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Lifespan of the turbo on a 1KZTE Prado

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Mike TLC
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PostPosted: Mon Apr 29, 2019 16:26    Post subject: Lifespan of the turbo on a 1KZTE Prado Reply with quote

Does anyone have any experience of the turbos (no inter-cooler) on this model?

I have a 220,000 km /136,000 miles Prado that has no visible turbo problems such as whining, grey/blue smoke, nor excessive oil consumption (1/2 liter every 10,000 km/6000 miles) and am just wondering what the common signs of failure are and how long they last?

Servicing has been according to the book.

Also, I'd appreciate any information from owners with more miles experience as to what would be considered "normal" engine oil consumption from this point onward.


Cheers  Smile
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diggerdave
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PostPosted: Tue Apr 30, 2019 11:05    Post subject: Reply with quote

Common wisdom is that - correctly serviced - the turbos are trouble free.

My engine uses almost no oil (202000 miles). I still check regularly but it's very rare that it needs topping up, and never by much
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Mike TLC
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PostPosted: Tue Apr 30, 2019 20:19    Post subject: Reply with quote

Thanks Dave

I never really top up between services but do it occasionally just to see how much is needed to get to the top of the dipstick. It fluctuates more with some oils than others, more or less viscosity, with more or less motorway...  as I said 1/2 liter at the most  gets it to full.

If I do not check the level in the morning with the vehicle parked in exactly the same position the level fluctuates too much to be of any use anyway.

Do you strip your turbo to service it?

Other than regular oil changes (more than required) and letting it idle (slow down/lubricate) for a while before switching the engine off, I've not done any turbo maintenance.
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diggerdave
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PostPosted: Wed May 01, 2019 10:22    Post subject: Reply with quote

Quote:
strip your turbo to service it


Ah, sorry I was less than clear. I just meant regular oil changes. As long as that's done, conventional wisdom is that the turbos are bombproof.

That's all I do for mine, I try to let it idle for a few moments before turning off, but nothing excessive and certainly not the minute or more that some recommend.

I got my car with 140000 on the clock and have put on 60000 with oil changes every 5000. I have no idea how well the previous 10 (yes, ten) owners treated it mechanically but it seemed to have been unloved. So, yes, bombproof, I'd say based on my case study of one. And turbo problems are not something that gets mentioned on the two UK forums very often (almost never)

Do you suspect turbo problems then? Is that why you're asking?
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Mike TLC
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PostPosted: Wed May 01, 2019 10:33    Post subject: Reply with quote

Nope!

I was just wondering whether it was something I should be expecting to have to deal with at some time.

Glad to hear that they look bombproof.

The thing seems pretty bombproof in general apart from the head issue.
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diggerdave
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PostPosted: Wed May 01, 2019 13:31    Post subject: Reply with quote

... and rust on the rear axle. Don't forget to clear the drain holes on the upper suspension arm turrets (rear AND front of the turrets) every time you service it, or more frequently.

To help with the possible overheating issue, you can fit a 76 degree thermostat instead of the 82 degree one. Threads on here and elsewhere about it - arguments for and against (mainly for), and it's something I saw the sense in doing. Also, changing the oil in the viscous fan to ensure it's working as intended (very difficult to test in a meaningful way, so better just to change the oil as a precaution). Otherwise it seems to be enough to make sure that the 'only just adequate' cooling system is in good order.

Happy driving, I love mine and apart from welding on the sills and the back axle it's been great.  Very Happy
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PostPosted: Wed May 01, 2019 17:24    Post subject: Reply with quote

I live in France - no rust - none at all. Well none that I can find...

I did Waxoyl everything when I got it, but we do not have salt on the roads in winter.

We are on the same page apparently, put in a 76C stat and an aftermarket temp gauge on the outlet coolant housing, I also replaced the viscous coupler and water pump a few years ago. I posted some temp readings on the "cracked head thread" a couple of days ago.

Drain holes? I shall have to look for those...
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PostPosted: Wed May 01, 2019 19:40    Post subject: Reply with quote

If you look at the two turrets on the back axle that support the ends of the upper suspension arms there are drain holes. The ones facing the back are fairly obvious but there's also a hole at the base of each turret facing front (on mine they were so gummed up and rusted that they were not very obvious). They're a slightly flawed design as they are too small and get gummed up with crud, rust and leaves meaning the turrets fill up with water/mud that can't then escape. They are implicated in many a story of rusted/cracked turrets... cleaned mine out with a drill initially and occasionally I poke a screwdriver up to clear them.
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PostPosted: Sat May 25, 2019 19:52    Post subject: Reply with quote

Mine has done 330k km and still going strong Smile
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PostPosted: Fri Jun 14, 2019 4:54    Post subject: Reply with quote

Remove EGR if it has one is more important to prevent cracking IMO...  

Strip one that has cracked and I'll put money on the issue being right near the port where the EGR dumps VERY hot gas right into the manifold just by the head...  I think it creates un-even heat across the head, therefore undoing all the so call environmentally good stuff it has done!

Just my opinion though before I'm sued by eco warriors!
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PostPosted: Wed Jun 19, 2019 15:29    Post subject: Reply with quote

I'm not sure about removing the EGR. You will get hotter combustion temperatures

Up to 300F/150C hotter in each chamber...

From the EGR page on Wikipedia :"The exhaust gas, added to the fuel, oxygen, and combustion products, increases the specific heat capacity of the cylinder contents, which lowers the adiabatic flame temperature"

This will certainly make a difference to the running temperature of the head.

Keeping the EGR clean is very important.

In addition, removing the EGR it is not really an option for me, the French equivalent of the MOT is being told to specifically look for owners blanking off their blocked/dirty EGR systems in order to pass the pollution test. Automatic fail  Crying or Very sad
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PostPosted: Wed Jun 19, 2019 18:19    Post subject: Reply with quote

I'm not sure I agree with that at all - the EGR dumps 700+ degree gas direct into the inlet port of the head, rather than COLD air....  

Might increase Exhaust Gas Temp marginally BUT the biggest problem is that it is not dumping this piping hot air in evenly, the port is right on one side of the manifold, so I expect it is effectively warming the inlet side of the head and cooling the exhaust side on just one end of the head (Plus everything on the exhaust side is expecting to get super hot)

Far better to have even temp to avoid a crack! We aren't saying the head is melting!
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PostPosted: Wed Jun 19, 2019 21:41    Post subject: Reply with quote

Hi Dave, I do not mean to be antagonistic here. Just hoping to move the ball forward a little.

I did think about blanking the EGR off years back but when I looked into it, I realized that it was not a simple yes or no problem, more a swings and roundabouts affair unfortunately.

The maximum EGR rate for a diesel engine is about 50% with an exhaust gas temperature of about 450C/850F when the EGR is running (a DI diesel runs hotter).

The combustion gases in the cylinder are hotter than the exhaust gas in any event. The EGR is therefore injecting its hottest mixture of 50% ambiant air and 50% exhaust gasses. Even in summer this is a 50/50 mixture of gas at about 450C and air at say 25C. So the inlet manifold is going to be about 250 maximum (right next to the EGR), a lot cooler than both the combustion chamber and the exhaust manifold.

The exhaust manifold will be much closer to the combustion chamber gas temperature and it is also bolted onto the head.

Most of the time the EGR mix is much less than 50% exhaust gasses and therefore a lot cooler.

Expect cylinder combustion gasses to be increased to about 600C/1150F without the EGR running. This is the temperature value you quote and it corresponds to a 'normal' diesel engine's exhaust gas temperature, but not to the temerature of the air/gas mixture being put back in by the EGR.

I agree about the temperature gradient possibility, given the EGR's position.

But which is worse?

I have no idea! Take your pick and trust to luck!
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PostPosted: Wed Jun 19, 2019 22:56    Post subject: Reply with quote

I know not a Toyota but I ran and recorded Exhaust temps on a Landrover and on a VW that we were playing with. Both had on board temp sensors so we could tune the Diesel after). Anyway before we played with the Diesel we removed EGR, and I can tell you now that the Exhaust Temp at nearly all the rev range dropped....  Go Figure! But that was actual recordings not theory, maybe duff sensors who knows!

BUT all that apart - it's just the Stupid location of the EGR on the EU Spec 1KZTE....  if you have one of those contact temp sensors, place it on the manifold each end - big difference with EGR on, no difference with it off... Also look where the heads crack, the two I have done have both cracked right by the inlet port nearest the EGR end, NOT near 1 and 2...

I'm not arguing the temp theory, just saying in my experience it's doing more harm than good (To the Engine, maybe not the Environment if you account for the reduction in poisonous Nitrous gases etc LoL)!

Also the first one I changed to an AMC Head removed EGR and has done circa 145K Miles since, no further problems (No new radiator or anything either)...
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Mike TLC
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PostPosted: Thu Jun 20, 2019 10:55    Post subject: Reply with quote

You also have a good quality head...

From the Rough Trax page on the Toyota head problem:

https://www.roughtrax4x4.com/blog/cracked-cylinder-head/

"The most common areas the cylinder head will crack are on the combustion chamber, and hairline cracks in-between the valves. This is due to a poor water chamber design that cannot withstand the fluctuations in temperatures, and the faster speed limit in the UK when compared to Japan - Which is where the engines were originally designed for where the speed limits are much slower to the UK."

https://www.roughtrax4x4.com/wp/wp-content/uploads/2015/03/Cracked-Between-Valves.jpg
https://www.roughtrax4x4.com/wp/wp-content/uploads/2015/03/Cracked-Combustion-Chamber_2.jpg

"Toyota recognised this and later sold cylinder heads where the combustion chamber was increased to avoid cylinder head cracking.

Cheaper Chinese cylinder heads are manufactured from not only cheaper materials but are the original combustion chamber thickness, therefore cannot withstand the fluctuations in temperatures, and the faster speed limits just like the original thinner casting."


If you have one of the newer Toyota heads or a non-Chinese aftermarket one you are likely to be OK Long Time  Very Happy
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