Re: CAC lesson learned Reply #25 – July 25, 2018, 09:20:29 am My '81 defaults to high also. Happened on the way to Phoenix International Raceway back in 2002 made enough noise to get my attention as the fan on it is loud on high. Quote Selected
Re: CAC lesson learned Reply #26 – July 25, 2018, 09:26:19 am Phred I used to point to the electrical valve in the engine bay and explain that if the power failed the fan cane on high speed.As you said, safe mode. Quote Selected
Re: CAC lesson learned Reply #27 – July 30, 2018, 04:41:25 pm Here's an update on my hyd fan speeds as promised. With a cold eng fans don't run until coolant temps reach 150 deg then they both turn on to what I assume to be low speed. After about 20 seconds they reduce their speed by at least half and remained like that until I shut the eng off when the temp was 160 deg. I realize the thermostat was still closed but I wasn't sure if I could get the temps up with a high idle alone so I shut the eng down. After I finish flushing and changing the thermostat and hoses and refilling with new coolant, I will do a test drive and try and determine when the fans change speeds. Quote Selected
Re: CAC lesson learned Reply #28 – July 30, 2018, 05:23:36 pm Quote from: rbark – July 30, 2018, 04:41:25 pmHere's an update on my hyd fan speeds as promised. With a cold eng fans don't run until coolant temps reach 150 deg then they both turn on to what I assume to be low speed. After about 20 seconds they reduce their speed by at least half and remained like that until I shut the eng off when the temp was 160 deg. I realize the thermostat was still closed but I wasn't sure if I could get the temps up with a high idle alone so I shut the eng down. After I finish flushing and changing the thermostat and hoses and refilling with new coolant, I will do a test drive and try and determine when the fans change speeds.If you have VMspc, probably a good idea to look at intake manifold temps while you are watching your fan speeds. As mentioned, Cummins recommends a max of 30 f over ambient temp. Quote Selected 1 Likes
Re: CAC lesson learned Reply #29 – July 30, 2018, 05:32:13 pm Intake temp on the Silverleaf was my first clue when we had fan controller problems. It came up way before the coolant did. Quote Selected
Re: CAC lesson learned Reply #30 – July 30, 2018, 06:10:45 pm After draining the water from system and refilling I started the coach again. Before I brought it up to a high idle ( 1500 RPM ) I looked at the fans again. They were turning at a slow speed!?! I can only guess that the last time I ran it, the fans were stuck, although this time when I started it the temps started off at about 115 deg whereas the first time the temp was below 100 deg. I did look at the VMSPC but didn't record anything as I saw nothing unusual. When I run my final flush tomorrow with distilled water I will record the intake manifold temps also. Will drive it so the thermostat will open also. Thanks for that info. Quote Selected
Re: CAC lesson learned Reply #31 – July 31, 2018, 03:44:46 pm Ok, here's some photos of the eng. warming up, then a short 9 mile drive to get temps above 180 so the thermostat could open thenat idle before shutting down. As they say, " a pictures worth a thousand words" so here's 10,000 words. My longesr post ever! From what I can tell, I see no issues with this system. Quote Selected 1 Likes
Re: CAC lesson learned Reply #32 – July 31, 2018, 04:26:17 pm Looks good, but all your readings were at low loads and low boost pressure. If your manifold temps stay within 30 degrees of ambient when you are running 20 or more lbs of boost, then you know everything is fine. Quote Selected 2 Likes
Re: CAC lesson learned Reply #33 – August 05, 2018, 12:23:17 am For anyone interested in where the transmission cooler office is located, I took some pictures of what it looks like when I changed the thermostat. Here they are. Quote Selected 5 Likes
Topic: CAC lesson learned