Pagoda SL Group
W113 Pagoda SL Group => Drive train, fuel, suspension, steering & brakes => Topic started by: austinado16 on August 25, 2022, 16:28:30
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Thought I'd give some feedback on the URO radiator fan clutch that's available through the common vendors.
I recently installed one, as a precautionary measure, due to the unknown functionality of the Behr clutch that was on the car, and due to the car being stored from 2009 until Jan. 2019.
Following installation, I immediately noticed that other than at idle, the fan roar was always present. So much so, that there was no more of that wonderful 6 cylinder spooling up sound; it was completely being drowned out by the whine/howl of the fan. Thinking the fluid and the clutch in the URO fan just needed some time to go through a few heating and cooling cycles, I left it in place. Since Jan. 2019, the car has been parked and rarely driven (I had other stuff going on. It had a dragging rear brake issue, and due to the condition of the interior and the paint on the roof and trunk, it was embarrassing to drive).
Fast forward to the here-and-now: I've put a ton of time into the car, it's back to being a proud daily driver, and I'm just tired of the fan noise. I drove around town with it this morning to get it hot, shot some temps of the radiator, cylinder head, water pump and pipes areas (with an infrared temp gun), and then swapped on my Behr clutch. Took the car right back out, drove the same route, the same way, including some hard acceleration, and some just letting the engine run at 3,000rpm in 2nd gear. The fan noise is completely gone, and just slightly heard in the background. The fan no longer "instantly makes noise" upon acceleration, as if it's bolted directly to the water pump. Re-shot the temps, and had the same readings. I'm very pleased to have the Behr clutch back on, and the car so much quieter.
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Hi,
the visco clutch works hydraulically and temperature-dependent and is controlled by a bimetallic spring.
When cold, the fan should rotate without play and with a noticeable resistance.
When the engine is running cold, the fan runs first, you can hear it blowing, then it only runs at low speed without power flow.
If the engine temperature rises above 90 degrees C, the bimetal reacts and opens the oil reservoir of the clutch via a pressure pin.
The fan gets power flow again and runs with approx. 3500 rpm. The function can now be heard and felt again.
Here you can see how it works: https://www.kfz-tech.de/Engl/Biblio/Kuehlung/Viskoluefter.htm
Maybe there is too much oil in your clutch which causes permanent connection.
My experience with different manufacturers of such clutches is rather bad, most of them didn't work at all. But I didn't have a clutch with permanent operation.
...WRe
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Thanks! Yes, very aware of how a fan clutch works (not saying that to sound like a jerk). The URO Parts fan does "slip" as one would expect it should. In other words, with the engine off, cold it can be spun by hand with minor resistance felt, and with the engine at 80*C/180*F, it still only has slight drag/resistance. So just in "testing" it that way, one would think it's functioning properly. However, in actual driving conditions, whether right after first cold start, and during the initial .8km/.5mi of driving, or after 30min to an hour of driving, it performs exactly the same, literally being so engaged that it roars all the time. The Behr clutch feels just like the URO Parts clutch, when just hand spinning it, either cold or hot, however, it is silent, as it should be, during normal driving.
I too have had poor results from aftermarket radiator fan clutches. I only purchased the URO Parts clutch because I couldn't find an OE at the time, and it was only $46.... so I was thinking: The car is just going to be driven around town, and short trips on the freeway, in mild/pleasant temps, so even a low priced (potentially low quality) clutch should be able to survive that. Oops.
I have a '90 GMC Suburban with clutched fan on a 5.7L/350ci V-8. That clutch gets a full workout, because I tow, in the mountains, and in the heat, at low speeds, as well as towing out across the desert in triple digit heat. When cold, that fan is fully engaged for about .8km/.5mi, indicating it's alive. Then it suddenly goes quiet, and the fan is not heard again, either until the next cold start, or until it gets so hot that the fan engages. It sounds like a diesel locomotive when it engages on the freeway
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It's been a problem for many years where people fit the incorrect viscous coupling.
For me the most common occurence is on 124s where a diesel viscous is fitted to a petrol engine. There's always an immediate elevation in noise level due to different drive characteristics that often goes un-noticed to the customer.
The elevated noise will automatically result in higher fuel consumption.
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Thank you Todd for the detailed explanation. I wish that peoples reviews and observations were as detailed as this.
That being said, I wonder if this might actually be the wrong or inappropriate part that was given to you, or a defective unit? It’s not up to you to do the testing for this Parts manufacture but you would have to get a second unit to see if it behaves the same as the first unit.
Some manufacturers and parts suppliers including Mercedes-Benz themselves, have been known to do such inappropriate parts assignments. I bought, from Mercedes-Benz, the “correct” oil dipstick for my car and let me tell you it’s not even close. I also bought a passenger door pull and that too was not correct.
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Good points.
I think more so than ever, buying parts for "old" vehicles has become very challenging. There is a lot of stuff being miss manufactured, and the parts sellers have no idea. They're simply buying from someone's parts catalogue, where someone else has put together the string of model numbers, years, and part numbers that the replica part is supposed to fit. I go through this constantly because I don't own anything new. Recently ordered hundreds of dollars of rear brake parts for my VW Rabbit Pickup, and all of it was so poorly made that not only does it not fit, but it doesn't work.
Regarding this URO Parts fan clutch, I've owned the car for 30yrs, so I have a good feeling for how the car "should sound." So when the engine went from being that amazing mechanically injected straight six, throaty, and just exhilarating at full throttle, to sounding like a child's bicycle with cards in the spokes, I knew that fan clutch was trash. The only time there should be that much noise from a clutched fan, is during that first 3-5min of cold operation, or when the temp gauge is nearly at 90-95*C/200*F.
Anyway, I'm all smiles now because the car is back to being as it should be, and I've just wrapped up a large amount of work on it, so that it's even nicer to drive.
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URO = yoU Replace Often.
Fan clutch systems work on two principals. Heat and RPM. A thermo strip expands and pushes on a pin that allows a viscous fluid to circulate which makes a turbine spin. Once the fan reaches a certain RPM, a spring loaded lever moves under centrifugal force which closes a port so that the RPM is regulated.
I had one seize up and a couple of fan blades actually broke off and dented the bottom of the hood. ( 107 450SL ) Never stand above or beside the fan when revving up an engine. You could get ventilated. :(
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URO = yoU Replace Often.
Ha! That's great. I normally avoid this stuff like the plague, same as Meyle products. Should have saved my money.
Haven't broken blades off a fan yet, but did have a water pump shaft sheer off in the Suburban, on the freeway. Turns out, GM grooves the water pump shaft, and the front bearing runs in that groove! Ingenious...I mean, why run an inner bearing race, right? My fault though, so I can't blame GM. I've heavily modified the 'burb to tow in the heat, so I installed the much wider, larger 454 big block radiator and fan shroud, as part of my group of mods. The big block is longer, and reaches further forward toward the radiator, than my small block. So that left my fan too far rearward of the fan shroud. I installed an aluminum spacer block (from NAPA), to get the blades up into that happy 1/2-2/3rd of the blade "into" the shroud, zone. Ran it that way for several years, but having that massive steel OEM fan moved so far forward of the bearing finally snapped the WP shaft. Sent that big fan mostly through that gorgeous 454 radiator, on a Friday evening, 100mi from home, with a 'burb full of wife, daughter, XC high school assistant coach, and 5 of my daughter's teammates....heading to LA for an XC meet the next morning. Less than ideal. Thankfully the big upper radiator hose caught the fan, and kept it from coming through the hood.
Have heard of those thin "Flex Fans" shedding blades and killing a few people.