i need help!!!

ok, i have a 96 d21 td27t dual cab 4by navara. it has been getting hot since i bought it 2 years ago.only on approx 100ks under load,as i back off and cruise back down to 60-80ks it cools back down. my first step was the thermostat, then to the radiator shop and had tanks removed and cleaned out. next i fitted an aftermarket water pump and thermo clutch fan. still no luck. i have recently fitted a new motor, turbo version.still no change. had another radiator joint talk me into another flush. and finally today i replaced the water pump with a genuine nissan pump and thermo. i am completely p!$$ed off and ready to burn it.i have also taken off the spotties to increase air and i think it may have made a microscopic bit of difference,but it still climbs into the hot. the radiator is only 25mm thick and i wonder if i should try and fit a larger radiator......my mechanic mate reckons the radiator is too small, but i think if thats the case every model like mine would do the same.... im desperate for help. sorry for no caps, got my 4 month in my left hand.

hey mate. is it using water at all or just getting hot. whats the cap like thats a common overlooked problem (if its using any water that is.)

Has the system been pressure tested?

Yeah new cap with last flush, and been pressure checked.

Any water being used?

Not a drop , i thought of head gasket, but id have to be pretty unlucky for that to be the same in 2 motors.

yeah. thats a bit sus mate how bout the fans you sussed them out.

Its just the standard fan running off the water pump, it looks fine.

Has this problem been sorted? I run a radiator shop and I'm willing to help.

What's the rolling resistance like? On a flat section of road, can you push it without getting a hernia?

Wrong temp sender?

No not sender. Havent tried to push it. Where abouts is your radiator shop, I think Im looking for a larger radiator. I think all of the little things like large spotties Custom bar blocking airflow makes the standard rad struggle.

I am in south Sydney. Before spending money on a new radiator I just want you to check a couple of things for me.

Firstly, make sure the temp gauge is actually reporting the correct temp. This is a simple thing to do if you own or know of anyone that owns a non contact IR thermometer. Just take a reading from the metal immediately surrounding the temp sensor.

From what you have described it sounds like you have a problem with the flow of coolant through the cooling system (provided the temp sensor is working as it should). So things to look for are a blocked radiator, (I know you say you have it cleaned twice before but are you sure it has actually been taken apart and cleaned properly, I've had cars overheating where the customer swears the radiator has been cleaned but I have still found significant blockage in the radiator, also was the block flushed out when the radiator was cleaned, I have cleaned out radiators that have blocked up again inside a month because the customer didn't flush the block). Next is the water pump, I know its a different engine but has this been checked, you didn't by any chance reuse the old pump, and if you did, did the impeller show any signs of corrosion, or was the impeller cracked to the point that it was loose on the shaft and not spinning as it should (I've seen this a few times). Next, and this is the one I have a feeling it might be, is the lower radiator hose, with the radiator cap off give it a squeeze, does it feel firm or soft. What RPM is the truck doing at 100 kmh (or what ever speed it overheats at), find that out then have a friend rev the engine to same RPM while you are looking at the lower radiator hose, does it flatten itself out and thus restrict flow, and while your there check the top one as well, obviously do this when the engine is a t operating temp. If so its time for a new radiator hose. And don't discount that last one as BS, please do check it cause it has caught alot of people out before (including me).

hi icon, the radiator cap hoses are new, i bought a brand new genuine waterpump 2 weeks ago and it slightly helped but when aircon is on and its a hot day on the highway still gets hot. radiator was flushed and they showed us it with the tanks off, we also fitted a sock in case any scale did still come out of block. block was also cleaned. I didnt think too much about sender as it only climbs up when on highway at around 110 then as soon as you back back down to 80 it sits back down at the normal driving running temp no matter how hot the day is.

And here I was thinking the TD27 radiator was a bit oversized...

Does yours do 3500rpm at 110 like mine does?

A mate of mine had a sort of similar problem with a 4 cylinder petrol Pintara where the thermostat was installed backwards but I doubt that's your issue.

Yeah that sounds about right, I have replaced the thermostat twice and im pretty confident its right.

G'day olgus, I'll be interested in the answer to this as my Z24 did much the same before the enforced holiday (loss of license) as the time draws closer, it's one of the things I have to address.
Cheers, Pete

Does it fuel correctly? Obviously your EGTs go up under the load of doing 110km/h, maybe it is overfuelling? Much black smoke when giving it the beans?

No smoke. Seems to run quite well...

How did you go about adjusting the wastegate when installing the turbo motor? Is it overboosting?