Jump to content

Loud radiator fan - 76 620


ErickwithnoK

Recommended Posts

My pickup sounds like an f16 at takeoff when I rev it. I believe it is the radiator fan. After doing some reading, I think what is happening is my fan clutch is siezed, it is worn and the oil has leaked out of it causing the fan to be constantly engaged. It seems like my options for a fix are limited. Should I buy an ebay water pump with a cast impeller, or should I look for a fan with less blades and go for a clutchless fan. Really I'm looking for ratsun opinions. I don't want to sacrifice a lot of gas mileage/power, but if it is a minor difference I'm all about lowering the complexity of the parts I replace on the truck. I'm not a very talented mechanic so the simpler the better! Thanks for the opinions, I just want to hear my motor and the sweet exhaust note of my new 2 and a quarter inch exhaust without the extremely loud whining noise of the fan. 

  • Like 1
Link to comment
  • Replies 47
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

The silicon oil is what provides the friction to engage the fan. If it all leaked out it will spin freely, slip or run slower than designed. There is a bearing inside the clutch part that can seize and the blade will be locked and over spin sounding like a jet. As the clutch is integral with the pump it can't be replaced separately.

 

Yes you can get another year pump without the clutch fan, but you will also need the bolt on fan and pulley (two things) to go with it.

 

I would spend the money and get a proper replacement for it.

  • Like 2
Link to comment

personally i'd buy the ebay water pump. i like the look of the stock fans though.

 

best test for seized fan clutch, if you pop the hood and grab the fan and it doesn't spin. mines shot as well

 

I also like the look of the stock fan! By "it doesn't spin" you mean the fan clutch doesn't spin when I turn the fan? Or do you mean that when I try to spin the fan the fan doesn't spin? My understanding is that the siezed fan clutch would allow the fan to spin freely, when it should be keeping it from doing so (or just providing resistance)

 

Thanks for the advice. Once I'm sure it's the fan that's making my noise (pretty sure it is, as I've read other people have similar compalints about the noise and conclude it is the fan) then I'll be buying a CAST impeller replacement. 

  • Like 1
Link to comment

I also like the look of the stock fan! By "it doesn't spin" you mean the fan clutch doesn't spin when I turn the fan? Or do you mean that when I try to spin the fan the fan doesn't spin? My understanding is that the siezed fan clutch would allow the fan to spin freely, when it should be keeping it from doing so (or just providing resistance)

 

Thanks for the advice. Once I'm sure it's the fan that's making my noise (pretty sure it is, as I've read other people have similar compalints about the noise and conclude it is the fan) then I'll be buying a CAST impeller replacement. 

 

see below, i bolded it for you

 

The silicon oil is what provides the friction to engage the fan. If it all leaked out it will spin freely, slip or run slower than designed. There is a bearing inside the clutch part that can seize and the blade will be locked and over spin sounding like a jet. As the clutch is integral with the pump it can't be replaced separately.

 

Yes you can get another year pump without the clutch fan, but you will also need the bolt on fan and pulley (two things) to go with it.

 

I would spend the money and get a proper replacement for it.

  • Like 1
Link to comment

The silicon oil is what provides the friction to engage the fan. If it all leaked out it will spin freely, slip or run slower than designed. There is a bearing inside the clutch part that can seize and the blade will be locked and over spin sounding like a jet. As the clutch is integral with the pump it can't be replaced separately.

 

Yes you can get another year pump without the clutch fan, but you will also need the bolt on fan and pulley (two things) to go with it.

 

I would spend the money and get a proper replacement for it.

 

Thank you for your explanation Mike, that gives me a much better understanding of how it works. Since mine seems to rev with the engine, that would mean I have a seized bearing, since just a lack of fluid would mean it wouldn't spin enough. Is that generally correct? Either way it needs replaced, but just for understanding's sake. 

  • Like 1
Link to comment

Inside are two surfaces close together. One being turned directly by the fan belt. The other is on a bearing and ids only connected to the fan blades. Between the two surfaces is a oil somewhat like 10W30 that gets pulled around by the driven belt and imparts some spin on the fan blade side but isn't directly coupled. Fan speed is limited to 1,500 rpms regardless of how high the engine revs. Engine off try to turn the fan blades by hand. If working properly there is a firm resistance to turning but it will turn smoothly. If it spins with little effort or spins freely the fluid has leaked out. If it won't spin the bearing is seized.

 

The fan belt reduces engine load when cooling is not required as in warm up and out on the highway where vehicle speed above 45mph forces enough air through the rad anyway. There is also a thermostat that senses over heating and increases the clutch grip and speeds the fan up about 2,200 rpms.

 

 

 

 

I would spend the money and get a proper replacement for it.

 

Saves gas by not moving air that's not needed and quieter.

  • Like 2
Link to comment

Inside are two surfaces close together. One being turned directly by the fan belt. The other is on a bearing and ids only connected to the fan blades. Between the two surfaces is a oil somewhat like 10W30 that gets pulled around by the driven belt and imparts some spin on the fan blade side but isn't directly coupled. Fan speed is limited to 1,500 rpms regardless of how high the engine revs. Engine off try to turn the fan blades by hand. If working properly there is a firm resistance to turning but it will turn smoothly. If it spins with little effort or spins freely the fluid has leaked out. If it won't spin the bearing is seized.

 

The fan belt reduces engine load when cooling is not required as in warm up and out on the highway where vehicle speed above 45mph forces enough air through the rad anyway. There is also a thermostat that senses over heating and increases the clutch grip and speeds the fan up about 2,200 rpms.

 

 

 

Saves gas by not moving air that's not needed and quieter.

 

Great, thanks. I have my answer. Now for the brand...Is Beck/Arnley reputable? This is a cast impeller but if there's a close to oem option out there I would appreciate any insight as it seems like this kind of thing could be ebay garbage and fall apart in a year. 

 

http://www.ebay.com/itm/Beck-Arnley-131-1752-New-Water-Pump-/172067449884?fits=Make%3ADatsun%7CModel%3A620&hash=item281004ec1c:g:drcAAOSwqu9VNMKU&vxp=mtr

 

And for those of you who hate links:  [/url]">http://http://s1253.photobucket.com/user/erickwithnok/media/pump_zpsrn0ashtx.png.html'>pump_zpsrn0ashtx.png

  • Like 1
Link to comment

my car did the same thing and the clutch fan was froze up 

I bought one off eBay showed a pic of a cast impeller and was a steel stamped one when it arrived 

also the brand new fan clutch didn't work 

I forgot the brand but it was a local Calif bay area auto parts seller 

if they have a phone number call them first to verify impeller 

I was having heat issues anyway so i went aluminum radiator and duel electric fans 

I couldn't be happier 

  • Like 1
Link to comment

my car did the same thing and the clutch fan was froze up 

I bought one off eBay showed a pic of a cast impeller and was a steel stamped one when it arrived 

also the brand new fan clutch didn't work 

I forgot the brand but it was a local Calif bay area auto parts seller 

if they have a phone number call them first to verify impeller 

I was having heat issues anyway so i went aluminum radiator and duel electric fans 

I couldn't be happier 

 

Thanks for the tip! I'll call in if possible and verify the impeller material. Glad your setup works out for you

  • Like 1
Link to comment

I've never seen one seize up in So Cal. Typically when they go bad they spin too fast and causing minor overheating issues to give you a heads up when it needs replaced before they die completely vs. an electric that will quit and you may not know it isn't working over the sound of your exhaust then you have a major overheating prob. Either way, Good reaso to always watch temp gauge.

 

If you go stock clutch fan Rock Auto has the same BA pump fur $53+ shipping comes out to the same price. They also have a Gates and a AC Delco pump for less. You can contact RA and they will contact seller to see which pump has a good cast iron impeller vs. a inferior stamped one.

 

FYI the last BA pump And the last AC Delco pumps I bought both had cast iron impellers.

  • Like 1
Link to comment

the one i bought was an airtex  usually a good brand but it was made in china and it was bad 

the airtex had a cast impeller

i had a gmb one made in Taiwan had a stamped impeller

and a signature series one made in USA had a cast impeller

I ended up replacing the airtex bad one with the GMB Taiwan one but i had to C clamp the cast impeller on till it seated where it should have been  

that is all the info i have for you 

good luck

  • Like 1
Link to comment

I've never seen one seize up in So Cal. Typically when they go bad they spin too fast and causing minor overheating issues to give you a heads up when it needs replaced before they die completely vs. an electric that will quit and you may not know it isn't working over the sound of your exhaust then you have a major overheating prob. Either way, Good reaso to always watch temp gauge.

 

If you go stock clutch fan Rock Auto has the same BA pump fur $53+ shipping comes out to the same price. They also have a Gates and a AC Delco pump for less. You can contact RA and they will contact seller to see which pump has a good cast iron impeller vs. a inferior stamped one.

 

FYI the last BA pump And the last AC Delco pumps I bought both had cast iron impellers.

 

I usually like to go rock auto but I counted them out when I saw both the images for their fan clutches were stamped steel and not cast iron impellers. I'll contact them and see what's up, thanks!

  • Like 1
Link to comment

I remember people taking the two halves of the 'clutch apart and filling with grease to get a loose fan working. This was probably because it was done on the engine and it's hard to fill with oil in that position. Grease would be too thick I would think. Engine oil would be better.

 

Here's one of mine apart. Has a yellowish silicon based fluid in there as the coupling agent

720stuff002Large.jpg

  • Like 1
Link to comment

Rock auto...... free replacement for life. Free replacement doesn't pay for the tow home and the time spent actually replacing it. I remember my dad having a free replacement muffler. It would rot out every 2 years and he had to pay them for the labor to do it.

Link to comment

I got my part from rock auto and it was a cheapie. No cast impeller. I decided to slap it in anyway, and quickly found the bolt pattern for the fan is wrong. It's supposed to be a 4" diameter bolt pattern, it's more like 4 3/4. So I'm sending it back and looking into other options again...off to O'Reilly's, CarQuest, AutoZone....whoever has it. As long as it isn't Napa  :sick:

The pump I removed is also a cheap stamped impeller, so it has been replaced in the past since I'm assuming they were cast impellers from the factory. Not surprising on a 41 year old pickup. I don't know if it's a pump meant for a different model or not, because every website I check shows a 4.72 inch bolt pattern for the fan blades, and my 7 blade fan is a 4 inch diameter, which I can't seem to find a replacement for. Is this the difference between A/C and non A/C models? My truck is a non A/C model as far as I know. 1976 620 l20b.

 

Rock auto...... free replacement for life. Free replacement doesn't pay for the tow home and the time spent actually replacing it. I remember my dad having a free replacement muffler. It would rot out every 2 years and he had to pay them for the labor to do it.

 

I'm only 22, I can go through a lot of free replacement parts before I die. They don't know what they're getting into. 

 

For what its worth, an L16 pump, pulley, and fan blade will drop right in.  Plentiful stuff.  I've had nothing but terrible luck with aftermarket clutch fans, and warranty support is just as bad as the way its produced.  Rockauto being the exception with warranties.  

 

After receiving my pump from rock auto....I'm considering exactly that. You say it's plentiful stuff but I have yet to see a fan for sale anywhere! I'm sure I'm just looking in the wrong places. The new pumps to fit an l16 (no clutch) are definitely plentiful. Also (I'm really vain about my engine bay) that set up looks nice. 

Link to comment

If it leaves you stranded somewhere needing a tow home is my point. They don't pay for the tow or the anti freeze lost or the head gasket blown from over heating.
 
motorclutchfansLarge.jpg
 

Early L series on left and later Z series and L series with air con on right.

  • Thanks 1
Link to comment

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.