john_harris Report post Posted May 7 Have 2007 Holiday Rambler Endeavor with 400 HP Cummins ISL with 88,000 miles, original owner. Started experiencing overheating issues on return trip from Pacific Northwest while outside temps were 103 to 105. Started seeing engine temps running in 220 range on even moderated grades but only at 224 did check engine light come on till cresting grade however in the 205 to 208 degree range i started experiencing engine derating or loss of power on grades. As I had filled up with biodiesel for first time on Washington State, thought may have fuel filter issue so had them changed in Utah. Problem persisted but i limpen back to WV and immediately went to local Cummins Engine Service Center. Diagnostic codes only showing overheating issue but had cooling system checked out and flushed, new fuel filters again, fan checked out, water pump and t'stat replaced, and a sensor that is tied into engine derating replaced. Derating problem continues. engine preforms great on level grades and generally temps do not get extreme until heavy grades. On even moderate grades the stop engine light is coming on at anywhere from 197 to 210 and a significant loss of power starts to occur on moderate grades. on one extreme grade i did have engine temps exceed 224 and Check engine light came on as temps went to 228 before cresting hill. pull the hill only maintaining 25 miles per hour. again limped home home ant took it to Cummins. they seem to be at a loss. I question EGR but their diagnosis seems to point to no issue. Anyone else experience similar issues or have thoughts to point me in a direction. Share this post Link to post Share on other sites
wildebill308 Report post Posted May 7 Is that a side or rear radiator coach? Are you manually down shifting on the hills? Do you have the "Econ" button on the transmission on? Bill Share this post Link to post Share on other sites
john_harris Report post Posted May 7 Bill, Yes this is a rear radiator coach. yes I tried manually downshifing to keep RPM at 1800 to 2000, as well as leaving it on automatic. and no, I do not use econo setting on trany. For first 16 years no problems with overheating unless radiator was choked off with dirt and debris but even then no derting until temp reached 228 to 230. Share this post Link to post Share on other sites
rayin Report post Posted May 7 I would use Simple Greene Extreme to clean the radiator fins and the entire "sandwich" of cooling radiators.. Only the Simple Green Extreme is safe for aluminum. FWIW, you may want to read this tutorial on the Allison Econ-mode feature. You will need to sign in again for the Diesel Club forum. https://forum.dieselrvclub.org/index.php/topic,4960.msg7180.html#msg7180 Share this post Link to post Share on other sites
wildebill308 Report post Posted May 7 Ray beat me to it. You cleaned the inside of the radiator but getting the outside and especially between all the stacks cleaning may help. Just be carful that you don't use to much pressure and damage the fins. Bill Share this post Link to post Share on other sites
wayne77590 Report post Posted May 8 Have you checked the CAC (Charged Air Cooler? Has it been cleaned out? I would expect that Cummins would have done that when you brought it to them. Share this post Link to post Share on other sites
elkhartjim Report post Posted May 8 I would check the diesel exhaust particulate filter. If it is clogged it will cause these symptoms. Share this post Link to post Share on other sites
john_harris Report post Posted May 9 Radiator has been cleaned inside and out. CAC has been cleaned also. we will confirm if Diesel Exhaust filter has been cleaned or replaced but i feel they have looked at this too. Share this post Link to post Share on other sites
wildebill308 Report post Posted May 10 I would think the 2007 is before the exhaust filter. Easy to tell just look. The filter is much bigger and more complicated. Bill Share this post Link to post Share on other sites
