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Thread: Fitted a viscous fan today

  1. #1
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    Fitted a viscous fan today

    Following a thread on REMLR where Bob (Robert42) mentioned fitting a Patrol clutch fan, it occurred to me that I had a Patrol fan and viscous clutch among my pile of Nissan parts. It came off a GU which was fitted with a TD42.

    After removing the Isuzu fan, it was encouraging to see that the 4 bolt PCD was exactly the same, however the Nissan hub uses M6 mounting bolts. The holes in the viscous hub flange were easily enlarged with a cordless drill to match the Isuzu M8 bolts, which still left plenty of edge clearance.

    The fans are very similar in size, with the Nissan fan being about 5mm bigger in diameter. After doing a trial fit, the Nissan fan rubbed slightly at the top of the fan shroud. This was more due to the fan being further forward rather than the diameter of the fan. However, there is (at least on the Perenties) an alloy spacer fitted outboard of the water pump pulley which pushes the fan forward about 25mm. This spacer is easily removed and the Nissan fan hub then goes directly onto the front of the water pump pulley. No more shroud clearance issues and plenty of clearance between the fan blades and the radiator. I'd describe the position of the fan as ideal once the spacer is removed.

    Shorter M8 bolts (4 of) are required, both because the spacer is deleted and the need to get the bolts in between the hub flange and the body of the hub. I had some suitable M8 studs which I fitted to the Isuzu water pump which made fitting easier.


    On this particular Nissan hub, the machined recess which fits over the water pump shaft was slightly undersize (31.5mm vs 32mm) and needed a touch with the die grinder to allow the fan hub to seat fully on the end of the water pump shaft. Bob didn't mention any issues with the hub he used. "Its Sunraysia 4 wheel drive Phone 03 5024 6407
    Ask for a NC60 Viscus Hub matching Fan Nc52"


    Alternatively Patrol viscous hub are available on ebay for around $90. Fans to suit are also on ebay for around $55.

    I took a few photos along the way, but cant get them off the phone at the moment.

  2. #2
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    G'day Mark
    I'm in the bush a long way from a nut and bolt shop. I've also bought the fan and hub. Do you know the length of the M8 bolts you used so I can pick some up on the next trip to town.
    Pete

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    Hi Pete

    I didn't measure them, but the biggest issue I had was finding some among my bolt collection which were short enough manouver to fit between the flange and hub body.

    Definitely no longer than 20mm, possibly even 15mm. This allows 10mm into the water pump, 3mm for the pulley thickness and say 4mm for the flange thickness, plus a washer. I'd grab 4 x 15mm and 4 x 20mm to be safe.

    I used 8mm studs (and nuts) which I pulled out of a head I had lying around. These had about 12mm of thread on one end, about 3mm of unthreaded part in the middle and about 20mm at the other. The short threaded end went into the water pump flange, its about 10mm thick.

    You could make some studs by cutting a longer M8 bolt and loctiting it into the water pump flange. 35mm would be about right. Its also easier to fit with the studs. There's enough thread on the Isuzu mounting bolts to convert them to studs (mine were 35mm fully threaded) if you cut the head off.

  4. #4
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    To add to this, I bought a brand new fan blade and viscous unit for a TD42 from ebay for $120 total and fitted to my isuzu.

    I had to enlarge the M6 holes to M8 and trim the fan blades. The viscous unit recess was a perfect fit to the water pump pulley though, I didn't have to do anything there.

    Hole enlarging:



    Trimming:




    Short bolts are required.



    Bolt it up:

    - Justin

    '95 Disco 300TDI - sold
    '86 County 110 Isuzu
    2006 Range Rover Vogue td6

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    Quote Originally Posted by Judo View Post
    To add to this, I bought a brand new fan blade and viscous unit for a TD42 from ebay for $120 total and fitted to my isuzu.

    I had to enlarge the M6 holes to M8 and trim the fan blades. The viscous unit recess was a perfect fit to the water pump pulley though, I didn't have to do anything there.

    .................


    Bolt it up:

    Your fan is on back to front.

  6. #6
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    lol really? Minor detail bee_utey. I have a feeling around the other way it is closer to the engine and sits slightly outside the shroud. I'll have to report back. If it moves it towards the engine, I can always add a spacer at least.
    - Justin

    '95 Disco 300TDI - sold
    '86 County 110 Isuzu
    2006 Range Rover Vogue td6

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    OK, now I'm getting confused. Does the fan push air into the radiator, or draw it through and push air into the engine?

    If the crank turns clockwise (right?) then aren't the blade the wrong orientation, no matter which way around the fan is? Or am I losing the plot?
    - Justin

    '95 Disco 300TDI - sold
    '86 County 110 Isuzu
    2006 Range Rover Vogue td6

  8. #8
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    The fan sucks air in from the front to the back. So it pulls air through the radiator and blows it back over the engine. U need to turn ur fan around as it looks to be fitted back to front.

    Cheers Rod

    Sent from my GT-P5110 using AULRO mobile app

  9. #9
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    Got it, thanks.
    - Justin

    '95 Disco 300TDI - sold
    '86 County 110 Isuzu
    2006 Range Rover Vogue td6

  10. #10
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    Quote Originally Posted by Judo View Post
    lol really? Minor detail bee_utey. I have a feeling around the other way it is closer to the engine and sits slightly outside the shroud. I'll have to report back. If it moves it towards the engine, I can always add a spacer at least.
    After many years of experimenting I'll confidently say that an engine fan like that will always work better if it is hanging out the back of a shroud. Don't move it forwards whatever you do. The shape of the blades is cupped like a swimmers hands, so when the fan turns clockwise it cuts into the air and accelerates it backwards along the curve. Also, unlike an aeroplane propeller, the blades are not twisted. This means that the air is also accelerated along the length of the blades and leaves mainly from the tips. If the tips are covered by a shroud you'll lose half the air flow. There's no point having a fan that pushes the air straight back like a propeller, because there's a dirty great lump of an engine in the way.

    So just flip it over and let it all hang out.

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