Why can’t the Japanese make a good diesel engine

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Tue 18 Apr 2023 19:42
Why can’t the Japanese make a good diesel engine - Steveieb

We’ve seen companies like Toyota making the most reliable petrol engines around.

Earlier they were not outstanding but reliable . Take the Hilux that refused to die for Clarkson.

Now we hear about Subaru s dissasterous attempts , Mazda CX5 destroying themselves and even the Yaris diesel with DPF breaking the tradition of peerless reliability.

But at least Toyota accepted the criticism and arranged a generous claim arrangement.

OK diesels are not popular in the US, Japan or Australia but it’s so unusual to level a complaint across all these Japanese Marques .

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Tue 18 Apr 2023 20:22
Why can’t the Japanese make a good diesel engine - badbusdriver

Am I getting deja vu here?

Might be a glitch in the matrix, but I'm sure a pretty much identical (with the same title) thread has been here before (not recently though)

As for the question, the Japanese can make good Diesel engines and have done plenty of times in the past.

But no real call for them these days so why bother?

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Tue 18 Apr 2023 21:19
Why can’t the Japanese make a good diesel engine - alan1302

Isuzu makes some highly regarded diesel engines as well.

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Tue 18 Apr 2023 22:23
Why can’t the Japanese make a good diesel engine - RT

Isuzu makes some highly regarded diesel engines as well.

The 3.0 V6 Isuzu diesel used by Opel/Vauxhall was quietly dropped because of reliability issues.

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Tue 18 Apr 2023 22:37
Why can’t the Japanese make a good diesel engine - Metropolis.
The Toyota 2.2 diesel in the Lexus IS was not very good, and I think one of the Land Cruiser 4 pots had a tendency to pop head gaskets, I think it was the 80 series.

Mitsubishi diesels seem OK, I think? Astronomical cost to replace a 3.2 diesel fuel pump on them though.

I dont see many large (as in 4 litres and above) Japanese diesels in this country, but the v8 and inline 6 diesels fitted to the larger land cruisers always seemed pretty good.

Honda had difficulty with their diesels as well, did they not?

Strange that Toyota have such limited offerings for full sized pickups in the US, the big 3 all offer different specs of dually, big diesels as well as petrol. Toyota persists with just the Tundra at that level and limited petrol/hybrid options.

Bring back Perkins!

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Tue 18 Apr 2023 23:39
Why can’t the Japanese make a good diesel engine - Adampr

Honda have made a few cracking diesels in fairly recent years; both the 2.2 and 1.6 CDTi.

On the 80s and 90s Toyota had a 2.4 diesel, the 2LTE, which was notorious for cracking cylinder heads at the slightest provocation.

My thought, based entirely on prejudices, is that Japanese manufacturers tend to build engines to fairly minimal tolerances and that approach doesn't really work for diesels, where the much higher compression and torque is better suited to over-engineered lumps.

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Wed 19 Apr 2023 12:33
Why can’t the Japanese make a good diesel engine - Heidfirst
The Toyota 2.2 diesel in the Lexus IS was not very good

Having had 2 of them in Avensis they were fine. However, iirc Lexus made an "interesting" gearing choice for the UK (it was probably fine in Germany).

Yes, in the early years there were a few issues with a very small % but in typical Toyota fashion they stood behind their warranty (even outwith warranty subject to dealer servicing & certain mileage/age limits).

Most of the issues were caused by inappropriate choice/use of a diesel (i.e. short trips where the engine never or rarely reached normal operating temperature). The same issues that afflict pretty much every modern common rail turbodiesel & especially with a DPF. Its not as if BMW, Mercedes, VW etc. engines are faultless either.

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Wed 19 Apr 2023 00:19
Why can’t the Japanese make a good diesel engine - SLO76
It’s all the emissions control equipment rather than the fundamental engine design itself that’s the problem in recent years, even Toyota couldn’t get it right. That said Honda DTEC diesels seem pretty well sorted after the lessons learned from their first diesel motor the 2.2 CTDi.

Going back though and there have been loads of fantastic (in one form or another) Japanese diesel engines over the years.

The 2.7 n/a and turbocharged 4cyl lump found in most LTi hackneys in the 80’s and 90’s and Nissan’s version of the Ford Maverick (it had it too) would run past a million miles if looked after. This was probably the toughest engine ever made. Low stress and mechanically simple, these things were hard to kill.

Nissan’s 2.0 4cyl diesel as used in the taxi driver favourite, the Bluebird could easily pass 500k. Slow and utterly gutless they might have been but a fantastic taxi. Tough as old boots, and came with standard PAS when rivals tore your arms from their sockets while filtering through rush hour traffic.

Toyota’s 2.0 4cyl diesel from the Carina and Carina E. I’ve taken these in from taxi operators with huge mileages up but still driving well. Last one, a Carina II 2.0 XLd had 472,000 miles up and the only fault I could find was a squeaky clutch pedal. The 2.4 diesel in the Hi Lux and Landcruiser was every bit as tough.

Isuzu’s 1.7 turbo diesel as used in the Mk III Cavalier and fondly remembered by taxi operators across the land. Half a million miles was the norm with these.

I remember encountering a very rare Mazda 626 2.0 supercharged diesel once. These had plenty of low speed pull, no lag as you would find with a turbo but Mazda UK never pushed them so they were rare. No great shakes on the economy front either. But they worked well on the road.

Mitsubishi used an under-stressed 2.0 turbo diesel in some models in the 80’s and 90’s which was later used by Proton in the Persona. These had no weaknesses other than slightly disappointing economy and two importers who didn’t push diesels at all. The Persona would’ve been a great taxi.
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Wed 19 Apr 2023 10:55
Why can’t the Japanese make a good diesel engine - madf

Far better than this thread should be "why after 50 years of making their own diesel engines cannot Range Rover make their reliable?"

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Wed 19 Apr 2023 13:23
Why can’t the Japanese make a good diesel engine - Metropolis.
Between the TD5 and the current crop of Ingenium engines, all diesels in the Land Rover lineup have been BMW or Ford/PSA. The notorious crank snappers are Ford built engines.
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Wed 19 Apr 2023 16:47
Why can’t the Japanese make a good diesel engine - gordonbennet

Toyota make good Diesels.

The 2.5 and 3 litre 4 pots as found in Hilux and Prado (badged Landcruiser here) have proved very reliable, i've had literally the same engine (mechanical injection in the first) in 3 different Toyota 4x4s, none have given any issues.

Denzo electronic injectors caused some issues, but these were replaced by Toyota under warranty if noisy, they some issues with the earliest 3.0 litre D4d due to copper injector seals being prone to leaking, most of these were replaced on recall with aluminium washers.

The problem often is owners, lack of servicing is always an issue and tuning boxes forcing through too much fuel can cause pistons to crack, serviced properly and left as standard they seldom give any trouble.

The little 1.4 Diesels don't seem to give any trouble.

Landcruiser 4.2 straight 6 was a legendary engine, don't know much about the 4.5V8 too expensive for my pocket.

Toyota's industrial arm Hino are well respected for their products, their trucks are tough and the engines pretty well bullet proof, have a poke nose on Youtube and you'll find them massively overloaded in various parts of the world crossing rivers dragging log trailers up mud tracks.

In parts of the world where lives depends on total reliability Toyota is numrber one choice.

Those car Diesels tjhat have caused issues, i'd like to look in depth at the service histories, not just oil and fuel filter changes but how long before the coolant was replaced, people neglect coolant changes which are just as important.

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