wolfe10 Report post Posted October 15, 2019 Look at the "reaction time" (which I am seeing as much longer than the quick reaction time of many of the side radiator hydraulic controls) and compare with what you see for coolant temperature change. Share this post Link to post Share on other sites
kaypsmith Report post Posted October 15, 2019 I have found to my surprise that not a lot of people working at diesel oriented mechanic shops do not have a clue what a CAC is, including the service writer. Therefore it is no surprise that one might get a bad diagnosis on whether it is clean or not. Share this post Link to post Share on other sites
manholt Report post Posted October 16, 2019 Kay, I have only run across one...mobil service. He does my engine, tranny & chassis now. Next service in Nov. in Frog City (Rayn, LA)! Mike, Tigers are #2 now! Share this post Link to post Share on other sites
fagnaml Report post Posted October 21, 2019 A quick update. This past Saturday (10/19/19) eldest son and I cleaned the charge air cooler / radiator from both sides even though once we accessed the CAG via the rear bathroom, it only had a fine coating of dust (the "pre-cleaning" photo of the CAG is shown below). We obtained very good water flow both directions and had clear water essentially all of the time (i.e. not enough dirt to discolor the water). . After all of that work, while driving the motorhome back to the storage facility, the engine temperature resumed its near constant 20-25 F fluctuation with the fan going into and out of high speed to lower the engine temp. I called FCCC again late Saturday afternoon and the service tech I spoke to gave me a different answer is that my engine temp should hold relatively constant. I asked him about what could cause the constant fluctuations and he didn't know. I asked about a partially stuck thermostat and his response was thermostats only get stuck in a full open or full closed position. So, thus far I've ruled out a dirty CAG or bad-acting fan clutch as the cause of the temp fluctuations. The coolant (which is the OEM fill "purple" heavy duty coolant with SCA's) test OK per the test strips. I'm still thinking I have a thermostat problem. Only other possibility is the water pump somehow not performing properly? I need the forum's expertise on what to try next. Or do I succumb to taking the motorhome to the Houston Cummins Coach Care.... Thanks for the help! p.s. In my Ventana LE, the bathroom sink is centrally located on the rear wall of the motorhome (with washer / dryer on one side and closet on the other side). Newmar did a really nice design of including an engine access door (hidden behind a cabinet panel) below the bathroom sink cabinet for easy access to clean the CAG. I didn't have to mess with pulling up the floor panel to clean the CAG. Share this post Link to post Share on other sites
manholt Report post Posted October 21, 2019 Mike, I believe your trying to over think this! Go and enjoy the Tigers! It's CAC. Share this post Link to post Share on other sites
fagnaml Report post Posted October 21, 2019 1 hour ago, manholt said: Mike, I believe your trying to over think this! Go and enjoy the Tigers! It's CAC. Help me understand how the CAC is the culprit. The CAC was not dirty except for a light coating of dust. After the thorough cleaning it looks brand new. Hence if the CAC is clean how is it causing the engine temp to continuously fluctuate 20-25 F? Share this post Link to post Share on other sites
wolfe10 Report post Posted October 21, 2019 Mike, I agree. A clogged CAC would merely limit heat transfer, so under higher loads, engine temperatures would rise more quickly than were there good air flow. It would not cause excessive temperature fluctuations under steady-state conditions (like I 10 across Louisiana-- for those not familiar with this section, it is FLAT-FLAT-FLAT). For peace of mind, might want to replace the thermostat (and gasket). It is either that or the fan clutch allowing/causing that much temperature fluctuation. As you can see, I do not think it is "normal" to have an 18 degree F temperature swing under steady state conditions. At least I would not find that acceptable. If the thermostat doesn't lessen the temperature fluctuation under steady state conditions, I would be on the phone to Horton engineers. Looking at this from another perspective, I would sure hate to be in the mountains and start up a long 6% grade with engine coolant temperature at thermostatic control PLUS 18 DEGREES F. Share this post Link to post Share on other sites
fagnaml Report post Posted October 21, 2019 Thanks for the additional contact info at Freightliner. There is decent air flow when I stand behind the motorhome with the fan is at low speed. When your clutch failed, did you have any air flow when the fan was at low speed? I made an appointment for next Tuesday at Houston Cummins Coach Care for the coolant change that is one year overdue per the owner’s manual. The very knowledgeable shop supervisor at Cummins (Justin McDonald) is also thinking a sticky thermostat based on the symptoms I’ve described. For the coolant change Justin said Cummins will use the “red” long life Fleetguard coolant for my 6.7L, 360 HP ISB engine. He said he doesn’t understand why Freightliner does OEM full with the short life “purple” coolant that requires monitoring of SCAs. Will let the forum know if Cummins finds anyother problems other than the suspect thermostat. Share this post Link to post Share on other sites
wildebill308 Report post Posted October 22, 2019 2 hours ago, fagnaml said: He said he doesn’t understand why Freightliner does OEM full with the short life “purple” coolant that requires monitoring of SCAs. My guess is that all the outher Cummins engins with cylinder liners require SCAs so it is cheaper/easier to just stock the one coolant. Bill Share this post Link to post Share on other sites
wolfe10 Report post Posted October 22, 2019 4 minutes ago, WILDEBILL308 said: My guess is that all the outher Cummins engins with cylinder liners require SCAs so it is cheaper/easier to just stock the one coolant. Bill Actually, PRICE is the only reason for using anything but one of the new-generation long-life coolant. In linered or parent bore engines, basically 6 years-- put it in and forget about it. Share this post Link to post Share on other sites
fagnaml Report post Posted October 22, 2019 During lunch I accessed Cummins Power Club to learn of any guidance Cummins provides for the my ISB 6.7L engine. I was surprised to find that in the maintenance service intervals that servicing (changing?) the coolant filter is recommended every six months. Presuming I have a coolant filter, I have to presume it has never been changed and if it is dirty that filter could be causing reduced coolant circulation which could lead to the temperature fluctuation I am experiencing. So, my latest question for the forum is do newer ISB engines have a coolant filter and if "yes" where is the filter located? Here is the link to the Cummins brochure with maintenance intervals for 6.7L ISB engines --> http://files.trypsi.com/cummins/maint_care/2013_ISB67_RVApps.pdf Your thoughts please !! Share this post Link to post Share on other sites
wolfe10 Report post Posted October 22, 2019 Check with Cummins with your engine SN if the Cummins document shows it to be mounted on the engine. Check with Freightliner for your VIN if the Cummins document shows it to be remote mounted. Be aware that the correct filter depends on exactly what coolant you have (whether long-life or one requiring SCA). If coolant is original, Freightliner can tell you what coolant you have. Share this post Link to post Share on other sites
five Report post Posted October 22, 2019 1 hour ago, fagnaml said: ....So, my latest question for the forum is do newer ISB engines have a coolant filter and if "yes" where is the filter located? Here is the link to the Cummins brochure with maintenance intervals for 6.7L ISB engines --> http://files.trypsi.com/cummins/maint_care/2013_ISB67_RVApps.pdf Your thoughts please !!.... If your engine has a coolant filter, it will have been put on by Freightliner....my engine does not have that filter. Also, Cummins and Freighlinger will have different standards for maintenance procedures. Freightlinger told me five years or 100,000 miles for changing coolant, which they put in, not the engine manufacturer. My coolant is plain ethylene glycol, with SCA, Freightliner does not put in extended life coolant. I have my transmission fluid tested every year, this year I'm going to have the coolant tested as well. No point in changing either if the chemical analysis comes back good. http://www.jglubricantservices.com/ Share this post Link to post Share on other sites
fagnaml Report post Posted October 22, 2019 Thanks for the feedback thus far. I call Freightliner about the coolant filter and that tech (yet another one) said I don't have a coolant filter (yay!). I explained my temperature fluctuation and fan behavior to him and his response was "not what he has seen". He did recommend that I call Cummins Customer Care at 1-800-286-6467 to discuss my situation (I hadn't found that phone number yet). The tech I talked to a Cummins told me my ISB engine is "programmed" to operate in the 187 - 207 F temperature range and the fact that the engine temp creeped up to 210-212 F as the fan was going to high speed was not a concern. The fan and cooling system is operating as it should. The tech said max engine temp for the ISB is 225 F. So if the engine temperature control is "programmed" to operating in the 187 - 207 F, I now wonder if I have nothing to worry about ?? I'm still taking the motorhome to Houston Cummins Coach Care next week for coolant change and thermostat change just so I can "check the box" for those routing maintenance items. Also, for the coolant change Freightliner to me to refill with the purple coolant with SCAs as the "probes" installed in the cooling system are for purple color coolant. If red color long life coolant is used the probes may not work with that color. My head is spinning with all of this varying information. I feel like an idiot who knows nothing. Can someone please give me a sanity check?? Share this post Link to post Share on other sites
dickandlois Report post Posted October 23, 2019 8 hours ago, fagnaml said: Thanks for the feedback thus far. I call Freightliner about the coolant filter and that tech (yet another one) said I don't have a coolant filter (yay!). I explained my temperature fluctuation and fan behavior to him and his response was "not what he has seen". He did recommend that I call Cummins Customer Care at 1-800-286-6467 to discuss my situation (I hadn't found that phone number yet). The tech I talked to a Cummins told me my ISB engine is "programmed" to operate in the 187 - 207 F temperature range and the fact that the engine temp creeped up to 210-212 F as the fan was going to high speed was not a concern. The fan and cooling system is operating as it should. The tech said max engine temp for the ISB is 225 F. So if the engine temperature control is "programmed" to operating in the 187 - 207 F, I now wonder if I have nothing to worry about ?? I'm still taking the motorhome to Houston Cummins Coach Care next week for coolant change and thermostat change just so I can "check the box" for those routing maintenance items. Also, for the coolant change Freightliner to me to refill with the purple coolant with SCAs as the "probes" installed in the cooling system are for purple color coolant. If red color long life coolant is used the probes may not work with that color. My head is spinning with all of this varying information. I feel like an idiot who knows nothing. Can someone please give me a sanity check?? Mike, I have not found any reference between coolant sensors and coolant formulation, but for a sanity check you might read over the information offered in these 2 links. If you can understand the information, then your sanity level is still in a normal range and I still find myself the RV 101 category. LOL. It could be in the Chemistry, but kind of out of my pay grade. It is all changing way to fast. http://labcheckresources.com/wp-content/uploads/2014/12/Coolant-System-Maintenance-Guide-FINAL1.pdf http://esource.alstribology.com/WB082_August2015/Coolant Formulation.html Rich. Coach care by location PDF File https://www.cummins.com/sites/default/files/2019-04/coach-care-locations-by-state-april-2019.pdf Share this post Link to post Share on other sites
jleamont Report post Posted October 23, 2019 Mike, I am going to make your head spin more. I have no idea the "probes" they are speaking of however all of our Freightliner trucks at work with the ISB came from Freightliner with RED Extended life coolant and have for the last 5 years. They were spec'd that way, they also came with this sticker on the coolant reservoir (photo'd below). This goes back to what you have already experienced, if you call back you will most likely get a different answer. I converted out 2002 Cummins over to Nitrate free coolant last year so I didn't have to fuss with checking it. If you ask the Cummins dealer you will most likely have that as an option. Share this post Link to post Share on other sites
wolfe10 Report post Posted October 23, 2019 From my Diesel Maintenance Presentation at FMCA Convention 2016-- sorry it doesn't paste very well: Freightliner Chassis Caution Freightliner Chassis have a: Coolant Level Sensor. Freightliner recommends using “regular” diesel coolant, not the new-generation coolants. As of 3/16, Freightliner is changing over to the new-generation coolant, but older chassis must use the “regular” coolant. Additional note-- check your overflow reservoir for the coolant level sensor. My ASSUMPTION is that the new generation coolant has conductivity that is enough different from the low silicate with added SCA coolant that the sensors do not function properly. Share this post Link to post Share on other sites
manholt Report post Posted October 23, 2019 Mike, I sent you a PM. Share this post Link to post Share on other sites
rayin Report post Posted October 23, 2019 On 10/7/2019 at 2:07 PM, fagnaml said: Ross -- Sorry, I should have provided chassis and engine info for my 2016 Ventana LE 4037 (which should be visible in my signature block). The chassis is a Freightliner XCR with a 6.7L, 360 HP Cummins ISB engine and Allison MH3000 transmission. The coolant is "original fill" Shell Rotella Fully Formulated with SCAs (purple color coolant) which, per test strips, was in good condition when I purchased the motorhome six months ago. Here is a link to coolant info --> http://shop.sclubricants.com/rotella-fully-formulated-antifreeze-5050 I don't recall seeing this engine temperature fluctuation while driving my previous motorhome unless while climbing a hill or large bridge. The engine temp fluctuation I experienced yesterday is on I-10 which except for a few bridges is very flat. Cummins says each engine has different specs. I emailed and was told they could not help me without my engine serial #, I obtained that and replied back. I was then told the normal coolant temperature specs for MY ISC was 180° up to 212°F, beyond that is overheating.. Share this post Link to post Share on other sites
five Report post Posted October 24, 2019 Be careful what information you use that comes from the engine manufacturer.....Freightliner/Spartan put the coolant in, not the engine maker. Share this post Link to post Share on other sites
fagnaml Report post Posted November 5, 2019 Quick update for my cooling system. This past Friday (11/1) I took the motorhome to Cummins Coach Care (located a bit northeast of downtown Houston) as I've had superb service from them. Justin McDonald, a very knowledgeable, very customer focused shop supervisor found the following: There was a Cummins recall for ECM programming but because my engine was never registered by the original owner (nor me!) the recall work was never completed. The new programming has some improvement to engine temperature control along with other improvements (what I don't know yet) The Horton fan clutch is performing as it should Radiator and charge air cooler all easily passed pressure tests The coolant was very clean with no signs of rust, particulates or other contaminants. The coolant quality was good per SCA test strips. Expect to see very little of anything when the cooling system is flushed tomorrow. The themostat showed some "scoring" and has some sticking as it was manually opened Because of the type of level probe Freightliner installed in the coolant tank, the "purple" heavy duty coolant with SCAs is required i.e. can't change to the red extended life coolant without changing the level probe. Found the engine block heater to have "darkened" wires -- heater will be replaced The ECM programming update, engine block heater and thermostat replacement fall under the Cummins five year, 100,000 mile warranty so no cost to me except for $100 deductible. I'll still need to pay for coolant change / flush service. Per Justin, this work should help stabilize my engine temperature some, but on a hot 95 F+ day still expect to have the fan go into / out-of high speed to maintain engine temperature. Any comments from the Forum on the above findings? Share this post Link to post Share on other sites
wolfe10 Report post Posted November 5, 2019 Mike, Let us know how the update/upgrade work in the "real world". Share this post Link to post Share on other sites
fagnaml Report post Posted December 9, 2019 Quick update on my experiences. Replacing the "scored" thermostat helped as the new thermostat starts opening as it should at ~190 F and is fully open at ~195 F. Engine temperature holds in the 195 - 205 F range with an occasionally up-tick to 210 F at which time the fan goes into high speed to cool the engine down to ~187 F. Cummins Coach Care Houston confirmed my Horton clutch is functioning properly. The fan speed cycling is "normal" per the Cummins shop supervisor (Justin McDonald) to help maximize fuel economy. I also had a "stupid me" moment with Justin. He reminded me my previous motorhome (2007 Damon Astoria) had a 300 HP 5.9L ISB engine with a five speed Allison 2500 MH transmission. With that "set-up" my engine speed was ~2200 RPM at 65 mph which provided considerable more fan air flow to keep engine temp ~190 F. My current "set-up" is a 360 HP 6.7L ISB with a six speed Allison 3000 MH transmission. At 65 mph my engine speed now is ~1600 RPM meaning reduced air flow versus what I was "used to experiencing". Justin assured me everything with my cooling system is working as it should! I had zero problems during my November jaunts between Houston and Baton Rogue to watch the LSU Tigers go 12-0 in regular season play. Share this post Link to post Share on other sites
fagnaml Report post Posted March 9, 2020 Quick update about my fluctuating engine temperature experience. I haven't taken the coach out for a fun weekend journey since the last weekend of November but it has been out for its monthly 45 minute drive. With cooler ambient temps during December - February the temperature fluctuation between 187 F and 207 F continued but not as frequently. Since my last update, Justin McDonald at Houston Cummins Coach Care provided this simple narrative on my cooling system design and ECM control. As previously noted, the ECM "modulates" engine temperature between 187 F and 207 F. When the engine temp reaches 207 F, the fan control switches to high speed to cool the engine to 187 F at which time the fan returns to low speed mode. Per Houston Cummins, this fan speed modulation is one of several ways Cummins uses to achieve somewhat higher fuel mileage. The wife and I are taking the coach to the Texas Hill Country the weekend of March 27 - 31 to enjoy the Wine & Wildflowers Journey. Will let the forum know how the cooling system performs. Share this post Link to post Share on other sites
hermanmullins Report post Posted March 9, 2020 Nice chart. When your temp rises you can always drop down a gear which will increase fan speed and in most cases lower your temp. Herman Share this post Link to post Share on other sites
