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radiator fan question

ashman

ashman

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I've been working on a '79 vette for awhile and it's having overheating issues.

Right now it has a 6 blade flex fan on a 350 small block. I was thinking it would have better cooling with a stock fan and clutch, but the only option I found was super expensive.
vette fan.png

What I'm trying to figure out, is what's so special about this fan? AFAIK it should be the same as any other small block 18" fan. Any reason that this wouldn't work?
dorman fan.png

pic for fun:
20240516_204813.jpg
 
Holy crap that’s EXPENSIVE for no good reason!!
A good seven blade fan ( even an aftermarket one ) would do just fine - it’s the fan clutch in conjunction that will really help out.
Get a truck “severe-duty” application clutch for a C/K 30 series 454 in the mid-eighties year span.
It will have a little more drag on the engine but will pull some serious air movement at speed as well as at idle.
 
Yeah, flex fans basically suck. Good idea to get rid of it.

Overheating can be a complex beast. When it overheats, condition of cooling system components, etc.

Certainly can't go wrong with OEM cooling setup, it worked from the factory. Apparently that GM part number you have was used for a LONG time, on a lot of different vehicles, so it doesn't seem like it was a one-off Corvette piece at least. 469580 seeming to be the updated part number.
 
Same problem with Eileen's car. Flex fans suck. Never got hot in traffic, but would warm up enough that I wanted to do something about it. Make sure that fan is not reverse rotation. Made that mistake. I ended up using a truck fan and cut the diameter down. No issues on a 95* day with the AC on. Make sure the fan sits halfway into the shroud.
 
Cooling issues have been an issue on vettes as long as I can remember... .

Get a 7 blade fan + heavy duty fan clutch .

Power wash the. Fins. On the cores. ...

Do a flush / acid wash on the radiator.....

If you still have heating issues.....time for a new four core radiator....

It's not OEM, but I'm partial to the composite plastic fans ( lots os small fins) on diesels + equipment.....they look like a turbine fan blade..... they move alot of air.

The one on the left was from.a Chevy / Cummins conversion. ( It's 18")

The other with the clutch is from my diesel jeep.

IMG_20240518_083040564.jpg

IMG_20240518_082718209.jpg
 
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fan and clutch.png

Looking at this combo from Summit. fan is 18" and the clutch is "severe duty".
One question, there were a ton of different clutch options, and they look quite a bit different. Are they all the same length? Seems like there would be a bunch of length options depending on how far the radiator was, but I couldn't find any dimentions listed.
 
Also, a severe-duty listing for different applications applies - if possible select an application such as this and it will pull extremely strong at idle as well as not disengage as easily and often at higher RPM’s.
Use this application: 1983 GMC K-3500 454 with a 4.56:1 gear ratio.

Originally the catalogs had foot notes on this because the higher numeric gear effected the operation of the clutch and this type stayed engaged much more than other types.
As the years have gone by and part numbers get superseded some foot notes with this info seemed to be dropped and just lumped in with the designation “severe-duty” - but you must select the proper application and the severe-duty that goes along within that category.
Example: heavy-duty can be listed for an S-10 as well as a K-30 but the parts are spec’d widely different.

Use the makers catalogs to verify dimensions of the hub distance.
 
70jimmy said:
I just ordered somebody a tool for straightening fins. A condenser fin comb.


I hadn't ever seen one.
Click to expand...
Not knowing how that tool worked I looked it up on the Tube. It doesn’t seem to work on fins that are corrugated like in this video, but I did see one being used on fins that are vertical like on an ac unit. You need to be able to get it started on fins that are not damaged first then comb them straight.

 
U can clean up zig zagged cooling fins with a small pick, probe, scribe ... Tedious, but you can gently clean up minor impacts..

The above plastic comb is for air conditioning condensers or hydraulic coolers
 
FYI - Back around 2000 GM had a advisory recall on blade fans for the K5. The fan blades were riveted and could separate when running. GM recommended a new part number for the fan. I don't know if this is tru for corvette also.

The bad GM fan part number: 336032
GM Replacement: 461317
 
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got the new fan setup installed.
old shitty flex fan:
20240521_221601.jpg

new 7 blade fan and severe duty clutch:
20240522_203608.jpg

Initially I had the fan bolted on backwards, but luckily I caught it before installing it in the car:
20240522_200109.jpg


I couldn't figure out why the fan blades were contacting the clutch while bolting it down. :doah:

The new clutch and fan assembly ended up pretty much exactly the right distance into the shroud, but one thing I didn't think to check was the clutch pilot hole size. The severe duty clutch I bought had a 5/8" pilot hole and the vette water pump has a 3/4" pilot. Easy enough fix though:
20240522_200119.jpg

I got it drilled out and installed and holy crap does this thing push a LOT more air. It was super obvious the first time I started the car.

Unfortunately, it still seems to get hot rather quickly. The upper radiator hose looks like it might be collapsed a little bit, so I might try replacing it. Also probably pull the radiator and get a better look at it and see if there is anything I can improve there.
 
Am I seeing a big gap between the shroud and rad at the bottom? If so there may be more air coming from that gap than through the rad.
 
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