Go Back   iRV2 Forums > MOTORHOME FORUMS > Class A Motorhome Discussions
Click Here to Login
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on iRV2
Thread Tools Search this Thread Display Modes
Old 02-21-2015, 03:39 PM   #15
Senior Member
Smitty77's Avatar
Join Date: Aug 2010
Location: Over the next hill, around the next curve...
Posts: 3,498
Sure could be flaky gauge readings, but does not sound like it.

Steve O's advice to get the fluid sample is both inexpensive, and would tell you quite a bit about the actual condition of the cooling system. Sure would be a prudent step to take.

I also know that when I changed over to Final Charge, my all around temperature ranged dropped down some.

And in addition to these steps, I'm a fan of having as much accurate info on engine condition as possible. The Silverleaf PC option is not all that expensive in the scheme of DP ownership. And it sure provides much better and more accurate info then the standard dash gauges. As mentioned, I might just show that your chasing a non problem. Though the temperatures you reported seemed to indicate to me that the gauges were not completely in error.

Very possible that you have a mix of conditions too! So it makes it easy (NOT!) to figure.

Good luck on your next few moves, and please circle back and let us know root cause (if any).


Roo II is our 04 Country Coach Allure 40'
OnDRoad for The JRNY! Enjoy life...
Smitty77 is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free!

iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 02-23-2015, 08:10 PM   #16
Senior Member
Rich-n-Linda's Avatar
Join Date: Nov 2011
Posts: 884
Cummin ISL-400 overheating

Something a little different to check...this happened to me with our Mandalay. This is also a Freightliner chassis with the side radiator and the ISL 400.

The exhaust clamp at the exhaust side of the turbo came loose. This allowed the exhaust pipe to move away from the turbo about an inch, resulting in a massive exhaust leak...right behind the radiator! All those hot exhaust gasses swirling around under there disturbed the air flow through the radiator. The radiator was still pulling clean air from the outside, but on the output side of the fan, that cooling air met the exhaust gasses and could not clear properly.

The symptoms were that the engine would cool OK on level ground, but a long hill would cause an overheat, even if I shifted down to a lower gear to keep the revs up.

When I discovered this problem and got it fixed, the overheat problem went away.

Rich-n-Linda is offline   Reply With Quote
Old 02-23-2015, 08:35 PM   #17
Senior Member
Bumps's Avatar
Winnebago Owners Club
Join Date: Sep 2013
Location: FTer Class of 2015 Origin: Evergreen, Colorado
Posts: 1,536
I, too, had the over-heating problem on my 400ISL. Had to stop and cool down while climbing I70 westbound into the Rockies. Again and again. Did that three times and then took it to a local shop. Diagnosis was a broken lip (it was hidden under the radiator cap) on the top of the plastic surge tank. Replaced the plastic tank with a metal one and the over-heating problem went away. Was more frustrating than it cost in $$$ to repair. Ugh! \ken
Ken & Deb (WIT Club, FMCA, SKP, Harvest Hosts, and grateful volunteers with SOWERs)
2005 Winnebago Vectra 40FD w/400ISL and Allison 3000MH on Freightliner's Evolution chassis, Onan QD7500, 1000w Renogy solar, BlueOx tow gear, and 2015 Cherokee TrailHawk toad.
Bumps is offline   Reply With Quote
Old 02-24-2015, 04:48 PM   #18
Senior Member
Coma's Avatar
Monaco Owners Club
Join Date: Nov 2010
Location: The Emerald Coast
Posts: 1,757
Two things you don't mention. What is your RPM when you overheat and at what altitude.

You should operate your ISL at ~2000rpm and about 80-85% of your max boost when pulling grades. You should down shift until you achieve that operating condition.

I left Colorado last September and went eastbound to the Eisenhower tunnels. I run 2k rpm and 20lbs boost and water temp was 192F. 22lbs boost and it went to 198F. Because of the low air density temperature issues show up quickly. The tunnels are at ~11kft.
Jim and Jennie, Cats=Bittles and Potter, 2000 Dynasty 350 ISC
2013 Silverado 4x4 Towed with R1200GS in bed.
PROV23:4 Do not wear yourself out to get rich; have the wisdom to show restraint.
Coma is offline   Reply With Quote
Old 02-24-2015, 05:22 PM   #19
Senior Member
YC1's Avatar

Holiday Rambler Owners Club
Join Date: Jun 2011
Posts: 6,195
I would change the thermostat out even though they claim it was opening. Inexpensive and easy to do. The original has been replaced by a newer design. It may not be opening fully. Put the old and new one in a pan of water and heat it up. Watch as they open. You may see a difference.
Myron & Deborah
08 HR Endeavor 40 SKQ
2012 Ford Edge Limited FWD 3.5L
Aluminator tow bar, Demco base plate
YC1 is offline   Reply With Quote
Old 02-24-2015, 06:46 PM   #20
Senior Member
Tiffin Owners Club
Join Date: Apr 2009
Posts: 212
Hope I am not providing obvious info but I had an overheat problem on long pulls in my 2004 Winnebago with CAT c7 engine. It was a rear radiator. Externally, the radiator fins looked clean but the radiator in my coach was a combination of radiator and "charge air cooler" which looked like a second radiator behind the first one. This was noted in one reply above. When I took the engine cover off (from inside) and inspected the front side of the composite radiator I saw that 75% of the fins were clogged with a thick oily film. In my coach the engine breather tube exhausted an oily vapor which was sucked into the radiator fan housing and was deposited on the front face of the composite radiator. Dust stuck to the oil and the film clogged the radiator.
Before you pull the radiator pls check the inside face to see if it might be clogged. If this is the case, a thorough cleaning with 50% simple green could solve your problem as it did mine. I found that the sludge could not be cleaned from the outside but required under the coach and above the engine cleaning.

On newer coaches, the crankcase is closed and the "slobber" tube that exhausts oily vapor does not exist. Check earlier posts on thread below.

"2004 Journey with CAT 330hp overheating on long pulls"

hope this helps,
jim & debbie
jimmccreary is offline   Reply With Quote
Old 05-30-2015, 05:52 PM   #21
Junior Member
Join Date: May 2015
Posts: 17
A lot of Alpines being used and not a lot of problems with over heating so I don't think radiator size a issue. WRV was known for using quality/adequate size equipment. Cat had some problems with their aluminum radiators. Lots of great info, recommend start by replacing thermostat and go from there but gauge accuracy could definitely be the issue.. Good Luck, Great Coach..
Mklbrook2 is offline   Reply With Quote
Old 05-30-2015, 05:58 PM   #22
Senior Member
Steve Ownby's Avatar
Join Date: Nov 2008
Location: Cosby, Tn
Posts: 6,477
Originally Posted by Mklbrook2 View Post
A lot of Alpines being used and not a lot of problems with over heating so I don't think radiator size a issue. WRV was known for using quality/adequate size equipment. Cat had some problems with their aluminum radiators. Lots of great info, recommend start by replacing thermostat and go from there but gauge accuracy could definitely be the issue.. Good Luck, Great Coach..

Agree that WRV was a quality coach builder but as they build their own chassis (Peak), they supplied the radiator package. The engine builders give minimum requirements but they don't provide the cooling equipment.

Steve Ownby
Full time since '07
Steve Ownby
Full time since 2007
2003 Monaco Signature
Steve Ownby is offline   Reply With Quote
Old 05-30-2015, 09:03 PM   #23
Senior Member
Join Date: Feb 2010
Posts: 623
Have you checked to make sure your fan is coming on high when you are overheating? I would disconnect the ground to your direct fan control and see if it goes to high speed.

2008 Thor, Four Winds Mandalay 40G. Cummins 400 isl. Freightliner chassis
koda59 is offline   Reply With Quote


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Cummins 400 ISL Overheating Problem JLAppel Class A Motorhome Discussions 16 10-17-2016 08:07 AM
ISL 400 error 233 12 controller 2 Dupdyke Monaco Owner's Forum 2 08-11-2014 09:51 AM
2 fuel filters on 04 400 ISL TS04 rhusak Travel Supreme Owner's Forum 3 06-15-2014 11:11 AM
Change the Fuel Filter on an ISL 400 gemini5362 Tiffin Motorhomes Owners Forum 7 02-08-2014 07:27 PM
Isl 400 ecm codes Dupdyke Monaco Owner's Forum 4 09-12-2013 07:16 PM

» Featured Campgrounds

Reviews provided by

Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 02:54 AM.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2018, vBulletin Solutions, Inc.