Technical Faulty Fan/Impotent Impeller

Currently reading:
Technical Faulty Fan/Impotent Impeller

Joined
Mar 7, 2005
Messages
6,225
Points
1,612
Location
Nairn
I wonder has anyone ever had problems with the impeller breaking up?

Commonsense told me, that when I had cleaned up the very surface-rusty fan that was on my 650, the fact that the blades could then be heard to gently rattle when shaken was not a good thing.

So I was planning to get a new one until I realised that I now have a good spare from the very oily 600 engine.....no rust there:D

How reliable are these things? I imagine that it might be a disaster if one was to break up.

I am aware of the aluminium ones but I wouldn't trust one of those either to be as efficient, well-balanced or tough; although I know that's the very reason why people fit them.:D
 
I have heard of them breaking up but not experienced that yet. Have to wait for drier days.
biggrin.gif



If you were concerned I don't see the harm in adding a couple of tack welds on each blade?
Personally can't see the point of going aluminium. Unless you are going for losing weight.
 
They reckon the aluminium ones are better balanced so only really necessary if you balance everything else
 
Before I was aware of the potential weakness of the fan after some tuning work I took my 499ccs 500L out for a run with a rev counter connected. The engine would rev up to 6500 rpm but not for long as the fan let go bearing in mind with the standard belt drive the Dynamo is spinning at close to 10000rpm. It was all over in a fraction of a second and later inspection showed that two of the vanes had pierced holes in the steel tinware.
I discovered that I had a steel and high density plastic fan on another tuned engine so fitted that. I also had a few good standard fans powder coated to prevent any corrosion and improve integrity. I also run one of the alloy fans on my 126.
 
In the VW aircooled world... they have welded and balanced fans when you run the engines at high revs....
 
I have heard of guys welding original fans to make them stronger. Part of the solution with high revs is to go for the reduced ratio toothed belt drive to the Dynamo. I have never seen any of the steel / hdp fans for sale anywhere and they look the best to me. I came across another one when I rebuilt an engine for a pal and the one on my engine came from a 795ccs Alquati that was prepped in the mid 80's
 
The engine would rev up to 6500 rpm but not for long as the fan let go bearing in mind with the standard belt drive the Dynamo is spinning at close to 10000rpm.

A standard engine doesn't rev that fast does it?:eek:
I didn't think the difference in pulley sizes between the engine and the dynamo was so great that it gears the dynamo speed up so much.....it makes me even more concerned.
I am planning to use an unmodified, original fan in good condition, but I think I will try a bit of welding on my rattly one and test that out first....nothing to lose because otherwise it's bin-time.
I'm not sure it will be a good idea though, because these things look very carefully designed and balanced.
 
Welding wise...
Tig with no filler rod, that way no metal is added and in theory the balance should not really be affected too much...
Mig would add metal and the balance would be all over the place...
 
I have experience of this and advise extreme caution. Any actions taken must not take the fan out of balance - and how can you ensure this?
It a bit specialist- not that i doubt your abilities!
 
not that i doubt your abilities!

I do!!!!!!:D

Usual thing...one lot of people suggesting something...another lot wisely cautious.
I meant to do it just as a "play" thing.
The impeller in question, although looking quite tidy, may already be well out of balance judging by the amount of flaky rust I was able to dissolve from its surface.:mad:
I think it will distort in any case.
 
It's not exactly the same problem with the fan disintegrating with tuned engines? Back in the day my dad and I were working on the Gamine's engine, now my dad smoked a pipe and the Gamine has a large open access to the air intake to the fan. After completing our work my dad was looking around for his pipe I started the engine up and heard this almighty greating noise with loud bangs and you've guessed it we found my dads pipe. This is the only time I have heard of a fan disintegrating instantaneously. Every time I tell this story it always puts a smile on my face.

Ralph
 
Welding wise...
Tig with no filler rod, that way no metal is added and in theory the balance should not really be affected too much...

It looks like that's how this one is prepared. The standard fan is nearer to 40 Euro. So that's a big price for a relatively small input.

https://webshop.fiat500126.com/en/cooling/fan-wheel-reinforced-and-well-balanced-black-painted

Has anyone fitted one of these? I'm hearing a chattering noise from the fan housing on initially pushing the throttle, (other possibilities eliminated by removing the belt and running the engine). It needs investigation and may turn out to be a loose impeller. But if any vanes are loose or missing I may as well have the best available....no, I don't want an alloy one. :D
 
............... I'm hearing a chattering noise from the fan housing on initially pushing the throttle, ................ :D

told you .. it's stowaways....

and you do want an alloy one..... thin end of the wedge has been and gone....
 
Re: Faulty Fan/Impotent Impell

Has anyone fitted one of these? I'm hearing a chattering noise from the fan housing on initially pushing the throttle, (other possibilities eliminated by removing the belt and running the engine). It needs investigation and may turn out to be a loose impeller. But if any vanes are loose or missing I may as well have the best available....no, I don't want an alloy one. :D

You probably remember I had a noise coming from my fan housing when I first put the 650 lump in and I was convinced it was the fan catching the tinwork slightly. If I recall I took all the tinwork off, with the engine in situ, on that side to see if I could find a problem only to find out it was the alternator bearings. Mind you it was more of a rumbling noise and I was surprised how loud it was, once I discovered what was causing it.

My biggest mistake was trying to replace the alternator with the engine it situ. It was a lot easier with a dynamo but a pig of a job with the alternator.
 
You probably remember I had a noise coming from my fan housing when I first put the 650 lump in and I was convinced it was the fan catching the tinwork slightly. If I recall I took all the tinwork off, with the engine in situ, on that side to see if I could find a problem only to find out it was the alternator bearings. Mind you it was more of a rumbling noise and I was surprised how loud it was, once I discovered what was causing it.

My biggest mistake was trying to replace the alternator with the engine it situ. It was a lot easier with a dynamo but a pig of a job with the alternator.

I do remember that, but we don't all have your elfin physique. So it's likely to be the whole left-hand side of the cowlings off.:D It's giving me the notion that the impeller is not gripped properly. But all is smooth and knock-free when I turn it by hand. There's no rush to fix it...I've a lot of things to do at the moment, but it limits the range I feel safe in; yesterday was almost 200 miles.

2gxhhlf.jpg
 
and you do want an alloy one..... thin end of the wedge has been and gone....

If you mean that you're thinking I'm being modification-resistant then I'm not. I haven't seen any explanation which gives evidence how the aluminium fan is better balanced or better at cooling. I can see that it would be unlikely to self-destruct at speed, butI doubt that I hit those engine speeds.

It's actually a good price, so I would like it to be the choice, but I'm just a doubting Thomas. Something must have prompted suppliers to stock a standard fan with the added security of welding.
 
If you mean that you're thinking I'm being modification-resistant then I'm not. I haven't seen any explanation which gives evidence how the aluminium fan is better balanced or better at cooling. I can see that it would be unlikely to self-destruct at speed, butI doubt that I hit those engine speeds.

It's actually a good price, so I would like it to be the choice, but I'm just a doubting Thomas. Something must have prompted suppliers to stock a standard fan with the added security of welding.

I know what you mean.... perhaps producing a welded balanced std fan is more expensive simply that reason...

people who raced 356 Porsche's used welded fan but even removed alternate vanes so as not to over cool at high revs...
But Fiat/Abarth saw no need to have alloy fans....
My only worry with an alloy fan would be if the car was used in anger that the actual fitting may have some play and eventually fail..
 
Back
Top