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Timnjulie

2005 300-hp cummins diesel overheats easily

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Recently purchased 38' 2005 Damon Astoria M-3679 with 300 hp cummins diesel pusher. Had motor, chassis, entire RV serviced at authorized RV shop. 1st trip going up hills or exceeding 65 mph on flat roads engine guage goes to red zone (210 deg. f-220 deg. F) and warning comes on info center. Returning from trip took if to RV shop and they put in new air filter, flushed radiater, put in new coolant, no change, still overheats. RV shop says they don't know what else to do, any suggestions?

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Wish I had a good answer for you, but I can advise that you get as far away from that RV shop as possible.  What they did is sinful.  None of that would have caused your problem.  A simple thermostat may be more likely, or a fan clutch.  They wasted your money and time.  I would try to find a Cummins repair shop, usually at or near truck stops.  They know what to do and have everything there.  They keep over-the-road trucks on the road and don't mess around.  You can even join Cummins club and get discounts on parts and service.   Good luck.  Please let us know how things work out.  

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Sounds like a partially plugged radiator. I don't think any amount of flushing will fix that. I notice with mine pulling a grade on a hot day it will hit 210 to 220 but I will not get a warning light. I would definitely look for Cummins service and not a RV shop.Also usually when doing a coolant flush and change there is a air bleeder on the motor to get all the air out. That can cause it too. They most likely have seen this before.

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1 hour ago, sstgermain said:

Sounds like a partially plugged radiator.

Agree with this statement, but don't forget the CAC (charge air cooler) may need a thorough cleaning also.

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I bet you have a dirt build up on the front of the CAC and on the front of the radiator. I doubt it is a problem with the coolant (as long as the level is right). You may need to manually downshift when the temp starts to climb. This increases water flow and fan speed.

Bill

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Did I miss where that shop cleaned the radiators "sandwich" of debris and oil buildup? This is external, flushing is internal.

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11 hours ago, Timnjulie said:

Recently purchased 38' 2005 Damon Astoria M-3679 with 300 hp cummins diesel pusher. Had motor, chassis, entire RV serviced at authorized RV shop. 1st trip going up hills or exceeding 65 mph on flat roads engine guage goes to red zone (210 deg. f-220 deg. F) and warning comes on info center. Returning from trip took if to RV shop and they put in new air filter, flushed radiater, put in new coolant, no change, still overheats. RV shop says they don't know what else to do, any suggestions?

Tim, Welcome to the FMCA Forum to both of you !

  Attached are pictures of an extremely dirty Radiator and CAC / Air Cooler setup and what they look like when clean.

Cleaning them yearly is a good plan, but they do need cleaning every 2 years in most cases to keep the engine running cool. 

Note! Pictured is the setup for a rear mounted system that was way to dirty to work, the side mounted systems also need attention.

Clean things with Simple Green Extreme .  This product is made to clean Aluminium, other type cleaners can damage aluminium.  The other way to clean things is with a Steam cleaning system.    DO Not use high pressure when cleaning, this can bend the cooling fins that decreases cooling. 

     Cleaning the system is a messy  job. One can get very dirty and wet when doing it properly.

Rich.

Rardiator and CAC setup.jpg

IMAG0025.jpg

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Wow!!  I have been through this recently.  I have a 2006 Holiday Rambler diesel pusher with a 300 HP Cummins engine.  Based on my experience I would highly recommend finding a Cummins Service Center.  That being said, I've been to other shops for this same problem and at one shop to the tune of more than $3,000 had the radiator removed/cleaned/flushed, flushed engine, new thermostat, hoses and coolant.  They also checked my temperature gauge to find it actually reads a bit high.  So I added a "Scan Gauge" plugged into the motorhome computer.  On my first trip I started receiving check engine high temp warnings where I saw 233 once, upper 220s other times.  I finally found a Cummins Service Center where they quickly isolated the problem to one of two items.  I was able to eliminate one for them but the other was the thermostat (remember I have a new one already in place).  They pulled out the "new" thermostat and quickly realized that it was an aftermarket and not an official Cummins version and the difference between them was considerable.  $1250+ later everything works great and I have since driven clear across the US with no further problems.  I now only go to Cummins for my Cummins diesel work (including my Cummins generator).  This is a long story for me, very frustrating and very expensive so I have condensed it here to avoid going into extensive details.  Good luck!

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That's an expensive way to resolve the problem but glad to hear it's working good for you. Thanks alot for your feedback, I appreciate it.  I plan to take it to the Freightliner dealership that works on semi diesel engines,  I'll do what I can.  Thanks again!

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An aside to this topic;

A few weeks ago I contacted Cummins  Technical Support asking about the normal operating temperature for my engine, here is the email reply in copy N paste:

The man said he must have my engine serial# in order to locate the exact specs, as each engine  can differ from others of the same displacement, HP and torque.

"

Ray,

 

 

According to the curves and data sheet the engine should not go past 212 degrees. If it is getting 220 degrees you need to bring it into a shop so they can check it out. Have a great day.

Brent
Cummins Care Representative

SR#:  1-103373773861

If you have additional questions please feel free to respond to our support staff by e-mailing care@cummins.com or by calling 1-800-CUMMINS (1-800-286-6467) within the U.S.  Additional calling options for outside the U.S. are provided on our website.  When contacting us, please refer to the SR (1-103373773861) number listed above, if applicable. 

Visit us at www.cummins.com  or  www.cumminsengines.com 

-------Original Message-------

From: fowlerr@hotmail.com
To: TSRTechnicalSupport@cummins.com
Cc:
Subject: Re: email response \ SR#: 1-103373773861   

 

External Sender

re: my ISC engine is in a 40' motorhome; the CPL is 2695, serial # 45902455. I tow a 2013 Chevrolet Silverado K1500, that weighs close to 5,600lbs. The coolant temperature will reach 220° pulling long mountain grades on hot days, but returns to just below 200° after cresting the mountain. Is there a maximum time for the engine to stay at 220°
I was told it will harm a diesel engine to reach 220°, thought I should ask the experts who build the engines.
 
 

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Tim, Think your coach has a 6.7,but it could be a 5.9 and they are a little easier to change the thermostat.

The 2004 engine did not require an EGR system and the 2005 engine has the EGR valve and the cross over pipe sits above the thermostat and needs to be removed, to get to the thermostat.

The video link is for a Dodge truck 6.7 replacement. The hardest part might be getting to the engine on the RV. Not sure what might be in the way and how tight it is on your coach.

Watch the video it does point out the process wrench sizes and do not loose the gasket(s) used at the EGR line couplings.

 The video does show the seal failure on the top of the thermostat.

Hope you can get to it without to many issues.

Because of the engine being turned around, whats on the left in the video is on the right as you work on the coach engine.

Rich. 

 

 

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I replaced the thermostat with  Cummins part, cleaned CAC and radiator good.  Started engine and immediately got stop engine light and alarm, did I trap air?  I vented radiator thru upper petcock until I got coolant for a few seconds and had heater running. Noticed temperature guage did not move either. 

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Did you pull radiator and CAC off to clean them.  If you can, remove the thermostat and fill the engine with antifreeze until level with thermostat opening then reinstall thermostat.  Afterwards fill as much as you can with antifreeze then you have less chance of air pockets.  

 

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I ended up up venting thru the air bleed on top of the 'stat housing. and added more coolant.  No more alarms! 😀 Test drive on freeway and temperature remains on the cooler side of normal at75 mph and on grades. So new Cummins thermostat,  clean CAC, clean radiator, no more high temperatures.  Thanks everyone from rookie RVers!

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