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Old 02-27-2014, 08:10 PM   #1
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1989 34.5' Airstream 345
Hanalei, /Chino Valley , Hawaii / Arizona
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Engine fan clutch ??s

All of a sudden the engine fan is roaring away in there way too much of the time,
Seemingly unrelated to engine temp. It will free up and quite down over 50mph, but at any lower speed its roaring.
This clutch is less than one year old and was working fine till a month ago.
I checked it to day with the engine cold and not running and there is quite a bit of resistance when trying to turn it by hand maybe four or five pounds of pressure. Clearly not freewheeling.

Is it supposed to be freewheeling when cold?
Is there some maintiance that I've been missing?
Is this a sign of a failing clutch? After less than a year?
Is the switch of a thurmo/mechanical nature and internal ?

Thanks for any details you can share.
Richard
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Old 02-28-2014, 12:26 AM   #2
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Hi Richard,
PM Dadstoy about your fan clutch. Seems Dean has had the most 'experience' with this situation.
Good Luck, Derek
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Old 02-28-2014, 08:00 AM   #3
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If the fan is running at lower road speeds I would ask when was the last time you had the radiator rodded and cleaned?

The fan is temperature activated and for some reason the engine cabin temperature sounds like it is just too high until the road speed can forces enough air through to cool thing down.
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Old 02-28-2014, 11:13 AM   #4
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1991 30' Airstream 30
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I had the exact same problem. I replaced the fan clutch myself, and it fixed the problem- I could see that it was leaking fluid. There should be resistance when cold. If your running at normal temps on your motor this is probably the issue.
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Old 02-28-2014, 07:07 PM   #5
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1989 34.5' Airstream 345
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Thanks for the replys, I've been pretty sure that the clutch needs replacing.
I drove down to Pheonix today (about 2.5 hrs ). And it is still acting up. The air temps today were cool and the gauge never reach 210, generally under 205 indicated and the fan came on whenever the speeds dropped below 50mph, sometimes it was roaring at over 60.

Is there a brand to look for? Like I mentioned earlier, this one is less than a year old. And there is the rub for me. I don't mind replacing old parts and renewing the coach's systems. But am not too stoked replacing newer parts that were not up to the job.

I guess I'll bite the bullit and put in a new one.

Cheers Richard
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Old 02-28-2014, 07:13 PM   #6
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Your running temperature causes me to repeat my question. When was the radiator last cleaned?

If you have a 190 degree thermostat in the truck why are you running 205 plus and having the clutch fan cut in?
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Old 02-28-2014, 09:31 PM   #7
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I'm not sure about your comment, HowieE. From what I gather these 454 engines do run in the range I mentioned or higher as a matter of course.

And the fan will now engage whether the engine is just started or has been running for a while and is warmed up.
Since the weather is cool this time of year where I am operating I would not expect to hear the fan engaging unless climbing a long steep climb. Then I would have switched the aux. electric fan in front of the rad to aid in cooling.

But to answer your question, I have no idea when or if the rad has been cleaned. The cooling fluid is clean and I see no gunk, nor is the fan usually this active. Just a sudden change in its operation with no apparent reason.

Cheers Richard
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Old 02-28-2014, 10:18 PM   #8
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I was worried about operating at those temps until I read the manual that came with the 310 when new. I don't recall the exact numbers, but I do remember that 200-plus was normal.
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Old 02-28-2014, 10:27 PM   #9
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Richard, Call Raveson, I'm certain he could tell you if the radiator has ever been rodded and cleaned. Funny that it's now acting up, especially considering Raveson took the 345 on a 4 month long coast-to-coast trip last year.

As far as parts are concerned, I'd try RockAuto, or NAPA parts, simply because they stand behind their parts, and the part is usually assembled in US.

Good Luck, Derek
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Old 02-28-2014, 11:18 PM   #10
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I don't feel that this is an overheating issue, the opperating temps indicated have not changed thru out the time I've owned the coach. Granted this has all been since Nov. in cool times of the year. So I have not run the rig in temps that would really test the cooling system badly, and so far it has seemed up to the task.

No, the issue is the engine fan now, all of a sudden engaging much more that before, and at engine temps that were not causing the fan to kick on before.
So I guess we have kicked this around enough for now. I'll report back once the new fan clutch is installed and let it be known if that did the trick

Thanks again for the input and suggestions.

Cheers Richard
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Old 03-01-2014, 12:27 AM   #11
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I've put three different fan clutches on my MH. First was one from Autozone. It cycle through engaging/disengaging about every 70 seconds. That was a miserable trip to Yosemite!

Second fan clutch was from Napa. It was engaged about 60% full time! Another bad experience.

Then I bought an AC Delco fan clutch from a real parts house. It works!

I went cheap with the first two and ended up paying for my mistake in the long run. The AC Delco unit is more then the first two put together, but there is nothing like driving down the highway in a very quite Airstream!
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Old 03-01-2014, 09:25 AM   #12
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Thanks Dean for the A C Delco tip, exactly what I needed to learn at this point.

As far as engine running temps goes, am I mistaken in thinking that the range between 200 and 208 degrees is about normal for these BBCs in a motorhome.

What sort of temps are ya'll seeing when cruising your motorhomes?

HowieE, still trying to understand your question. My understanding is that the thermostat helps to bring up the engine temp to safe running temps quickly when cold starting ( to assure good lubrication). So the 190 degrees you mentioned is the temp at which the devise opens to allow cooling fluids to start to circulate after that temp is reached.

I would like to see normal operating temps around 185. But it not clear to me that these BBCs are capable of running that cool. Am I mistaken in this?
Ps. I really do like that mailbox you put together, very cool!

Cheers Richard
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Old 03-02-2014, 08:15 PM   #13
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Many of our temp gauges are famous for not being accurate and that was the reason I got a infra-red gun to verify engine running temps as well as anything else you want to point it at. They don't cost much. Great for checking wheel hubs on trips.

After a not so accurate fan clutch I got from NAPA I spent the extra $$ and got one from local GM Dealer a few years back. This one works as it should but I think fewer dealers are having them on the shelf.
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Old 03-03-2014, 08:36 AM   #14
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The thermostat is there to keep the engine at a given temperature. It remains closed until water passing through a small hole in it reaches the set temperature. At that point the temperature sensitive element of the stat open and closes to maintain that set temperature. The stat can only do it's job if the radiator and fan have removed enough heat from the water leaving the engine to allow the stat to regulate the flow entering the engine.

Under normal conditions the radiator should be able to remove enough heat to allow this. As the load on the engine increases, pulling a hill, the clutch fan is designed to come on to increase the air flow over the radiator and thus remove more heat. The fact that your fan was on at an abnormal rate was why I originally questioned the condition of the radiator.

Now another point. Factory supplied GM clutch fans have an abnormally wide range to engage. 160 to 190 degrees. This range is far to wide and can cause problems. If you have one that is close to the 160 degree engage point it will come on far more often than required. That may have been the case with some of the units noted above. But in any case the clutch fan should not come on during normal driving unless you are crossing the desert in mid summer.

Another thing to consider is the size of the radiator. Manufactures design to the lower limit and often end up with an undersized radiator. This is common when people add a heavy trailer or the engine is stuffed into an under ventilated compartment.
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