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  #16  
Old 20 May 2009
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Melted Pistons?

OK I maybe talking complete junk here but I would assume smoke equals un burnt fuel. Pouring diesel in to the cylinders and NOT burning it will actually have a cooling affect.

A non turbo diesel will be more robust / safe in this scenario when compared to a turbo engine.

We’ve been up to 3000m+, six adults, trailer and pretty heavily laden in our normally aspirated G Wagen (6 cylinder, 3litre). Lots of smoke (not as much as a turbo diesel) and no ill effects.

If you are concerned I would get an EGT fitted though.
Or rig up something by using a multimeter with a thermocouple attachment to measure exhaust temp. by placing the probe on to the exhaust mainifold.

IMHO smoke in these conditions is of no consequence though.

Oh and I would definitely steer well clear of messing with the pump and fueling, definitely asking for trouble.
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  #17  
Old 21 May 2009
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Moodoo - lucky you!

I think the 1990 80 series we did Manali-Leh in did have a HAC, although it seemed to smoke a bit and wasn't very fast at that altitude. But it's academic, for you wouldn't want to go fast anyway - both for safety and scenery reasons.

My advice - go slowly and enjoy the stupendous views.

Mark

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  #18  
Old 22 May 2009
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Quote:
Originally Posted by Quintin View Post
I wouldn't bother. This happens with all diesel engines at increasing altitudes. The problem is that you will never get the mixture exactly right. Injection pumps are impossible to set up correctly without specialist equipment and furthermore you may find you will run lean when you get down to "normal" altitudes. This can be potentially harmful for a diesel and is far worse than running rich.

Q
I'm sorry, your advice is incorrect.
Diesels run leaner than stoichiometric; petrol motors always richer than stoichiometric. Stoichiometric is defined as just enough fuel for the air to burn completely.
A diesel, when overfueled, can develop very high EGTs. A petrol motor can develop high EGTs when underfueled.
So running at high altitude can cause high EGTs and damage an engine. This can be mitigated by installing a turbo to supply more air but not turning the fuel up..
All underfuelling a diesel causes is low power output.

Charlie
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  #19  
Old 22 May 2009
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Originally Posted by RussG View Post
OK I maybe talking complete junk here but I would assume smoke equals un burnt fuel. Pouring diesel in to the cylinders and NOT burning it will actually have a cooling affect.

.
I'm sorry, you too are wrong. Extra unburned fuel tries to keep burning after the exhaust valve opens, leading to very high EGT and burned exhaust valves. Plus, overfueled diesels tend to melt pistons.
An unmodified naturally aspirated diesel at very high altitude might not burn valves and pistons, but on the other hand it might. Overfueled engines at sea level certainly do.
If a person were to take up residence at high altitude de-tuning the pump will lead to decreased fuel consumption and decreased EGTs, relative to leaving it alone.
Toyota's system on some of their diesels of an anaeroid ("DAC") and a throttle body to measure air flow should adequately compensate automatically for altitude.

Charlie
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  #20  
Old 23 May 2009
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Not completely wrong:-)

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Originally Posted by m37charlie View Post
I'm sorry, you too are wrong. Extra unburned fuel tries to keep burning after the exhaust valve opens, leading to very high EGT and burned exhaust valves. Plus, overfueled diesels tend to melt pistons.
An unmodified naturally aspirated diesel at very high altitude might not burn valves and pistons, but on the other hand it might. Overfueled engines at sea level certainly do.
If a person were to take up residence at high altitude de-tuning the pump will lead to decreased fuel consumption and decreased EGTs, relative to leaving it alone.
Toyota's system on some of their diesels of an anaeroid ("DAC") and a throttle body to measure air flow should adequately compensate automatically for altitude.

Charlie
Well I was absolutely correct in one of my statements, I was talking complete junk. Just goes to show you shouldn’t believe a thing you read on the internet.

I subsequently did some research and you are correct. There you go you learn something ne everyday

I guess it’s less of an issue with electronically controlled pumps. Certainly our VW TDi measures atmospheric pressure and manifold pressure.


Cheers,
Russ
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  #21  
Old 31 May 2009
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Interesting that rich = hotter EGT with aspirated diesels. So what advice are we giving our friend in the 60 heading for the high passes? Should he manually adjust his injection pump (can't recall if that is possible) or just take it easy?

Ch
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  #22  
Old 1 Jun 2009
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My advice would be to leave the injection pump alone and just drop down a gear (and revs too). If you are comfortable playing with IP settings then maybe a different story. I am no pump fitter, but I can do some basics - but I would just take it easy and enjoy the scenery at a sedate pace than start messing around... especially on a vehicle with no EGT. At the end of the day as Charlie points out leaning the fuel will do no harm - but you have to be sure you are leaning! Toyotas (well the rotary Denso pumps AFAIK) generally for example you turn clockwise to increase fuel which is sort of against what you would expect! Even n/a stock vehicles can approach excessive EGT on long hills, but if you are aware and drive accordingly (or even better run a pyrometer) then you should be fine. If you boot it on long hills in 4th/5th with a trail of smoke then.... well alloy pistons will melt, heads will crack etc. If you are lucky you MIGHT see an increase in coolant temp - however (again for example) Toyos have a notorious dead spot in the factory gauge, and EGTs can rise very, very quickly.

Injection pumps can and are set up all the time with nothing more than a pyro gauge and watching for smoke... Black smoke indicates overfuelling - not sulpher. (my car runs on diesel with more than 100 times acceptable sulpher by EU standards and doesn't smoke at all). The overfuel can be due to worn injectors or the pump being worn - usually both together!

I run a boost gauge, a decent quality pyrometer as well as a digital coolant gauge - having played only a bit with my 1HZ, I like to have an idea what is going on down there! But on a stock vehicle I would just be careful and I am sure no problems will arise.
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  #23  
Old 4 Jun 2009
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Hey guys just wanted to comment here as I have some experience overlanding and driving at altitude in an old diesel 60. My truck is a 1981 BJ60 (same truck but with a 4 cyl 3B engine instead of the 6 cyl 2H) with no HAC and I have taken it above 13,000 feet WITHOUT a turbo, and above 17,000 feet WITH one.

I will second the ih8mud.com link above. The diesel cruiser community on that site is what has kept my cruiser alive all this time, and where I've learned anything I know about them.

If you are thinking of driving above 10,000 feet for any length of time or for serious overlanding, I would definitely suggest getting a turbo installed. The 2H engine will take well to it, and there are plenty of resources available (ih8mud.com) for information on doing it. Make sure you do it right though... a crappy turbo install can leave you bleeding oil in the wrong places or worse, as happened to me eventually. A good turbo install set up for nothing more than altitude compensation should not adversely affect the reliability of the cruiser, and of course will increase longevity of the engine if you are driving at altitude a lot or with heavy loads.

***The black smoke is bad, yes it does mean high EGT's. The cruiser can handle a litle bit of it, but the advice I've always followed is "if you see the black smoke, let off the pedal until you don't see it anymore".***

Quote:
Originally Posted by RussG View Post
A non turbo diesel will be more robust / safe in this scenario when compared to a turbo engine.
Also not true IMO. A turbo forces more air mass into the engine block, which has a cooling effect. Adding a turbo will keep your engine's EGTs cooler in all conditions. However if you DO have a turbo and you are seeing black smoke, it is true that this is slightly more serious as you obviously have a problem with your turbo.


A poor man's safety net if you don't have the money for the turbo would simply be to install an EGT gauge so you can make sure you're not burning up and know exactly when to back off on the pedal. This should cost you about $120 US, and the install is as easy as drilling a hole. If you are planning on turbo'ing down the road, you will still want this gauge so its a win-win addition really.

I would suggest adding a turbo. Although mine blew up in the end due to a poor install and welding decision on my part, I would not have been able to enjoy the high altitude deserts in Bolivia without it, and that is something I would not have wanted to miss out on. Your engine will be more powerful and happier, and WAY more powerful and happier at altitude.
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  #24  
Old 4 Jun 2009
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Oh, and be kind to your cruiser... don't do the 500,000km oil change thing. Cruisers are meant to be maintained forever, not driven into the ground for 500,000km's.
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  #25  
Old 6 Jun 2009
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Manali > Leh > Srinigar, hopefuly no damage . . .

Thanks all for the advice, much appreciated. It was a great route to take and in my opinion well worth any risk.

We ended up driving very slowly for all of it, a lot of the time second gear / 1250rpm / 18kph, and never over 40kph the whole time. The scenery is so spectacular that it wasn't as frustrating as you would expect. Over 5000m the engine sounded so rough that I really didn't want to push it anyhow. The local drivers were amused though. Judging by the amount of black smoke they were kicking out they really don't care about high EGTs

A turbo would be nice, and what a great justification to get one! However cost-wise for now I'll probably go with fitting a pyrometer...

Cheers,

Andrew

Last edited by Moodoo; 6 Jun 2009 at 08:28. Reason: repunctuate
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  #26  
Old 8 Jun 2009
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We've done that stretch also with our BJ45. It has the 3B [4 cylinders] engine. Just keeping it slow and steady, we were able to drive that road without problems. Even the road to the Nubra valley. The so called "highest motorable road in the world" wasn't a problem. You can play with the accelerator a little bit and see where the car still feels ok and the black smoke is the least.

We are now on our way again to Bolivia. Same story; altitude. But other conditions make it worse here; head winds, washboard gravel and small dunes. You want to speed up to comfortably take on the washboards, but you can't. And slowing down gets you stuck in the small dunes In comparison this makes the Leh - Manali road easy...
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  #27  
Old 8 Jun 2009
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Yeah you should probably get a turbo. The engine is designed to handle it... you are really pushing it and taking a risk even with your foot barely touching the pedal IMO. At the least you should do the pyrometer and I've found it also helps to widen/shorten the exhaust.

Then again you know what they say... go big or go home! Don't forget to air down on those washboards if you have a compressor to air back up again afterwards...
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  #28  
Old 11 Jun 2009
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These things are designed to run stock without any problems.. I don't see why you should install a turbo? We are not in a hurry, and the engine is not stressing at all... What's next; leather heated seats?
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  #29  
Old 13 Jun 2009
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Originally Posted by mailking View Post
These things are designed to run stock without any problems.. I don't see why you should install a turbo? We are not in a hurry, and the engine is not stressing at all... What's next; leather heated seats?
There's a reason they started shipping them with pretty much the exact same engines, only turbo'd just a few years later (3b=13bt, 2h=12ht). I don't think they were ever designed to run stock above 10,000 feet, let alone 15,000 feet. The HAC would have helped prevent damage, but only by limiting power...? Simply the naturally aspirated diesel engine just isn't meant to do that, and asking it to is asking for trouble... it's choking and starving... the fact that the components CAN handle the stress maybe is not the best guiding factor.

Sure, it can handle it... just like it can handle 500,000km oil changes, pulling far too much weight, being driven badly with almost no oil, being constantly overheated... etc., . I personally wouldn't do it if I had a choice though... My cruiser takes care of me because I take care of her.
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