So my first test drive turned into a full fiasco.
I had new black fan blades, I bought new heavy duty clutch haydem 2747 ( which a lot of people were recommending as a heavy duty replacement for stock one) I trimmed the blades as clutch was a bit bigger then stock one.


after 10 mins of driving , with car at normal temperature and everything going smoothly, I pushed the throttle and blades flew off, rad killed in several places, coolant gone.

sure will recore rad, will get new blades, but why it happened? I can’t believe fan blades flew off because of clutch being a bit harder( because a lot of people on forums using it) could it be because I lost a bolt or nut in the engine bay and it got into the blades?

i Dont know now should I use Hayden or get back to stock one. Please advise.

 

I can't help but wonder if the trimming compromised the strength of the blades


Cheers
DD

 

Hi Mouserider

Really sorry to hear that but could it be that the Fan Blades hit the inside of the Fan Cowl

It always pays to make sure that the Fan Blades can Spin unimpeded, or its going to get expensive as you have just found out

 

AS OB said, the blades must have hit the cowl. Remember that the cowl is fixed but the engine moves on its mountings as it revs. Trim the next one a little more, and use a bandsaw or something that will not stress the blade as it is cut.

But what I do not understand is if the fan blades are OEM ones, why did they have to be trimmed at all?

 

could be, yes, but few things that makes it unlikely , basically everyone who using 2747 should trim blades, as clutch is a bit bigger and there is no way you can fit it without trimming. Also all blades went off not on the trim area.

 

Hey Greg, as i said, i used hayden 2747 HD clutch and its bigger in diameter, so you have to trim innner parts of blades (mb 3mm) otherwise you cant use it, apart that it fits perfectly
how blades could hit the cowl? they are stock blades, stock cowl, and the only thing i have changed is clutch, so it wont affect positioning of the blades, the only difference with stock clutch as its a bit longer, so blades are 1/2 inch closer to the rad, but that shouldnt really affect anything.

also im examining the cowl and i dont see any signs of blades hitting it.

 

Ok, another clue, while removing rad I have noticed that I’m missing 2 out of 3 rubber seals from shroud, found several destroyed pieces of it . I can’t believe rubber piece can cause blade to brake , but who knows

 

This is the std black fan I fitted to my car with a std clutch.

as you can see the bottom of the blades are moulded with a curved sort of finish and the blades are thicker at the bottom where they are moulded into the centre ring. Looking at the picture of your fan and please don’t think I’m being rude but it looks like you just hacked the fan blades to fit the hub with a hacksaw or something and left it rough. I can only think cutting the fan to fit has weakened it causing it to fail. I would suggest a new fan and std clutch is the way to go. Mine works perfectly.

Rob.

 

I really hope that was the case ) but as I said everyone using this clutch had to trim the blades, mb I did it wrong. When you say std clutch which one you mean exactly?

 

NBC2215AA Is the part number for the std clutch.
https://www.jagspares.co.uk/product/...a%2a1%2a%2a%2a
I purchased mine from David Manners along with the black fan. No cutting needed straight replacement for the original yellow fan and clutch. Works a treat.

Rob.

 

I think by trimming the inner end of the blade (I had not appreciated that this is what you meant, I thought you had trimmed the outer end) you have done one of two things, or both:

• weakened the root of the blade, and
• set up harmonic vibrations in the blades that caused them to shatter.

I would buy the OEM setup as Robbo has shown above, and all will be well. XJSs with mechanical fans do not overheat if the system is on good shape.
Your first post photo now makes sense, the blades have clearly failed at the cut point.

 

Mouserider,

Yes, they definitely look as if they've failed at the cut points.

But don't feel too bad, as you've got away really lightly, seriously!

I've seen XJS fanblades shatter and punch holes out through the bonnet, destroy the rad and all the top hoses and everything at the front end.

Honestly, count yourself lucky, and just put it down to experience.

Cheers

Paul

 

Another lesson learned, thank you.
Im done with it, im going efans

3 clutches, 2 fan blades

 

Make sure they are SPAL or OEM quality ones (eg BMW or Merc) cheap ones cannot take the XJS under hood environment. Also make sure you have a clear understanding of how they are going to be controlled; Grant's system is the best one and very robust.

 

​​​​​​​Hi Greg, im looking at SPAL fan, https://www.spalusa.com/products/fan...2ffans%2f16%2f
16 inch 1500 CFM
but what about smth like
Derale 16
https://derale.com/product-footer/el...o/16016-detail

its more expensive and gives 2100 CFM

i guess, everything around $100-150 should be a good enough and CFM above 1500?

Thank you

 

This is what I have
https://www.malpasairflow.co.uk/itm/...ling/30102803A

You can watch th temperature guage drop! I have found anything needing less than 23 or 24 amps will not do the job.

 

oh thank you a lot!

i got your point, but, out of curiosity

how is that SPAL fan draw 30 amps with 2000CFM
and for example very solid and well known flex-a-lite made in usa is doing 2600 CFM with 11amps draw? 16-inch Flex-Wave™ Reversible Electric Fan (flex-a-lite.com)

What am i missing here? air flow is an air flow.

 

It is because airflow numbers are basically make believe! Bitter experience has proved this for me, only the amp draw is a reliable guide to the fan's ability.

 

Very Interesting!!
(Now, she sez to herself, to remember this if she ever goes to E-fans)
(';')