While we write about our Korean car projects most of the time, we were also busy having stuff done to a 2002 Nissan Patrol. We shifted some of our focus from getting the racecar ready because we wanted to save this rig from premature death.
This big brutish beast is powered by a ZD30DDTi engine. This 3.0-liter direct injection, turbocharged and intercooled diesel is high-tech and powerful enough to pull around three tons of all-terrain terror, while at the same time being a relative miser at the pumps. However, the ZD30 has the worrying reputation of being somewhat of a hand grenade as it ages and in low-load usage, even when the car is exclusively run an urban setting.
Our friends from the Nissan Patrol Club of the Philippines advised us to invest in a group of parts and fixes that are wittily called the Nissan Anti-Detonation System (NADS). These modifications address the major causes of ZD30 engine failure. The vehicle’s owner was convinced to undertake this project so as to avoid major motor catastrophe. Breaking a Nissan is never cheap in the Philippines, due to expensive prices of spare parts here, relative to other Japanese brands of course. Couple this fact by this particular Nissan being a Patrol, and you can expect even higher price premiums for its parts.
In conjunction to this, we were trying to resolve a problem that this unit had. During long drives, it has a propensity to overheat. We had an inkling that it had somethng to do with what the NADS aims to resolve, and we think we are partially correct in that assumption.
Henceforth, we will be exploring the parts consisting the NADS, and hopefully you would find this information useful on your own Patrols.
Causes of Engine Failure
dronus4x4 of the myPatrol4x4.com forums detailed the various reasons for ZD30 failure. It can be summed up to three: dirty intake tract, high exhaust gas temperature, and poor boost control.
Diesel engines, most especially those that employ exhaust gas recirculation (EGR), typically accumulate soot and dirt in the intake system. EGR is employed by the manufacturers only as an emission control strategy. By letting the engine “eat” some of its “waste”, emissions of Oxides of Nitrogen (NOx) are reduced. But this makes the intake very dirty. In the Patrol, this grime fouls the Mass Air Flow Sensor (MAFS), the device that allows the engine computer to see the amount of air coming in. The muck also accumulates at the intake manifold, and over time obstructs air flow into the middle cylinders, causing uneven combustion, high exhaust temperature, and eventual failure.
You would think that high exhaust gas temperature (EGT) is not so bad. Come on, you may think, you’re forcing air and fuel to ignite as a matter of course, so heat is good, right? Well, too much heat is bad. An excess of heat can melt things like turbo turbine fins, pistons, cylinder heads, etc. For a diesel engine, high EGT means that there is too much fuel combusted in the engine, a “rich” condition.
High EGTs may be the root cause of one of the Patrol’s drivability issues. The engine was overheating while it was under heavy strain, in situations like climbing a mountain or pulling a trailer. This is despite a cooling system that is in perfect working order.
The excess fuel condition was exacerbated by the the Patrol having poor boost control, either having too little or too much boost at any given time. The ZD30 engine is fitted from the factory with a variable geometry turbine (VGT) turbocharger. Instead of a wastegate regulating boost pressure, there are vanes in the turbine housing that move, allowing the variance of the A/R ratio, speeding or slowing down the turbine based on the engine’s requirements and/or target boost pressure. VGT turbo diesels are pretty commonplace in Korean CRDi mills locally, but to see this technology on a 13 year-old car just proves that this engine was pretty trick for the time.
Stock maximum boost is 16psi, but we have seen upwards of 20psi on short 1st gear bursts before NADS installation. But infuriatingly, the norm was to see too low a boost pressure that again leads to high EGTs.
Really, these issues plaguing the ZD30 is a downright shame. Dax Santiano of TS Tuning/Insane 4×4 Garage pointed out to us that the ZD30DDTi is a pretty well sophisticated engine in and of itself, with double overhead cams, four valves per cylinder, and low for a diesel 17:1 compression ratio. He says that if these faults are addressed immediately, then we can expect our engine to live a long life.
The Nissan Anti-Detonation System (NADS) consists of the following:
- Boost and Exhaust Gas Temperature Gauges
- Oil catch can
- EGT block
- Boost control
- Free-flow Exhaust System
The above modifications and parts help resolve the ZD30’s propensity to fail. We haven’t done all of the list, and some not really in the recommended order, but we have already noted improvements that will make the powerplant live long.
The first thing to do is to get instrumentation as these will inform you of impending destruction. Boost and EGT gauges will allow you to see elevated temperatures and abnormal boost control conditions, respectively. By having them fitted to the Patrol, it made us want to tackle the boost control issue posthaste.
The gauges are the exact same Auto Meter stepper motor gauges from Project Elantra. We have pilfered this from the race car as it is getting new sets of gauges. But enough about the Elantra….
We discovered that the boost gauge was reading a bit high. When backchecked with an “aircraft-grade” mechanical boost gauge, the Auto Gauge unit showed 2 more psi boost at maximum pressure. Even though there is a discrepancy, it does not bother us because what matters is the ability to monitor for any drastic changes in boost in the future. Perhaps they can be calibrated, but we don’t really want to bother with the effort of doing so.
A custom aluminum double gauge mount was fabricated by TS Tuning. Mounted near the driver-side A-pillar, the auxiliary instruments are easy to see, and are entertainment in themselves as they have an opening and closing ceremony, just like the more-known Japanese brand of gauges that we Definitely won’t mention here.
EGR Block and Intercooler Upgrade
In conjunction with the gauge install, we had TS Tuning block the EGR valve. It is understood that by disabling an exhaust emission control device, a marginal contribution towards polluting the environment was done. But the improved longevity of the powerplant was paramount in our minds when commissioning the work. Forgive us if the polar ice caps melt a fraction faster because of this.
We also had the Patrol’s intercooler upgraded. The OEM intercooler is known to leak boost as its end tanks are crimped onto the core instead of being welded. So many moons ago, we had a leak test done to it, and it was confirmed that our I/C was Swiss-cheesed. Replacing it with a brand new unit from the dealer would cost us a bomb. And plus, the stock intercooler was top-mounted. It’s never a good idea to have something that cools something placed on top of a hot engine.
Not long thereafter, we found and got a good deal on an OEM Mitsubishi Lancer EVO IV intercooler for the rig. It’s not a small unit, probably more than twice the frontal area of the stock I/C and just as thick. But we surmise that the size of the EVO heat exchanger is just right for our 3.0L turbodiesel.
TS Tuning did an excellent job at installing it. It could have been easier for them to do a top-mount intercooler conversion, but we are glad that we all saw eye-to-eye, in that a front-mount relocation was for the best. A lot of detail work went into the install, from clean welds, intelligent placement of components, to solid bracketing and pipe layout. Mad props to them for the effort.
We never determined beforehand the space available for an intercooler behind the front bumper. Luckily, and with the skill of Dax and his crew, they were able to shoehorn the huge EVO IV I/C. It really is a tight fit, and it can be seen behind the car’s licence plate. The end result looks stock, which is great since this car isn’t supposed to stand out. The work was reasonably priced too, the conversion costing around less than half the cost of a brand new replacement intercooler from the casa.
After the above conversion we felt that the Patrol had more power than before. We then took it for an out-of-town trip. But EGTs were still going pretty high due to the lack of boost pressure at a sensible amount of throttle position, and the engine’s water temperature was correspondingly getting critical. We were afraid of nuking the engine, so we figured out that a deliberate press on the gas pedal was what it took so that EGTs would remain low and thus the car won’t overheat and allow us to get home. And this leads us to…
Internet guides to NADS advocate the controlled leaking of vacuum to and from the standard VGT actuator, via the use of a needle valve and something called a Dawes valve. As far as we can understand, they bleed off vacuum in a controlled manner, regulating the standard vacuum-operated actuator in a manner similar to a boost-dependant one.
Instead, Dax recommended deep-sixing the OEM actuator entirely and converting to a boost-actuated unit. When schedules permitted, we went back to TS Tuning to have an original Garrett actuator fitted. This part was designed to open the vanes at 14.7psi, and most importantly was a direct fit to the existing brackets of the standard turbocharger. Minor adjustment to the pushrod got the boost stabilized at 16psi in full chat.
Drivability has drastically improved, with power coming online at lower levels than before. Off idle, the turbo is already producing boost, and it does not take much RPMs to hit max boost. But the major benefit is with regards to EGTs. Even how hard we step on the throttle, and even while climbing road inclines, EGT has remained within low levels, not even exeeding 300deg. in most occasions. We think that the engine will really be very robust for the long term
We haven’t done any exhaust modifications yet, and we haven’t bought an oil catch can for the car. Once the owner of the Patrol has some extra funds, we may do some exhaust mods in the future. As for oil catch can, we can probably install one ourselves, as we were able to do so with Project Elantra.
However, most troubling for us is the fact that we were not able to locate the root cause of our high speed overheating. We will be attempting to seal the hood scoop, change the engine’s thermostat, clean the radiator, and fill some silicon oil at the clutch fan.
But for now, with a couple of thousand kilometers driving the vehicle in both urban and long-distance settings, the Patrol seems to already be prepared to stand the test of time with most of the NADS done. We are looking forward to seeing this beast on the road for years to come.