Cummins Block Heater

[mjurgen889]

We recently purchased a very well maintained '05 Horizon with a Cummins 400HP diesel. We live in the Memphis, TN area. While it doesn't get too cold here, it does periodically go below freezing. I plan to periodically visit the coach in storage to start things up, run them awhile, watch some TV and then shut it down. When should I turn on the heater prior to starting the engine?

Thanks and Happy Thanksgiving! - Maiden voyage is the week of Dec 4th to the Gulf Coast.

[GaryKD]

Hi mjurgen889,
Consider not doing what the OP mentions. Starting an engine and letting it idle a while will not help and may hurt it. Call Cummins and verify this. When I lived up north the coach was put to sleep and stayed that way until I was going to use it.

The generator is a different story. If you want, start the generator and run it for 1 hour with 1/2 or more load on it.

To answer your question, I turn the block heater on the night before using the engine when the temp will go below 60 degrees F. Every engine is different. If I don't do this my Cummins will start hard with rough idling and smoke out the exhaust until it decides it has pouted enough. Some say they do not use the block heater until the temp gets much lower. Experience will tell you what your engine likes. Once learned, go with it.

[Mike Thomas]

Letting one idle is not a good idea. The temperature never really gets high enough to burn all the fuel. The extra fuel then washes down the cylinder walls, causing extra wear. The oil gets diluted with the fuel, so other parts suffer from poor lubrication, and moisture gets trapped in the engine. If you are going to take if for a drive and get it warmed up good that is one thing. Starting it up and letting idle, is worse than a waste of time.

[Mekanic]

I kinda agree either run it and then drive it or don't start it at all. if you must do a cold start below 40'F 20 min is suffient time to let the block heater work.
Starting the gen set and charging all batts is a good idea.
There is a reason for many many years OTR truckers let thier engines idle at the truck stops and rest areas. Cold starts are not the best thing for diesels.

[mjurgen889]

Thanks guys - that's the kind of information a rookie needs. I did read that if you let the engine "sleep" for more than 30 days, Cummins recommends disconnecting a particular wire to the fuel control and motoring the engine over in order to pump oil to the bearings to insure they are lubricated prior to actually starting the engine. Comments on that idea?

[mackpeteno]

Quote:

Originally Posted by mjurgen889 Thanks guys - that's the kind of information a rookie needs. I did read that if you let the engine "sleep" for more than 30 days, Cummins recommends disconnecting a particular wire to the fuel control and motoring the engine over in order to pump oil to the bearings to insure they are lubricated prior to actually starting the engine. Comments on that idea?

There is really no need to disconnect the wire.If your engine has not been started in a while.You will probably notice that it will start and die instantly.It will start without oil pressure but will not run.My opinion.

[Mekanic]

My Ford truck that has a Cummins has safety system for both oil pressure, coolant temp and coolant level. It has like a 20 sec delay so it can start. When you just turn the key it has a very annoying chime. My truck has 111K miles on the odo and it makes oil pressure in about 5 secs on a cold start. So its nothing I worry about.

[GaryKD]

Hi mjurgen889,
Remove no wires. Do not touch the engine until you are ready to drive the coach. Don't make this harder than it needs to be. Cummins and Allison are almost bullet proof. Make sure the engine oil and filter (fuel filters too) are changed as you put her to bed. Let her sleep until you're ready to travel again.

[ottffss]

Do what GaryKD is trying to tell you. It is exactly right. KISS is also very good advice. Don't be intimidated by these motors.

When/how long the block heater is a personal preference as Gary has said. Many follow the easiest advice and turn it on the night before a departure if it is going to be "cold" (however you define it) that night.

Me? I only tend to run block heater for an hour or so before starting when it stays below 35F or so. I've done sustained -15F starts and will run it longer in those cases (maybe a couple hours to overnight whichever is easiest). If I am WalMart-ing on a winter run where it stays below 20F (and all the way down to -35F), I'll run the engine preheat off the AquaHot all night instead of starting the generator for the electric block heater (you may not have this feature).

I've started my dead cold Onan diesel generator as low as -20F. It isn't a pretty sight for a while (it's actually a frightening sight), but it will start and run that cold. Let it warm enough to stop belching smoke before you load up the genset though.

[stuhly]

Best to run the block heater on some else's meter. When it's cold they like electricity.

[mjurgen889]

Great stuff - thanks Guys!!! Happy Thanksgiving and safe driving to you!

Mike

[Mekanic]

Quote:

Originally Posted by stuhly Best to run the block heater on some else's meter. When it's cold they like electricity.

Yes most OEM block heaters have something like a 600W elemant.
When I had my towing service most calls were between 1AM and 6AM.
So when I parked my tow truck I had a light timer set for 11PM-6AM That way it kept my electric bills in line.

[JBDISCOVERY]

Question: My block heater for my ISB 275 HP cummins has a short. Trips the ac circuit. How difficult is it to remove it from the engine? What does one need to watch out for? Will the block drain?
Thanks for your help.
JB

[sc3283]

double check you wiring to the heater...many times they are not secured properly and can get an abrasion. While it could be the heater itself...most heater failures end up with the heater not working period...not creating a short.
Are you sure the outlet it is plugged into is not being used by some other heavy electrical drawing appliance?
Most heaters can pull up to 14 amps...this doesnt leave much for other items if on a 15 or 20amp circuit