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Veteran
Posts: 148
 
| Hi again 
For a few days now I've been dealing with a new noise coming from the fan. It is a roaring or grinding noise. I tested everything: it is NOT the water pump. It is NOT the pulley. It is NOT the spacer. What could be wrong with the fan that causes it to make noises that were never there before? A fan with six blades was installed. I replaced it with the OE four blade fan. Still this noise that was never there before. Could both fans be defective? Do I have to buy a new fan? Any ideas about this?
I'm again completely at a loss. |
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Veteran
Posts: 180
Location: christchurch New Zealand | I had a squeaking creaking noise from a fan on one of my cars recently, like you i checked everything and all good.
In desperation i changed the water pump with a new one and noise gone, the old pump looks good and feels good
guess the bearing was on its way out.
Geoff |
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Veteran
Posts: 148
| If only the belt is mounted on the pulley, without the fan, the noise will not be heard. So it can't be the water pump/bearing......
btw...the water pump is brandnew , mounted only a few weeks ago...
Edited by Todd 2024-03-15 11:42 AM
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Expert 5K+
Posts: 9902
  
Location: So. Cal | You've narrowed it down to the fan. Sounds like the fan is hitting something very lightly, like something sticking up from below, or the bottom of the upper hose, or the belt driving it. The belt tends to wobble quite a bit while running, so if you don't have enough clearance, it can periodically hit the fan. I might suspect a loose blade, which would be very bad, but you say you get the same sound from 2 different fans.
Edited by Powerflite 2024-03-15 1:00 PM
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Board Moderator & Exner Expert 10K+
Posts: 13068
Location: Southern Sweden - Sturkö island | Check the bolt lenght, might be that someone mounted too long bolt/s? |
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Elite Veteran
Posts: 702
Location: Finland | That thing has happened to me a couple of times . Then it has been the fan grinding inside the fan shroud due to me leaning my old elbows too heavily on the shroud... |
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Veteran
Posts: 148
| thanks all for your thoughts on this. ok...the bolts are perfect, not too long (i replaced the bolts also with new ones).....i don't have a shroud, the fan turns free, i already checked this, with belt demounted it ca easily be turned by fingers.
blades are in fine condition, the oe fan with its 4 metal blades is also in top condition. The fan ist tight when screwed on.......Is it possible that the noise is coming from the water pump bearing given the additional weight of the mounted fan? What I noticed.... the bearing of the old and also the new water pump: it squeaks slightly when you turn it. Is that normal? theres no play and no grinding noise, only slightly squeek.
in general.....is a thermal fan clutch recommended? i only have a spacer an the fan (no AC)
Edited by Todd 2024-03-16 7:24 AM
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Board Moderator & Exner Expert 10K+
Posts: 13068
Location: Southern Sweden - Sturkö island | Todd, the forces of the fan makes it want to go forward, hence pulling outwards on the shaft. Try to mount the fan backwards (blowing through the radiator) and see if the grinding goes away - if so, there's something wrong with the water pump.
It's always god to mount athermal fan clutch with the appropriate fan blade - lesser sound at hight speed and lesser hp-consumption.
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Extreme Veteran
Posts: 443
Location: McCleary WA | wizard - 2024-03-16 5:48 AM
Todd, the forces of the fan makes it want to go forward, hence pulling outwards on the shaft. Try to mount the fan backwards (blowing through the radiator) and see if the grinding goes away - if so, there's something wrong with the water pump.
Umm, mounting a fan backwards does not change the direction of airflow. Only reversing its angle of blades, or its direction of spin, will do that. (I had to draw a picture to confirm that...). Any angle flipped 180 degrees is still the same angle. |
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Expert
Posts: 3804
Location: NorCal | Might also want to check the rivets that hold the fan blades to the fan hub for signs of looseness. |
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Expert 5K+ Passed away 30th Sept 2024. You will be missed Chuck!
Posts: 8954
Location: WHEELING,WV.>>>HOME OF WWVA | spray the pullies/groove with soapy water! ------------------------------------later
Edited by 60 dart 2024-03-16 6:22 PM
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Board Moderator & Exner Expert 10K+
Posts: 13068
Location: Southern Sweden - Sturkö island | Darryl T - 2024-03-16 8:21 PM
wizard - 2024-03-16 5:48 AM
Todd, the forces of the fan makes it want to go forward, hence pulling outwards on the shaft. Try to mount the fan backwards (blowing through the radiator) and see if the grinding goes away - if so, there's something wrong with the water pump.
Umm, mounting a fan backwards does not change the direction of airflow. Only reversing its angle of blades, or its direction of spin, will do that. (I had to draw a picture to confirm that... ). Any angle flipped 180 degrees is still the same angle.
Yes, my bad, brainfart. Must find another fan for different direction of spin, or twist an old fanbelt with a temporary idle roller.
It just might prove if the rivets are bad if the fan is turned? |
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Board Moderator & Exner Expert 10K+
Posts: 13068
Location: Southern Sweden - Sturkö island | Mount the pulley without the fan. Adapt a wooden stick to fit between the enging and the pulley, smear some grease on the contact surface. Start the engine (oviously witout the stick in place) Insert the stick and apply some pressure outwards - if the sound reappears, then it's the water pump.
Take care when doing this so you don't entangle fingers in the fan belt or slip with the stick.
Since you have the sound with two different fans, it's very plausible that the problem is the pump. New or renovated water pumps today is most probaly made in China |
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Veteran
Posts: 148
| Dear people, thank you again for your thoughts on my problem. You're all so helpful, it's wonderful.
I think I've figured it out; I tightened the new bolts exactly as specified and the noise disappeared. either they were previously too tight or too loose or unevenly tightened. Now every bolt has exactly the same tightening torque - the noise has disappeared. One of the oe bolts also had an issue on its thread, which i noticed now. That was my stupid mistake, please excuse me. I should have checked that carefully first. |
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Board Moderator & Exner Expert 10K+
Posts: 13068
Location: Southern Sweden - Sturkö island | No sweat Todd, it's important to use torquewrenches and respecting the shop manual. Also, it's even more important to check the threads on bolts and nuts, because damaged threads will give wrong torque. |
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fan with grinding noise
