Fan shroud

[bmclaurin]

I haven't seen this posted before, so I guess I'm the only one, but the fan seems to rub slightly on the fan shroud on my kit. I have the OS105HZR, and I have performed the obligatory light Dremeling of the shroud to make it fit nicely with the 105's cylinder head. But no matter where I position the shroud spacer within the allowed slotting in the frame, I get a slight rub. It's almost as if there isn't quite enough clearance or tolerance in the part of the shroud that envelops the fan--another millimeter of height and it would probably be fine. I did notice that that part of the shroud was ever so slightly "concave," perhaps a very minor defect in how it was molded at the factory. After the first installation attempt, I removed it and made modest use of a heat gun in an effort to slightly reshape it. And that made a small but noticeable improvement in the fit, but it's still not quite right. Any tips out there on how to get this to fit better? My N5c shroud never had this issue with the 55HZR.

Barry

[Ross Lawton]

Hi Barry,

I have used the same engine in my N7 and  with the OS105HZ a slight amount of trimming is required with this engine for clearance of the velocity stack and also the fins on the body of the engine. I am also using the Hatori 105 3D pipe on mine and a slight amount of trimming required for this particular exhaust due to the floating manifold used with this particular exhaust.

One thing to make sure is that the fan shroud itself is not touching the engine at any point. I found that the section which goes over the cyclinder head needed trimming as the shroud was touching the cooling fins of the engine and causing a stress in the shroud which was causing the fan to catch so it might be worth checking to make sure your fan shroud is not touching anywhere.

Hope this helps, let me know how you go and if you need any help just give me a shout.
Cheers,
Ross

[Chris Sexton]

Make sure when you screw the two peices of fan shroud together that the tongue and Grove is straight and seated all the way. This helps hold the shroud open around the fan.

sent from my Verizon Samsung Galaxy Note 2

[eobie]

Yep,

Have the same issue here with the same setup. I spent about 2 hours dremeling and fitting last night and almost have it right. Just need to trim a tad more from the shroud and it should be good to go..

[Rodney Kirstine]

The  modification for exhaust pipe clearance was the part that bit me because I didn't know about it until I had everything together and in the frame when I mounted the pipe.  At least it's easy to get the whole thing in and out of the frame.

[bmclaurin]

Man, I wish I would have seen Rodney's post an hour ago. (And I just realized that Ross' post also mentioned this as well, but I failed to take note of that when I read it the first time.) I had just finished re-Dremeling the shroud and finally got it installed with no rubbing on the fan. After re-attaching the skids, I went to install the pipe. Doh!  More trimming required, so out comes the engine again. Hopefully others will read this thread before starting their build.

Thanks, guys, for the pointers. As Ross suggested, I needed to Dremel a few more spots to keep the shroud from touching the cylinder head at all. That did the trick in terms of the original problem of the fan rubbing on the shroud.

[mdu6]

One other trick.

Before installing the shroud/engine into the machine and after cutting the shroud for the muffler (!),  put the shroud/engine on a table (same orientation as if mounting in the machine) standing on the 4 bolts of the engine back cover. The end of the shroud should be touching the table, and if you center the shrould around the clutch - try to turn the engine - the fan should not be touching anything.

This is true for the YS91 - maybe others could confirm for other engines.

[Gary Lau]

Could you guys post some pictures of the modified fan shroud please?!  A newbie here want to see it first before go ahead to trim it.  Thanks.

[mdu6]

For the YS91 the cutouts (it's more trimming than cutting out) are quite simple - see the 2 areas that I have circled on one side.  The edge of the shroud along the head of the engine on the other side also needs to be trimmed so it does not touch the engine fins.