Loss of Power after New Fan Clutch

[jonaz]

Hello Everyone,

I have a 2007 Dodge Ram 1500 5.7 and it blew the water pump and fan clutch at the campsite. Got it towed to a auto repair store in San Diego and they replaced the fan clutch, water pump, and thermostat.

Since they replaced everything, I noticed that new the fan clutch is unusually loud and tends to stay on a lot (yes, it was a very warm day in Southern California). The fan clutch seems to be matched to my throttle acceleration...meaning the fan clutch roars more with when I apply the gas pedal. Going up into the mountains where I lived, I noticed a significant loss of power..I really had to floor it to maintain 40mph when I could easily do 50mph before.

I hate towing my trailer now and the new fan clutch engages a lot. Ive owned this truck for three years now, and it ran great, never even noticed the fan clutch before. I read that there are thermal and non thermal fan clutches? Do you think they put in the wrong fan clutch? Looking for some advice.

Thanks in Advance

[Grit_dog]

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.

If you replaced with an aftermarket parts store unit, the chance is great that it’s defective.
If I have to go to a Vato Zone or O Really?s, or even Nappy anymore, for an actual mechanical/electrical part, I accept or expect about. 50/50 chance that the part will either A perform as intended out of the box, or B will have a reasonable or expected lifespan.
Was not the case years ago, and having worked as a mechanic professionally as a teenager (30 years ago, some parts stores were quality and some were cheap like the strip mall chain stores) and performed 99% of the work on all our vehicles since then, I’ve seen a sharp decline in quality in the last 10 years or so.

[Grit_dog]

@benk, many newer fan clutches are electric operated including the OPs truck. Not like your old iron. Newer ones are able to and come on in stages as needed.

[Cummins12V98]

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.

[jonaz]

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.

[BenK]

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.

[Devo_the_dog]

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]

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.

[Grit_dog]

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.

[Devo_the_dog]

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




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.

[Beaker]

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.

[killerbee]

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.

[BenK]

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...

[ScottG]

Devo the dog wrote:

ScottG wrote:
Devo, that is a complicated question. Under the conditions you state, it probably takes no power at all - fan can be disconnected. But When conditions are at their worst, like climbing mountain w/AC and heavy trailer, it takes a lot of power My truck uses up to 23 HP just to turn the fan.

If it's a complicated question, yet you have a solution, then it's not a complicated question.

You said it yourself: it doesn't take any HP.

If the OP is experiencing this problem a lot and "everything" was replaced, then there is a problem that still exists. I also think it's funny that coolant and oil temps aren't even mentioned.

But, we know that the fan roars and the truck is 10 mph slower. LOL. Something is wrong.

BTW, how are you measuring that it takes 23 hp to turn your fan? Dyno?

I see the usual downward slope of this thread so this is my last post on the subject.

First, I said it doesn't take any power just going down the highway under light load.
Second, I don't know that I presented a solution - I simply made a suggestion. In no way am I or anyone else here qualified to redesign the OP's cooling system.
I have worked through cooling problems on vintage V8 cars though and have learned a few things. There are far more variables to it than most think.

I think the OP should use it as-is and see if his results are consistent. Indeed, it is hard to believe he lost that much speed but I won't discount his experience. OTOH, a fan roaring while it's working hard is a good thing. If it's roaring anytime he's under 10 MPH, even when the eng is at normal op temp and the AC is off means that clutch is junk.
My new OEM clutch does roar anytime I'm going that slow with the AC on - that's a positive change. Not only will the AC work better but the pressures will be lower as well, making life easier for the compressor.

The 23 HP figure is what Dodge engineering reported. This is not the power it uses just going down the road under light load. It is the amount of power it *can* use when called on.

Have a good day.

[Devo_the_dog]

ScottG wrote:
Devo, that is a complicated question. Under the conditions you state, it probably takes no power at all - fan can be disconnected. But When conditions are at their worst, like climbing mountain w/AC and heavy trailer, it takes a lot of power My truck uses up to 23 HP just to turn the fan.

If it's a complicated question, yet you have a solution, then it's not a complicated question.

You said it yourself: it doesn't take any HP.

If the OP is experiencing this problem a lot and "everything" was replaced, then there is a problem that still exists. I also think it's funny that coolant and oil temps aren't even mentioned.

But, we know that the fan roars and the truck is 10 mph slower. LOL. Something is wrong.

BTW, how are you measuring that it takes 23 hp to turn your fan? Dyno?