Toyota Prado v6 Petrol auto

[Archer63]

Was thinking about upgrading my old 2003 3.8 petrol Pajero ( still in good nick mechanically at 188 thou ) and get a late model diesel.
After reading all this stuff about common rail diesels... I am not sure which way to go.
Looking at perhaps a 2010 ish Prado...but have also read about D4D problems which is no doubt the same as what you blokes have been talking about.
What to do

[Old Techo]

Archer, don't let my negative comments deter you excessively.

From personal experience I am only referring to the Prado 120 series. Even then they changed the injector type either 2 or 3 times. My 2007 had the earliest injectors with issues. I don't know if later injectors in the 120 improved the situation. Now what was the problem?

As I have posted before, in detail, the injectors are controlled by the engine CPU and it has the ability to adjust the volume of fuel passed by each injector. For example it does so to achieve a smooth idle by balancing the power in each cylinder. It can compensate for other variables like compression ratio variations between cylinders. Even the injectors themselves have personalities. They are made to such microscopic tolerances I believe it difficult to get 2 the same - hence the many digit code each one carries and this code must be given to the CPU so it understands the personalities - perhaps akin to managing different people or your kids.

At the risk of exceeding my skill/knowledge level, as injectors wear/change along with other engine parameters the CPU can manage individual injector needs, but only up to a point. Once that point is exceeded the risk of injector over-fuelling rises. Worst case leads to cylinder over-heating and piston failure which often means engine replacement.

None of the above scary stuff need apply if injector health is regularly monitored. It should be standard procedure for every servicing mechanic to run engine diagnostics at every 10,000 kms specifically for injector status and other less critical parameters such as the suction control valve that manages fuel pressure. My SCV is a bit tired and my next job. If any injector is found close to the tolerance limits then replace them (as a full set if done properly). I suggest not much different to replacing worn tyres - the difference being the owner/driver will spot worn tyres.

So regular and proper maintenance should prevent any injector issues on the 120 series. As I also posted, Toyota (somewhat belatedly) seemed to have changed their definitions and despite the prices now regard expensive injectors as consumables, like spark plugs.

Another issue with the 120 series was also Toyota's fault. The injectors (just like some spark plugs) have a sealing washer (seat) to ensure no gas leakage between the injector and head. The early seats they fitted to the then new 120s were prone to premature leakage. This allowed oily/carbon crap to get into the engine lube system and finish up in the sump. Particles of this crap would be sucked up by the oil pump and gradually block the pump intake screen filter. Ultimately so much blocking occurred that the pump gradually suffered oil starvation and engine failure would eventually occur.

After numerous early failures Toyota changed the original copper seats to an aluminium coated copper design and instructed dealers to use them as replacements. Also they added to the servicing schedule the routine replacement of these seals at I think 60,000 kms.

So Archer these 2 specific issues with the early 120s may not be indicative of later models. Besides, as I said, these issues were addressed and may only continue to arise where owners do not receive adequate servicing.

I'm afraid the modern vehicle is becoming so complicated and dependent upon technology requiring regular diagnostic checks beyond the abilities and facilities of the home mechanic. The first foot in the door for us homers is access to said diagnostics. Fortunately the Toyota software may be had via Ebay although I'm certain Toyota are very unhappy about this. Without said software I'd be buggered and could not have identified my injector issues nor carried out the replacement work. Getting similar software for our Hyundai has been impossible thus far

[Archer63]

Thanks for the heads up O.T.
Still have plenty of time to think about it and weigh up the options.
If and when the time comes to upgrade....I will be having a very close look at the service history.
Cheers
Rob