Plastic engine fan fail!? Electric fan size?

mrtask

mrtask

Well-Known Member
Reading in another thread about what colour the fan should be, I took a closer look at my engine. Rather than a metal fan with riveted metal blades, my V8 wears a plastic fan with curled edge blades. It would appear to be too flexible, having in fact chewed the tips off the blades against the underside of the fan shrouding, and against the inside of the radiator matrix. Great! A hole in my recently refurbished rad. Happy happy joy joy. Is/was this plastic fan a factory fitment or an aftermarket item fitted by a previous owner?
I have a spare rad, but don't want to fit it before I sort out a fan! I'm thinking electric fan in front of the rad and no more engine driven fan. Who here has succesfully fitted an electric set-up in front of their V8 rad? What fits, what is the recommended bit of kit and from which supplier?
I think the engine is twisting too much under heavy acceleration, and the fan against the rad must have been the nasty metallic zipping sound I heard a couple of times. Looks like the driver side engine mount has failed. New less than three thousand miles ago, like the rad core. Given that I've already sacrificed quite a lot of comfort by stiffening the base unit and uprating the coil springs, I reckon I could live with a bit more vibration from the engine. Are there firmer engine mounts available?
If I fit electric fans and do without the engine driven fan, can I take the nose off the water pump and shorten it a bit?
 
Hi Alasdair,

From your description, the fan would certainly appear to be an aftermarket item.

The engine will twist too much under acceleration if the bushes within the stabiliser are either missing or have degraded, or its position is inadequate so as to provide sufficient engine stability. The engine mounts otherwise will not fail in such a short time. Oil contamination of the engine mounts will also shorten their useable life.

Ron.
 
rockdemon wrote,...
could it be a viscous fan?
Click to expand...

Hi Rich,

No. The nylon viscous fan is quite rigid and although the blades have a twist along their long axis, they don't curl at the ends. Both the nylon P6B fan and the later SD1 fans are non interchangeable, and neither will attach to the non viscous water pump pulley.

Ron.
 
Al, I've fitted a Kenlowe HD 2 speed 13" fan in front of the radiator and removed the fixed fan. You can't shorten the waterpump nose any more though as there's a bearing inside the bit that sticks out.



I had to make a cut out in the front valance just behind the grill to clear the motor, but other fans may be slimmer.



It seems to keep the car cool on hot days in traffic, but it does sup some juice - the ammeter swings right across when it's on high speed. Maybe a larger fan with a less powerful motor might be better.
 
testrider said:
but it does sup some juice - the ammeter swings right across when it's on high speed. Maybe a larger fan with a less powerful motor might be better.
Click to expand...

Hi, that is because of where you have taken the supply from, i.e. the 'wrong' side of the ammeter
shunt. try taking it from the back of the alternator.

Colin
 
colnerov said:
testrider said:
but it does sup some juice - the ammeter swings right across when it's on high speed. Maybe a larger fan with a less powerful motor might be better.
Click to expand...

Hi, that is because of where you have taken the supply from, i.e. the 'wrong' side of the ammeter
shunt. try taking it from the back of the alternator.

Colin
Click to expand...

Yes, but it's also got a 285W motor!
 
Hi, When the engine is running the alternator supplies all the power not the battery. So with
something like this drawing a reasonable amount of power (24A) it is best to have it from as
close to the supply as possible to avoid overloading the existing wiring which may already
have a load on it. It sounds like you have it connected to the battery post in the floor? In which
case the 24A load is going through the alternator wiring, the ammeter shunt and down to the
floor post.

Hope this helps and/or makes sense :)

Colin
 
So my fan turned out to be an aftermarket item, and it was fitted with longer bolts through a spacer plate which moved the fan closer to the radiator. I've borrowed the metal fan off a P5B belonging to a mate of mine, for the time being. It has shorter bolts and sits further away from the rad. It has a smaller diameter which couldn't foul against the underside of the guard plate above the rad.
I am going to look for an electric fan, I expect I'll have to make a similar cut-out to the top inner lip pf the valance to accomodate the motor. Once I've decided which fan I'll be back to ask y'all how best to wire it in, my understanding of matters electrical being basically none at all!
I found a new motor bushing as well, in amongst my spare parts, which is a result. So, how best to support the motor whilst I swap it? Drivers side (RHD) needs replacing. Is it just a matter of loosening the steady bar and propping the engine from beneath sump with a little trolley jack? Or easier up on the lift? I don't have a gearbox jack with a long cradle, that might have to be the next workshop acquisition!
 
colnerov said:
Hi, When the engine is running the alternator supplies all the power not the battery.
Click to expand...

I'd say that depends on 2 factors. 1) what's the electrical current being drawn at the time and, 2) is the engine idling?

If the motor is pulling 24A while the engine's idling, I wouldn't be surprised if the battery had to lend a hand.
 
Yes, it's only at idle that the ammeter shows battery discharge with the fan running and the fan switches off a few seconds after the car is moving again.
 
testrider said:
...but it does sup some juice - the ammeter swings right across when it's on high speed
Click to expand...

testrider said:
Yes, it's only at idle that the ammeter shows battery discharge with the fan running and the fan switches off a few seconds after the car is moving again.
Click to expand...

Ah. I think we were under the impression that when the fan is on, the ammeter needle was swinging to the right (the + (charging) direction), but actually the ammeter needle moves to the left (the - (discharging) direction)
 
in process stripping my rad out ( leaking even after Bars leaks added) have an electric fan that goes in front of rad ( making sure it pushes not pulls so air flow right way) it fits neatly in front of rad and between front skirt ( apron) behind bumper. my son says they do an even thinner one and 2 speed etc .though sadly mine only 1 speed with adjustable thermostat settings but as keeping original metal fan ( was good enough in it's day ) don't think will need 2 speed . ( plus looking at. getting uprated rad alway) power supply. is form. fusebox at Moment with 20A fuse . looking at what has been said about overloading wires.. I might have to rewire to direct alternator too? fan. loading is 120W 12v
 
You can cool the V8 with less than 70W of fan and no cutting: My cooling project

The secret is the right fan (gigantic) and a 2 speed thermoswitch. The main purpose of the 2 speed is to control noise and lower the transient currents i.e. when the fan spins up to protect fuses. As by far the best method is use standard thermoswiches, then 2 speed is a no brainer as they screw into the same boss. The controller i.e. a 100W resistor is about £2.
 
I have a dual SPAL 11" assembly in my 4.7L V8 Porsche, and it does the job in a very tight engine bay, and is generally inaudible inside the car. Peter's fan is rated at 1610CFM, the dual 11" at 2720 CFM, but pulls 30A, and is only designed as a puller. It would be easy to use a 2 range switch to stage bringing the fans on.
jp
 
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