more alternator troubles!!!

it seems like every step of the way to refurbing my engine is throwing up problems!!

this time, I went to fit the pulley I removed from my dynamo, onto my new alternator. before the back half was fully seated down the rear lip started binding on the alternator case ....so I took it off

I put a straight edge across the back edge of the pulley and measured the depth to where the back face of the keyway and shaft go through - about 27mm, I then measured from the base of the alternator shaft to the face of the alternator where it was catching - about 17mm

so are there differences between alternator and dynamo pullies? ....am I using the wrong one???

I dont think I could grind off the back face of the pulley as this would either weaken it or throw it out of balance, and I dont think a spacer behind would work as the pully would be half on, half off of the woodruft key

....any suggestions other than refitting the dynamo

cheers

 

I have seen a couple of the new Chinese alternators that the casing rubs on the pulley and have had to grind the pulley down a bit but not that much

 

cheers mate.

just re-measured and it was barely 1mm difference

I think I will be able to skim a touch off with a file .....I blame the thick layer of chinese chrome ......the chrome will probably peel off in a few weeks anyway

2nd problem, it doesnt seem to want to sit on the pedastal correctly , with the fan housing in place, I can slip a bit of card between the alternator and the stand ......seem to be a bit of the alternator casing catching on the stand also

....will packing it slightly with a bit of 1mm rubber between the stand and alternator be a bad idea?

 

Are you sure the fan housing is sitting right as if tilted the alt will not sit right either

 

^this. Try loosening the side fan housing mounting bolts and jiggling things around, if you haven't done so. When you do get it to sit right, worth checking that the crank and alt pulleys are in alignment ie vertical.

 

Dosent the alternator earth through the stand?

 

Is there a washer on the alt shaft?

Loosely fit the pulley and check the alignment between top and bottom pulleys, as you might find that you need a washer behind the top pulley to align it with the bottom one...

 

thanks guys

all very good points .....especially the earth I didnt think of that!!!

the fan housing was only in loosely, so I guess that could be one of the problems regarding how the alternator is sitting.

there is a small coller on the end of the alternator (pulley end), I did fit a copper washer between the coller and pulley to space it out....and it worked....kind of. with it all back in place (and spacer washer fitted) I checked the allignment to the crank pulley....and the alternator one is about 1mm too far to the rear of the van if the engine was fitted ....this was with no spacer washers between pulley halfs.

seeing as how the missalignment was about the width of the washer I fitted, I took it all apart and ground off about 1mm from the rear of the pulley, refitted with out the coppper washer. It now no longer binds on the alternator...but I've not re-tried fitting to check allignment again....but I suspect it will be better

however, I'm also having trouble at the other end....with the fan. It was rubbing the back plate, further investigation looked like it was sloping to one side as there was a bigger gap on one side of the backing plate than the other, I could have kept putting more packing in, but the bigest gap was over 5mm by this point. taking it off again I noticed the centre of the fan has been repaired at some point and there was a bit of weld which had not been ground back fully.....so I ground it back....and its still not sitting flat....I can wobble it a bit ....no matter how I tweeked it I couldnt get it right, so it looks like a new fan is next on the shopping list!!!

 

Looks like it dude!! I'm amazed that it hasn't flown to bits being like that... especially as fan speed is greater than engine speed

 

I was amazed my engine hadent overheated when i pulled the fan to find over half of it full of bits of rag

 

Just goes to show how well engineered they are

 

Thats why they were so renound for reliability because you can have half the bits missing and other bits worn out and they still run
That much lack of care over such a long length of time does take its toll though

 

Yep be careful as if unbalanced it will be a problem and you will probably need new alternator bearings pretty quickly, a new second hand fan would be a good idea

 

thanks guys,

the thing is, I dont remember the fan rubbing or being a problem before I dismantled it .....but then it has been nearly 3 years since I ran it last

heres a pic of the rear of the fan, you should be able to just make out the small raised areas of weld in the center



I ground them down but it still wasnt sitting flat, so I'm hoping to order a new one today.....and as it happens, I think I've got a single port fan so I'll buy a twin port one - I'm guessing they shift more air so more cooling??

going back to the pulley problems, this was the measurement I had taken from the pulley



and to compensate for it catching on the alternator case I fitted a copper washer



but that put the allignment of the pullies out when I refitted it



......I took it apart, removed washer and ground about 1mm off the back of the pulley, it no longer binds on the alternator but I've not refitted it to check allignment

from the pic above you can see it is also at an angle as the alternator wasnt sitting on the stand fully, and I could get a bit of cardboard under it (the blue bit in the pic)



and I think this was because the alternator casing was hitting the stand at the front



so not sure if I need to take a small bit off the casing with a grinder? - any one else had this problem?

I've also noticed that the shaft the fan mounts on is a different length to the dynamo shaft .....so when I did fit the fan, the special nut was only on half way after all the spacers etc were fitted .....any one else encountered this?

cheers for the help

 

Stand is alloy so I don't think so

 

Diddy, it's hard to see what's going on, but one thing for sure is you need the alternator strapped down before deciding you need spacers anywhere. And if you do need spacers -NOT COPPER - it's too soft.
The Single and twin port fans are different thicknessess and so are the fan housings. If you have a doghouse fan housing, you have, and must have, a twin port fan.
Yes to the problem with the casing not allowing the alternator to seat correctly - I ground a bit off mine. I think it was the new stand to blame.

 

Alloy still conducts current

 

Oh ok you learn something new every day

 

what if you twist the alternator so that the main elec pin is upright will it fit then

 

thanks every one

I dont think I could rotate it, as the position is dictated by the backplate bolting to the fan housing....and the back plate needs to be in the correct orientation with hte 'opening' facing down I believe.

now I have removed the copper washer ans skimmed off the back of the pulley, I think the allignment will be much better (but I'm waiting for a new fan an reassemble before I put it all back together again)

thanks for the heads up about grinding the casing zed ......I dont really want to do it but I think it is that which is stopping the alternator sitting on the stand properly and thus the different angles between the pulleys. The stand is a genuine one.....although I like the new shiney ones I had been advised they can crack and an original one is much better all round

I still have the length of the alternator fan shaft playing on my mind though I will be ordering a new hub for starters, as the dynamo hub was shapped like a top hat with the flange closest to the alternator.....this meant that most of the hub was filled with shims and a spacer. I've notice the fan hubs I've seen on line have the flange about 1/4 of the way down the hub......still not sure if that will help with the special nut not going fully on