Long steep grade

[Cuda67bnl]

My exhaust brake is always on. Won’t hurt a thing.

[RobRoy]

Originally Posted by NWCycle

Just a sidetrack question,
I have a 8.3 Cummins
Just got back from a trip from the smokiies,
I do the brake and release as not to overheat brakes, I even tried to used the lower gears and for some reason that didn’t seem to work
If I use the exhaust brake, will that cause any type of excessive issue or damage?
I just replaced an exhaust manifold recently, not sure why it cracked, assuming it was bad design

Read post #12 here twice by YC1 ...it is dead on IMO

Happy Trails

[YC1]

The exhaust brake is built around the system engineering. Whatever type you have, use it.

Go down a long summit such as I 80 going into Truckee Calif and you could get some hot brakes in a hurry.

Watch the trucks descending while traveling in the right lane with their emergency flasher on and remember you too are a massive rig with the same braking systems.

Enjoy that beautiful view as Donnor lake glistens in the distance versus white knuckling and hoping those wheel thingies do all the slowing down for you.

[oldguy70]

You need to use the exhaust brake on the hills, it won't hurt the engine.
I don't use the brakes to keep my speed down on hills I just use the
exhaust brake and gears. The steepest hill I have gone down is 18%
and I used 1st gear and the exhaust brake and that held it without
brakes. If you overheat your brakes you will be going for a wild ride.

[dca81]

Quote:
Originally Posted by NWCycle View Post
Just a sidetrack question,
I have a 8.3 Cummins
Just got back from a trip from the smokiies,
I do the brake and release as not to overheat brakes, I even tried to used the lower gears and for some reason that didn’t seem to work
If I use the exhaust brake, will that cause any type of excessive issue or damage?
I just replaced an exhaust manifold recently, not sure why it cracked, assuming it was bad design

Read post #12 here twice by YC1 ...it is dead on IMO

Happy Trails

Maybe so for a Cummins but my prior MH was a CAT 3126 with an exhaust brake. I found that if I left the exhaust brake on for long grades I would overheat the head (backing all gases/heat into the head) and it would go into limp mode. The engine temp gauges always indicated the engine to be cool coming down the grade. But once to the bottom I would get no throttle response and would have to pull over and reset the engine (turn off and restart). After I figured the issue out I would occasionally turn the exhaust brake off and on during the downgrade to let the head breathe. May not be an issue with the Cummins because dealing with a bigger engine/better exhaust brake?? Just my experience.

[RoadTrip2084]

Originally Posted by dca81

Quote:
Originally Posted by NWCycle View Post
Just a sidetrack question,
I have a 8.3 Cummins
Just got back from a trip from the smokiies,
I do the brake and release as not to overheat brakes, I even tried to used the lower gears and for some reason that didn’t seem to work
If I use the exhaust brake, will that cause any type of excessive issue or damage?
I just replaced an exhaust manifold recently, not sure why it cracked, assuming it was bad design

Read post #12 here twice by YC1 ...it is dead on IMO

Happy Trails

Maybe so for a Cummins but my prior MH was a CAT 3126 with an exhaust brake. I found that if I left the exhaust brake on for long grades I would overheat the head (backing all gases/heat into the head) and it would go into limp mode. The engine temp gauges always indicated the engine to be cool coming down the grade. But once to the bottom I would get no throttle response and would have to pull over and reset the engine (turn off and restart). After I figured the issue out I would occasionally turn the exhaust brake off and on during the downgrade to let the head breathe. May not be an issue with the Cummins because dealing with a bigger engine/better exhaust brake?? Just my experience.

Interesting. On my (Cummins) C8.3 (mechanical) using my exhaust brake actually cools the engine faster, or so it seems.

Though the manual states that using it when the engine is cold will help warm it up faster, I've often found that if I'm at say 200 deg. at the top of a large hill, then on the downside as soon as I've got the exhaust brake activated the temp drops back down to 180 in no time.

[Cuda67bnl]

Originally Posted by RoadTrip2084

Interesting. On my (Cummins) C8.3 (mechanical) using my exhaust brake actually cools the engine faster, or so it seems.

Though the manual states that using it when the engine is cold will help warm it up faster, I've often found that if I'm at say 200 deg. at the top of a large hill, then on the downside as soon as I've got the exhaust brake activated the temp drops back down to 180 in no time.

When the exhaust brake is activated, it makes the transmission downshift, which raises the rpms. Higher rpms spins the water pump faster, which helps cool quicker.

[wolfe10]

Originally Posted by Cuda67bnl

When the exhaust brake is activated, it makes the transmission downshift, which raises the rpms. Higher rpms spins the water pump faster, which helps cool quicker.

Correct.


With throttle closed, no fuel injected, so no "heat source".


Water pump turning faster at higher RPM sends more coolant through the radiator.



Yes, on descent, with exhaust or engine compression brake, engine temperature should return to thermostatic control.

[RobRoy]

Originally Posted by dca81

Quote:
Originally Posted by NWCycle View Post
Just a sidetrack question,
I have a 8.3 Cummins
Just got back from a trip from the smokiies,
I do the brake and release as not to overheat brakes, I even tried to used the lower gears and for some reason that didn’t seem to work
If I use the exhaust brake, will that cause any type of excessive issue or damage?
I just replaced an exhaust manifold recently, not sure why it cracked, assuming it was bad design

Read post #12 here twice by YC1 ...it is dead on IMO

Happy Trails

Maybe so for a Cummins but my prior MH was a CAT 3126 with an exhaust brake. I found that if I left the exhaust brake on for long grades I would overheat the head (backing all gases/heat into the head) and it would go into limp mode. The engine temp gauges always indicated the engine to be cool coming down the grade. But once to the bottom I would get no throttle response and would have to pull over and reset the engine (turn off and restart). After I figured the issue out I would occasionally turn the exhaust brake off and on during the downgrade to let the head breathe. May not be an issue with the Cummins because dealing with a bigger engine/better exhaust brake?? Just my experience.

A few years ago I drove my friends RV with a Cat 3126 from Ohio to the Keys and back with the Exhaust brake on with no issues as you describe.

I driven my 500ISM in the Rockies from B.C Canada to NM. more than once with no issues and with using the Jake 99.9% of the time in as low as 2 gear for very long periods.

I don't speak Diesel nor CAT-3126 for that matter but that said my common sense filters tells me that if CAT sold power train that was meant to overheat the head using the Jake brake for extended periods from the factory they couldn't get past the Government National Highway Safety folks and been reported here
( https://www.nhtsa.gov/recalls) and that if for some bizarre reason CAT did get around it ( not a chance) and did? they would have warning signs and flashing warning lights come on when you went to use it.

Please don't get me wrong, I believe your story and what you seen, but I would bet the farm that your system was not meant to operate the way you describe from the factory and that it was not your cylinder head overheating from your exhaust brake causing your issue.

There was some other underlying issue that was not discovered and was truly the issue causing it to go into limp mode.

Did anyone check data or for fault codes the on that CAT-3126 PCM /ECM with a factory level scanner when doing so?...or any scanner for that matter?

How did someone determine the cylinder head was overheated using the exhaust brake ( on decel ta boot) but yet the cooling system was running normal?


Happy Trails

[YC1]

I agree RobRoy.

Maybe an exhaust manifold leak when back pressure was applied do to the exhaust brake. Could have been breathing on the head ?

[777 Driver]

Originally Posted by YC1

One other thing he suggested. Using the service brakes in a daily flat drive that the slack adjuster might not get adjusted automatically.

I found my front brakes had not contributed much to my stopping on that hill based on the lack of heat coming from them. I adjusted them manually and since then I step on the brakes hard several times doing the air down check and when dumping air.

Myron, you give great advice for a long descent.

Regarding slack adjusters, automatic slack adjusters were mandated on all new vehicles manufactured on or after October 1994.

A properly adjusted and working automatic slack adjuster will keep the brakes adjusted throughout the brakes friction materials life.

A very well qualified service technician shared his recommendation for automatic slack adjustment. On a level surface before the first drive of each day, release the parking brake. Perform 2 or 3 full service brake applications. This allows the rear drum slack adjusters to automatically adjust for proper brake force application. Note: Disk brakes automatically adjust under normal braking.

This procedure should keep your automatic slack adjusters properly set so that when needed, your drum service brakes should operate properly.

Take care,
Stu

[YC1]

I think my favoring the exhaust brake versus the service brakes over time let my front brakes get out of adjustment.

Learning to exercise them by pressing them hard when airing down has prevented any further issues.

I keep things well lubricated. It has been a lot of years but I seem to remember crawling under the coach after a good cool down and physically adjusting things.

Never any issues after that but I learned to keep it in a low gear and not rely on the brakes. Disc Brakes would be great but the monster drum brakes do a great job overall and tens of millions of trucks can't be wrong.

[wolfe10]

Service brakes are for slowing you down.


Engine brake/transmission lower gears are for controlling speed of descent.


If your speed on descent is building when using of the engine brake/transmission gear use the service brake long enough and hard enough to allow you to select a lower gear.


Repeat until you have a combination that keeps your speed in check without use of the service brake (except as described here).

[oldguy70]

If you are overheating your head while using your exhaust break something is wrong
as should be fixed. There is a lot less heat generated when using the exhaust brake
then powering up a hill.