ZD30 woes

[philws]

Hello everyone,



Following on from my post re pyro temps it appears that I have a problem with my new truck :animierte-smilies-f. before I embark on the 'getting it right' journey I would like to make sure I understand the principles behind the zd30 issues, I have read the ref doco and think I understand it. ok here goes. from what I have read the primary reason for zd30s going boom is abnormally high combustion temps, these are caused by overfuelling, this occurs primarily in the 3rd and 4th cylinders. the cause of the overfuelling can be attributed to a few factors; firstly the MAF sensor becoming either fouled or damaged thus giving incorrect information to the ECU which then delivers a rich fuel/air mix to the engine, secondly a combination of PCV fumes and EGR gasses mixing in the intake manifold and causing an oily/sooty residue to buildup which restricts the flow of air into the engine again creating a rich mix thus increasing temps. Also the EGR gasses already being hot increases the EGTs.
How am I going so far?
Also from reading the ref doc I believe that boost actually cools down the EGTs because it is forcing more air into the mix thus leaning off the air/fuel mix in the engine, reducing temps?
Overboost is an issue for these engines as well, however I am not sure what problems it causes? apart from blowing intercoolers what does it do to the engine? what effect does it have on EGTs?

Before I bought the car I did a bit of reading and I thought I understood the issues and how to prevent them. I am, however, now not so sure.

Also I have:
2003 GUIII Manual ZD30 140000 ks on the clock, EGT gauge fitted.

Any help or clarification would be really appreciated. Also thanks to all those who have already helped out with info.

Cheers

Phil

[Chaz]

Phil,
You have it pretty much in a nut shell. There are a few other contributing factors that also get addressed when we fit a manual boost controller and bypass the ECU boost control solenoid, such as the varying temperature ranges we see with factory boost/EGR control. These are sometimes thought to contribute to piston and cylinder head cracking due to the fluctuating temperature extremes. A factory setup will see EGT’s constantly range from 550C plus down to 200C under varying driving conditions, which must result in fatigue, particularly to aluminum components.

A modified boost control system that delivers constant boost levels depending on rpm and load will give even temperatures that don’t alternate nearly as much and consistently remain at lower levels without the huge differential.

Boost spikes generally aren’t a big issue, but when the boost control system can’t control spikes quickly enough we can see spikes beyond 25psi which can damage intercoolers and split intercooler hoses, which will develop into a rich mixture condition and eventually contribute to extremely hot combustion temps. Eliminating the chance of high boost spikes will eliminate this from happening.

A few years ago, I write an article on ZD30 problems (http://www.chaz.yellowfoot.org/zd30_engine_problems.htm), issues and remedies that you may find interesting.

Cheers,
Chaz

[teleman]

You definitely have your info correct. But, as i urge every GU owner that i can, Dont worry about it!!!!!
I have an 01 series 2 GU and have had very few problems.
Heres my tip, Every service, change the oil, clean the MAF sensor and inspect the block for buildup.
If you have a good mechanic they will do it for you. Remember, it is a Nissan and it is a Diesel which means it will last forever with regular servicing and a thoughtful owner.

[Sir Roofy]

you definitely have your info correct. But, as i urge every gu owner that i can, dont worry about it!!!!!
I have an 01 series 2 gu and have had very few problems.
Heres my tip, every service, change the oil, clean the maf sensor and inspect the block for buildup.
If you have a good mechanic they will do it for you. Remember, it is a nissan and it is a diesel which means it will last forever with regular servicing and a thoughtful owner.

ill second that regular services and learning about your rig keeping an eye on things