Refurbishing a vintage 4WD diesel
Vintage 4WDs are greatly prized by their owners and some of these pre-emissions diesels are still around in the used market. Here’s Allan Whiting’s experience with his 1993 LandCruiser 75 Series tray-back ute.
Basic 4WDs still have particular appeal for serious off-roaders, who don’t want the complication of high-pressure fuel injection systems and multiple emissions-reducing after-treatment components – EGRs, diesel oxidation catalysts (DOCs), DPFs and selective catalytic reducers (SCRs) that need an AdBlue tank.
The most popular older diesels power Nissan Patrols, Toyota LandCruisers and HiLuxes that dominated the 1990s Australian 4WD market. Early examples were naturally aspirated, but by the late-1990s, all were factory turbocharged.
Refurbishing one of the factory turbo engines is pretty straightforward, unless you’re after more grunt than the standard engine produced. Then you could run into problems that include overheating – especially Patrols – cracked pistons and bent conrods.
High-mileage engines – anything over 500,000km – really should be completely rebuilt, with new or rebored liners, new pistons, new conrods, recon or new cylinder head, camshaft and valves.
Refurbishing one of the naturally aspirated engines is also straightforward, if you’re content with spending a lot of money and finishing up with a poorly performing – by modern standards – 4WD. Most rebuilt, naturally aspirated diesels are fitted with after-market turbochargers by their owners and the standard naturally aspirated engine components mostly aren’t up to that.
Turbo’ing an engine that wasn’t designed for increased combustion heat and pressure is a risky business and how risky is what Allan W set out to discover with his own 1993 LandCruiser 75 Series ute. He expected trouble and he got it.
He’d bought the vehicle second-hand – two previous Queensland owners – in 2010 and its stand-out attraction over other used 75s was a wheelbase stretch of 700mm and a GVM upgrade to 3300kg, making it eminently suited to carrying a roomy, slide-on camper.
It came with 320,000km on the clock and Allan W was told that the engine had been rebuilt at 200,000km. That seemed odd, until he later discovered hints that it had been turbo’ed at some stage. Mods to the heater hoses and an extractor exhaust manifold pointed to a removed turbo and cheaper exhaust headers than a genuine Toyota exhaust manifold.
With his vintage-look, slide-on camper on board, Harry the 75 Series was a slug on the highway, so he decided to fit a turbo. Experienced people warned about likely engine drama, but he fitted a pyrometer, to monitor exhaust gas temperature and took a punt.
Complicating things a little was short period of possible engine ‘dusting’, caused by an ill-fitting air cleaner gasket, plus a slight oil leak at the back of the cylinder head.
Performance was greatly enhanced by the turbo and, for around 100,000km of on and off road tripping, there were no obvious issues. Then he noticed that the head oil leak had accelerated and there were small flecks of oil in the coolant. Troooble at mill.
A subsequent tear-down showed a cracked cylinder head, some piston-top deterioration and scored bores and bearings. Some of this may have been pre-existing from the original turbo fitment and the dusting episode may have contributed to the bearing wear.
He checked our options that included selling the ute as it sat, but where would he get a stretched wheelbase, GVM-upgraded equivalent? Second hand factory-turbo, 1HD-T engines were available as replacements, but with ‘driveway’ warranty. One of his mates went down that route, but when the engine pooed itself six months later, the owner was up for a full rebuild, making it a total $30 grand exercise, including the engine purchase.
So, Allan W figured the safest route, at the half-million-kilometre mark, was a thorough engine rebuild that would take into account the additional stress of turbocharging. At least that way, he’d know what he’d paid for.
His regular servicing shop – AJ Automotive Services Bowral (NSW) – engaged Southern Engine Reconditioning, of Kembla Grange (NSW), to do the job. This highly professional outfit rebuilds engines up to 12-cylinder earthmoving gear size and puts a 12-month, unlimited-kilometre warranty on its work. However, if you’re looking for ‘cheap’, go elsewhere.
SER has plenty of experience with rebuilding Patrol and LandCruiser engines for turbocharging and they know exactly what components need upgrading over the standard bits.
Block pre-bored requiring sleeve due to cracked head corrosion
The only surviving 1HZ component was the block that was completely refurbished. After boring, one of the cylinder liners showed residual corrosion at the top, where the cracked head had been leaking coolant into the cylinder.
Block bored-out with a step to seat a semi-finished sleeve
It was professionally repaired, with an overbore that created a bottom step for a new liner insert, after which the refurbished block was ‘decked’.
Block being decked after being sleeved and bored
Testing showed that the crankshaft had a small crack, so it was junked and the head, camshaft, valve gear, pistons and conrods were scrapped.
The replacement pistons had much bigger gudgeon pins and ceramic-coated tops. A brand new crank, head, camshaft and valve gear went on, along with a new injection pump and injectors. A replacement timing case incorporated a higher-capacity oil pump.
Allan W popped into the shop a couple of times during the operation and was impressed with SER’s attention to detail. New, heavier-duty conrods were being fitted, but only after a thorough balance check of big and little ends.
The standard tolerance was + or – 2.5 grams, but SER’s star engine builder was happy only when all rod weight measurements were exactly the same.
Turnaround time was around one month, before the rebuilt engine went into Harry. In the meantime, AJs had fitted a brand new copper radiator and all engine bay hoses, including normally tricky-to-access power steering plumbing. The flywheel was machined, of course and mated to a new heavy-duty clutch.
It’s early days for an assessment, but the rebuilt engine is quieter across the rev range and is much, much smoother. In the running-in phase, in late 2022, it’s way too early for a performance comparison, but we’ll publish that in early 2023.