Toyota Land Cruiser Prado Diesel Engine Issues

And now we reached the scariest and the most expensive issue these engines can have – cracked pistons.

• The piston can crack suddenly without any prior symptoms! Symptoms of a sudden piston crack: knocking noise from engine, black smoke from exhaust, lack of power, misfire/uneven engine running, excessive crankcase pressure. Ignoring the symptoms is gonna lead to a total engine failure.
• The piston can also crack very slightly – which means that the car is going to drive fine for a longer time only with one prior symptom – a louder knocking from the engine + oil consumption can appear too. Ignoring the symptoms is gonna lead to a total engine failure.

knocking engine video (slightly cracked pistons)

good engine sound video (pistons ok)

THE REASONS

Some say it’s because of the faulty/weak piston design and someone is perfectly sure that it’s caused by the faulty injectors only. But one thing is for sure, this issue affects cars made from 2006 which comply with the EURO 4 emission standard. Mostly cars made from 2006 to 2009 are prone to this failure, BUT the newer 150 models equipped with these engines – mostly up until 2013 are not safe either, there are only less cases of piston crack from these newer 150 models. But since the latest piston revision was in 2017, we can speculate if the 150 models aren’t slightly affected even until 2016!

Actually, there are cases of cracked pistons even in cars made in 2015 for example, so the newer cars made in 2015, 2016 and early 2017 should be affected too.

Toyota acknowledged the problem as well, so in 2014 they released a document about this issue. According to this document Toyota improved the injectors and they changed the piston shape to get rid of this problem. So the injectors causing wrong combustion and the pistons themselves should be the 2 main reasons:

Pistons?

First, let’s check out the pistons: I would lean more towards the bad piston design, since according to the parts catalog in august 2006 Toyota updated the pistons, and from 2006 there is this possible issue. A big contributing factor to the crack is also the heat. So it seems like the top of these pistons can overheat and it also seems like the oil channel in the pistons is not sufficient either.

By the way: this kind of a piston crack can sometimes occur in other diesel engines from other car manufacturers too. But I have to add, that on the other diesel engines the crack is mostly caused by faulty injectors only (unlike in these 1kd Toyota engines where the piston sometimes cracked even with good injectors). So yes, a faulty injector can cause a crack in the piston, but if the piston is weak or if it has bad design then it can crack even without an injector failure. This is why specifying an only, single and concrete reason for this problem is not really accurate and there are also many shady variables which can contribute to this.

Injectors?

Then there are the injectors which are gonna get worn over time. Yes, they can work even after 400 000 km or 500 000 km, but their performance is gonna be weaker as the mileage and age increases + the possibility of failure is gonna increase too.

• An incorrect injector spray pattern is going to cause wrong combustion and a wrong combustion is going to increase the chance of a cracked pistons
• The faulty injectors can drip fuel which can easily damage the piston as well
• And lastly, the injector can end up stuck in open position – so the injector fails and over fuels the cylinder which can melt the piston and also damage the cylinder wall – but this is pretty rare

“In many cases owners said that bad fuel caused an injector failure and a burnt hole through piston. Can a bad fuel cause a sudden injector failure? Well, if you are like really unlucky then yes, but this is more of a side contributor I would say.”

Now you can ask: if I change the injectors do I prevent piston failure? Well no, since you still have the pistons with seemingly improper/weak design fitted. However with new injectors and with using good quality fuel you will at least eliminate the incorrect combustion.

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OTHER COMMON PROBLEMS

-check the frame for excessive rust (mainly on cars used on winter salty roads), the frame on these cars is going to rust you like it or not. This is in many cases still not a big concern today, however it’s not gonna get any better over time. Holes in the frame can appear too, so in the future it is definitely going to be a problem if you leave it as is!

The car can look great from the outside but it can have already a big amount of rust on the frame + sometimes even holes in it !!

–the front brake caliper pistons can more often rust and seize up: mostly cars used on winter salty roads. This will cause: uneven brake wear, slightly weaker brake force, eventually noises from the front brakes. (“there are brake caliper piston repair kits which are cheap or complete rebuilt calipers”)

-the front wheel bearings can get worn more often even before 200 000 km

-the optional air suspension on the rear axle is gonna sooner or later fail: the air struts are going to leak and the air compressor is going to break at some point

-occasionally the transfer case actuator can act up

–slight oil leak from the transfer case can in many cases occur

-AC gas leaks can occur

-coolant leaks from the radiator can happen too

–the fuel filler hose under the car can leak (more often on petrol engine cars)

–the steering rack can slightly leak more often

-the turbo actuator can fail, as well as the EGR on the 1KD engine. Turbo actuator failure symptoms: limp mode/loss of power and a P1251 fault code (the actuator can be replaced separately – you can buy it under $500)

–SCV valve can fail on the 1KD engine, causing: limp mode/loss of power, stalling, weak acceleration, check engine light, bad engine starts

-water leaks in the trunk and interior can often occur: because of the trunk door seal, because of the 3rd brake light, because of roof rack bolts or because of cracked sealant under the roof racks

-the dashboard is going to crack sooner or later, if it’s not cracked already

“Its good to REPLACE THE GLOW PLUGS IN DIESEL ENGINES EVERY 100 000 km – mainly preventively, because sometimes the glow plug tip can fall off into the combustion chamber and that’s obviously not good.”

SUMMARY

That would be it I guess. But if you still don’t know what to do and if you are still completely confused, let me summarize the things up a bit:

If you are buying any of the 1KD engines then right after buying you should definitely:

1. Check the oil pickup strainer:

• if the oil pickup strainer is clogged → remove the oil pan and clean the strainer + replace the injector washers + have the injectors at least tested or replace them if you want to be on the safe side
• if the oil pickup strainer is clean, but you don’t have any solid proof that the injectors or the washers were replaced in the past → then consider removing the injectors to have them at least tested + replace the injector washers and seals, but if you want to be on the very safe side then replace all the injectors

2. If you don’t want to spend money to replace the injectors or have them tested, then at least pay attention to the faulty injector symptoms

3. If you are frightened from the piston crack issue then choose a car made before 2006 which is not complying with the Euro 4 emission norms

And if you have personal experience with this car or if I fucked something up, then you can write it into comments!

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on the next page: Technical Service Bulletin related to piston crack