Cooling fan fell off

[egleaves]

Got off of the highway and stopped at a light.  Left light and head a loud "POP" come from front of truck. Pulled over and found cooling fan separated from water pump and coolant spraying from face of radiator. 

What would cause the fan to separate from the water pump shaft?  I appears to be pressed on and it looked like some of the splines may have been stripped out. 

Right now I'm radiator shopping and wondering if I need a new water pump as well.

[bd]

Please include Year, Make, Model etc.. when posting

The water pump flange presses onto the impeller shaft.  Replace the water pump and fan with quality name brand parts.  Make sure that all of the fan retaining studs & nuts are automotive grade and properly tightened.

[egleaves]

Year, Make, Model etc are in my signature as always.  Thank you.

[egleaves]

I'm drawing the conclusion that I will need a new water pump before I'm done with this repair, which especially sucks because the engine and water pump are barely a year old.  The fan itself is one of the few remaining original engine parts.

I'm still unclear on the cause of my failure.  Could the clutch fail and cause the clutch/fan assembly to come off the shaft?  Was I sold a crappy water pump? Or was this somewhat of a fluke?

What are some fan/clutch combos that people have good results with?  An electric fan is not in the budget.

[bd]

Year, Make, Model etc are in my signature as always.  Thank you.

When you withhold the vehicle description from the body of your initial post, it forces your readers to hunt for the information and then assume you are working with that vehicle.  As a result, you are limiting the number as well as accuracy of responses you'll receive.  Simply declaring the vehicle information (even though it is already in your signature) is to your benefit.  You're welcome.   

I'm drawing the conclusion that I will need a new water pump before I'm done with this repair, which especially sucks because the engine and water pump are barely a year old.  The fan itself is one of the few remaining original engine parts.

I'm still unclear on the cause of my failure.  Could the clutch fail and cause the clutch/fan assembly to come off the shaft?  Was I sold a crappy water pump?  Or was this somewhat of a fluke?

What are some fan/clutch combos that people have good results with?  An electric fan is not in the budget.

Can you post pics?  In over 40 years of professional experience, I've never encountered a separation of the water pump flange from its shaft by simply slipping off the end; ...broken water pump shafts, impeller separation, bearing failures, frozen clutches, bent/cracked/broken fan blades, bent/cracked/broken pulleys, missing/broken studs/nuts... yes, but simple axial displacement that resulted in fan clutch separation is new, or at least not common.  Be thankful no one was working on the engine when the failure occurred.

Inferior materials and/or poor manufacturing could be the root causes, while any misalignment, wear or damage resulting in vibration may have contributed (e.g., a frozen or improperly mounted clutch, bent/cracked fan blade, loose or missing clutch/fan retaining hardware, bent or broken pulley, etc).  Be sure to source decent quality parts in your repair.  Inspect all of the parts closely.

What are the high, mean and low temperatures where the vehicle is dominantly used?

[VileZambonie]

Year, Make, Model etc are in my signature as always.  Thank you.

Read this:

http://forum.73-87chevytrucks.com/smforum/index.php?topic=5220.0

[egleaves]

Wow. Lets move past the point of my truck stats not being exactly where some people would like to see them. They are there.

Can you post pics?  In over 40 years of professional experience, I've never encountered a separation of the water pump flange from its shaft by simply slipping off the end; ...broken water pump shafts, impeller separation, bearing failures, frozen clutches, bent/cracked/broken fan blades, bent/cracked/broken pulleys, missing/broken studs/nuts... yes, but simple axial displacement that resulted in fan clutch separation is new, or at least not common.  Be thankful no one was working on the engine when the failure occurred.

Inferior materials and/or poor manufacturing could be the root causes, while any misalignment, wear or damage resulting in vibration may have contributed (e.g., a frozen or improperly mounted clutch, bent/cracked fan blade, loose or missing clutch/fan retaining hardware, bent or broken pulley, etc).  Be sure to source decent quality parts in your repair.  Inspect all of the parts closely.

What are the high, mean and low temperatures where the vehicle is dominantly used?

I'll take a look and try to get a pic when I get home from work, but I know I saw splines exposed.  This all happened after dark last night and I haven't been able to inspect thoroughly yet. 

I'm in central California where temps swing between about 50 and 90 degrees this time of year.

I'm really starting to question the quality of the accessories that came with the turn-key crate engine I purchased from GM.  It's barely a year old and I'm on my second distributor cap, the starter housing exploded this summer, and now this with the fan.

[bd]

Have you determined whether there is any warranty remaining on the water pump?

So, Summer temps can soar as high as 113° F and in Winter drop as low as 20° F.  Summer temps are the more important extreme to reconcile, especially if you use your truck for towing or hauling heavy loads during the warm months.  Install a severe-duty fan clutch, such as available from Hayden in conjunction with a Derale fan blade, both designed for clockwise rotation.  Measure the existing fan diameter and procure the replacement with at least as many blades, but no fewer than six.  The severe-duty clutch and fan should move significantly more air than the original, but will result in increased noise with a slight decrease in fuel mileage.  The "wind" noise will be more pronounced when the engine is first started in the AM.  Use an AC Delco service replacement water pump, or a Milodon high-volume iron pump.  Don't rely on the linked part numbers without further research on fitment.  Of course, other brands and combinations may also work.

[Stewart G Griffin]

Did the fan separate from the water pump flange?    Or did the flange itself (with the fan) separate from the water pump?

[egleaves]

Turns out the fan clutch separated from the spindle that then bolts to the water pump flange. The water pump is intact. It appears that the point of failure was the clutch/fan assembly. The two pieces were pressed together (poorly?) and in the end the internal splines were stripped out of the clutch. What bothers me a bit is this....the dealership that installed the engine used the fan blades from the original engine and a new clutch. The fan blades are installed between the two pieces that just separated from each other, which means they were pressed together at the dealership. Right?
 I'll work on posting a few pics.

[egleaves]

Have you determined whether there is any warranty remaining on the water pump?

So, Summer temps can soar as high as 113° F and in Winter drop as low as 20° F.  Summer temps are the more important extreme to reconcile, especially if you use your truck for towing or hauling heavy loads during the warm months.  Install a severe-duty fan clutch, such as available from Hayden in conjunction with a Derale fan blade, both designed for clockwise rotation.  Measure the existing fan diameter and procure the replacement with at least as many blades, but no fewer than six.  The severe-duty clutch and fan should move significantly more air than the original, but will result in increased noise with a slight decrease in fuel mileage.  The "wind" noise will be more pronounced when the engine is first started in the AM.  Use an AC Delco service replacement water pump, or a Milodon high-volume iron pump.  Don't rely on the linked part numbers without further research on fitment.  Of course, other brands and combinations may also work.

Interesting. My motivation for having this engine installed was to pull a 30' travel trailer from Ohio to Florida to California. I did that. The engine left Ohio in October just as night temps were dropping below freezing. 4 weeks later it was in the Florida Keys where 70F was "cold". 4 weeks later it was in Phoenix, Arizona where the weather man can't count below 70. It has since been through a central California summer. So, now that I think about it the engine has seen plenty delta T.

[egleaves]

Should there have been grease inside a pressed together assembly?  The splines were covered in a light-gray grease. I have pics but I can't post them until tomorrow.

[bd]

Turns out the fan clutch separated from the spindle that then bolts to the water pump flange. The water pump is intact. It appears that the point of failure was the clutch/fan assembly. The two pieces were pressed together (poorly?) and in the end the internal splines were stripped out of the clutch. What bothers me a bit is this....the dealership that installed the engine used the fan blades from the original engine and a new clutch. The fan blades are installed between the two pieces that just separated from each other, which means they were pressed together at the dealership. Right?
 I'll work on posting a few pics.

Well, I've been discussing a Gen I small block and just woke up to the fact that you have a Vortec.  Different animal.  Post pics.  The "gray grease" is probably anti-seize.

[egleaves]

Posting pics. Probably in random order, I don't know.  I'm not good at putting pics on these fora.

[bd]

The pics certainly clarify the issue.  The fan clutch came apart.  The 'gray grease' is the silicone fluid that makes the viscous clutch function.  Now, you need to determine whether it was a manufacturing defect or if there was a vibration that contributed to the separation.

Clarify the following:  When you unbolted the clutch stub shaft from the water pump flange, were all of the bolts tight?  Any missing - I see three?  When you removed the four bolts that retain the fan to the clutch, were they tight?  Describe the fit between the fan hub and the clutch.  Is it snug and concentric without the bolts installed?  When you place the stub shaft into position on the water pump flange, is it a snug fit on the pilot?  Grab the water pump flange and wiggle it side-to-side.  Is there any radial movement?


Edit:  restated the questions after closer inspection of the images.