D40 overheating

recently while towing a 2 ton van the Nav started to run towards the red while going uphill. as soon as you start downhill it cools quickly. thermostat has been replaced, pressure tested and radiator core cleaned. The Nissan dealer has had one go at it along with a Diesel mech that did the thermostat. Seems to run o.k. when not towing the van, any ideas as I am a completely useless mechanic. It has been chipped, hotside pipe done and EGR block. Performes exactly the same but with less power if the chip is blocked off also.

theres not alot to the cooling system as you may know, if the thermostat has been replaced along with a nice cleaned out radiator plus a good working radiator cap the last thing which will cause your problem is the Clutch Fan. several guys have had your same issue and the cause was the clutch fan hub, not the fan blades but the main fan housing . so if your 100% positive the radiator has been cleaned pout correctly you no doubt need to replace this fan hub. don,t go to Nissan for one as you might fall over when they hit you with the price, try Ebay or aftermarket . sorry i can,t think of the correct name for this fan hub unit for the life of me.

Viscous fan Jonney!, and yes a common issue with failure.

thanks John just had the dreaded brain blank. sounds like this would be the cause , what do you think ?

Absolutely spot on guys. Happened to me - twice, only while hauling our caravan (2.5T). The stupid thing has more names than King Henry VIII had wives. Fluid couple, viscous hub, fan clutch, viscous clutch, fan coupler, fluid drive ... click here to see the one that I bought (from the place that I bought it). They post ... and it's a reasonable price.

Thanks

Thanks for the help, its at the dealer at the moment, service mgr and offsider are friends outside work so they should look after me. Hopefully.

Dayco clutch fan drives are good quality, about $169 from memory.
Nissan quoted me over a grand for a genuine one ��
Recommend getting some "silicone oil" from a Toyota dealer and adding two small bottles to the reservoir in the new fan drive unit.
This means the fan kicks in a little earlier, and will hang in till the motor cools a little more than is standard.

Hey czechmate, i want that mini bike. and your right the Dayco are not a bad brand atall, i used to buy there timing belt kits and waterpumps for my other cars owned.

My input to this issue is...
Went for a road trip to Melb 5 or 6 weeks ago and had the same problem. Not towing, camping gear in the back and four people. Cruising @ 110ks and some climbs on the way, Temp would be at 95deg upto 115deg on the climbs and instantly nack down to 93/95 on down hill and flat road. I jumped on here, asked for suggestions and did all checks. Finally got to Melb and took it to local mechanic. REPLACED Thermostat, pressure cleaned cooling system and radiator obviously... $360.
Driving back to Brisbane same problem + now leaking through thermo cover. Not tight or damaged seal when pulled.apart in Melb.
the guys at OFFROAD 4x4 at BRENDALE took me in straight away as they have done before... $1550 later (same day afternoon) and diagnosis was SHOT radiator, so I had a new one put in, expansion or header tank replaced and thermo cover gasket replaced also...

you may wanna double check the radiator as its most likely to be the culprit to your heating problems..

I hope my opinion helps... no heating problems since...

Had same issue when towing that migrated to any time under load and after having done all the usual things it was suggested that it could possibly be the cat converter.
I had an after market exhaust fabbed up years ago by an exhaust shop in Sydney and it turns out they used a petrol cat. 180000km later this thing was sooted up to the point were it was a major restriction. Had been getting odd boost readings too so I guess it makes sense.
New redback cat free exhaust and it runs as cool as ever and boost is spot on. Sounds good too.

So, would it be safe to assume that a vehicle that has less than 12months on the new radiator that the fault would be the Viscous fan if it's fine on the normal road, but after some beach driving she gets HOT and I need to stop the car, and let the temperature drop (which it does, quickly - especially if i put the heaters on full too).

Only happens when the car is loaded up in soft-ish sand.

AND - how hard is it to swap out at home, or is it more a garage job?

That's a fairly safe assumption, yes, but of course test it first before spending money!

I changed mine myself (in my front yard) using spanners from my Aldi tool kit.

Let me tell you, my truck running up to Sydney towing a small camper. I can easily hit 650+ post turbo temps.
And that's at 110 on a highway.
I'd be throwing a egt probe in mate if she's hot there you really need to see where else as well


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Did some checks yesterday and last night after a drive. Viscous Clutch Coupling Fan Thingy is buggered! Little to no resistance both COLD and HOT. I can free spin it multiple times and it never gets any harder..

Downside is stockist of the Dayco replacement are closed over the xmas / new year period...

Repco mate

eBay - $160
Repco - $245

I'll wait 5 days and save $85!

This is the one I've got.

This is what I ordered.

http://www.ebay.com.au/itm/Dayco-Fan-Clutch-suits-Nissan-Navara-D40-2-5L-Turbo-Diesel-YD25-YD25T-/251027942415?hash=item3a726e6c0f:gBEAAOSwZQxW2RJR

Same part - just cheaper and free postage.

I did get offered one that was replaced at 110,000km for $50, but for that bit extra I get brand new and peace of mind.

Dayco ia good

Dunno where they're manufactured but dayco gear still seems to be pretty top notch.
No ratty casting or stripped threads or nuts like some imported brands.
On another topic completely was recently disappointed to find when i went to buy a second front wheel bearing hub assembly for a d40, Burson auto now supply a nasty Chinese unit instead of the previous high quality GMB Korea part. *sadface*
Same Bursons box and part number, same price. sigh.

What about an electric thermo fan. Could also install a run on timer to remove heat from engine bay after shutdown. Heat under load could also be intercooler issues, clogged air passages oil inside core or fault fan if fitted.

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