Offroad-Express

hi all,

back hear again for sum much needed help!

iv got a 99 Nissan Pathfinder with the zd30 engine, im well aware of there reputation although mine has done 302000kms on the original engine (owned since 150000kms).

Iv read heaps of posts of these engines but they seem mainly from patrol/navara owners & iv come to realise they are setup.a bit different in the terrano/pathfinders.

its developed a loud whistle from the turbo when under load & i cant for the life of me find the cause. could it be the inlet manifold gasket, fins, vnt valve?

also it randomly at times fills up the overflow bottle mainly wen its been travelling up nd down hills. now its never overheated, no oil in water, no water in oil. iv been told its the gasket but i ran it without radiator cap and there are no bubbles plus it runs mint.

could It be the thermostat? I service it regularly with 10w40 diesel oil with no issues?

any help would be great cheers

My cruiser was doing exactly what your talking about, head has been off and pressure tested fine. Head is going back on today with a new gasket. Head guy said the only other thing it could be would be the Oil Cooler, but 1HDT might be very different to yours...

check the intercooler, quite common to get cracks and they can whistle at high boost.
the other can be inlet restriction like blocked air filter. check the boost is not going to high.
depending the type of noise, could also be turbo bearings. check the impellers for play.

the patrol is pretty much the same setup as the pathfinder/terrano. the navara is quite a bit different.
but 300 tho kms is fairly good.

radiator bottle filling up, it could just be radiator cap not letting water to be sucked back in. even a crack in the water pipe can mean it sucks air back in instead of water.

im going to pull it all apart tomorrow and see what the go is.

truck has new radiator, water pump and hoses but will try new rad cap.

turbo whistles from about 1500rpm upwards and gets louder the more load gets put on obviously as the boost climbs.

will see what happens tomorrow!