Unknown problem

I have discovered what could be a problem with my Navara. At idle its as tho the turbo is pushing air back into the air filter. Its making a sound very similar to what u hear when u have a leaking manifold but its actaully coming from the air cleaner casing. I put my hand over the seals of the case and could actually feel the air being pushed out. Any idea what may be causing this, or if its actually normal. Its a ZD30.
Cheers

That dosent sound possible. if air is passing through the exhaust, theoretically there cant be air being pushed out of the air cleaner. Air in one end & out the other.

ZD30 3.0L engine displaces 3 litres of air every revolution of the engine, Idles at 800rpm so 3 x 800 = 2400 litres of air passing through your engine every minute at idle.

Are you sure the air is coming outward fo the air cleaner? If you get a piece of paper and lay it over the inlet does it get blown off or sucked in?

sometimes the vortex makes it feel like the airflow is opposite.

will said:

ZD30 3.0L engine displaces 3 litres of air every revolution of the engine

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Four stroke - every fourth revolution.

nashy said:

I have discovered what could be a problem with my Navara. At idle its as tho the turbo is pushing air back into the air filter. Its making a sound very similar to what u hear when u have a leaking manifold but its actaully coming from the air cleaner casing. I put my hand over the seals of the case and could actually feel the air being pushed out. Any idea what may be causing this, or if its actually normal. Its a ZD30.
Cheers

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What made you look for this...

are you having problems...

is this with the filter and airbox cover removed, if so put it back together and see if you still get "air pushing back out" from the intake...



The only way 'at the moment' i can think what could cause this symptom is if an intake valve is burnt or not seating.

But you need to provide other symptoms, if that is the case..ie backfiring.

sounds like you have some poor seals on the air box.

diesels can put a lot of pulses back up the intake. my old atmo its quite noticeable and blows air out the water outlet. tho i would be suprised if such pulses got through the turbo.

i would check how much is gas is flowing out the breather. you may have tons of blowby which is what pressurizing the intake so much. i guess if you undo the oil cap on top of the motor and the pulses out of the airbox stop then its blowby issue.

I would assume if blowby was at the stage where its blowing past the turbo you would be getting smoke as well...

and then how well would the engine be performing with all this contaminated intake air?

its not blowing past the turbo, blowby goes through the breather which is inbetween turbo and air filter. when one piston fires you get a big pulse going down the breather line which puts a pulse inbetween air filter and turbo. if motor/turbo is not drawing a lot of air ie at idle then that pulse could well be enough to blow air out the inlet pipes if they are loose or poorly sealed.
smoke, not necessarily so. it will handle a fair bit of blowby before it smokes. tho lots of blowby plus egr would make it a bit gutless and probably blow smoke (which they may not notice or think its normal)
a little bit of testing will soon sort it.

i wonder if they are getting it mixed up and its actually air being sucked in not blown out??? possibly the intake is blocked up a bit before the filter.

tweak'e said:

i wonder if they are getting it mixed up and its actually air being sucked in not blown out??? possibly the intake is blocked up a bit before the filter.

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Its hard to say with only Nashy's short description and not witnessing this "situation" occuring in person.



My (I'm assuming this engine has some mileage behind it) reasoning about blowby smoke is that if blowby is so great, it usually is brought about by a well worn engine with larger ring end gaps due to wear thus creating large volume of crankcase pressure/gases and some smoke,
and not the creation of smoke after combustion of the normal intake charge together with blowby gases..

and i had the breather hose mixed up with a PCV system which would be plumbed to the inlet manifold,
but your right,
the breather is connected prior the turbo.

Ok guys, thanks for the quick replies.
1. I checked it cause i could hear a faint drone as in a leaking manifold etc so decided to check everything over
2. Yeah the engine does have some milage on it, over 250k
3. The engine doesnt seem to be having any other problems at all. Drives brilliantly, idles well and still goes like a wounded bull. No smoke either
4. I did do the EGR mod the other day, if that makes any difference to the situation
5. I tested out the theory on blowby and pretty certain thats what it is. There is a bit of blowby coming through, I took of the oil filler cap and u could hear it. plus after turning the engine off there was some smoke coming out of the filler cap

So looking at all that it looks like its a blowby issue. Would I be correct.? And what reccomendations would u guys have.?

nashy said:

Ok guys, thanks for the quick replies.

3. The engine doesnt seem to be having any other problems at all.

Drives brilliantly,

idles well and

still goes like a wounded bull.

No smoke either

And what reccomendations would u guys have.?

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Thats easy......If it aint broke, dont fix it!


Just keep it serviced and maintained.

All engines have blowby, just the more worn they are the more they have,
Dont stress.
250k on a well serviced engine isnt that bad.

Happy 4wdrivin.

Cheers Krankin. So its not too much to stress about. This is my first diesel car, and being the ZD30 I'm a little jumpy about anything out of the ordinary, although thankfully from what i've heard and read the Navara doesnt suffer the same problems as the Patrol does. Would running a different oil help minimise the amount of blowby. I.e a slightly thicker oil. At present i run Valvoline super diesel in it.

nashy said:

Cheers Krankin. So its not too much to stress about. This is my first diesel car, and being the ZD30 I'm a little jumpy about anything out of the ordinary, although thankfully from what i've heard and read the Navara doesnt suffer the same problems as the Patrol does. Would running a different oil help minimise the amount of blowby. I.e a slightly thicker oil. At present i run Valvoline super diesel in it.

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No, it wont make the piston ring end gaps smaller.

Tho if you want to use the best engine oil use a full synthetic,
but a good quality turbo compatible mineral oil will suffice together with regular changes.

nashy said:

5. I tested out the theory on blowby and pretty certain thats what it is. There is a bit of blowby coming through, I took of the oil filler cap and u could hear it. plus after turning the engine off there was some smoke coming out of the filler cap

So looking at all that it looks like its a blowby issue. Would I be correct.? And what reccomendations would u guys have.?

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did they pulsing out of the airbox stop when you took the cap off ?

don't worry about the blowby and white smoke coming out of the oil cap. the timing chain is almost right below it so you get all the pulses coming up from the crankcase straight up through the cap. so it looks worse than it is.
that white smoke is oil mist.

The pulsing didnt fully stop, but it did lessen quite a bit..