Well, I was hoping I’d never have to make this post, but I always knew it was a possibility. Since my truck was the first Hiace pickup/Dyna that I'm aware of to get a turbo installed and others have shown interest in doing the same, I wanted to share an update—for better or worse.
The Issue
A little while ago, I started noticing occasional smoke at startup after the truck had been sitting for a while. The smoke lasted about 20 seconds and was light-colored, but I couldn’t tell if it was white or blue—so I wasn’t sure if it was oil or coolant. My initial thoughts:
- Moisture in the fuel system
- A cracked head leaking coolant into the cylinder when parked
- Bad valve stem seals letting oil seep into the chamber
However, I wasn’t seeing any significant coolant loss or an increase in oil consumption, and once the truck was running, everything seemed fine.
Diagnostics & What I Found
Since the symptoms were inconsistent, I ran some tests:
Compression Test:
- Cylinder 1: 480 psi
- Cylinder 2: 450 psi
- Cylinder 3: 440 psi
- Cylinder 4: 280 psi
- Wet test on cylinder 4: 300 psi
Cooling System Pressure Test:
Started at 15 psi, dropped to ~12.5 psi after an hour.
Not sure what’s normal for these old trucks, but no sign of a massive coolant leak that would cause a compression drop like that.
Leak Down Test on Cylinder 4:
25% leakage at 100 psi, all coming through the crankcase.
Was hoping it was just a cracked head, but everything leads me to believe there’s localized damage in cylinder 4 piston or rings. My best guess is that the low compression at cold start is allowing unburnt diesel through the exhaust until the engine warms up enough to burn it properly. I was pretty prepared to do a head swap at some point, due to the reputation of these engines, unfortunately it looks like I won't be able to simply swap the head and will need to pull the engine.
Hard to say what happened, but the tuck has never overheated, and I’ve been careful with EGTs.
- Coolant temps: ~185°F during normal driving, low 190s on the freeway, never over low 200s.
- EGTs: Kept under 900°F post-turbo. Momentarily kissed 1000°F a couple times.
- 14 psi Boost
I haven’t pulled the head yet, so I can’t say for sure what failed or if the turbo install directly or indirectly caused it. That said, I’m not confident in the work the shop did—I’ve already had to redo a bunch of things, and was planning on refining the rest of the installation this summer (finally have a daily driver so some downtime on the truck isn't a big deal).
Where Do I Go From Here?
Going back to an N/A 2L is out of the question—the turbo setup made the truck damn near perfect. So I see two real options:
- Rebuild the 2L and do a more professional turbo install. I've learned a lot since I had the turbo installed and know I could do a much better job now.
- Swap in a 1KZ
Right now, I’m heavily leaning toward the 1KZ. A factory turbo, larger displacement, and stronger internals would give me more confidence long-term. While they have their own issues, they’re well-regarded engines, and I’d be running it at stock power levels—not pushing it beyond its design. I feel like the 2L will always be slightly too small, working too hard to push the 5000 pound truck up steep hills, and just not as bullet proof as I’d like.
Would the 1KZ Fit?
That’s the big unknown. The fact that some Hiace vans came with the 1KZ gives me hope. My truck has the R351F transmission, which those vans also used, so with the right bell housing, the gearbox should bolt up. From what I’ve found, swapping a 1KZ into a Hilux (from a 2L/3L/5L) typically requires:
- Moving the engine mounts back ~40mm
- Modifying the mechanical pump to use with the 1KZ
- Swapping the bell housing, clutch, fork, slave cylinder, etc.
If the same applies to my truck, it’s definitely a challenge, but doable. That is, if the engine will even fit in the bay. The fact that the turbo is mounted low makes me think it might work. There's plenty of room behind my current engine, as there is a removable hatch that could easily be modified. I'm not sure how much taller the 1kz is, though, and that's where I'm most concerned about space.
Next Steps
I’ve got some time to think about it while I figure out storage for the camper, so I can fit the truck in my garage. Pulling the engine should be fun—planning to take it out through the cab on the passenger side. Should be… interesting.
Would love to hear people’s thoughts—both on what might have gone wrong and on the 1KZ swap. Appreciate any insight or advice!
