Buying a used ZD30DI can be tricky, I would not buy a vehicle between the years of 2000 and 2003 without factoring in a rebuild or crate engine replacement. Once you get into 2003 the engine is much improved and later models even better. I would buy a clean 2004/5 tomorrow no worries. My own vehicle is a 2000 DI that I bought new and serviced regularly and didn't thrash, it grenaded at the end of 2006 (not all do as mentioned below) at the end of a 1000k work trip home, I had done around 6 of these that year where I jumped in the car drove quickly 1000k to the work site stayed a week and went back home, the repetition, high speed and not having an EGT gauge were big contributing factors.
The engine was rebuilt and the search was on to make the old girl as reliable as I possibly could, so the following is the direction I took mine to maximise it's life, 8 years down the track she is stronger than ever.
Particularly for older ZD30’s, don’t for one moment think that fitting all this stuff will save your early ZD30 from cracking heads and pistons, the reasons this happens are quite complicated and a vehicle can sit on the threshold of blowing up for very long periods of time and then one day the combination is right and it goes, but, rest assured for every ZD30 that blows up there are a myriad of it's brothers that didn't, you only hear about the bad ones not the good ones, as said the reasons can be complicated. If you have rebuilt a ZD30 I would do this straight away. I did around 25-30,000k after my rebuild before I got into this.
NOTE: We occasionally hear of repeat engine blowups, most of the time this is a direct result of skimping on the head when the original blowup occurred, if you are going to rebuild, do not short change on the head, do it properly or it will come back to bite you later and you won't enjoy the years of trouble free motoring you should have.
Nads steps and logic part 1.
This mainly applies to the ZD30's built up to around 2005, after that the ECU was a little better at controlling boost, but still applicable right up to the advent of the CRD (which doesn’t usually require the Dawes Needle combination but may be beneficial in some cases).
I would strongly recommend that between each step, drive the vehicle for a week or so to see what happens, the education you will gain is well worth the wait, steps 1 and 2 can be done together and after a learning period so can 3 and 4, leave a gap and do 5 as this one may cause it's own little problems as mentioned in the step.
1. Fit EGT gauge, this is the single most important thing you will ever do to your troll, this way you get to see what is happening in your engine under the conditions you normally drive with, you will be surprised even shocked and you will change your driving habits and style. Treat 550C as a usable maximum on a DI.
2. Fit Boost gauge, this way you get to see the effect of boost on EGT, by this time you have modified your driving and will see the effects of ECU boost control on a standard vehicle, if you have an early one it will be quite erratic at times, particularly at highway speeds.
3. Fit Dawes and needle valve (or whatever manual boost controller you decide to fit, they are basically all the same, NOTE, the only setup difference between Dawes and Tillix is the Dawes has a built in Vacuum T and the Tillix has a separate vacuum T) as described in articles you will find with a search. The reason this is done is to take control of the boost away from the ECU, which will make the boost jump around and in some cases drop right off, this may result in very high EGT (the boost on my old girl would drop off to 2-3psi at around 115k then on hitting a hill and powering the EGT would skyrocket, later model ECU's did have better control but still not great). The boost will become linear and EGT will respond better. This step entails bypassing the vacuum switch beside the airbox, I have my system outlined in my Albums and just above in post # 6. Suggest fitting a good quality needle valve such as a DV06 1/8” BSP valve, Darren Dawes has a new needle valve available with 10 turns open to close so it is very easy to adjust, most good needles will have at least 6 turns and you should only be open 2 turns at most otherwise your boost will drop off too much. The needle can be situated under the bonnet but for greater flexibility (especially if you tow) put it in the cabin, there is a spot under the steering wheel where it will slot in quite neatly. My method of setup is to close the needle while you set the max boost, once you are happy with that, set the needle to achieve the spoolup rate mentioned below
3.1 Set the needle to spoolup the turbo at around 5-6psi @ 1500rpm, 10-12psi @ 2000rpm, these are rough guides not necessarily hard and fast rules (we thought at one stage that fast spoolup would cause turbo damage but we really have not experienced that, my current spoolup rate is 21psi under 2000rpm but it took a lot to achieve that). In doing this exercise you will learn more about the effects of the needle on spoolup and performance. Remember that low boost = high EGT, high boost = higher fuel usage, there is a nice spot somewhere in the middle.
3.2 When you fit the Dawes Needle combination (or whatever controller you have chosen) start low, suggest 13-14 psi and see what happens, adjust higher later if your confident, usually limp will occur around 16psi particularly under 3 grand, but this is MAF voltage related (see limp mode note below). The secondary part of this is VNT adjustment but this should be thought about and investigated carefully before attempting, many problems have occurred due to loss of original position. But having said that it is actually quite simple, just a little daunting at first, see VNT Adjustment in one of the albums in my signature.
3.3 This is my dual Dawes setup Dual Dawes and Needle valve on Nissan Patrol ZD30 DI - YouTube
Also a clip on dismantling a Dawes and adjusting it Dawes Valve Dismantle and Adjustment - YouTube
Dawes Note: It is not uncommon for the spring inside the Dawes to require a stretch, Darren has been asked about this and he says stretching is not a problem, small variances in spring compression during manufacture can have an impact. To stretch, take a measurement and stretch 5mm only and try again. From memory mine went from around 12psi at full adjustment to 15 at half way, on rare occasions a second stretch has been required.
NOTE 1: There is an optional HD spring available from Darren, Dawes Devices by 3 Bar Racing Inc. | Dawes Devices, the Best Manual Boost Controllers
NOTE 2: The needle valves purpose is to slow spoolup rate, this is done by opening the needle valve (rotating to the left), which feeds in clean air from its source and lessens the vacuum available to thye VNT, if opened too far there will be a severe drop off in performance. Closing the needle valve (rotating to the right) puts the vacuum back to maximum effect on the VNT and putting spoolup to maximum for the conditions. The needle valve can also be used to improve fuel eco out on the highway by adjusting cruising boost down a little
Note 3: With the advent of the remap for the ZD30DI in late 2017, limp is a thing of the past for those that choose to do it, this allows me to use 21.5-22psi, which we consider a safe 'boost' for our std Garret 2052. I have also stopped using my Dawes and needle valve, after much experimentation I am using a device called a Digibooster, it's from a Scottish Company, this controls max boost as well as maintaining turbo vanes in optimum position, this gives greater 'driveability' and can marginally improve fuel eco.
There is a separate system these days that uses 3 needle valves, have placed a schematic Supplied by Bidja's in Post #6 with the other Dawes Schematics.
The engine was rebuilt and the search was on to make the old girl as reliable as I possibly could, so the following is the direction I took mine to maximise it's life, 8 years down the track she is stronger than ever.
Particularly for older ZD30’s, don’t for one moment think that fitting all this stuff will save your early ZD30 from cracking heads and pistons, the reasons this happens are quite complicated and a vehicle can sit on the threshold of blowing up for very long periods of time and then one day the combination is right and it goes, but, rest assured for every ZD30 that blows up there are a myriad of it's brothers that didn't, you only hear about the bad ones not the good ones, as said the reasons can be complicated. If you have rebuilt a ZD30 I would do this straight away. I did around 25-30,000k after my rebuild before I got into this.
NOTE: We occasionally hear of repeat engine blowups, most of the time this is a direct result of skimping on the head when the original blowup occurred, if you are going to rebuild, do not short change on the head, do it properly or it will come back to bite you later and you won't enjoy the years of trouble free motoring you should have.
Nads steps and logic part 1.
This mainly applies to the ZD30's built up to around 2005, after that the ECU was a little better at controlling boost, but still applicable right up to the advent of the CRD (which doesn’t usually require the Dawes Needle combination but may be beneficial in some cases).
I would strongly recommend that between each step, drive the vehicle for a week or so to see what happens, the education you will gain is well worth the wait, steps 1 and 2 can be done together and after a learning period so can 3 and 4, leave a gap and do 5 as this one may cause it's own little problems as mentioned in the step.
1. Fit EGT gauge, this is the single most important thing you will ever do to your troll, this way you get to see what is happening in your engine under the conditions you normally drive with, you will be surprised even shocked and you will change your driving habits and style. Treat 550C as a usable maximum on a DI.
2. Fit Boost gauge, this way you get to see the effect of boost on EGT, by this time you have modified your driving and will see the effects of ECU boost control on a standard vehicle, if you have an early one it will be quite erratic at times, particularly at highway speeds.
3. Fit Dawes and needle valve (or whatever manual boost controller you decide to fit, they are basically all the same, NOTE, the only setup difference between Dawes and Tillix is the Dawes has a built in Vacuum T and the Tillix has a separate vacuum T) as described in articles you will find with a search. The reason this is done is to take control of the boost away from the ECU, which will make the boost jump around and in some cases drop right off, this may result in very high EGT (the boost on my old girl would drop off to 2-3psi at around 115k then on hitting a hill and powering the EGT would skyrocket, later model ECU's did have better control but still not great). The boost will become linear and EGT will respond better. This step entails bypassing the vacuum switch beside the airbox, I have my system outlined in my Albums and just above in post # 6. Suggest fitting a good quality needle valve such as a DV06 1/8” BSP valve, Darren Dawes has a new needle valve available with 10 turns open to close so it is very easy to adjust, most good needles will have at least 6 turns and you should only be open 2 turns at most otherwise your boost will drop off too much. The needle can be situated under the bonnet but for greater flexibility (especially if you tow) put it in the cabin, there is a spot under the steering wheel where it will slot in quite neatly. My method of setup is to close the needle while you set the max boost, once you are happy with that, set the needle to achieve the spoolup rate mentioned below
3.1 Set the needle to spoolup the turbo at around 5-6psi @ 1500rpm, 10-12psi @ 2000rpm, these are rough guides not necessarily hard and fast rules (we thought at one stage that fast spoolup would cause turbo damage but we really have not experienced that, my current spoolup rate is 21psi under 2000rpm but it took a lot to achieve that). In doing this exercise you will learn more about the effects of the needle on spoolup and performance. Remember that low boost = high EGT, high boost = higher fuel usage, there is a nice spot somewhere in the middle.
3.2 When you fit the Dawes Needle combination (or whatever controller you have chosen) start low, suggest 13-14 psi and see what happens, adjust higher later if your confident, usually limp will occur around 16psi particularly under 3 grand, but this is MAF voltage related (see limp mode note below). The secondary part of this is VNT adjustment but this should be thought about and investigated carefully before attempting, many problems have occurred due to loss of original position. But having said that it is actually quite simple, just a little daunting at first, see VNT Adjustment in one of the albums in my signature.
3.3 This is my dual Dawes setup Dual Dawes and Needle valve on Nissan Patrol ZD30 DI - YouTube
Also a clip on dismantling a Dawes and adjusting it Dawes Valve Dismantle and Adjustment - YouTube
Dawes Note: It is not uncommon for the spring inside the Dawes to require a stretch, Darren has been asked about this and he says stretching is not a problem, small variances in spring compression during manufacture can have an impact. To stretch, take a measurement and stretch 5mm only and try again. From memory mine went from around 12psi at full adjustment to 15 at half way, on rare occasions a second stretch has been required.
NOTE 1: There is an optional HD spring available from Darren, Dawes Devices by 3 Bar Racing Inc. | Dawes Devices, the Best Manual Boost Controllers
NOTE 2: The needle valves purpose is to slow spoolup rate, this is done by opening the needle valve (rotating to the left), which feeds in clean air from its source and lessens the vacuum available to thye VNT, if opened too far there will be a severe drop off in performance. Closing the needle valve (rotating to the right) puts the vacuum back to maximum effect on the VNT and putting spoolup to maximum for the conditions. The needle valve can also be used to improve fuel eco out on the highway by adjusting cruising boost down a little
Note 3: With the advent of the remap for the ZD30DI in late 2017, limp is a thing of the past for those that choose to do it, this allows me to use 21.5-22psi, which we consider a safe 'boost' for our std Garret 2052. I have also stopped using my Dawes and needle valve, after much experimentation I am using a device called a Digibooster, it's from a Scottish Company, this controls max boost as well as maintaining turbo vanes in optimum position, this gives greater 'driveability' and can marginally improve fuel eco.
There is a separate system these days that uses 3 needle valves, have placed a schematic Supplied by Bidja's in Post #6 with the other Dawes Schematics.