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| [GMCnet] Fan clutch follies [message #272224] |
Wed, 18 February 2015 09:51  |
glwgmc
Messages: 1014
Registered: June 2004
Karma: 10
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When the new S&J engine was installed in the Clasco I also added the aluminum radiator, the new plastic fan, new water pump and 180 Robert Shaw thermostat. That combo cooled way too much. 150 to 170 all the time up hill or down and the fan clutch was always on to some extent so very noisy. Now three different fan clutches later and I still have not found one that will play properly with the plastic fan.
I had a Hayden 2797 severe duty on the coach when the new engine went in and could not get the belts tight enough not to screech like crazy at anything over 2500 RPM. Then tried an ACDelco recently purchased from Peter Huber which he described as a 2053 so not sure of what it is. I changed to a double belt drive and same story, way too much cooling, loud screetching, finally locked full on so really loud. Next came an AZ version of a Hayden 2705 standard duty. That was much better with no belt screetching (small chirp when downshifting) but it also came on and stayed on once at highway speeds.
We drove home yesterday down the I-5 and over the five passes between Roseburg and Grants Pass, OR. It was unseasonably warm, in the low 70's, and engine water temp never got above 175 and stayed at 165 to 170 most of the time. I have two independent water temp indicators (one in stock location at the front of the intake manifold and one in the heater hose) which were consistent at those temps and I confirmed with a hand held IR. At least the roar of that fan clutch stuck on was less than with either of the others, but I am going back to the stock metal fan until someone finds a fan clutch that will play properly with this plastic fan. When I purchased the 2705 I also bought an AZ boxed Hayden 2747 but don't see how it could be any better than the others and I am tired of changing fan clutches.
I have no explanation for why these fan clutches are locking up and staying on at such low temps, nor do I have an explanation as to why the engine water temps are staying below the thermostat set temp even when climbing the five passes yesterday. Yes, I did also replace the new Robert Shaw 180 thermostat with a new Mr. Gasket 180 that looks identical to the RS, just a different color, and that had no effect on the temps.
My only guess is that the plastic fan puts so much drag on the fan clutches, even at low speeds, that they get hot on their own and fool themselves into thinking the air coming across the radiator is hot enough to engage and stay locked on.
For the record, all the fan clutches I found cross referenced to one of three Hayden numbers and this info is from Hayden:
Hayden 2705, standard duty, 60-70% of input shaft speed when on, 20-30 when off, designed for 1 1/2" pitch fan.
Hayden 2747, heavy duty, 70-90% when on, 25-35 when off, designed for 2 1/2" pitch fan
Hayden 2797, severe duty, 80-90% when on, 20-30 off, designed for 2 1/2" pitch fan.
If any of you have found a fan clutch that works with the plastic fan, I would sure like to hear what it is.
Jerry
Jerry Work
The Dovetail Joint
Fine furniture designed and hand crafted in the 1907 former Masonic Temple building in historic Kerby, OR
Visitors always welcome!
glwork@mac.com
http://jerrywork.com
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Jerry & Sharon Work
78 Royale
Kerby, OR
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| Re: [GMCnet] Fan clutch follies [message #272226 is a reply to message #272224] |
Wed, 18 February 2015 10:27  |
armandminnie
Messages: 864
Registered: May 2009
Location: Marana, AZ
Karma: 2
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Jerry, I don't know about the fan clutches but I am thinking there is some sort of bypass that is defeating your thermostat. I fought the battle of trying to figure out why the fan clutch "thought" it was time to turn on when it shouldn't and have settled on air flow in the engine compartment. Funneling the air through the radiator instead of around it and using a "spoiler" to pull the air out the bottom has fixed that problem in my coach. I use a lighter duty AZ fan clutch and the standard fan and have none of those problems even in Arizona in the Summer - I did before. By the way, make sure that thermostat is a "fail open" type?
Armand Minnie
Marana, AZ
'76 Eleganza II TZE166V103202
visit my gmc blog
click here to visit gmcws.org
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| Re: [GMCnet] Fan clutch follies [message #272275 is a reply to message #272226] |
Wed, 18 February 2015 21:04 |
powwerjon
Messages: 849
Registered: March 2013
Karma: -2
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Armand,
I have run the new nylon fan assembly for about 2400 miles so far and I am using an AZ 2747 fan clutch. It is much quieter than the 7 blade metal fan. I run a 190 deg thermostat and a stock radiator. It sets at 190 on the dash gauge with the temp moving up and down a little bit as the thermostat opens and closes. You can hear the fan the fan engage and disengage, but nothing like the stock steel fan. You can hear the fan slightly on cold engine start and then it goes away just like the stock fan.
In the 15 years and 70000 miles that I have owned GMC’s I have never had the issues that some have described including you. I have had 2 fan clutch failures in the last 15 years. One was when it just failed to engage and the other was when it failed locked on. That was a bit noisy but I only had to go about 60 miles to get home. The best bang for the buck IMPO is the addition of a air dam spoiler on the front of the coach and side panels to direct the air flow thru the radiator. The coaches with the 403 had the air control panels from the factory, We did a lot of testing of the front air dam type spoiler back in 2002. Actual road testing was done by Arch on several trips out west during the summers of 2001 and 2002.
http://www.appliedgmc.com/prod.itml/icOid/1019
and
JR Wrights Air Spoiler Dam
J.R. Wright
30' Buskirk Stretch
Michigan
On Location in Tucson
> On Feb 18, 2015, at 9:27 AM, Armand Minnie wrote:
>
> Jerry, I don't know about the fan clutches but I am thinking there is some sort of bypass that is defeating your thermostat. I fought the battle of
> trying to figure out why the fan clutch "thought" it was time to turn on when it shouldn't and have settled on air flow in the engine compartment.
> Funneling the air through the radiator instead of around it and using a "spoiler" to pull the air out the bottom has fixed that problem in my coach. I
> use a lighter duty AZ fan clutch and the standard fan and have none of those problems even in Arizona in the Summer - I did before. By the way, make
> sure that thermostat is a "fail open" type?
> --
> Armand Minnie
> Marana, AZ
> '76 Eleganza II TZE166V103202
> http://www.minniebiz.com
> http://www.gmcws.org
>
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| Re: [GMCnet] Fan clutch follies [message #272294 is a reply to message #272275] |
Thu, 19 February 2015 07:19 |
armandminnie
Messages: 864
Registered: May 2009
Location: Marana, AZ
Karma: 2
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JR, do you mean that you have not experienced the fan turning on at highway speeds? I have heard from many people about the same problem and still have the same opinion: the fan should not be turning on at 60 mph. If it does there is some issue that needs to be fixed. I am using an Autozone Torqflo 922747 which I think is a medium-duty clutch on the standard fan. I can tell when the clutch is engaged but it does not make much noise and it does not engage so that I can hear it once I get over about 45 mph.
Armand Minnie
Marana, AZ
'76 Eleganza II TZE166V103202
visit my gmc blog
click here to visit gmcws.org
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| Re: [GMCnet] Fan clutch follies [message #272345 is a reply to message #272294] |
Thu, 19 February 2015 17:58 |
powwerjon
Messages: 849
Registered: March 2013
Karma: -2
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Armand,
I have read your paper on the cooling issues you experienced and your observations were similar to conclusions that GMC discovered on their commercial motorhome chassis in the 70,s that air flow control is the Key to the problems of cooling. GM added the air control baffles to the GMC commercial motorhome chassis and commercial ”P” model chassis and on the GMC classic motorhome when they went to the 403 engine at TZE167V101285 for the motorhome, TZE337V101287 for the 23’ TransMode and TZE367V101312. Our first GMC the 77 Eleganza II 403 had the air control panels factory installed and it was about 40 coaches past the changeover. Our fan clutch was never that obnoxious in noise except when it failed and I did use the Hayden 2797 clutch as a replacement at that time. Fan Clutches have been a reoccurring theme since almost the beginning. They would come on and people reported that it sounded like the transmission downshifted. With many many articles in GMC motorhome marketplace and in the GMCMI Newsletter. I did add a front air dam spoiler of my design back in 2001 to direct more air into the radiator air path and to use the negative pressure after the spoiler under the coach to help extract hot air our of the engine compartment. It is the same one that is now sold by Jim K and works as advertised. As has been found by you and others the current selection of available fan clutches is not as good and/or reliable as they were 10 or more years ago.
http://www.gmcmhphotos.com/photos/general-pictures/p57278-engine-cooling-gm.html
Now to the present configuration on our stretch coach. Coach weight loaded aprox. 14700 lbs and pulling a 3800 lbs towed. For the last 2300 miles I have been running the John B. 10 blade nylon fan using the same 9222747 that you are using and the same unit that was used when running the 7 blade. When it is engaged It is difficult to hear the fan run as it is much quieter than the 7 blade metal fan, but you can hear it cycle as for it engaging over 45 I don’t hear it. IMHO I think the balanced even number of nylon fan blades will reduce the failure rate of the fan clutches along with less load on the impeller shaft of the pump. I have one of the AC Delco Heavy Duty Fan Clutch, like Jim K. sells, that I got from Rock Auto a few years ago that I want to test with this new fan when I get home. That way I will have almost 5K miles on the 10 blade fan and will be able to compare the 2.
Temperature gauge observations:
In the our first coach the 1977 the other items in the cooling loop were a 180 Robert Shaw 180 deg thermostat, the radiator has been recored with the HD core and I was using the newer temp sender that made the temp gauge mean something. The coolant would come up to temp, (180) and sit there all day long. If we were in hills or mountains then it would elevate just a little bit and you could hear the fan clutch engage slightly, and then shut off again.
The stretch has a very large air scoop under the bumper to direct air into the radiator but does not yet have the side and divider panels. I plan on adding the air direction baffles similar to Ken H. addition in the spring when I get home. It runs 190 deg thermostat and the temp stays locked at 190 except when when we are climbing in the mountains out west where it might move up a few degrees. I have a Mac Dash with all the gauges ( analog ) and the good sender here also.
This has always been a topic of great discussion for many years with many possible and different solutions.
J.R. Wright
30' Buskirk Stretch
Michigan
On Location in Tucson
> On Feb 19, 2015, at 6:19 AM, Armand Minnie wrote:
>
> JR, do you mean that you have not experienced the fan turning on at highway speeds? I have heard from many people about the same problem and still
> have the same opinion: the fan should not be turning on at 60 mph. If it does there is some issue that needs to be fixed. I am using an Autozone
> Torqflo 922747 which I think is a medium-duty clutch on the standard fan. I can tell when the clutch is engaged but it does not make much noise and it
> does not engage so that I can hear it once I get over about 45 mph.
> --
> Armand Minnie
> Marana, AZ
> '76 Eleganza II TZE166V103202
> http://www.minniebiz.com
> http://www.gmcws.org
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| Re: [GMCnet] Fan clutch follies [message #272350 is a reply to message #272224] |
Thu, 19 February 2015 21:40 |
Chris Tyler
Messages: 458
Registered: September 2013
Location: Odessa FL
Karma: 7
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Anyone know what clutch was used in the original plastic fan application? Or for the matter what that was?
Curious as I have been considering changing out the fan while adding the missing fan shroud to help with summer cooling issues
76 Glenbrook
[Updated on: Thu, 19 February 2015 21:41] Report message to a moderator |
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| Re: [GMCnet] Fan clutch follies [message #272438 is a reply to message #272351] |
Sun, 22 February 2015 06:05 |
Chris Tyler
Messages: 458
Registered: September 2013
Location: Odessa FL
Karma: 7
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[quote title=powwerjon wrote on Thu, 19 February 2015 22:25]Chris,
If your missing the fan shroud your at a disadvantage to have correct cooling, especially in hot weather. Just adding the shroud will greatly enhance your cooling. I am going to make a personal suggestion for the fan clutch. I would suggest the AZ 9222747, it is a medium duty fan and I find it works well without excessive noise.
J.R. Wright
The PO removed the original shroud and placed a black magic electric fan, retaining the stock fan with a HD clutch that works. Although I have the original shroud I have a 2 piece FG one from Jim K. I would like to keep the electric fan but will need to modify the mount to retain it.
THE AZ on your part number...is that Autozone?
76 Glenbrook
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| Re: [GMCnet] Fan clutch follies [message #272474 is a reply to message #272224] |
Sun, 22 February 2015 20:11 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Most have found the electric fans just block air flow. Electric fans are good at low speeds but my coach has no problems in stop and go with AC on Stock 77 setup.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: [GMCnet] Fan clutch follies [message #272477 is a reply to message #272438] |
Sun, 22 February 2015 20:26 |
powwerjon
Messages: 849
Registered: March 2013
Karma: -2
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Chris,
I went back and reread you first email and at the end you say that you have "summer cooling issues”. You also state that you have a Black Magic electric fan, what is the model number and size? Electric fans over the years have had limited success when used on the GMC coach. Your electric fan housing is most likely restricting the air flow thru your radiator and that becomes more noticeable when your weather gets warmer. Your signature line doesn’t say what part of the country you live.
I am going to offer my personal suggestions on what I would do having learned over the past 15 + years with the GMC coach, and trying many different setups, others may vary and you need to do what is best for you:
NOTHING move more air thru the GMC radiator more than the factory cooling set up. Yours is a 76 coach and came with the shroud, venturi ring and venturi seal that was bulky and harder to work with than the shrouds that were on the 77 and 78 coaches. I would lose the electric fan and install the new split shroud as that will make it easier for future work on the front of the engine and it lines up on the fan better. The 7 blade fan is good if that is what you want to use and until this past fall all I have used, but I am now using the John B. Nylon 10 blade fan. The biggest observation that I have noticed with the new nylon fan is the reduced fan noise as compared to the stock fan using the same fan clutch (2400miles). I presently use a 2747 clone sold by AutoZone under part#922747. Excuse the other part number as I fat fingered too many 2’s. It is a good medium duty fan clutch and with the new fan I can barely hear it engage. I have used the 2797 severe duty fan clutch on and off and it can be noisy when it engages but the 2747 should work just fine. When they discontinued the 455 and start using the 403 in the 1977 coaches starting at TZE167V101285 for the motorhome, TZE337V101287 for the 23’ TransMode and TZE367V101312 for the 26” TransMode. At the same time GMC added the baffles to control the air flow thru the radiator. See the following:
OEM baffles here:
http://www.gmcmhphotos.com/photos/miscellaneous-bryant-stuff/p31392-baffle.html
http://www.gmcmhphotos.com/photos/miscellaneous-bryant-stuff/p31393-baffle.html
--
Bill Bryant
In 2002 I added and front spoiler which I designed and built and still do.
http://www.gmcmhphotos.com/photos/g3358-front-air-dam-spoiler.html
and
http://www.appliedgmc.com/prod.itml/icOid/1019
and
JR Wrights Air Spoiler Dam
My 77 Eleganza II with a 180 thermostat and the air control package never got over a few degrees above 180 deg even when the temp was in the 90’s+ at 64 MPH and towing a 4dr Tracker. It ran that way till the day I sold it. Never got hot!
Again these are my observations and mods that I used over the years that worked well for me. You have to make a choice on which direction that you want to go in, I wish you luck!
J.R. Wright
GMC GreatLaker
GMC Eastern States
GMCMI
78 Buskirk 30' Stretch
1975 Avion (Under Reconstruction)
Michigan
On Location in Tucson
> On Feb 22, 2015, at 5:05 AM, Chris Tyler wrote:
>
> [quote title=powwerjon wrote on Thu, 19 February 2015 22:25]Chris,
> If your missing the fan shroud your at a disadvantage to have correct cooling, especially in hot weather. Just adding the shroud will greatly enhance
> your cooling. I am going to make a personal suggestion for the fan clutch. I would suggest the AZ 9222747, it is a medium duty fan and I find it
> works well without excessive noise.
>
> J.R. Wright
>
> The PO removed the original shroud and placed a black magic electric fan, retaining the stock fan with a HD clutch that works. Although I have the
> original shroud I have a 2 piece FG one from Jim K. I would like to keep the electric fan but will need to modify the mount to retain it.
>
> THE AZ on your part number...is that Autozone?
> --
> 76 Glenbrook
> _______________________________________________
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| Re: [GMCnet] Fan clutch follies [message #272755 is a reply to message #272224] |
Sat, 28 February 2015 13:28 |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
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Senior Member |
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I think that fan clutch discussions have been going on as long as the net is old. I recall that Steve Ferguson did an exhaustive study that can probably be found here. I never paid attention to fan clutches until my original Delco failed. Then I got caught up in numerous clutch trials and concluded that no matter what the brand, origin, or part number, your chances of getting one that works well is a total crap shoot. When a person suggests a certain part number that works, it doesn't for the next person. When Ken B found some original Delco units on Ebay, I bought one and it duplicated the great performance of my original. I hope it lasts a few more years since I don't want to go through that fiasco again. BTW, my experience in AZ is that the fan will engage ocassionally at highway speeds when the ambient is 90F or over.
Bob de Kruyff
78 Eleganza
Chandler, AZ
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