Some good info here, answers why GM says 240F is ok place to turn on aux fan http://www.tuneruniversity.com/blog/...-radiator-cap/

 

Not meaning to throw the proverbial 'turd' in the punchbowl, but...

Flex fans can be risky. By their basic design, they flex; and when they flex, they put stress into the web areas between the fan blades. Eventually, ALL flex fans would fail in the web somewhere. Fortunately, most folks (and most vehicles with them) would no longer have the cars BEFORE that failure might occur.

But several folks have had such failures. When it happens at idle or slow speed, it's no big deal. When it happens on the highway or at high rpms (the most likely time for them to fail), there is an explosion under the hood and the hood/radiator/etc will likely be damaged. Fan blades have shot through hoods on several occasions.

I just feel obligated to inform you of such risks, if you are running a flex fan.

 

All that is certainly true. Thanks for posting. To me, it's like any other "item under the hood". You need to keep an eye on it. In many cases, (just like any other part wearing out), you will see signs of fatigue etc.

I have seem some "disasters down at the track", BUT I've actually seen more instances of a stock clutch fan "coming apart" at the shaft and doing quite a bit of damage as well. Agreed, they don't do as much damage as a flex fan coming apart (in most cases), but I've seen more worn out shafts on clutch fans that could be pulled apart / or failed by themselves, than I have of a flex fan imploding. (But that's just my circumstance - nothing scientific). I can see where flex fans can cause a ton of damage - that's for sure..

On my "Newer" BMW's, they went with a plastic fan attached to a "standard looking clutch". For the most part, the clutch holds together, but the blades were commonly known to degrade due to heat, "spider-web" and grenade under the hood. My Mercedes had the same problem. Luckily in each case (before the problem was well known / documented / found online etc, I had replaced numerous fans due to "common sense" after seeing stress cracks beginning).

I know most all of us on this forum have run across "wobbly" clutch fans on our cars and replaced them before disaster struck. (sadly, some don't check them / notice them failing - and of course, a sudden failure is certainly possible).

Great timing for the post, while checking oil on my Grand Cherokee last week, I noticed that the clutch fan has some play. It should be here any day.

I think in the case of a flex fan / any performance part etc, the user has to be aware of an average lifespan and keep an eye on things and look for signs of failure to avoid exactly what you mention.

All that being said. I don't don't care for them on street driven cars for the following reasons:

1. "direct drive" / no clutch / always "fully engaged" / some parasitic loss etc.

2. I personally believe that they do take a toll on the water pump / shaft / bearing and lend to more frequent failures / replacement.

And of course - as you mention - They are one additional item that you have to really keep an eye on because they do fail . And when they fail, they fail - BIG TIME. I've seen them go through fiberglass hoods and do serious damage to steel hoods. And the damage to Hoses, radiator / anything else under the hood can be extensive. I don't want to even think about one of those letting loose with the hood open and someone under there.

I think I put an average of about 20-30 miles on my T/A per year - if that. The flex fan is a temp item on that car. But that being said, I've been pretty lucky with the 3-4 I've used in the past. (When I was younger, I used to like that "blower sound", but man can that get old....

 

Yes

 

Yes

 

Honestly, I'm not sure what kinda fan, flex or not, it's been laying around in my garage for years, he'll, idk where I got it, it's all steel

 

Deleted. (At first glance, I thought the fan was installed correctly... I'm wrong..)..

Man... that would have been an easy fix !!!!

 

Mine always rises above 220 when I first start driving it, then it goes down to about 190 200. You just keep driving it and see if it comes down after it goes up a bit. I dont think anything is wrong with your car. The only time mine ever went over 210 after the initial warmup was on a big long hill in blazing heat.

 

Here's a look at my engine bay after converting from cfi

 

I think some of this has to do with air flow to the radiator, I pulled my hood off yesterday to do some stuff, drove it around today probably the same or a little more & the temp didn't get past 180, I don't have the stock hood anymore so I think I need to come up with a way to force air to the radiator maybe fabricate some inserts that force air down to the radiator

 

The biggest improvement with mine (besides installing a new DeWitts radiator) was installing all the seals around the radiator.

Russ

 

Will do. Thanks for your input

 

Ya. I sealed mine up except for 1 place, still trying to figure out a way

 

Thanks

 

One important thing I noticed from your photos is the 'fit' of the fan to the shroud opening. I think that fan might not be the correct diamater for that shroud. But, you will have to take measurements to be sure.

The tips of the fan blades should be about 1/2" from the inner surface of the shroud. The larger than gap becomes, the less efficient the fan. And that efficiency decreases rapidly as the gap increases. At about 1" (tip gap), the fan is pretty useless.

Also, the fan blades should be about 2/3 inside the shroud envelope. In other words, only the back 1/3 of the blades should show behind the back edge of the shroud. Again, the less blade material inside the shroud, the less efficient. (This is also the case for a blade that is too far INTO the shroud.)

If my eyes are getting the right info from your photos, you may need to get a larger diameter fan and/or shim it to get the proper depth into the shroud.

BTW, have you checked to see that the lower radiator hose (suction side of the pump) has a metal spring inside to keep it from collapsing when rpms are above 2500? If your heating happens mostly at 50 mph and higher, that could be one of your problems. As well, the lower air dam (under the nose valence) is very important in directing cooling air UP and into the radiator. If that is not there, your car WILL have symptoms of overheating.

 

Oh wow., that's good info, I will be doing some measuring when I get hone, thanks so much for the info

 

leave the stat you got in there its something else
Clutch fan will do a lot more damage when it comes apart than a flex. It really doesnt matter though not like either of them do none at all

They do make a lot of noise (except the black plastic ones) but man do they cool. Cant get my truck "warm" if I tried on a 100+ deg day

GM had to design these things for emissions part of th ereason they had the fans come on at 240 Sorry man no way anyones going to convince me thats good for anything except mfr regulations. Thats pretty toasty.

 

Yes I agree 240 is not a good idea

 

The thermostatic mechanism for the fan can be purchased with different temperature settings. The stock unit was set around 200*F (used a 195*F thermostat). Never heard of one set at 240*F; of course that would mean that your coolant was boiling out when it decided to turn ON.

The thermostatic fans did not engage until temps reached unit's temp (or somewhat beyond), so the fan was very quiet and did not absorb powert to operate until then. Now folks have electric fans that don't come on until that preset temperature. I guess the only difference is that one is mechanical and one is electric. Otherwise, they work similarly.

 

This is very important don't overlook this.....