Posted by Michael 14/02/2024 0 Comment(s) TECH TALK,


Operation 200 continues this month as we travel to the NSW Southern Highlands for vital reliability upgrades and a significant power boost.

Over the last few months, we have subjected our previously bog-standard LandCruiser 200 Series to many upgrades before hitting the road for a 20,000km tour with our offroad caravan strapped to the back.


The many changes included a Tough Dog GVM boost, Monster Wheels and Yokohama offroad tyres, a Bendix offroad brake upgrade, a REDARC battery and inverter, an Ironman bullbar and roof rack and a set of MSA 4x4 drawers. While we have created a much better and safer towing vehicle, it came with a weight penalty and bigger tyres that sap the fuel economy.

As much by chance as good management, our journey home took us south along the Hume Highway past the home of Berrima Diesel Service in NSW. This family-run business operates on farmland in the genteel Southern Highlands community and has been the go-to fount of diesel knowledge since the 1970s. Three generations of the Leimroth clan have fettled, saved and improved countless numbers of 4WDs going back to the flinty BJ40 LandCruiser and the G60 Patrol.

When I called ahead to see if they had time to discuss our fuel use issue and what we could do about keeping the 4.5L V8 in good order, they suggested we drop in for a yarn. Andrew Leimroth recommended a performance and protection package to suit our towing needs. He promised to maximise reliability and operation, so we arranged to return a few weeks later.


Berrima Diesel was founded by Reinhard Leimroth, who trained in Germany as a Bosch diesel engineer before moving to Australia. His son Andrew joined him in the early '80s, and Andrew's two sons Baden and Trent jumped on board a few years back.

The basic Berrima Diesel package for a 200 Series comprises an intake manifold clean, a pre fuel filter and a catch can for reliability and performance, a throttle kit and a DP computer chip. However, for our specific towing needs, Andrew suggested a custom remap of the ECU and a fan kit to increase airflow over the intercooler.



We arrived back at Berrima Diesel bright and early, welcomed by a brisk spring morning and Andrew’s two sons, who specialise in the latest common rail engines. We started by cleaning the exhaust gas recirculation (EGR) system and intake manifold. Like most vehicles, the 200 Series has an EGR that vents crankcase gasses back into the engine via the intake manifold after the air cleaner. Over time, the carbon and oil residue builds up inside the manifold and restricts airflow to the engine. Some diesel mechanics remove the manifold and vapour blast the manifold internals. But Berrima Diesel takes a different path and uses a unique cleaning solution that pressure sprays foam into the air pathways to clean the internals as the engine runs for about half an hour. Then, a quick run on the road soon removes all the hardened soot. The team has run tests to show that their cleaning method does as good a job as removing the manifold. Their cleaning method also takes less time and eliminates any problems that might occur when reinstalling the electronics.

Now, with a revitalised manifold, Baden installed a ProVent Catch Can Kit to eliminate gunk buildup inside the manifold. The kit includes a custom mount and all hoses. With the kit installed, crankcase gasses divert to a plastic housing with a filter that traps any oil or water before returning to the crankcase as clean air. The can and a 25mm overflow tube hold the dirty oil that must be emptied every 3000–5000km or so.


Company founder Reinhard joined us during the catch can installation on the driver-side wheel arch and confirmed the catch can was a significant improvement. He added that they are fitted on many European brands and should be standard on all engines.


It was very interesting chatting with Reinhard about the changes to technology over the last 20 years. At 83, he is as sharp as a tack and has knowledge about diesels that would fill many volumes. I made the mistake of asking which is his favourite engine because it's the 1HD FE from the 100 Series, which is the vehicle we swapped from when we upgraded to the 200.


Reinhardt likes the sensible and under-stressed design of the 1HD straight six — which has seen service in some vehicles that have more than one-million kilometres on their dial — even if the service intervals aren’t too flash. The same engine as a Yanmar diesel has made significant reliable power in boats for years.

Somewhat deflated by Reinhard's verdict on the 100 Series, he offered some positivity around our stock but ghastly looking GX snorkel head. "That's the best air intake on the market," he told me. OK, I might keep it as a badge of honour.

The senior Leimroth didn't dismiss the technology in the 200 Series out of hand but advised that they must be maintained meticulously because of their increased technology.

The importance of proper engine maintenance, regardless of brand, is a consistent theme at Berrima Diesel.

While we worked on the driver side of the engine, Baden checked the air cleaner, which we had changed about 5000km ago. He was happy with the condition and that we had emptied the lower cyclonic pre-cleaner when we changed the filter. He wasn't too pleased with our aftermarket filter, though, preferring to stick with a genuine Toyota version. He cautioned that it is critical to avoid any of the infamous ‘dusting’ problems by installing the filter correctly, which is done by pushing it down and towards the engine to ensure the filter’s rubber lip isn’t distorted.


One of the major problems seen in modern diesels comes from contaminated fuel that can cause severe damage to intricate fuel injection systems. Berrima Diesel recommends a pre-filter in the fuel line before the primary Toyota filter, rather than a post-filter after the primary filter. Their reasoning is the post-filter can affect fuel pressure. They also recommend changing the filter at 10,000km and using a genuine filter. Ours wasn't, and Baden pointed out dobs of glue, most notably on the clean side of the non-genuine filter, that meant it couldn’t work correctly. When talking about this later, Andrew added that it's bad practice to wait for the filter change light to show on the dash before changing the filter. Prevention is better than cure.


Heat is the enemy of an engine, and when air is compressed by the turbocharger, it gets hot very quickly. So, turbo diesels use an intercooler between the turbos and the intake to cool the air, making it denser and more oxygen-rich. You can now increase the amount of fuel in the combustion for more power. The intercooler uses fins and plates to cool the air but relies on the air flowing through scoops under the engine bonnet for its supply. Restrictions like bullbars and driving lights can reduce this airflow, but Baden noted our Ironman 4x4 bullbar was less restrictive than many he had seen.


When towing or in challenging offroad conditions, airflow through the intercooler heats up so much that sensors on the engine reduce the power output to avoid engine overheating and damage. Reinhard explained that many customers complain they lose power on long climbs, so Berrima Diesel has fitted electric fans for many years. He said electric fans work especially well with the 200 Series’ top-mounted intercooler. The team of diesel experts sell and fit the Queensland-made twin fan kit from PWR, and once installed into our 200 its laser-cut base sat neatly over the intercooler onto the bolts of the stock engine cover. When the bonnet closes, the original Toyota rubber boot seals around the fans for an effective flow of air and the fans operate continually when the ignition circuit is on.


The next part of our upgrades is a PlugNGO throttle controller. The 200 Series has a ‘fly by wire’ or electronic throttle instead of a cable throttle of the past. The PlugNGO takes any lag out of acceleration but does not alter engine tune, power or torque settings. It improves performance by changing the throttle curve electronically to give a faster response for quicker acceleration. The unit plugs straight into the Toyota throttle loom at the accelerator pedal. The switch panel mounts to a space under the instrument cluster where it can be quickly set for 18 levels of control from most sensitive to an Eco mode for a more gradual response offroad.

We tested the PlugNGO on the road, and the difference between having it off and maximum sensitivity is remarkable. Even in stock trim, a 200 Series has impressive power, but with the throttle controller fitted, acceleration improved dramatically on Sport+ mode and is also quicker in the lower settings for average use. Peddle pressure was less, so on long runs that should make driving easier.

An offshoot of the road tests, Baden found the engine noise in the cabin was higher than it should be, which he traced to a degraded boot around the steering column, a common fault on GX models. We have since packed the gap with a short section of pool noodle, and we’re back to near Sahara cabin sound insulation.


Berrima Diesel has long advocated the DP performance chip, which piggybacks onto the vehicle engine control unit (ECU). Still, with the advances of common rail engines and more sophisticated ECUs, the team has graduated to custom tunes of the vehicle software. Andrew had suggested we would achieve a 20 per cent increase in power over our standard setup, and Baden was keen to get started on the remap.

We drove the 200 Series onto the dynamometer for runs at its stock settings with new filters and fans. After three runs, the data showed 135kW and 984Nm at the wheels (in third gear), which Baden said was good for a 200 Series.

To start the remap, he downloaded all the parameters of the stock settings and found the engine's software identification number, for which he already had a map to suit. As we went through the procedure on his laptop, he explained how it is easy for inexperienced tuners to change the mapping and eliminate the program’s limiters for increased performance. But he explained the following:

“The problem with ECU tuning is you've got this big file in front of you, and someone could just highlight everything and set the parameters at 100 per cent, and that's when it blows the motor, and no one knows why. So, to tune properly on these mappings, you have to know what RPM, what load, what fuel injection time you want to be coming in, when you want the fuel injections to occur, for what periods and at what throttle to be safe.

"When it comes to these remaps, it's very easy to go wrong, but it's very hard to actually do proper tuning because you've got to understand how the whole map works and how everything interacts with everything else. It's very complex, and you must understand what you are doing. Our tunes are reliable, and they work without overstressing these engines.”

With the new map loaded into the ECU, our second run on the dyno delivered 160kW and 1163Nm. The difference in how the car behaved on the road was remarkable. The 200 Series accelerated much more quickly and showed virtually no drop in speed on hills. I was impressed. We will report back when we have had a chance to live with the car for a while and check how it tows when hooked up to our van.

Our time with the Leimroth family was thoroughly enjoyable, and I learned a lot of valuable information about maintenance. Their knowledge about diesels and 4WDs, in general, is astounding, and I'm confident we have a much better and more reliable car. Berrima Diesel is about an hour's drive south of Sydney, but their reputation as the go-to place for diesel performance and problem-solving is well deserved.