Will a lighter mechanical fan saves gas? NO !

[letank]

While shopping at the local recycling yard.... I found this cool lightweight fan by 1/2 lbs CORRECTION 2.2lbs is the total weight DIFFERENCE OF THE FAN AND CLUTCH ASSY.... it is aluminum, installed on a fast car that redline at 5500rpm..... it has more blades.... is smaller by 1", it fits, but not tested as it was borrowed .... A new merco oem clutch fan is $teep $200, but dirt cheap at the junkyard, it is from a merco 560sl, very fancy design with 2 different types of notches on the blade endings, the 450sl has a different shape and is smaller by 2".



Test fit a the yard, lucky me they had an FSJ that day, you will need to bore the center hole of the fan clutch a 1/4"

[AwesomeJ10]

I would try that in a minute.

What vehicle did that come from?

[ScottsMojo]

It will save .0008 miles per gallon...

[Stuka]

As far as fuel savings, not much by itself. Takes lots of little things together to make a difference.

If you want to make a difference, get an electric fan. The drag on the engine is quite a bit less than a mechanical fan. Yes there is some drag from the alternator, but its less parasitic loss than a huge mechanical fan. Makes a big difference in throttle response too.

[letank]

I would try that in a minute.

What vehicle did that come from?

560sl, mercedes mid 80's, the 450sl has a 16" fan.

May not save too much gas, but may be less loss of power, after all this is rotating weight. The e fan needs more electrical, and all those german v8s are using mechanical fans coupled with e fan for AC use in stop and go traffic.

Dying to try but it was borrowed.... so when I get it back.... It will be tested and results posted.

[ScottsMojo]

So thats a plastic fan blade? That would be quite a bit lighter than the stocker. I ended up using a 7 blade (aluminum blade) fan from a big block cheby with the stock style fan clutch and that combo has worked really well for me. I have zero cooling issues.

[letank]

So thats a plastic fan blade? That would be quite a bit lighter than the stocker. I ended up using a 7 blade (aluminum blade) fan from a big block cheby with the stock style fan clutch and that combo has worked really well for me. I have zero cooling issues.

it is aluminum,

update the price of the fan clutch found it on car parts 4 less, for $45.... ordered one, I may not recover mine.... installed on a friend's vehicle that needed it more than me....and it was a knuckle buster.

[letank]

Installed, the clutch needed a little trim, even as being for the same vehicle a 560SL, and little larger hole to fit the nose of the water pump, a 5/8 drill did the trick. Went around a few blocks, let it idle for 10-15 min and the temp is about the same, of course this is not a hot day, but still warm at 64F, this after doing the valve stem seals, so I was more concern about oil leaks...

The fan is standing close to the radiator than the OEM, inside the shroud.



from above

[Stuka]

Cool. Will be interested to see how well it works out.

[letank]

Took it for a longer drive 25 miles round trip. Now that I am not burning 1q of oil every 400 miles... there is more power.
Fan is working well in stop and go traffic, no temp fluctuation even after a steep climb followed by an idle at a stop light, today was in the top 60's, T-shirt day. Engine is overall quieter, I can hear a ticking... time to recheck those headers bolts.

[ScottsMojo]

Took it for a longer drive 25 miles round trip. Now that I am not burning 1q of oil every 400 miles... there is more power.
Fan is working well in stop and go traffic, no temp fluctuation even after a steep climb followed by an idle at a stop light, today was in the top 60's, T-shirt day. Engine is overall quieter, I can hear a ticking... time to recheck those headers bolts.

I've the same problem. I ran a flex fan for years. Decided last year to build a shroud and re-install a stock type fan with clutch. Overall noise went down. Decided to install a quieter exhaust, more noise gone. But wait, what are all these new noises I hear?

So, I am now to the point of chasing squeaks, rattles, etc which is good, as its motivating me to replace parts that are worn out or in need of repair.

[letank]

Took a weekend ride to the far side, the sierras, with some hill climb, as I needed to test the fan as well. Fan is kicking in, and I am not seeing that slight heat surge that stays a little longer. My previous fan and clutch were new 2 summers ago.
As for mileage, 405 miles and 27.2 gallons... Yield over 14.5 mpg which is 2 mpg over the usual. This is higway, freeway and secondary roads.
To follow...

[letank]

Well did another 400 mile trip and stuck in stop and go traffic with higher ambient temp... well not higher than 80's as we are having a colder than usual season.

Did the hill climb, keeping in 2nd gear with a stop at the top of the 2 mile climb, the temp gauge went a little over another needle width after the run, but went back to "standard reading" within a minute of crawling speed. Mileage is about the same at 14.x mpg... x ! well it is so much nicer not too burn oil after I replaced the valve stem seals that I have been keeping up with the traffic ... a 1000 miles and still have 2/3 oil on the dipstick.

[serehill]

So your're saying that this fan gave you 2 MPG???

[letank]

So your're saying that this fan gave you 2 MPG???

This is my best explanation, I do not think that the valve stem seals are the cause of the improved gas mileage. I used for reference the same route between relatively flat highways.

Ideally one should use a more accurate measurement, with a known amount of gas and distance, other conditions such as wind, temperature and humidity can affect the mileage, but going from mid 12's to mid 14's seems real as I never made over 13's with that FSJ 10 years ago when I got it. At that time, I installed new spark plugs, wires, TFI and large cap distributor with fresh oil in engine transmission and TC, and it was not using so much oil.

[letank]

And the answer is NO.... on the way to Ouray at 60 mph I averaged 15 to 16 mpg. In Ouray I installed the OEM 19" fan, I had some issue with gas boiling in the tank... and drove back 1200 miles with the stock fan... and average 15 to 16 mpg, I could definitively hear the fan cluctch kicking in even on the highway... it was hot, I even vapor locked between Green River and Price more than once... stopped and waited for the gas to cool... I should have added cool gas in Green River. But even with fresh gas in Price... I had to stop a few times... before being stuck in an unsafe area. I could smell the gas coming out of the tank purge vent... disconnected as it could keep up with the pressure at high altitude.

Having a more spirited drive I drop to 14.5 mpg which is still better than the 12.5 mpg... so is the difference due to replacing the leaky valve seals....

Comments....

[Stuka]

Sounds about right. Like I said above, it takes a lot of small changes.

Thing I like most about electric fans is improved throttle response (More important with a manual Trans) and of course, the lack of noise.


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