25 hp engine fan, unique to 25hp?

johnshenry · Posted: Tue Sep 04, 2007 7:22 am Post subject: 25 hp engine fan, unique to 25hp?

The fan came loose in my '50 on the way back from a show Sunday. Just rattling at high RPM. I pulled over to find that if I held the gen pulley, I could reach behind and turn it all the way around. I guess the hole is rounded out.

I have a whole pile of fans at home, most came off 36hp engines. Are the the same?

Luckily, at the last minute before leaving Sun morning I threw a 36mm socket in the tool bag. The nut was not "reaching" the fan well, and the gen pulley nut was very tight, else I would have stolen a washer from off the pulley. So I rifled the spare part box, and found a gasket kit and used an exhaust gasket as an extra "washer" under the nut, tightened it up and it got us home.
_________________
John Henry

'57 Deluxe
'56 Single Cab

Seb67

johnshenry

Blue Baron · Posted: Tue Sep 04, 2007 10:41 am Post subject:

Wow! I'm answering a question for John! Where's the smelling salts, someone revive me! Wink

The 25hp fan has fewer vanes that the 36 hp. (Never actually counted 'em, but compared them side to side and it's noticable.) the 25 hp fan also was not harmonically balanced, which accounts for the distinctive 25hp fan whirring sound.

johnshenry · Posted: Tue Sep 04, 2007 10:47 am Post subject:

Blue Baron · Posted: Tue Sep 04, 2007 10:52 am Post subject:

I'm really not sure whether the whirring sound has to do with the balancing or the fewer number of vanes. All I know is what I've read, and I picked up that tidbit about the harmonic balancing someplace.

HeSa · Posted: Tue Sep 04, 2007 11:41 am Post subject:

Here are some 25 hp gens with og fans.

Image may have been reduced in size. Click image to view fullscreen.

hazetguy · Posted: Sun Mar 20, 2011 10:18 am Post subject:

dredging up this older thread, because i am trying to find out which fan would be most correct for my 3/51 engine. which size holes would be most correct? both fans have 16 vanes and 8 holes. i have searched for pics of 1951ish 25hp fans, but to no avail.

the parts books i have from that era show a fan similar to one of the above, but i would like some real life confirmation and documentation, rather than going by a drawing in an old book.

here is a pic of an original fan on a 11/55 engine. i can't find any definitive pics of a '51 25hp fan.

another thread i referenced: http://www.thesamba.com/vw/forum/viewtopic.php?t=285840

johnshenry · Posted: Sun Mar 20, 2011 8:04 pm Post subject:

(sorry for not replying to your PM on this Jon, took me a while to get down to the box of fans and tins....)

I have 9 fans in my box of engine parts from engines I tore down over the years. Most come from a large parts lot that contained about 5 or so 36 hp engines and couple 25hp ones.

So 8 of the 9 fans I have are small hole, and one is large hole. Although I didn't check them all, I think they are all 16 vane fans. Given that most were from 36hp engines, one could infer that the large hole fan is from early split engines (?). OTOH, I think there was one 40 hp in the lot, so maybe it is the outlier? Or would that certainly have more vanes?

Geez, just when you think all the details are pegged, something new comes up! I looked in my Sept 50 service manual expecting to see a pic, but no pics of fans!
_________________
John Henry

'57 Deluxe
'56 Single Cab

hazetguy · Posted: Mon Mar 21, 2011 10:53 am Post subject:

hey John, no big deal, i thought i would throw this out to the masses to get some input.
a 40hp fan has the small holes and 28 vanes.
i have a '53 industrial engine service manual, but there are no definitive pics of the fan.
the early (late split/early oval era) parts books i have, have drawings of fans which look to have the larger holes, but those are just drawings.
can anyone verify the large hole fan is "correct" for a 3/51 engine? can anyone take a mirror and look in front of their fan shroud?
does anyone have pics of a fan with the larger holes? i know i have seen other large hole fans in person in the past, so i know the one i have is not an oddity.

johnshenry · Posted: Mon Mar 21, 2011 11:02 am Post subject:

I am certain msot of the small hole fans I have came out of 36hp engines, although not certain they are all 16 vane fans (I'll check again).

Another new engine detail to pour over! Nothing you can see just looking in the engine bay, but rest assured if I see you car Jon when it is done, I will reach behind your fan housing and fondle your holes to make sure they are right.........

{I'll fondle the fan on my '50 tonight and see what it has......... Wink

}
_________________
John Henry

'57 Deluxe
'56 Single Cab

hazetguy · Posted: Mon Mar 21, 2011 11:28 am Post subject:

wow, fondle my holes Embarassed

, i hope you buy me a few drinks first!

here are some pics from the parts catalogs i have:

split era (no date)

zwitter (shows split window/oval dash in body section):

august 1954:

nlorntson · Posted: Mon Mar 21, 2011 7:32 pm Post subject:

From my 1949 spare parts book:

Per Jon and John, I felt all the holes I have access to Laughing

. The fan on my 1949 engine has the smaller holes as did the 25hp replacement engine assembled in 1956. Also, a 1952 I have access to that is sporting a 1951 engine (not original pieces necessarily) also has the smaller holes.

Edit: I found a fan from a later engine and compared to what I had and the 49 et.al. fans are indeed smaller in comparison. What I thought was "large" is actually small.

Crashbox · Posted: Tue Mar 22, 2011 7:05 am Post subject:

hazetguy · Posted: Wed Mar 23, 2011 6:37 pm Post subject:

thanks for the info. can't say that i've ever seen a big hole fan on that "new" of an engine.
bummer, i really wanted to use the larger hole fan.

johnshenry · Posted: Wed Mar 23, 2011 7:22 pm Post subject:

I just fondled my '50.

Small hole.

Laughing

_________________
John Henry

'57 Deluxe
'56 Single Cab

nlorntson · Posted: Wed Mar 23, 2011 8:37 pm Post subject:

Since there was overwhelming evidence, I found a fan from a later engine and compared to what I had and the 49 et.al.

Fan holes are indeed smaller in comparison. What I thought was "large" is actually small.

52 split · Posted: Tue Aug 13, 2013 7:00 am Post subject:

need some help as no thread has answer to this question.this is for a june 52 car. i picked up a fan and backing plate for a 25hp motor from a long time samba member and tried to fit it to my seamed shroud and the backing plate is to big to mount to the shroud. the measurement is 24.3cm from hole to hole. as far as i can see 25hp ,36hp fans and backing plates are the same, less maybe the mount location of 9,3 for the backing plate. question could i have a kdf seamed shroud, and it uses a smaller backing plate.any one have one to measure. thanks

Sepi · Posted: Wed Aug 14, 2013 12:52 pm Post subject:

If your split is June -52, the fan shroud should be like this zwitter -52/53 - no seam anymore. The measurement between holes is about 24,3

usariemen · Posted: Wed Aug 14, 2013 1:25 pm Post subject:


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