Re Post 29813 & 29933 attn scottcamp

Submitted: Tuesday, Jan 24, 2006 at 21:49
ThreadID: 30075 Views:2491 Replies:10 FollowUps:16
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For all those who have not seen what a ZD30 looks like when they so called blow a piston.
No wars, debates or fights please.
The wording gives all the information I had at the time.
Attention scottcamp:- Please tell me how low sulphur fuel or the wrong oil does this and only to one piston, especially where the others are perfect.

P.S. I hope the photo album is working as the server has had a shocking month and is giving me all sorts of grief but I think you will get the idea.
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Reply By: Axle - Tuesday, Jan 24, 2006 at 22:34

Tuesday, Jan 24, 2006 at 22:34
Click Click No Photo??.
AnswerID: 150684

Reply By: gramps - Tuesday, Jan 24, 2006 at 22:39

Tuesday, Jan 24, 2006 at 22:39
Worked fine for me Axle. I might be a lot closer to 120scruiser's server though :))))

Try again.

AnswerID: 150688

Reply By: Exploder - Tuesday, Jan 24, 2006 at 22:42

Tuesday, Jan 24, 2006 at 22:42
Well it took its sweet ass time but it loaded.

I think what he was getting at is that the High sulphur diesel breaking down the Oil combined with other faults at the same time helped contribute to the engine packing in, the High sulphur diesel alone did not cause it.

That’s how I read it anyway.

That certainly is a high concentration of heat on a small aria, have all the ZD30’s you'v seen had the hole around the same location and size.

AnswerID: 150690

Follow Up By: Member - David 0- Tuesday, Jan 24, 2006 at 23:30

Tuesday, Jan 24, 2006 at 23:30
Thats the way I read it too.

To answer the question posed, try this little thought experiment - how do you get all pistons to fail at the same time? Pretty hard I reckon. The hottest/poorest lubed or whatever fails first.
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Follow Up By: Member - David 0- Tuesday, Jan 24, 2006 at 23:32

Tuesday, Jan 24, 2006 at 23:32
Odd that it was NO 2, that doesn't fit the previous failures does it?

That is a pretty concentrated little melt spot. Thanks for that link- worth looking at.
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Follow Up By: warthog - Wednesday, Jan 25, 2006 at 11:38

Wednesday, Jan 25, 2006 at 11:38
The sulphur theory is a bit dubious as far as I am concerned too. Why no faiures in the navara and why only this engine that couldnt handle sulphur when there are plenty of other direct injection tdis not failing.
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Follow Up By: Member No 1- Wednesday, Jan 25, 2006 at 19:01

Wednesday, Jan 25, 2006 at 19:01
scottcamp refered to the bottom end and acids etc etc....that I understand...
but i too cant see how acids can contribute to the burning of a hole in the top of a piston...thats the combustion area...and that is (generally) not lubricated from the sump
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Reply By: Member - Captain (WA) - Tuesday, Jan 24, 2006 at 23:34

Tuesday, Jan 24, 2006 at 23:34
Hi 120scruiser,

Very strange burn hole, what was the injector condition like? Was the tip eroded? Was the spray pattern more pencil like than spraying?

Going on from scottcamps theory, does high sulphur fuel affect high pressure fuel injectors and if so, perhaps fuel spray pattern is an issue? Either way, to only have 1 cylinder affected looks more like an individual injector issue rather than a common problem. But if this is typical of all series II 3.0TD failures, then whats causing the injectors to fail (if indeed it is an injector issue).

Or is it failure of piston cooling by the oil sprays under the pistons (caused by high sulphur fuel blocking oil sprays)???

Thanks for the photos, good to see what the actual problem is even if no-one knows the cause.


AnswerID: 150708

Follow Up By: 120scruiser - Wednesday, Jan 25, 2006 at 08:17

Wednesday, Jan 25, 2006 at 08:17
Hi Captain
I had all the injectors tested and all the spray patterns and pressures were perfect, not that you can do anything about them only throw them away and put new ones in at $600.00 each.
The other one I have seen was an identical hole in an identical spot. Not sure what piston though as somebody else pulled it down.

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Follow Up By: Member - Captain (WA) - Wednesday, Jan 25, 2006 at 09:52

Wednesday, Jan 25, 2006 at 09:52
Hi 120scruiser,

OK, if no obvious problems from the top, what about the oil cooling sprays from below? Were any of them blocked or restricted? One thing I have read about elsewhere is that the oil galleries on some series II were too small (poor casting) and hence why these engines were not rebuilt. But this is all 3rd, 4th and 5th hand rumour so don't really know if true or not.

Interesting that injector pattern good. If excess diesel was injected, one would expect black smoke, but have not heard this reported prior to engine going. To my way of thinking, this leaves either overboosting or lack of piston cooling (from oil sprays) as possible causes.

I do think scottcamp is onto a valid theory, maybe something to do with oil cooling? But no engine to date has seized so not your typical lack of lubrication problem.

The mystery deepens!!!


FollowupID: 404306

Follow Up By: 120scruiser - Wednesday, Jan 25, 2006 at 12:39

Wednesday, Jan 25, 2006 at 12:39
I can't give any further info on this one as it was a car yard and I was instructed to just put a piston in it so thats all he was paying for so thats all I did.
I instructed him to take it to Nissan to have injector pump checked and fault codes checked. As far as I know this is what was done. Shortly after the turbo failed due to the oil pressure relief valve failing so after that I can't answer as Nissan just close up. Our local Nissan dealer is very very difficult to deal with.
I have my engine machine shop do a ZD30 late last year but I haven't spoken to him yet. If I get any info I will keep you informed.

FollowupID: 404330

Follow Up By: Member - David 0- Wednesday, Jan 25, 2006 at 12:43

Wednesday, Jan 25, 2006 at 12:43
Yes the thot plickens

It does look very much like a combustion related problem, and extremely localised. One other owner reported that his had failed near the glow plugs. I can't think of a mechanism related to overfueling and glowplugs that could result in such a hole, but then I am not an expert.

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Reply By: Member - David 0- Tuesday, Jan 24, 2006 at 23:49

Tuesday, Jan 24, 2006 at 23:49
Go to the main site and click through the Patrol lin, some interesting comments including this one

The main piston to blow is number 4 however we have had number 1 go as well mainly from over fuelling.

AnswerID: 150710

Reply By: Nav 8 - Wednesday, Jan 25, 2006 at 12:35

Wednesday, Jan 25, 2006 at 12:35
What I find interesting is that the burn hole is outside the combustion chamber in the piston. To my mind only one piston being holed in a position like that would not be overfueling, maybe a misdirected injector spray causing detonation? dont know. A blocked or misdirected oil spray under that cylinder I would think would show up on the bore as lack of lubrication but from what has been said on this forum there is no mention of that. Would love to have a look at one that has failed.,,,Nav.
AnswerID: 150781

Reply By: kesh - Wednesday, Jan 25, 2006 at 15:37

Wednesday, Jan 25, 2006 at 15:37
I reckon an experienced forensic diesel engineer would sort this problem out fairly quickly.
From the photo, intense heat has broken down the alloy molecules causing local collapse of the piston crown. This is not a meltdown situation, but a hole burned by focused incandescant heat. I have (years ago) melted plenty of 2 stroke motor bike pistons by running too lean, and they didn't look like that one

So where does heat of this intensity originate?

Well, it is also stated that the head was cracked and would have been leaking.(which two cylinders?) Coolant (water) being 2 parts hydrogen and one part oxygen in gaseous form is a very formidable explosive combination.
If coolant is entering the combustion chamber at very high (superheated) temperature and pressure, is it feasible that at the point of diesel injection it could create a locallised flame of sufficient intensity and duration to eventually burn through the piston crown?
A qualified industrial chemist may have the answer here.

I am far from being an expert on anything, but I do try to look at all things objectively. So the above is to be taken as that, simply another point of view. Unfortunately, much of the hypothesis relating to the failure of the ZD30 has been of a subjective nature which I believe leads to a sense of false security. Until the complete answer is found, this problem is unfortunately going to exist.

I would hope that readers following Scottcamp's posts have also looked at the Banks Power site for more information.
AnswerID: 150833

Follow Up By: Member - Captain (WA) - Wednesday, Jan 25, 2006 at 23:15

Wednesday, Jan 25, 2006 at 23:15
Hi Kesh,

With regards to your comment "...(water) being 2 parts hydrogen and one part oxygen in gaseous form is a very formidable explosive combination.", I am sorry but this is just so wrong.

While hydrogen gas (H2) and oxgen gas (O2) are extremely explosive, you cannot break water (H2O) down to its base elements by simple heating within an engine (and I am a qualified Chemical Engineer with 20 years experience).

High pressure water (~>5,000kPa) could "potentially" cause localised failure of the sort seen, but this is not possible inside an engine from a coolant leak IMHO. There is simply not enough coolant in the engine even if there was a HP spray to cause that type of damage in the first place.

But its good to hear different theories, sooner or later someone will get it right.



FollowupID: 404484

Follow Up By: kesh - Thursday, Jan 26, 2006 at 09:09

Thursday, Jan 26, 2006 at 09:09
Thanks Captain, but was simply adding yet another "theory". I did say "in gaseous" form without any real idea how that might occurr.
I still believe these engines were dramatically over fuelled. Unlike (for instance) an older disco 300tdi which has a screw stop fuel limiter and a pressure regulated tubo boost (wastegate) the ZD30 has electronic control over both fuel and turbo boost.

Now I know as much about electronics as I do about chemistry, but I do have some understanding of air/fuel ratio. In a turbo diesel, power doesn't come solely from boost, it comes from a combination of fuel then boost. When the fuel injection to the cylinder has reached the calibrated maximum, boost should also be at its maximum, full engine torque output should be reached and exhaust gas emissions within required parameters. There is no such thing as "overboosting", earthmoving diesels do not usually have any control over the turbo, it will only boost to whatever maximum injection is. You want more power, turn up the fuel!

My contention remains that if the electronics controlling the amount of injection goes out of control, but the turbo boost is controlled, a serious overfuelling situation can exist. I accept that this should be accompanied by clouds of black smoke, something which has not been reported except at the time of failure where different sorts of smoke emmissions were noticed. However, the one I followed towing a horse trailer up a steep hill was belching out volumes of black smoke, unable go get over 15kph or so, had not expired at that stage (I stopped the driver to ask if I could help and he wanted to keep going). He had not particularly noticed the smoke! If the turbo boost is not controlled, more fuel will create more turbo boost (reports of up to 25psi have been noted) which whilst developing more engine torque at the correct air fuel ratio will also lead to extreme EGT, a situation which can quickly destroy the turbo itself.

How any engine copes with any degree of over fuelling would have to come back to (a) cooling and (b) fragility of the engine components to withstand the overdesign stresses. Its one thing to over fuel/overstress for 5 mins. ascending a hill, but make that several hrs. on end, high speed towing a load and its a different matter. ( THe RR Spitfire engine had an emergency supercharge boost to be used briefly in combat situations only) Overheating has not been an issue (from reports). Inherent strength of the engine is an unknown factor. (unlike the repution of the 4.2 Nissan)

It was commented widely that the high sulphur diesel could be affecting the performance of the injectors. These multi hole pintle type have been in use almost since the inception of the diesel engine, are reliable and able to give many thousand hours of service. At the moment of injection the initial combustion should take place within the piston top depression. This engine would have the injection timing controlled electronically through the ECU, perhaps another avenue of thought.

The mystery still unfolds.
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Follow Up By: 120scruiser - Thursday, Jan 26, 2006 at 12:24

Thursday, Jan 26, 2006 at 12:24
There was no coolant leaks into the combustion chamber.
They appeared to be heat crackes.
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Reply By: jorgejhandal - Thursday, Jan 26, 2006 at 05:46

Thursday, Jan 26, 2006 at 05:46
Mine had a similar hole but more to the center, in no1 piston and had another in number 2 , number 4 was cracked the area around the tip of the heate r was cracked, the block cracked to
AnswerID: 150986

Reply By: Kiwi Kia - Friday, Jan 27, 2006 at 11:45

Friday, Jan 27, 2006 at 11:45
Detonation caused that hole but why? Most prob have to look at fuel injector / system for an answer
AnswerID: 151259

Follow Up By: 120scruiser - Friday, Jan 27, 2006 at 12:13

Friday, Jan 27, 2006 at 12:13
As already stated the injectors were tested and performed perfectly.
They are not serviceable and have to be replaced at $600.00 each.
I have seen bad spray patterns in 1HDT engines due to bad fuel causing carbon deposits on the tips of the injectors there-fore causing bad spray patterns away from the combustion chamber and hence blowing head gaskets but this was not evident and is common to most 3.0 failures.
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Follow Up By: Kiwi Kia - Friday, Jan 27, 2006 at 14:53

Friday, Jan 27, 2006 at 14:53
Yep, Don't doubt that you have had them tested. However, the picture of the piston shows detonation damage.

What caused it ? The only things that could have been involved are fuel, air, spray pattern and timing. As the other cylinders seem to be ok then mixture (fuel & air) and timing are probable ok. So, what does that leave ? Injection and the propogation of the flame front.

I see damaged pistons and heads almost every day as I wonder through my neigbours engine o/h workshop (he only does engines). LPG, natural gas, diesel, mixture of diesel and natural gas, petrol and even some dragsters methanol and formulae 'X' fueled engines. I get to see some very interesting destruction paterns. The dragster engines don't even get dirty between over hauls (they usually run for less the 10 minutes before they explode !) There are also heaps of books and manufacturers wall charts showing great photos of various sorts of damage and what caused it.
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Reply By: Truckster (Vic) - Friday, Jan 27, 2006 at 12:25

Friday, Jan 27, 2006 at 12:25

How much for one of them pistons, would make a magic Keyring, or something to hang from rear view mirror...

AnswerID: 151265

Follow Up By: Member - Ed. C.- Friday, Jan 27, 2006 at 12:32

Friday, Jan 27, 2006 at 12:32
(apparently) there's no shortage of 'em, so shouldn't cost much;-)))
Confucius say.....
"He who lie underneath automobile with tool in hand,
....Not necessarily mechanic!!"

My Profile  Send Message

FollowupID: 404872

Follow Up By: Voxson (Adelaide) - Friday, Jan 27, 2006 at 14:16

Friday, Jan 27, 2006 at 14:16
I am driving past your front door next month,,, you can shine your torch up my pipe and give me your extimated time of explosion....
I should have bought a GREEN one,,, as all hand grenades should be painted GREEN... LOL.....
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Follow Up By: Truckster (Vic) - Sunday, Jan 29, 2006 at 21:57

Sunday, Jan 29, 2006 at 21:57
Would make the perfect trophy for a Stuff Up Award in a club too!!!

Call in when ya passing, but park that thing up the road, dont want my car to catch anything.
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