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NADS step by step guide

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Please check back for the full guide after I update this status.


Howdy all. Just reserving this thread so that I can post an easy to follow, step by step guide to installing the Nissan Anti Detonation mods for all to use.

I'm just gathering all of the photos from my camera, taking some new photos and updating the parts and price list.


The Nissan Patrol 3L di engine can have a few modifications to make it more reliable and avoid the dreaded 'grenade'. This thread is not here to debate the reliability of the engine, or compare it to the 4.2 or petrol variants, its here as an easy to follow guide for anyone interested in doing the modifications.

I have done these modifications to about 10 GU patrols now, and while I'm not a qualified mechanic I reakon I have it down pat. Many thanks to Chaz for teaching me.

Any advice on this thread is just that - advice. I am not a mechanic so if in doubt ask first!


NADS or Nissan Anti Detonation is a series of simple modifications that can be done to the di zd30 engine and exhaust to avoid the well documented issues with piston and engine damage.



There are 5 root causes for the zd30 engine failures.

1. Exhaust Gas Reticulation Valve (EGR). This valve recycles inert (but very dirty) exhaust gas back into the inlet manifold in an effort to reduce emissions. However the blank gunk deposited creates restrictions in the inlet manifold causing hot spots and starvation to mainly number 2 and 3 cylinders. See the install section for photos.

2. Oil Starvation. When the early engines came out, Nissan recommended that it only required 6 or so litres of oil. After a while they noticed many failures and "fixed" the problem by recalling the Patrols to shorten the dipstick. The correct amount of oil for the Di ZD30 is 8.3 Litres.

The modified length of the dipstick is (edit)cm

3. Overboosting. The ECU on the early GU patrols doesnt control the boost very well. The GU patrol has a Garratt VNT (Variable Nozzle Turbo). The way this works is - the pitch of the blades of the turbo are changed to create more boost at lower exhaust pressure. Think about how a turbo prop planes engine works. At a constant rev range the power (or thrust) can be increased, decreased or even reversed by changing the pitch of the blades. Like a fan!. The ECU has a pretty big job on its hands trying to control boost at the best of times - different engine revs, different load, the EGR opening and closing (which increases boost in the inlet manifold, after the turbo that the ECU doesnt know about). Nissan introduced an overboost sensor to try and over come this. It basically measures the boost (in the intercooler) and if it stays over a certain psi (it seems different for many sampled patrols) if puts the car into limp mode. You will know if you have limp mode if you are driving along, and all of a sudden if feels like you have no power. If you release the accellerator and reapply, it resets. Very annoying!

4. High EGT (Exhaust Gas Temperature). The Diesel engine is made to work. Good torque at low revs so you dont have to rev its guts out to get power. Its one of the reasons it is so fuel efficient compared to petrol engines) as a lot of the power is rquired just to get your 3T car moving! Obviously for the engine to run you need fuel and air and the combination of these can determine the temperature of the exhaust. Over fuelling or underboosting are common causes of high EGT. Why should i care about EGT? Well, at certain temperatures metals change caracteristics. They can get weaker (causing failure) or even melt! If your exhaust is glowing hot, think about how the pistons, cylinders, manifolds, oil and turbo are feeling!

5. Dirty or faulty MAF sensor. The MAF (Mass Airflow Sensor) is a small device located just after the air filter which measures the volume, speed and temperature of the incoming air. If the sensor is faulty, the ECU can over or under fuel the engine, causing high EGT and failure.

A common issue with MAF sensors is that they get oil on them. This is caused by the Crank Case Ventilation hose feeding back into the air inlet, just after the air filter. If you have a look on top of your engine, you will see the pipe coming from the top most part of the engine, it goes to the air inlet next to the passenger side battery. Oil mist causes the MAF to give incorrect readings. Regularly cleaning your MAF sensor, and fitting a good qulity catch can will certainly help. Its a simple thing that can be done relativly quickly. See the how to section for details.


If you have read this far, you are probably keen to learn about what is included in "the mods" - Well here they are!


What - Boost Gauge

Why - Monitor what your turbo is doing. Easy to install, do it first.

Where- Get a good boost gauge. It is the foundation of knowing what your engine is doing. myPatrol4x4.com.au vendors section (when it appears), Ebay, Patrol4x4.com vendors section or even your localauto parts shop. Dont get the el cheapo one - you will find yourself replacing it soon enough. I have a Garratt Boost Gauge. You dont need one that goes into vaccuum.. mine does but it doesnt really matter.


What - EGT Gauge

Why - Monitor your Exhaust Gas Temperature. This is just as important as the boost gauge. You will be impressed with the feedback it gives you about your driving style!

Where - As above. I have a Auber digital gauge. I prefer the instant accurate feedback from the LCD display, but others prefer an analouge dial.


What - EGR "Shim"

Why - *CAUTION* Blocking your EGR is probably not legal in your state. EGR's can "Fail closed" ;). Blocking hte EGR not only helps to keep your inlet manifold and oil clean, it helps you to control the boost that your turbo is producing.

Where - myPatrol4x4.com.au vendors section (when it appears), Patrol4x4.com vendors section, or make one up yourself



What - Dawes Valve

Why - A Dawes valve sets the upper boost limit.

Where - http://3barracing.com sell them, as does some local 4x4 shops (at a outrageously inflated price, Shame!) If you have time get it direct from Darren Dawes at 3 bar racing - it might take 3 weeks but it might teach the local shops a lesson for being so greedy. We can also organise a group buy - post interest in the other section!


What - Needle Valve

Why - A needle valve controls the spool up rate of the turbo once we take away the ECU's control. "Spool Up" is the rate of increase of boost from the turbo. Too fast and you might get limp mode, too slow and you will lose power and have high EGT

Where - Dependable Distributors in SA is where i got my Italian Needle valve.


What - Catch Can

Why - To filter the crank case ventilation pipe, keeping the MAF sensor and intercooler clean.

Where - The Provent 200 is a great option, seems to work very well. Some people choose to buy cheaper catch cans with varied success in catching the oil mist. Have a look on ebay, or http://www.westernfilters.com.au - the kit comes with most needed things.

What - Exhaust upgrade

Why - Having a less restrictive exhaust improves performance, and lowers EGT

Where - Most exhaust shops can knock something up, but i preferred to spend a bit extra and get a 2 3/4" Beudesert mandrel bent exhaust. The Catalytic Converter is 200ccm and it makes an impressive difference.

Other Items that are not high priority, but make life better

What - Intercooler upgrade

Why - The standard Nissan intercooler has crimped ends. They will leak over time, its a common problem.. If this is happening to yours, you may notice black stains on the fins near the ends, or an unexplained loss of boost. Neither are good for your engine :)

Where - If your wallet is bulging and you have 10 weeks up your sleeve to wait grab a Cross Country intercooler. ASETurbo are just down the road, they are cheaper and normally have them in stock. They also come with all new pipes and a fan. A few other places also recore intercoolers on ebay etc. When mine dies, ill go the ASE i think..



So you have decided to go for it! Congratulations! It might seem daunting at first, but if we break it into chunks and take the time to learn what we are doing and why, it will make it a great learning experiance.

Here is the order of how i would go about it... In the next post ill start to describe, in plain english with photos, how to eat this elephant!

1. Fit Boost Gauge.

2. Fit EGT Gauge

3. Fit Catch Can

4. Fit boost control

In between each step i encourage you to DRIVE THE CAR and observe how each change makes a difference, more on that to follow..

Edited by dronus4x4
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Depending on the type of gauges that you have bought, it will determine how you mount them. Some people use "Pillar Pods" which replace the drivers side pillar, encasing the gauges. They look pretty good.


PatrolaPart has them

So does

Extreme Limits Offroad

In either case, mounting the gauges in the cab is pretty sraight forward.

Some gauges are electric, and some are mechanical. A mechanical gauge has the vacuum pipe going to the gauge, an electrical gauge has a "sender" unit which measures the vacuum and informs the gauge what the pressure is. The wiring is pretty straight forward - generally they will have power (to light the backlight, or run the display), a signal wire to dim the lights when the headlights are on, and an earth of some sort. Follow the gauges guide for more info.

Installing the Boost Gauge

To hook the vacuum pipe up to the engine you are going to have to do a little bit of drilling and glueing.

There are a couple of ways to do it - here are some photos




Just run this pipe to your boost gauge and bobs your aunty.

Dont worry about hte other pipes you see in the photos for now, all will be explained in the next section!


Installing the EGT Gauge

The EGT gauge will come with a probe. The probe should be inserted into the exhaust system somewhere, but where? The Genuine Nissan exhaust doesnt come with a hole for the probe, but most aftermarket exhausts do (or you can ask them to put one in for you!). The proble should be on the dump pipe, within 50mm of the turbo outlet.

If you are going to replace the exhaust anyway do yourself a favor and do it now, as the next few steps are something you will only want to do once!

The Dump pipe is covered by a heat sheild. This will need to be removed to get access to the pipe. It is pain in the Butt... Once you remove the screws (Add photo here with arrows) you need to rotate the sheild and pull it out... Much easier said than done... Mark the position for the probe.

Use some WD40 on the bolts and undo the bolts holding the dump pipe to the turbo. Do the same for the bolts holding the dump pipe to the tail pipe. Take the dump pipe out. Weld a 1/8bsp olive into the dump pipe.







Run the wires to the cab and wire in as per the instructions.


Ok, so you have your gauges in WooHoo! What i suggest to everyone to do now is to order your Dawes valve from 3barracing.com (it will take a few weeks to get here) and drive the car. Watch the gauges and see how they behave when accellerating, climbing a hill, cruising, kicking back a gear. Take notes if you like, this is the bit where you get a baseline to work from in the next section.

If you were getting limp mode, watch the gauges to see what causes it to happen. What is your max boost? Wht boost are you getting at 1500rpm, 2000rpm, 2500rpm? What is your EGT doing? Jot it all down.

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This is one of the easiest mods to do.. In this section ill show you how easy !

During normal operation, the crankcase presurises and vents via the crankcase breather pipe. In the GU Patrol this pipe is connected back to the air intake, just after the air filter. Oil mist can contaminate the MAF sensor and intercooler as described above.

When doing this mod, it is a good idea to also remove your intercooler and clean it. While it is out, check it for oil stains and leaks. To clean the intercooler, firstly remove the 4 bolts which hold it to the engine, loosen the pipe clamps, undo the boost sensor probe plug on the front and take the intercooler out,

I cleaned mine using degreaser, and then flushed with water. i used a hairdryer to make sure it was clear before replacing it.

The crank case breather pipe is on the top of the engine, just to the right of the intercooler. Click on the photos for a bigger version...


It is normally piped straight to the air inlet here..


Basically what we do is put the catch can inline.. Take the pipe out and use the pipe which comes with the catch can to put the catch can inline..

Most people mount the catch can up against the firewall on the passenger side. Your milage may vary depending on if you have ABS.

Here are a few photos, please ask any questions as a comment below.




2011-09-17155758 (1).jpg


2011-09-17155742 (1).jpg


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Ok so now we have our gauges and catch can installed its time to install the boost control.

Before you install it i hope you have driven your Patrol and taken note of how the boost and EGT is behaving.

  • When you accelerate does your boost come up fast, drop down to near 5psi and then climb back up to near 15 - 17psi?
  • What is the maximum spike and sustained boost you are reading?
  • At times does your boost do a coles (go down, and stay down)
  • What are your EGT's around town, on the highway, climbing a hill.
  • How does changing down or up a gear affect EGT?
  • What is the Max EGT you are reading?
  • Any other observations?

Before we install anything, lets run through what we are going to do, the components used, what they do, and what we expect to change.

What are we about to do?

We are about to use a couple of devices to take the control of the boost away from the ECU to give us a more linear, controlled boost resulting in lower EGT and more power.

What do we use to do this, and how do they work?

  1. Dawes Valve. A dawes valve is a device which limits the maximum boost that the turbo produces by limiting the VNT Actuator rods travel. As decribed in the first post a VNT turbo adjusts the pitch of the blades in the turbo to produce more or less boost as required. This is done via a rod which opens and closes the vanes. The rod is connected to a diphram, which is controlled by vacuum applied to the other side. By limiting the maximum boost we can set the turbo to produce a precise boost, avoiding limp mode and damage to the engine by high boost.
  2. Needle Valve. A needle valve controls the rate of spool up that the turbo produces. Spool up can be thought of "how fast the turbo goes from producing no boost, to its maximum boost as determined by the Dawes Valve". Why do we care about this? Well, if the spool up is too slow the turbo doesnt produce enough boost to keep up with the load on the engine, which will cause it to appear sluggsh, and high EGT. If the spool up is too high the dawes valve may not operate in time to limit the boost to its maximum preset boost, causing performance issues when the overboost drops the vacuum (limp mode). Also, too fast a spool up can cause turbulance in the exhaust, which is not so good.

If you are going the whole hog and doing your exhaust upgrade, and EGR block you can either do that now to save you reconfiguring again, or do it later, it doesnt matter (depending on your cash flow by this stage, and time).

Ok lets start.

First things first. Make sure you have everything. You will need a Dawes Valve kit, a needle valve kit, any extra 1/8 pipe you can find, an extra 1/8 t-piece, cable ties, sidecutters, and your boost gauge fitted and operational.

Dont chop anything until you have read the following several times and fully understand it. Also, if it is going to rain, a swarm of bees are approaching or you are supposed to be going to a wedding in an hour, perhaps wait until you have more time.

The first thing we are going to do is to fit the needle valve. It is put inline with the VNT actuator and the vaccum pump. It also tees to the boost gauge on the non limited side.

Have a close look at the next photo. Spot the Dawes valve? The non-teed end has a short pipe connected to a t-piece (hidden by the blue pipe, ill get another photo). This t piece is inline with the boost gauge line. The teed end of the dawes valve gets put inline to the pipe which goes to the VNT actuator (the silver thing on top of the turbo). The pipe heading towards us goes to another t-piece.

Phew, still with me?

Ok, so where do these other pipes go? One of them goes to your vacuum pump. It was the line that was going straight to the VNT Actuator. The other pipe is going to head towards the front of the car, and end up in the needle valve.

2011-09-17155742 (2).jpg

Here is the second t-piece going to the needle valve


Here we are connected to the needle valve

2011-09-17155845 (1).jpg

and finally into the airbox. note the blanked off ports to the left, under the pipe


Can you tell which one is my engine bay, and which one is someone else's?



Adjusting the controls

Ok so you have the gear fitted. How do we calibrate it?

Remember how i said its important to monitor whats going onould like to achieve is a nice linear boost curveto a safe level. This will increase performance, lower EGT and keep your engine from going into limp mode.

First things first - what is your boost doing? is it too high, too low, or just right? When you accellerate, how fast does the boost spool up?

If you boost is going above 15psi, you need to adjust the dawes valve by screwing it in 1/4 turn at a time and re testing.

If you boost isnt making 15 psi (with the needle valve closed) you need to wind it out.

If after winding it out you still cant make 15psi, you may need to remove the Dawes valve and stretch the spring a tad.

Once you have got the max boost set, its time to control the spool up.

Experiment by loosening the hex key that locks the needle valve, and adjust it 1/4 turn at a time. Take the car for a drive and see what it has done. Opening the needle valve slows down the spool up, closing it speeds it up.



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I might add a little to this, use it if you want.

Failure of thes motors is a combinatiuon of a few things.

Weak intercoolers, as many have seen they have cracks in them and leak. Good sign of a cracked cooler is black oil marks on the cooler its self.

Cracked cooler, releases boost. Computer realise that boost is lower then needed and ups the boost.

Computer thinks the motor has X amount of boost but really has -X boost, more fuel is added do to the boost increase, but the extra boost is not really there. leading to high egts and holes in pistons .

This is how I understand it works. I may be a little off the mark. This may be more so in earlier zd's with poor computer control.

Intercoolers are a common problem, and i know upto at least series 4 they stilll crack. I can't comment of after that model because i have not looked at one.

I am going to do these mods to the father in laws series 4 zd.

Possibly, somethinkg about catch cans to might be good.

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Thanks, so as it describes, the NADS, stops it from going BOOM.

No, that is not entirely correct and there will be eternal argument over the year models this refers to, but the classic fail (cracked and holed #3 and #4 piston often taking the head with it) reduced dramatically by 2003, by far the 2000/2001 were the worst (and that's mine), sure the ocassional one happened but many blew for other reasons. If the damage has not already been done from excess heat etc, yes nads will keep the pin in the granade, but the damage can sit on the borderline for years and then an event pushes it over the edge.

To sum up, if NADS was installed on a brand new vehicle yes you wouldn't have a problem, many people have purchased a ZD30 with a lot of K on it and there has not been a problem then BANG. The damage has been done for some time it just never quite reached the tipping point.

When mine went I had just finished one of many quick work trips from Sunny Coast to Sydney about 1100k during that year, I would leave at 0400hrs and drive basically non stop, work for a week and come back, the last trip I got home and said the the missus damn the Troll has gone well and the eco was great, I got up the next morning and BANG. The ECU will try to compensate for things for as long as it can.

After the rebuild I installed my EGT and boost gauge first and drove the vehicle as I normally did, boost, well no worries, EGT....... 700C, frightened the s*** out of me and forever changed the way I drove the Trol. The old girl now will see 450C max no matter how hard I drive it.

We can probably mention the setup of the Dawes and needle, the work you have done on your vehicle will change many of the aspects. The boost readings at 1500 and 2000 are guides only and should be somewhere between 5-6 and 10-12 respectively. Now depending on whether you have bypassed the vacuum switch, therefore bypassing the ECU will have an effect on the outright boost the turbo will put out, control taken away from the ECU gives a more linear boost trend.

Limp can have 2 parts, boost and MAF voltage, if your EGR is blocked your MAF voltage will increase slightly ie roughly at idle 1.8v unblocked and 2.1v blocked, the voltage will also climb higher at revs blocked rather than unblocked.

My early DI will limp if I hit 3.98v under 3 grand, boost does not play a big part in my case, but it does under 2500, another story. So the degree of NADS and how it was done has an impact on the final outcome.

Great work Dronus.

Edited by geeyoutoo
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  • 2 weeks later...

Nice write up, but one question can I put the egr blocking plate on before I do the dawes valve, I have boast & pyro gauges, also have catch can. Need to order Dawes valve & boast control & hoses but would really would like to block egr off first.

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Nice write up, but one question can I put the egr blocking plate on before I do the dawes valve, I have boast & pyro gauges, also have catch can. Need to order Dawes valve & boast control & hoses but would really would like to block egr off first.

Howdy! Yep, apologies for my slackness in finishing this DIY, I've been flying around the country for work and adding in bits and pieces where I can..

I'll add the EGR plate bit next for you. Its pretty easy to do. Do you have a di or crd engine?

Sent from my Galaxy Nexus using Tapatalk 2

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Sorry guys it's a 2003 so it would be DI engine brought of an old bloke that only used it twice a year to tow his caravan. Have been watching the boost gauge & haven't seen any spikes in boost only gets up to 16psi & would like it to stay that way. I have a beaudesert exhaust & a steinbauer chip if that makes a difference.

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  • 1 month later...

Howdy. Blocking the egr is one of the best things you can do to keep your inlet manifold clean, and preventing build up and hot spots around the prone cylinders and pistons.

Unfortunately when you block the egr sometimes the system does not compensate for the lack of boost from the egr, you may experiance over or under boost. You mention you already have a chip and exhaust, I would be getting the egt gauge fitted and then the Dawes and needle valve. This way you can control the spool up.

By all means you can try fitting the egr shim first to see what effect it does, but make sure you leave enough time in the day to remove it if the results are erratic or undesirable (assuming the car is your daily drive) :)

Sent from my Galaxy Nexus using Tapatalk 2

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  • 2 weeks later...

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