Nissan navara

I am not a fan of Navaras D40 variety. Many of them were sold from factory with bent/malformed rhr chassis sections. Had first hand experience with 4 of them. I have pics of 2 brand new ones on the lot, chassis bent.
Gearbox hardening of shafts used to be an issue. Some diesel engine blocks warped and gasket failed.some folk have them and had no troubles, so if buying one it pays to thoroughly have it checked for mechanical and chassis integrity.

Spaanerman65

The D40 don't have a great reputation .

Better options out there .

Cheers

Diesels breaking timing chains & destroying the motor has been a serious issue.

There was a lengthy thread on here a while back where a guys motor blew with only 70k on the clock but outside the time warranty. He was fighting Nissan for all it was worth as he was stuck in a town on the road and on a pension from memory. A friend, (lady), had one and blew the motor before 100k too. I was interested in one a few years ago and my mechanic said no. All of this relates to the 2.5 diesel. I haven't heard anything bad about the 3litre v6 diesel 550nm model (not to be confused with the 3litre 4 cylinder grenade).

Cast iron con rods and cam shafts.

I do not recall ever seeing any factory automotive engine built in the last 50 years with cast iron conrods.

Cast iron is completely unsuitable for use as conrod material because it has enormous strength under compression, but very little strength under tension.
Cast iron conrods would fracture when the piston stops suddenly at the end of the crank throw.

Cast iron is used for camshaft material in 98% of automotive engines, because it is a highly suitable material for that use, and because it can be chill-hardened to extreme hardness, as required for camshaft lobes.

Cast iron is used for many crankshafts, because it provides satisfactory performance in that position.

The YD25 engine fitted to the D40 Navara is a bundle of trouble.
The problems are many, and they are all costly to fix.

1. The YD25 lower simplex (single row) timing chain is exceptionally weak, and it stretches, then breaks - with resultant major engine damage.
The cure is a replacement duplex chain - at sizeable cost.

For vehicle owners with original chains, it is recommended that the simplex chain be replaced at 80,000kms and inspected every 40,000kms thereafter.

Sometimes, if the engine doesn't fire up immediately upon cranking, it will stall and kick backwards - thus allowing the chain tensioner piston to travel backwards, and thereby giving the stretched chain enough slack to skip over the gear teeth - causing valve timing to go out of phase.
The result will be serious engine damage when the engine does start.

YD25 single row timing chain failures

2. The simplex timing chain tensioner is prone to excessive wear and failure. There are improved and modified tensioners available - at more cost.

3. The YD25 cast iron crankshaft is prone to fracturing at the number 4 rod journal between approximately 90,000kms and 160,000kms.

This is caused by poor quality cast iron, or poor quality heat treatment, and possible engine balance issues.
In essence, the YD25 engine has a weak crankshaft.

Changing the Dual-Mass factory flywheel to a solid flywheel will accentuate the crankshaft weakness, and cause earlier crankshaft failure.

4. All the major engine fasteners (conrod bolts, main bearing cap bolts, and head studs), are not re-useable.
This is because they stretch after one tightening, and lose their ability to fasten properly.
If someone has worked on the engine and loosened, and then re-used these fasteners, they are just waiting to fail prematurely.

5. A known issue with the YD25 is excessive bearing clearances from the factory, caused by poor engineering and poor assembly, resulting in inadequate bearing crush.

6. The YD25 oil pump gear is manufactured using a process known as "sintered metal". Sintered metal is a process whereby finely powdered metal is injected into a mold, which is then subject to great heat and pressure, forming a solid part in the process.

It is a process now extensively used in automotive manufacturing, because it is faster and cheaper than forging, stamping, or machining a part from a billet.
Properly done, sintered metal components are quite satisfactory in many applications, where stress levels are low.

Unfortunately, Nissan engineers miscalculated the strength needed for the oil pump gear on the YD25 and failures of this sintered metal gear are not infrequent.

YD25 oil pump gear failures

7. The YD25 EGR cooler has regular failures caused by the cooler splitting internally or around its flanged ends. Often the leaking coolant is not seen because it evaporates.

If the low coolant is not noticed, the engine will overheat and possible serious engine damage is the result.

8. The factory recommends 5W-30 oil for the engine. This is an unsuitable grade of oil for Australian conditions, and results in poor lubrication performance at high ambient temperatures, or high working temperatures.
A more suitable oil grade for the Navara in Australia is 15W-40.

A list of Navara recalls ....

Nissan Navara official recalls and problems list

Nissan actually gave some kind of weak apology in 2014, for the poor levels of build quality in the Navaras built between about 2005 and 2012 - but they still played down the substantial amount of Navara problems.

Nissan promises build quality will improve with new Navara

I'm not so sure that anything much has changed at Nissan - and one thing they are well-known for, is treating customers badly when the customer lodges a build quality, or vehicle performance complaint.

Cheers, Ron.

the problem with the d40 that old is the repair if you have a major breakdown .talking diesel ,a blown motor would cost more than the cars worth 2nd hand parts are expensive as nissan changed parts from one year to another even the 2.5 has 2 versions from 06-09 and one does not fit into the other.i have a 1 owner 2008 stx with a blown motor ran through evil bay and got max $2300 bid even with a warn winch arb bar duel bat long rang tank arb air locker with compressor safari snorkel ect . could not even give the tank and diff locks to a good mate with a 2013 model as the diff ratio is different the tank will fit but the senders are different mybe all cars are like that now i don,t know.my navara cooked the engine because i ran it without water, it was a good car that done the simpson x2 old tel track kimberly ect any best of luck in buying a 4x4 any way cheers warren

2 uncles have had d40 navs

The first uncle had a manual spain built which was crashed before it could break down.

The same person got a auto thai built d40 as a replacement this car had major problems with the EGR from about 50,000 kms at 160,000 it spat its first turbo and at 190,000 it did it second. All repair work carried out by a nissan dealer and took an eternity. The car also never had any power and the trans took ages to shift.

The second uncle bought his at the same time as the aforementioned manual car. This one was an auto.
It spat a turbo at 120,000 and the head gasket at 150,000 it couldnt handle sand driving without overheating aswell. This was before the head gasket replacement and after. The car was sold after being cleaned with a box of degreaser to hide all the leaks it had.

Both cars were the 2.5 diesel and neither were modified with the exception of a 2 inch lift

That said a close friend has a petrol d40 and has had no problems

And a d40 featured on 4wd action running 35 psi of boost so maybe the head gasket was a once of.

I would keep clear but feel free

Cheers jed