also to holding load back when coming to a stop. The latter is where the biggest difference was observed.

I actually never use cruise in the mountains and I see this is a large factor in your reference. Guess we are talking about the same thing only different;).

[bsmith0404]

An interesting point that I want to share. I typically don't use my exhaust brake when not towing, but since this thread started I've been experimenting with it. I noticed that my EGTs drop much quicker when using the exhaust brake. They drop to below 400 almost as soon as I let off the accelerator. They don't take long to drop normally, but it is quicker using the exhaust brake. Assume that is due to already cooled exhaust that is down the pipe getting forced back to the cylinder having a cooling effect on the new shot of hot exhaust.

[Desert185]

Mine is just the opposite. The EGT probe is between the turbo and the engine in the exhaust manifold, and of course the exhaust brake is downstream from the turbo. That's one of the reasons the engine warms faster with the exhaust brake actuated. Your probe must be in another location, maybe downstream from the exhaust brake.

[bsmith0404]

Mine is just the opposite. The EGT probe is between the turbo and the engine in the exhaust manifold, and of course the exhaust brake is downstream from the turbo. That's one of the reasons the engine warms faster with the exhaust brake actuated. Your probe must be in another location, maybe downstream from the exhaust brake.

My probe is right after the turbo. I'm curious what a pre-turbo probe would show. I can't imagine that it would be that much different than the post turbo probe, the turbo can't have that much of an effect on cooling the gases. I actually have 4 different probe locations, I haven't checked the ones further down the line since I'm only concerned with the EGTs near the turbo. Since the turbo is used for the exhaust brake, I guess that would be considered post brake for the probe.

[danisr1]

I own a 2015 Chevy and I cant speak on the Dodge, but every write up you read on the new HD line praises the exhaust brake/ cruise control set up and the ability the Chevy/GM has of holding a speed downhill under heavy load.

I am sure the Dodge is the same way, and in 2011 it may have been different. Technology and stuff changes pretty quick in todays automotive world.

[Desert185]

My probe is right after the turbo. I'm curious what a pre-turbo probe would show. I can't imagine that it would be that much different than the post turbo probe, the turbo can't have that much of an effect on cooling the gases. I actually have 4 different probe locations, I haven't checked the ones further down the line since I'm only concerned with the EGTs near the turbo. Since the turbo is used for the exhaust brake, I guess that would be considered post brake for the probe.

If the EGT probe is downstream of the turbo instead of in the exhaust manifold itself, the measured EGT will be lower. My understanding, depending on the application, is that the measured EGT could be 200dF cooler.

On thing to remember is that the Cummins is a six and the Dmax is an eight. One probe in the manifold before the turbo for the Cummins, and (I'm only guessing) for the Dmax. Perhaps the Dmax has just the one probe after the turbo/exhaust brake with accomodation for the lower EGT registered. I know some aircraft turbine engines have different internal probe locations with different EGT/TIT/ITT values based on where the temperature is monitored. The recommended EGT probe location for Cummins with aftermarket engine brakes (like mine) is in the exhaust manifold before the turbocharger turbine inlet. The EGT gauge yellow/red limit markings are based on that recommended probe location.

[Desert185]

As a followup to my last post, because the exhaust brake will cause exhaust manifold and turbocharger turbine section temperature to INCREASE because of the induced backpressure with the exhaust brake closed. That temperature increase is registered on my Cummins EGT gauge, but it would not be in your Dmax with the probe downstream of the brake itself.

For cooldown after a highway stint, one should ensure the exhaust brake is off to expedite the cooldown before shutting off the engine. There can be a 200dF difference on my system with the EB on or off after coming to a stop exiting a highway.

[LittleJoe]

Desert 185:

You are not talking about the same brake. Your truck is an add on butterfly type restriction after the turbo.

The newer trucks 2011+ Dmax and 2013+ Ram have a variable vane turbo that restricts the outlet of exhaust to cause backpressure.

turning off the brake on new trucks does not mmake it cool down slower or faster if it is at an idle

[65aircooled]

Maybe the 15 Dmax has been improved. The 13 Ram was the 1st of the new trucks with the Aisin.
Dodge introduced the Aisin transmission in 2007, not in 2013;)

[bsmith0404]

Dodge introduced the Aisin transmission in 2007, not in 2013;)

My understanding is it was only available in the chassis cab in 2007 and first became available in the 3500 in 2013 (based on Allpar.com and the history of the Aisin)

[Desert185]

Desert 185:

You are not talking about the same brake. Your truck is an add on butterfly type restriction after the turbo.

The newer trucks 2011+ Dmax and 2013+ Ram have a variable vane turbo that restricts the outlet of exhaust to cause backpressure.

turning off the brake on new trucks does not mmake it cool down slower or faster if it is at an idle

Doesn't seem like the variable vane type of exhaust brake would be as effective as the butterfly type.

[LittleJoe]

Desert 185. You are correct in that the butterfly type is stronger at very low rpm but the variable vane works very well on the road.

The issue with the variable vane is that they can soot up and get sticky/stick if they are not used regularly, which is why it is recommended to use them more rather than less.....

Also the Aisin trans that came out in 07 in the CC was upgraded for the 13 3500 to better handle the potential torque output of the HO engine if memory serves.