Hi guys!

I'm a little confused [nothing new there regarding what to expect when towing with a diesel.

I don't have an exhaust brake. On a long down grade will I have ANY type of compression braking? Wondering if it's that I have no compression braking until the engine is up against the governor, then at max governed rpm I have a compression back pressure slowing me; or will the engine just head for an over-rev condition?

I'll have a heavy load pushing the limits of my truck and need to know what to expect. Never towed with a diesel. Not in any hurry for the trip, so can lumber along in low gears no problem, IF it will help slow me on grades.

Thanks for advice and tips...

JimmieD

 

There is plenty of compression braking at higher revs. I will go down a big hill at 3000-3200. Depends all on the load and the hill how slow it'll keep you.

 

Without going into a lot of detail a diesel engine is built for pulling, not stopping power. But will give a certain amount of braking by using good judgment (judgment is the key word) you should be OK. Make sure that your trailer brakes are working good and keep speed low on the downhill side. The best things to remember is do not go down the hill faster than you could climb it. If you are green to towing heavy loads maybe a little slower. Don’t listen to what others tell you listen to you gut and you will be OK.
If you will be doing this on a regular basis I would recommend that you install an exhaust brake as it will pay for its self in brake shoes/ pads and added safety.

 

If you are haulin' butt the wind resistance will slow you down....
I've noticed that if I want to avoid using brakes,and keep it moving at a reasonable speed then I have to gear down quite alot!
Like patrick said...made for pulling,a gas engine holds back with compression alot better than a Diesel does (Built in brake,read carb-throttlebody)
A diesel is straight through.
But as long as you are carefull,have good trailer brakes,and keep an eye out for brake smoke you'll be just fine
Good luck

 

If I remember correctly, the specs on the '03 HO engine were 74 HP in deceleration at 2800 rpm. That's not a lot. Adding the Jacobs Ebrake boosts that to somewhere around 175. Both those figures are pulling from memory and should be close, but probably not right on the money. I know one thing, no way I would pull my fiver without one.
Bob

 

Hey fiver,whats all that weigh together?
thanks
Brian

 

Thanks, guys! This is the '67 Dodge D-100 Town Wagon I did a Cummins 4BT/NV4500 conversion on. '78 Dana 60 HD 4.1 rear, '70 D-300 front axle/brakes. Going to be towing a loaded '75 Traveleze 26 footer full time.

Lots of trailer hauling experience but none-zero-zip towing with a diesel. Don't want to hurt the engine over-revving, and sure don't want a runaway load. Unfortunately the engine doesn't have a vacuum or hydraulics pump right now and couldn't find or afford an exhaust brake after all the other expenses. So, run it like it is and hope for the best I guess. Not in any hurry to get anywhere so just ambling along and gawking tourist style

 

My understanding anyway: With a four stroke engine holding back a load on a grade, it takes power from the drivetrain to push the piston up on the compression stroke as the piston acts against the rising pressure. The problem is that the same amount of power is given back to the drivetrain when the piston is on the next downstroke (powerstroke) as the same pressure pushes on the piston on it's way down.

On a gas engine in a compression braking situation, the closed throttle plate creates a vacuum in the intake which acts on the pistons resisting their downward motion on their intake stroke. (Or another way to look at it is that it takes work/energy to create and maintain the vacuum in the intake manifold, and that energy is coming from the rotating force of the drivetrain). On a diesel, there is no butterfly closing off the intake...

Anyhow, yes, you can easily run a diesel over it's safe RPM range/governed speed on a downgrade in too low of a gear...

It looks like you have a pretty modest load, though, and I doubt you will have any problems as long as the service brakes on both tow vehicle and trailer are in good condition, and you use your head.

 

As has been pointed out, diesels don't have very much compression braking. What you'll get at high RPMs is more FRICTION braking. Even with an exhaust brake I seldom get above 2600 though. Those high RPMs sound too unnatural to me.

 

Thanks for the info, guys!

Actually I will have a pretty heavy load. Being an incurable gearhead my idea of a Recreational Vehicle is one packed full of my tools. spare Dodge parts, my '74 Honda XL100 hanging off the back etc. etc. etc.

I've towed a lot with an RV but the diesel is the new part that I don't understand. I've got two main concerns: don't wreck the truck, don't blow the engine! Brakes are new on the truck and I'll be checking/testing the trailer brakes. Also I'm in no hury to get anywhere so s-l-o-w is just fine. I guess I'll avoid screamer downgrades at first until I know what to expect, and an exhaust brake is hoped for ASAP, depending on $$$$?

Thanks!

 

I guess I kind of guessed that a 26 footer is probably going to be pretty light (meaning under 12k or so).

Anyhow, if this is the first time you are towing with a diesel, be prepared to never want to tow with a gas truck again.

 

Brian,

With full fuel (86 gallons) and full fresh water (82 gallons), empty holding tanks, full propane (2 - 40's), and loaded for a 5 month trip I weigh in right around 24,000 or so.

Bob

 

Yup, there is inherently NO 'engine' braking with a diesel because of the lack of a throttle plate to limit airflow to the engine. A diesel will basically 'freewheel' when pushed downhill by a load with the available braking power being from, as stated earlier, losses to friction inside the engine and the rest of the drivetrain. Notice how an exhaust brake pretty much looks like a carb/efi butterfly---same idea, just on the other side of the engine-using a flap to limit airflow. The only caveat with an exhaust brake is that one needs to upgrade the exhaust valve springs to handle the extra pressure safely.

 

Yep - for the 12 valve engine. It's not required on the 24 valve engines.

Rusty

 

I did not know that-thanks