Outer Limits 4x4 Board

Hi,

My 2.7tdi has 160 000km on it 2.5inch exhaust and dump. No real problems so far. But........in 2nd, 3rd & 4th gear, when i start to accelerate at the beginning of its torque curve about 1800rpm, I get a ringing noise from the engine until rpms pick up about 400rpm's or so and then noise disappears until I change up a gear and it all happens again. 1800rpm seems to be where the car settles to between changes. It is worse on hills as I guess the car is working harder to get the wheels spinning up hill, so you apply more boot, and the ringing noise is louder until it climbs those 400rpms or so.

Anyone got an idea what it may be? I'm don't think it is a Terrano II issue as such, its just the engine so hopefully anyone can have guess at what it is? If you need more specific info, let me know and I'll provide it. Cheers.

Could it be ???
Just a split intercooler hose leaking under boost ? or a turbo on its way out .
Or a gear box bearing on its last legs

Gearbox got rebuilt about 10000kms ago so I hope not!
Turbo on the way out? Would I notice other noises through the rev range?
Intercooler hoses seems fine. Seems to have a bit of blow by dripping from a front intercooler corners. Not sure if that would do it.
Thanks for the reply.

That could be the leak making the sound.
If the oil is coming from a weld or join in the tank that could be it
as some oil in the pipe work is normal .

What kind of place can I take the intercooler to to get checked, re-welded ect? It the front corner (drivers side) closest to the intake manifold on the engine. It can't be to significant can it? As it doesn't even leave an oil drip on the carport floor.

Another unrelated question, can any diesel mechanic check tappets and timing etc, or do you think it should go back to Nissan to get these done, as I haven't had them checked in probably 60000kms?