Nissan Patrol Petrol to Diesel Turbo conversion

The Donor Truck

I have a Nissan Safari (JDM name) that I’ve had since about 2014 that I’ve posted about before. I got it for $4200 It came with a stronk diesel 4.2L straight six, and I added a turbo to it in like, 2015 as well as an exhaust. That cost me like $1300 ($5000 if a shop had done it).

Its taken me and my now fiance all around the country on many road trips and amazing places, 4WD tracks etc. I put a bed in the back of it so we could camp wherever without needing to set a tent up in the rain. Probably done 20,000kms around the south island of NZ. I used to take my cat down to the beach in it for walks too.

My friend and I already replaced the engine once after I hydrolocked it, bending 2 conrods:

But last year I accidentally let the rego lapse which means she is never getting on the road again. Not a terrible thing considering it is pretty rotten as far as rust goes. Too many beach trips, even though I washed it after each one.

The new truck

A few months after that I found another one, Nissan Patrol (Aus/NZ assembled name) at the bottom of the country, with a very undesirable engine in it. 4.2L straight six carburated petrol. When it dropped to $7500 I put a deposit on it and my friend and I went to get it, with my Falcon and his car trailer, and towed the Falcon back so we wouldn’t have to drive 2 cars. The distance meant it cost me an extra $1100 in fuel alone :laughing: :sob:

Anyway… after suffering through flooding the carb occasionally, waiting 10+ mins for it to warm up on cold mornings, 5 minutes on warm mornings, and occasionally getting stuck in the road after thinking it was warmed up when it wasn’t and thus stalling it when going over 1500 revs, the opportunity arose for my friend to help me swap the engines.

The swap

After bringing his family to my house for a holiday, he drove my grey one home over the mountains. A few weeks later I headed over in my new one. As a final fuck you some random water hose blew and left me stranded on the side of the road in the mountains in the dark and rain for 2 hours while i fixed it. Had 2 people stop to offer help, one cutting some hose off his own vehicle for me to use. Turned the 3 hour trip into a 5 hour trip but made it in the end.

Pulled both the motors out:

This is the 4.2L straight 6 carbie petrol. The TB42.

This is the 4.2L straight 6 turbo diesel to go in. The TD42. You think they’d be fairly similar, but no. The turbo is some chinese thing sold by Scarles as an SCR320. In this configuration with the factory fuel and with the wastegate welded shut and a 3" straight through exhaust (made by the same fren), it hits about 15psi with the boost coming on at 1500rpm. Sounds amazing, esp in the forest at night.

(My friends sisters truck hits 25psi with the fuel turned up just a lil bit, doesn’t even roll coal, but he is building her a worked boost compensated engine)

We lost a day or so on this rust fix. Some silly badly designed gusset that lets water sit under it.

So good to have the donor truck, cos I needed the bellhousing since the diesel starter motor has 3 bolts, and bigger bolts than the petrol one.

Also had to move the PTO unit from the old gearbox to the new for when I put the PTO winch in. This required changing the gearbox oil and putting some Moreys oil conditioner in it since it was a little whiney.

Finally it was time to put the engine in.

That took about 20 minutes and went pretty well. But about 8 hours to get it running from here. We used the same fuel tank and lines, but used the air compressor to blow everything from the engine bay down those lines back into the fuel tank, and then blew diesel down them too, draining the fuel tank into a bucket. We did need to take the engine bay lines and diesel filter from the donor truck since the petrol just feeds direct to the carbie from the chassis fuel lines. Luckily all the screw holes and everything is all the same so it bolted right into where it needed to be.


The grey truck is 24v so I had to convert a few things for the 12v gold truck. So that was a new alternator, starter motor and we had to replace the fuel cut solenoid in the fuel pump with a 12v one. I also had to add a glow plug circuit with a new 100amp glow plug relay and install new 12v glow plugs. I also had to extend the alternator circuit since the diesel has it on the opposite side of the engine. Again, having the donor truck was great here since I could just cut what I needed from the loom and use all the factory plugs. This included the 65amp fusible link and all the wires and cradle for it.

I hadn’t considered the starter relay which would also need to be 12v cos I thought it would be in the truck. But I could not find it. Not knowing where the starter motor exciter wire went or what was on it, I opted to use it simply as the signal line. Luckily amongst my auto-electrical hoardage I happened to find a brand new 12v starter relay! Quite lucky since I am sure trying to run the diesel starter motor actuator off the exciter wire for the petrol starter motor would have fried it. It even fit the factory screw holes.

Note the uncovered hot line from the 65amp fusible link that I need to rectify sooner rather than later :grimacing: :eyes: I didn’t have any smaller crimps to use the rubber cover that came with the relay.

Then we tested it for about 10 mins by driving to the gassy to fill up with diesel and then I drove back home 3 hours over the mountains. It didn’t miss a beat.


So much easier with a donor truck.

It was also very handy to have another complete factory diesel truck there to check things on including wiring and electrical continuity of certain components.

Still a lot to do, I’ve got a proper cold air box to replace the janky pod filter. We’ve gotta do a 2" body lift and put my new rock sliders on. Then also the bullbars and PTO winch from the donor truck and make station bars that join the bullbars to the rock sliders. Possibly new shocks and springs too.

Then I have to get the govt to certify it through one of their vehicle certifiers and switch the registration from petrol to diesel.

I’m so lucky to have my friends help with this and with all the previous missions, I really doubt I could do it on my own. We did this swap in 4 days (would have been 2 without the rust fix). It sounds so much better and is ready to drive right after starting. Nothing like the familiar sound of a TD42 ticking away.


That is an incredible story, and very nice pictures !
I am always amazed to see those “older” cars being in such great shape, because here in Québec the rust starts eating cars after 5-6 years.

I have a little question;

Why would your government need to know on which type of fuel your car is ?

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Outside of North America governments get very picky and intrusive about a lot of things to include cars.

@penguinpowernz that is a an awesome project. Looks like you did a great job.


Taxes, in general.


Thanks guys. It hasn’t missed a beat yet, I went back over the mountains to do a 2" body lift and some bar work. Namely rocksliders and station bars:

I also took it out this past weekend over some bumpy stuff, including a 2.5 hour (only 25kms) trek each way over old mining roads high up in beech forests down to the hut.

That should’ve shaken out any bolts I forgot to tighten.

The old girl had her front taken to fix up a crashed one (my friend has about 6 of these things).

This one has some pretty bad rust, but only because of all the beach trips, we use grit here for snow/ice, not salt, not that I live in an area that gets that cold. The only reason the other one has little rust is because it spent most of it’s life in a dry inland region.


it’s kinda like how in the US you have different color dye in the diesel fuel for agri or on road vehicles… we have a registration for on road vehicles but not tractors.

So the diesel fuel is cheaper at the pump than petrol for the farmers, but for on road diesel vehicles you have to buy mileage at about $80 for 1000kms, which effectively brings diesel up to about the same cost as petrol.

Some people put switches on their odo so their mileage never changes but I would never do a thing like that :eyes: