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zacktown · 06-06-2014, 01:47 AM

I have spent a couple hours reading about fan issues that usually mention the fan running at full speed. My issue is a tiny bit different.

Before spending $700 on a new wax valve kit, I want to see if anyone might have heard of the fan closely matching the engine rpm. For the first 20,000 miles driving my 07 Monaco Camelot, I didn't even know I had a fan it was so quiet, just the sweet sound of a whistling turbo diesel (love that sound). Engine temp has always been rock solid around 180s. This past trip, it started "roaring", especially at high RPMs. The engine and tranny also run substantially cooler. I noticed that when I pull into and out of the campground, I can just go REALLY slow, like 5 mph, and it will just be a bit noisy. The minute I depress the accelerator, "ROAR!". It takes off and it becomes embarassingly loud.

It is a side radiator (rr8s chassis) and everything I read mentions a hydraulic fan controlled by an expensive wax valve. The main difference is that my fan doesn't go full speed at start up. I have to depress the accelerator to make it roar. Maybe it isn't the fan that I am hearing? Oh wait, I took it to the local bus repair shop here in Vegas and the owner said, "Its the fan and its normal.". I am 1000 percent positive that he is wrong since I drove the coach for 3 years all over the country with none of this noise.

Any thoughts or suggestions are greatly appreciated

McGalliard01 · 06-06-2014, 07:12 AM

hello,
I have a similar issue except my unit is new. The temp is not stable, it is below the mark until under load, temp goes above the mark, fan comes on with a roar for 30 to 60 seconds temp drops like a rock, fan noise stops. This goes on all day. Talked cummins and they say it is normal. My 5.9 does not do this pulling 16k, temp is stable, under very heavy load the fan will come on.

I think like in your case it is something to do with the fan clutch. Seems like it would have more than low and roar fan speeds. Not getting a straight answer. Like you, help.

Dave

koda59 · 06-06-2014, 07:45 PM

My Cummins 400 also runs my power steering also besides the radiator fan. In mine there is a filter in the bottom of the reservoir that needs changing every so often. Do you use hydraulic fluid or engine oil in the reservoir for your side radiator? Not sure when, but on my RV they changed from hydraulic fluid to 15w40 engine oil because they found out that the hydraulic fluid could not with stand the high temps.

Mr. Hipster · 06-06-2014, 08:14 PM

Coolant temp controls the fan clutch, assuming you have an air clutch. Temp sensor could be the culprit.

"007" · 06-07-2014, 03:29 PM

Seems like everyone suddenly are having fan issues must be warming up.
Check this out.

zacktown · 06-09-2014, 12:09 AM

DOH! My post got hijacked. I do hope that this information does help the second poster in this thread and others that will read the suggestions. As for me, I am going to do a bit more troubleshooting and perhaps create a new post to attempt to get back on point and hopefully help others with the issue that I am having. My issue doesn't even come close to resembling the issue of the second poster here.

The upside is all the additional research I am doing will help me train yet another "rv mechanic" on how to do their job.

Safe travels to all

waco kid · 06-09-2014, 11:49 AM

Your problem is most likely your fan controller or the sensors for it. Try unplugging it and see if the fan comes on. Some times cleaning the connections connections help. Also try jiggling the wires at the connection and on the controller itself. I had the same issue your having about 3 years ago and bought a new controller for about $850.00 from Monaco, now I'm starting to have issues again. I,m looking for more feed back about a thermal valve replacement that Source Engineering makes, but I haven't found much.....Bruce

zacktown · 06-09-2014, 11:24 PM

Waco Kid,

Thank you for the info. I am going to go to the coach tomorrow and give these suggestions a try.

As far as source engineering, I would suggest a call. I have spoken and e-mailed with Jim there and, whether your purchase from him or not, he knows his stuff. I got the impression that he doesn't mind a little phone troubleshooting. I bought sway bars from him last year and he gave me so much information during our conversations (beyond suspension stuff), that I would definitely buy from him again. I am not buying their wax valve kit (yet), because my fan isn't full on all the time, and I want to try your suggestions first.

Lastly, when I e-mailed Jim recently, I incorrectly mentioned that my fan was running at full speed because I forgot that it ramped up with the engine rpms. Probably because of all the reading I've done in these forums (subliminal?). With the "fan full on" symptom, he did say that his kit would take care of it and the monaco one would fail again if I went that route. I am not sure why, but I bet he would have some detailed information on the subject.

Thanks again

mytime · 06-10-2014, 05:29 AM

My fan ramps to high speed when the A/C is on., also with a failed controller..

waco kid · 06-10-2014, 05:56 AM

Thanks for the info zacktown, keep us posted......Bruce

gemini5362 · 06-10-2014, 10:04 PM

The Hydraulic fan is controlled by temp. The controller on my bus had to be changed because it was not letting the fan go to full speed. The service center manager told me that one of the symptoms of a controller going bad was having the fan on all of the time which mine had been doing. Start your engine up when it is cold and see if your fan is running if it is then you are probably going to need a new controller. Search this forum for the connector you disconnect to check the fan controller. I do not remember which connector it is but you can disconnect it and it defaults your fan to high speed. If it came loose that would cause the problem you talk about.

zacktown · 06-11-2014, 12:40 AM

Quote:

Originally Posted by waco kid

Thanks for the info zacktown, keep us posted......Bruce

I got started today a little too late to crawl under. It was 106+ here in Las Vegas today. I did record a little video (mp4 format). I checked the file on my mac and windows computers. It plays in either quicktime or windows movie player. I haven't tried posting a video to this forum, but I think this little 2 mb video describes the issue better than 1000 words. I am going to crawl under and take a look tomorrow and I will check back with, hopefully, the solution.

If anyone has any other thoughts, I will be checking back here often

Thank you all!

zacktown · 06-11-2014, 02:04 AM

I forgot to mention. Just so no one thinks the engine is revvin' all by itself, my wife is pumping the accelerator.

mytime · 06-11-2014, 05:43 AM

I'm thinking that my fan (C-400),that the ECM has parameters to control different temp settings. I had Cummins check mine awhile back and correct several. Might want to check the file section and view parameters.