Eitthvað fyrir patrol eigendur

Þetta er nokkuð áhugavert plagg að mörgu leiti. Rakst til dæmis á umfjöllun um af hverju 3.0 vélin væri að hrynja (kenning höfundar). Læt hérna smá úrdrátt fylgja, maður hefur nú heyrt um þetta hér og þar en þetta með loftflæðiskynjarann er nokkuð áhugaverð og kenning og einnig með stækkun á pústi, hvað finnst mönnum um þetta ?

There is a great deal of interest and argument on what is the cause of the ZD30 blown engine
issue, but since most blown engines seem to crack pistons 3 and 4, and it tends to affect the
older 2000 – mid 2002 models only, it seems to be one of engine design at that time.
It seems that the 2000 to 2001 model engine block was not designed with enough oil channels or
they were inadequate so the lower cylinder walls were not receiving enough lubrication. This
may have caused additional heat and may have contributed to the engine blow up issues we
hear of today. Also these versions did not have enough oil capacity in the sump so when driving
hard all the oil ended up in the top of the engine with the sump virtually running dry. Nissan had
a fix for the lack of oil capacity and shortened the dip stick on older models to increase the
capacity when being filled.

Nissans fix for the blown engines was an engine overhaul kit (part number MK101 VC128AU which
breaks into 12 individual part numbers and water connector 14075 VC100) which replaced the
engine block with a new one as well as new pistons etc. As this kit was available it seems there
was an issue identified. Although you will never find a vehicle manufacturer going public on any
major fault, the engines were repaired on an as required basis.
Here goes, now I am going to get a lot of argument on this one, why does the ZD30 engine have
the above issues? simply, because most people modify the engines away from how they were
originally designed. This is not as dramatic as it sounds but modifying the engine does change
its characteristics. For instance, did you know that if you put a 2.5” or 3.0” exhaust on your
vehicle, from the turbo back, it will cause the engine to over boost when highway driving?
Hence get a boost gauge fitted before you start modifying!

How does the ZD30 work? With the testing I have performed these are my basic observations;
• The engine has a Variable Geometry/Nozzle Turbocharger (VGT/VNT) also known by lots
of other names; check the glossary under VGT for more of an explanation. The VGT is
controlled by the ECU that decides, via sensors attached to your engine and throttle,
what it is going to do with turbo boost.
• It also checks the load on the engine to determine if it needs to give a bit more to keep
the power at its optimum level.
• If you need more power, like going up a hill, it will reduce boost and give you more fuel.
• If you are coasting at a regular speed down the highway, for economy reasons (I think), it
will give you less fuel but up the boost to ensure your power is kept to a maximum.
• While in the above state, it might as well make sure your emissions are within legal
requirements so it will adjust the EGR and give a bit more boost to keep the engine
combustion and temperatures lower.

If you take all of the above into consideration, most people seem to report that the engine goes
bang when out for a drive along the highway, may be either towing or under some other load,
on a flat bit of road doing 100, 110, 120 etc. This is the ideal state for a ZD30 to do some
emission control and fuel saving. The faulty MAF that is mentioned quite a bit around the place
is a good place to start.

So here goes, and again, let the arguments begin. The following is my opinion on why these
engines go bang;
• While cruising at 100 klms or more a ZD30 will go into maximum boost as determined by
the length of the VNT screw on the turbo.
• While in that state the EGR is opened fully to let as much hot exhaust gas back into the
engine to meet emission controls.
• You have a dirty or failed MAF that decides that there is heaps of air flowing from your
filter box so it decides to give you more fuel, therefore over heating and fuelling the
upper cylinder walls and piston.
• Your Patrol engine is now starting to feel the heat as the lower part of the engine is
getting super heated due to added friction from not enough volume of oil and possible
lower engine lubrication design, therefore it too gets hot and starts breaking down.
I have been advised that the most likely reason pistons 3 and 4 crack is the rear pistons on most
motors run hotter than the front ones. When you push a motor to the max it is often the rear
pistons that fail.

The above itself is enough to stress the engine and have pistons 3 and 4 crack, and it may need
to be happening over a period of time, there is nothing anywhere that states it happens all at
once, it may be little by little.
The final clincher is that you have installed a nice big exhaust to get the gas out quicker and
make the turbo spool quicker thereby getting rid of some of that low down lag and make it more
drivable, did you re-adjust the VNT to compensate? Over boost anyone!

Simple formula;
Cruise on highway = More boost = EGR fully open = Too much exhaust heat = Faulty MAF = Too
much fuel = Very hot engine internals = Exhaust or EGR modifications = More boost = BANG at
weakest and hottest point.

Fyrri hlutinn varðandi olíumagnið, kælirásirnar og þessi redding að stytta kvarðann og auka olíumagnið er að ég held rétt. Hversu mikið bullið eykst eftir það veit ég ekki

Já, maður er búinn að heyra alls konar sögur um af hverju þessar vélar voru að klikka, quick fixið að auka olíumagnið dugði í 155 þús.km á minni 2001 vél áður en 3 og 4 stimpill fóru eftirminnilega í Ártúnsbrekkunni. Maður er svo sem búinn að heyra það frá mörgum af hverju stimplarnir ofhitnuðu en hef aldrei fengið það á hreint hvað var nákvæmlega gert til að auka kælinguna. Þetta virðist alla vega vera komið í lag í dag.

Hér er svo mynd af innsta stimplinum mínum eftir að vélin gafst upp, nokkuð myndarlegt gat