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Home » Public Forums » GMCnet » Another fan clutch story (Trip report from the middle of Illinois)
Another fan clutch story [message #94887] Fri, 06 August 2010 19:20 Go to previous message
armandminnie is currently offline  armandminnie   United States
Messages: 864
Registered: May 2009
Location: Marana, AZ
Karma:
Senior Member
Trip report so far - the fan clutch is the big issue.

We are driving from Tucson, AZ to the East Coast and back over a planned 6 week period. I have been fighting engine heating problems for some time and, just before we left on this trip, we installed a new aluminum radiator. The fan clutch is a Delco 15-4644 which I installed out of frustration with the old radiator. With the old radiator the Delco clutch would keep it cool enough to drive but normal operating temperature for the engine was about 220 without a tow car and I didn't want to chance towing a car across the country in the summer with those kinds of temperatures.

Since I had been working on the interior I had not had time to test drive the coach and I figured that with the aluminum radiator and the Delco clutch I would at least be safe. I carried my Hayden 2797 with me as a spare.

For three days, all across the Southwest, I could only hear the fan and my wife's complaining. I used a stop watch (on my phone) and found that at 85 degree ambient air temperatures the fan was on about 70 percent of the time. I talked to Steve Ferguson and he suggested I put the Hayden clutch in and I finally had time to do it when we spent two nights in Kansas City.

Wow, what a difference! Steve had suggested that I change both the thermostat - to a 180 degree one - and the fan clutch. I don't really have the time or place to change the thermostat since campgrounds don't want you doing that and, while we could do it in a parking lot I figured why not just change one thing at a time anyway and change the clutch.

The Hayden fan clutch was so quiet that Carol didn't think it was on. When I say "quiet" I mean when compared to the Delco and that Carol couldn't hear it. The trip can continue in peace - it was so bad that it was making the trip less than enjoyable and we thought that if we couldn't improve the situation we might consider cutting the trip short.

My observations (4 days of driving about 6 hours per day) are that the Hayden seems to come on at a lower temperature but rotate at a much reduced rate from the engine RPM. I would have to guess, based on the noise and the engine temperature readings (more on that later) that the Hayden's rate of rotation percentage goes up with the temperature. The Delco on the other hand seems to be either on or off - a close match to the engine RPM even at 60mph. The result is noise - lots of noise with the Delco - and relative quiet; you can hear it but it is hard to distinguish from the engine noise, with the Hayden.

The engine temperatures were much better and steadier with the Hayden. With the Delco, the engine temperature would oscillate between about 190 to 210 and, occasionally, it would get to 215 if it was really hot and we were climbing even an average hill in New Mexico, Texas, Oklahoma and Kansas. With the Delco the temperature virtually never stayed the same for any time at all - it was always moving either up or down. With the Hayden the engine temperature was very steady - at just under 200 - and would only move a little if I was climbing a hill. It never got above 205.

The difference in the weather was pretty notable. With the Delco we drove through ambient air temperatures from low 70's to 105. When the temperature would get to 80 the cycling would begin and the only thing that changed was the rate of temperature climb - when it was hotter the engine got hotter quicker. Today, we left Kansas City with the temperature at about 80 and spent most of the day with it at around 85 and it got to 91 for a little while. The engine temperature stayed steady throughout the day.

Armand Minnie
Marana, AZ
'76 Eleganza II TZE166V103202
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