RansMail #025  June 5th 2004

 

Well this is more of a progress report on my own problems & questions that rear up rather than a news e-mail.

 

The new cooling fan belt and holding tool, plus a few spare shims I was offered by 'Ridgeway', were taken to the strip yesterday where I carefully removed the engine - quite easily. The fan pulley nut was so tight I wondered if I could ever prevent the holding tool from jumping off the fan side whilst I tried to hold the engine from moving and undo the nut all at the same time. Eventually I used a mole wrench to lightly clamp the tool to the fan face, reaching it round a convenient gap between the blades. Then I thought my troubles were over, as Graham had explained that after that the fan just came off by hand.

Not so in my case & I eventually had to hammer it off with a block of wood from behind. The reason turned out on inspection that a previous owner had forced the fan on without taking care to align the slot with the key on the shaft, so it effectively cut its own tight groove, making it almost impossible to get off. Now a couple of fan blades were damaged in the process.

 

I rang the Ridgeway yesterday afternoon & again this morning but got no answer & I fear he may not have one as his standard price list doesn't show stock.  On Monday I'll try the main Skydrive Rotax agent as they're closed today too. If I really can't locate one I could saw & file off the damaged blade sections to make a pair of 2/3 width blades and equally do the same to the opposite blades for balance, that's a last resort however.

 

Ed suggested I get a pdf off the Rotax web page; I entered the engine number (3769482) and type etc but the search facility didn't function & directed me to Skydrive, who said-

"We believe the problem with the site may be due to the age of your engine - we can supply a photocopy of a repair manual for your engine at £5 including post, but unfortunately the post has been collected today, so the earliest I can despatch this will be Monday.  The information should also be in your operators manual.  You will also need a fan holding tool (and shims) - if you do not have one - but we are waiting for stocks from Rotax so cannot supply this at present."

 

Graham kindly posted me a CD with a pdf of the Rotax manual, some details cannot be determined.

 

a)    I assume the shims not in use go behind the metal pulley half as they'd get damaged if under the securing nut's spring washer, but technically that does mean the pulley centre line moves a fraction depending where the shims are - I must assume that the belt is flexible enough in sideways deflection to accommodate that small offset ? Also the parts drawing shows about 6 shims I only found two in situ, so that's a puzzle.

 

b)   The pictures show the 3 long cyl. head studs I was curious about, but apparently with plain standard washers under them towards the head. No mention of them having the nyloc type insert in one end which I've discovered, nor if so which end should go where. And has someone in the last 13 years added thicker spacers ?   However I can see the regular cylinder head nuts also have approx. 8 mm thick spacers under them too, but the manual says nothing about these ? Their height influences the air gap between cylinder head fins and its aluminium cover plate

 

c)    Next the head cover plate is pictured with all the securing screws at the sides going through holes. Mine has slots except for the two in front under the reinforcing strip. After all these years thus, it's probably unimportant but I'd like to know what's right if I can.

 

d)    My microlight 'friends' say the '447' has points driven ignition but the manual only describes an electronic triggered device. Is this manual too modern, bearing in mind Skydrive's comment ??  Again it is important to know, as points do need maintenance.

 

If anyone has any feed back I would be very pleased to hear.

 

Mike.