Fan clutch acts up immediately after replacing radiator

[wildbill23c]

The new radiator is it a larger capacity than the original? If so you will definitely experience an increase in fan engagement as your radiator is now sitting closer to the fan clutch and thus heating up that little spring in the middle of the clutch which engages the fan.

 

[cbxer55]

Anyhow, over at LightningRodder.com, the discussion comes up frequently. It's agreed by everyone that the stock clutch fan works better than electric fans. Especially for street driven vehicles in stop-and-go traffic. It's even been agreed upon that the electric fan doesn't save anything power wise because the alternator has to pick up the slack to keep the battery charged. When the alternator is working overtime, it adds more drag to the engine.

So, Six-Of-One, Half-Dozen-Of-The-Other. Years ago, had an efan that I had put on another truck, die on me in city traffic. Just gave up the ghost and quit working. Worked fine,, til it didn't. I swore I'd never do one again. Then I got swayed into trying one on my Lightning. Got it all mounted and wired, started truck, when the fan should've come on, big bunch of smoke came out from in between the fan and motor. Big, thought the truck was going to catch fire. Don't have a fire extinguisher in my garage. Will soon. Took off efan and wires, tossed it all in the round-open-top-file. NEVER AGAIN!!!!!! Wrote off the monetary loss as a live and learn experience. NEVER BUY ANOTHER DAMN EFAN! Tried em twice, got stung twice. Once is a mistake. Twice is pure stupidity. Yup, I'm stupid, dumb as a box of rocks. For having done it a second time.

I'm not concerned with a few hp, nor a few mpg. Not worth the risk. I'll keep the clutch fans.

 

[RonD]

Yup, opinions vary, but there is no defensible position for mechanical fan over e-fan, just opinions

 

[8thTon]

The only question is how large is the parasitic load of the clutch fan when it is coasting? I’ve never seen any good numbers on that. There’s an old test from 1970 where Pontiac claimed 4-5hp at 6000rpm, but my engine never goes there, it was likely a bigger fan, and it doesn’t tell you the average load for normal driving with the fan mostly coasting and airflow to help spin it. I doubt it averages 1hp, but it clearly isn’t zero like an E-fan under the same circumstances.

Balanced against that is more air flow capacity when it is on full, plus less complexity. I doubt cost is much different, and I seriously doubt you’d see any mileage change at all in normal driving.

These are the kinds of tradeoffs engineers make all the time, and I wouldn’t switch.

 

[88workcar]

Actually an e-fan is better than a working or broken mechanical fan, not even an arguable point, mechanical fans are just cheaper for car makers, but more and more are switching to e-fans to get the better MPG numbers

On a year of change, Chevy did NOTHING BUT go to a E Fan, rated the engine 10-15hp more than the previous yr. It's a cost issue, $2 of savings over 2 million car/trucks is what drives the decision for the automakers.

I check every tank for MPG, on both of my vehicles. Not a one tank test, but when the one tank shows better or worse you know something changed. (weather, load, roads, driving habit ect...) Watching mpg is a hobby for me. My big truck, Ram Ecodiesel finally broke 30mpg last week, now due to driving conditions it dropped to 27.6.

I have had a E Fan on three different vehicles and all with a gain to mpg. I'm sold on them.

 

[Shran]

I've done a bunch of experimentation with the three fan clutches available - the severe duty one is indeed engaged most of the time. I thought it would be a worthwhile part for my Explorer since I wheel it a lot and if I'm out on a multi-day camping trip, I've got probably 600 pounds of extra gear... plus all the skid plates, bumpers, and other gear. I'm guessing it weighs over a thousand pounds more than it did in stock form.

Anyway the severe duty clutch sure keeps it cool but when that sucker kicks on, it's hard to maintain highway speed. I replaced it with a "heavy duty", the next step down... works great. It still gets hot if I'm idling with the AC on but never any other time and I think the clutch engages when it should.

In regards to the other argument here, e-fans vs mechanical: it all comes down to the CFM rating. An inadequate fan of any style will cause problems, but that's my one argument for using a mechanical fan... it's kinda hard to find electric fans with high flow numbers for certain applications.

 

[RonD]

Yes, specific use fans need to be researched a bit

Mechanical fans don't generate their max air flow until engine is above 2,000rpm, which is why you can get a bit of a temp rise just after stopping after running engine hard, double whammy of the slower water pump and mechanical fan speeds

CFM air flow for e-fans can be researched and you can get what you need, for most an e-fan from wrecking yard works fine

For off-roading and especially for water crossings, the e-fan setup can be equipped with an OFF ON manual switch, which can keep engine bay dry if water gets up to fan level


Found this article, not about e-fans, lol, just tests on different mechanical fans and CFM: http://carnut.com/ramblin/dyno.html

So about 1,500 CFM at idle(800rpm), and 2,100 CFM at 1,600rpm with mechanical fan

Also interesting bit about alternator HP draw with an electrical load, I though it would be more, 1.25HP

 

[8thTon]

On a year of change, Chevy did NOTHING BUT go to a E Fan, rated the engine 10-15hp more than the previous yr. It's a cost issue, $2 of savings over 2 million car/trucks is what drives the decision for the automakers.

I check every tank for MPG, on both of my vehicles. Not a one tank test, but when the one tank shows better or worse you know something changed. (weather, load, roads, driving habit ect...) Watching mpg is a hobby for me. My big truck, Ram Ecodiesel finally broke 30mpg last week, now due to driving conditions it dropped to 27.6.

I have had a E Fan on three different vehicles and all with a gain to mpg. I'm sold on them.

Nonetheless you stated upthread that your original fan was loud and the clutch was broken, so the mileage improvement you got does not represent the improvement over a properly functioning stock clutch fan. I'd still like to see some actual data on that, but have not been able to find much. I have no doubt the manufacturers know what it is.

I've done a bunch of experimentation with the three fan clutches available - the severe duty one is indeed engaged most of the time. I thought it would be a worthwhile part for my Explorer since I wheel it a lot and if I'm out on a multi-day camping trip, I've got probably 600 pounds of extra gear... plus all the skid plates, bumpers, and other gear. I'm guessing it weighs over a thousand pounds more than it did in stock form.

Anyway the severe duty clutch sure keeps it cool but when that sucker kicks on, it's hard to maintain highway speed. I replaced it with a "heavy duty", the next step down... works great. It still gets hot if I'm idling with the AC on but never any other time and I think the clutch engages when it should.

In regards to the other argument here, e-fans vs mechanical: it all comes down to the CFM rating. An inadequate fan of any style will cause problems, but that's my one argument for using a mechanical fan... it's kinda hard to find electric fans with high flow numbers for certain applications.

Most E-fans operate on a 30A fuse. Even at a full 30A that's barely 1/2hp, so this is all that is available to drive the E-fan. The load on the alternator to generate this will need to be quite a bit more than that due to losses. It does get some CFM improvement from closer clearances to the shroud, but the mechanical drive of the clutch fan has as no real drive power limit. Both the operating temperature and the fan rpm can be set by the fan clutch to make use of that

 

[RonD]

"clutch fan has as no real drive power limit", yes and thats the problem, lol

Read that article above

Idle and slower speeds is when fan is used/needed that's the CFM number needed, doesn't matter if mechanical fan can generate 6,000cfm at 3,500rpm, just sucks HP away radiator doesn't need it and can't even use it

If e-fan can generate 2,000cfm at .3-.5hp then thats all you need

 

[8thTon]

"clutch fan has as no real drive power limit", yes and thats the problem, lol

Read that article above

Idle and slower speeds is when fan is used/needed that's the CFM number needed, doesn't matter if mechanical fan can generate 6,000cfm at 3,500rpm, just sucks HP away radiator doesn't need it and can't even use it

If e-fan can generate 2,000cfm at .3-.5hp then thats all you need

The fan, radiator and clutch will be designed as a system, not just a bunch of random parts bolted together. The fan speed is dependent on whether the clutch in engaged or not plus the rpm of the engine, but regardless the fan won't spin faster than some max rpm determined by the viscous coupling, so hp loss tops out there. The hp loss does not keep rising with rpm.

The max cfm at idle will be determined by the fan design - I think it's a fair assumption that the engineers have used a fan that can cool the engine at max heat load at idle, regardless of what kind of fan they used. If the rpm is up with normal loading and there is airflow through the radiator the clutch will not be engaged and the fan will bee coasting with minimal hp loss. That is the typical operating condition in normal driving, and represents the power loss the clutch fan will use - just like an E-fan, most of the time it's doing (almost) nothing.

That's the kind of info I'd like to see, but it's going to vary a lot based on expected heat loss for an engine. A big block is going to generate a lot more waste heat and going to have a fan that can produce a lot more cfm, and use a lot more power to do it. It will also have higher loss when coasting. From the article they were not able to get the big block fan to disengage properly, but even if they had it would have different loss and cfm numbers than a Ranger fan.

"One other note....the themo-clutch was difficult to get to perform consistently with what we set up. We would heat it up and everything was fine then all of a sudden it would lock up under high rpms. We never could get it to stop all the way....even after putting it in the refrig over night. The results posted here took the most time to get the consistent 4 pulls and all of the results were averaged anywho! I would suggest that it would work more consistently in a car with a larger heat source etal. "

 

[fred m]

Just an update, the fan clutch started acting completely normal. I drove it over 1,000 miles in the last couple days, and have not heard any excessive fan noise. My fuel economy has returned to normal, as well.

There is no problem worse than an intermittent one. As of right now, this fan clutch shows no signs of being bad, so I'll just let it be. If it starts locking up excessively again I will replace it with a Motorcraft standard duty clutch.

 

[8thTon]

Just an update, the fan clutch started acting completely normal. I drove it over 1,000 miles in the last couple days, and have not heard any excessive fan noise. My fuel economy has returned to normal, as well.

There is no problem worse than an intermittent one. As of right now, this fan clutch shows no signs of being bad, so I'll just let it be. If it starts locking up excessively again I will replace it with a Motorcraft standard duty clutch.

Maybe something fell into the fan/clutch assembly while you were working that locked it up, and has now been ejected?

 

[fred m]

Maybe something fell into the fan/clutch assembly while you were working that locked it up, and has now been ejected?

Perhaps. I did not lose any tools or anything, but any number of things could have happened

 

[wildbill23c]

Sounds kind of odd that it just suddenly went silent. Is the fan still spinning when the engine is idling?

 

[88workcar]

The fan, radiator and clutch will be designed as a system, not just a bunch of random parts bolted together. The fan speed is dependent on whether the clutch in engaged or not plus the rpm of the engine, but regardless the fan won't spin faster than some max rpm determined by the viscous coupling, so hp loss tops out there. The hp loss does not keep rising with rpm.

The max cfm at idle will be determined by the fan design - I think it's a fair assumption that the engineers have used a fan that can cool the engine at max heat load at idle, regardless of what kind of fan they used. If the rpm is up with normal loading and there is airflow through the radiator the clutch will not be engaged and the fan will bee coasting with minimal hp loss. That is the typical operating condition in normal driving, and represents the power loss the clutch fan will use - just like an E-fan, most of the time it's doing (almost) nothing.

That's the kind of info I'd like to see, but it's going to vary a lot based on expected heat loss for an engine. A big block is going to generate a lot more waste heat and going to have a fan that can produce a lot more cfm, and use a lot more power to do it. It will also have higher loss when coasting. From the article they were not able to get the big block fan to disengage properly, but even if they had it would have different loss and cfm numbers than a Ranger fan.

"One other note....the themo-clutch was difficult to get to perform consistently with what we set up. We would heat it up and everything was fine then all of a sudden it would lock up under high rpms. We never could get it to stop all the way....even after putting it in the refrig over night. The results posted here took the most time to get the consistent 4 pulls and all of the results were averaged anywho! I would suggest that it would work more consistently in a car with a larger heat source etal. "

I am an open eye kind of man, you have presented a case good enough for me to try a new clutch on the old set up.