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Open Roads Forum  >  Tow Vehicles

 > Loss of Power after New Fan Clutch

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BenK

SF BayArea

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Posted: 06/22/21 11:49am Link  |  Quote  |  Print  |  Notify Moderator

There isn't enough data and can only guess.

The OP said: " really had to floor it to maintain 40mph when I could easily do 50mph before."

To me, they were 'floored' in both cases (40MPH now & 50MPH before)...so their ICE was at max HP capabilities and adding in a 'new' fan clutch dropped the MPH

That says they got a higher level fan clutch than OEM. Meaning the HD or SD fan clutch couples *MORE* water pump shaft RPMs, that then takes *MORE* HP...but they were already 'floored'...therefore no more HP available...


-Ben Picture of my rig
1996 GMC SLT Suburban 3/4 ton K3500/7.4L/4:1/+150Kmiles orig owner...
1980 Chevy Silverado C10/long bed/"BUILT" 5.7L/3:73/1 ton helper springs/+329Kmiles, bought it from dad...
1998 Mazda B2500 (1/2 ton) pickup, 2nd owner...
Praise Dyno Brake equiped and all have "nose bleed" braking!
Previous trucks/offroaders: 40's Jeep restored in mid 60's / 69 DuneBuggy (approx +1K lb: VW pan/200hpCorvair: eng, cam, dual carb'w velocity stacks'n 18" runners, 4spd transaxle) made myself from ground up / 1970 Toyota FJ40 / 1973 K5 Blazer (2dr Tahoe, 1 ton axles front/rear, +255K miles when sold it)...
Sold the boat (looking for another): Trophy with twin 150's...
51 cylinders in household, what's yours?...

killerbee

PHOENIX USA, Never hot

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Posted: 06/22/21 12:51pm Link  |  Quote  |  Print  |  Notify Moderator

If you don't have an intercooler, you don't need a thermoviscous fan, which is what you have, now overdriven with an oversensitive temperature strip. You can get a bunch of that HP back by going electric if your alternator is decent capacity. But hear is a pro tip if you would like to stop the short cycling...either replace your radiator and condenser or have them professionally cleaned. The dirt those fins have accumulated since 2007 has killed the cooling stack air flow efficiency, and the slower moving air across the fan clutch has become hotter over time. When you get rid of the resistance in the fins, you will see less fan engagement. If they replaced your thermostat with the wrong one, that can cause unnecessary engagement also.


Michael, Systems Engineer and Professional DURAMAX Diesel Tuner
Killerbee Performance


Beaker

Brevard, NC

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Posted: 06/22/21 01:38pm Link  |  Quote  |  Print  |  Notify Moderator

In 13 years I have heard that roar 2x, both times about 30 secs on my Duramax.
Yea, I know, different truck, different etc, etc,.
If it happened very often I would have junked the truck. That is a terrible noise!!
Along with reduced power, you know something is wrong.
Take it back to where it was repaired and don't take no for an answer. You know people would not be buying trucks if that is normal.


2008 Silverado 2500HD Duramax
2010 Cruiser 26RK

Devo the dog

Moved out of crazy California

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Posted: 06/22/21 04:33pm Link  |  Quote  |  Print  |  Notify Moderator

I've heard the fan kick in on my F350 and have other other trucks I've owned. But, it doesn't happen often and the loss of power has always been minimal. The race cars/trucks/etc all have electric fans, and much larger radiators and more oil cooling.

The last time it happened on the F350 was during the big heat wave and fires in Colorado (June 2018) and I was pulling our 5th wheel up and over Monarch Pass. We got to the summit a little after 5 pm so it was the hottest part of the day.
2005 V10 with 4:30s, all new fluids, new belts, hoses, etc., plus a clean condenser and radiator.
The fan only came on once for about 20 seconds 1/2 way up.

The entire trip was hot. But the fan only kicked in once.

Here's the elevation profile
[image]

[image]

FWIW, all the other trucks shown in the foreground of the photo were mutual aid Firefighters heading home to Oregon, after spending 3 weeks in Colorado. Every crew truck had a gas engine.


The dodge fan boys hate the dodge/ram dealerships. Now that I have owned a Mexican Fiat Oui-Oui (La fiat wee-wee), I understand why.
The only thing more incompetent than Ram is Bye-don and his supporters.

Grit dog

Black Diamond, WA

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Posted: 06/22/21 07:00pm Link  |  Quote  |  Print  |  Notify Moderator

It appears the OP was just venting, and or looking for some magic beans with which to fix his truck. 1 n done on this thread probably.

I'm presuming one of the components failed, took out the belt which took out the other (probably water pump murdered the fan with a thrown belt). Regardless, without more info, who knows....
Heck, maybe the new t-stat aint opening all the way, causing the engine to run hotter and thus the fan to be working overtime.
I don't think an old Hemi has any de-fueling due to temperature built in. 06 6.1 Hemi Charger we had, went about 2 years with increasingly failing electric fans. To the point only one of them would work at low speed and the other didn't respond. That car would still chit and get even though under the right conditions it would run around 230 degree coolant temp, until I replaced the fan assembly.


2016 Ram 2500, MotorOps.ca EFIlive tuned, 5” turbo back, 6" lift on 37s
2017 Heartland Torque T29

BenK

SF BayArea

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Posted: 06/23/21 11:03am Link  |  Quote  |  Print  |  Notify Moderator

Fan clutches are not digital...meaning that they are only on or off with no middle coupling

They are analog...meaning that they will start to couple more over their parasitic as their thermo sensor says it is getting hotter...until it says to turn FULL ON. At which point it ROARS

You can get by with a much smaller mechanically coupled or electric by increasing the radiator's thermal rejection capacity (larger frontal area, but stuck with the vehicle sheetmetal opening...or increasing the stack...and/or increasing the tube/fin efficiency)

It is a whole system...thermal management of the ICE coolant ICE oil, and auto ATF. Toss in the AC radiator.

Heck, even the flow rate (both PSI & GPH) of the coolant running through the radiator matters...as it is a component of how the thermal system works.

When towing heavy, my Suburban's SD fan clutch rarely ROARs, but when it does...a quick look at the dash thermal gauge shows it is crept up to 200*F. That then has the gauge needle drop like a rock back to 180*F (my thermostat rating). Maybe a few seconds if on the flats, but on inclines it might ROAR for a few minutes and will cycle if that incline is long.

Devo the dog

Moved out of crazy California

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Posted: 06/23/21 01:49pm Link  |  Quote  |  Print  |  Notify Moderator

The radiator fan on my Fiat Qui-Qui comes on after pulling away from a stop and and stays on until 25 mph. Doesn't matter if it's 100 degrees or 20 degrees. Dealers have said it's normal. Since I'm not familiar with the Qui-Qui's, I have learned to ignore it.

BenK

SF BayArea

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Posted: 06/23/21 01:51pm Link  |  Quote  |  Print  |  Notify Moderator

Another potential that is forgotten about the current OATs & HOATs coolants

They all have a nasty reaction, or activation, during a very high temp event.

Since the 'A'cid component works by etching metal down to clean metal & plating a protective layer of organic...it leaves the etched off oxide(s) floating in the coolant till it is flushed at the manual's recommended frequency (miles and/or time based).

During a very high temp event, that floating glob of acid/oxide reacts in that high temp area. Most typically inside the radiator tubes by sticking to it. While there, it attracts more of these floating globules. Creating a narrowing of that tube, which reduces the coolant flow, which exacerbates the thermal rejection rate, which then creates an ever hotter spot.

Also eats away the radiator tube from the inside. This also happens in other coolant radiator tubes...like the heater core.

Meaning the OP's radiator might be compromised and needs either rebuilding the radiator by rodding it out & new tank gaskets...and/or...a complete coolant flush.

jonaz

Southern California

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Posted: 06/27/21 07:06am Link  |  Quote  |  Print  |  Notify Moderator

Thank you everyone for your replies. There definitely is a problem with the new fan clutch. At this point, I am going to replace it with OEM.


[blue]2007 Dodge Ram 1500 4x4 5.7 Hemi (3.92 gears) Prodigy brake controller,Weight Distribution Hitch 2021 Coachman Catalina 263BHSCK

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Cummins12V98

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Posted: 06/27/21 07:44am Link  |  Quote  |  Print  |  Notify Moderator

jonaz wrote:

Thank you everyone for your replies. There definitely is a problem with the new fan clutch. At this point, I am going to replace it with OEM.


Good call.


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