I've read through the archived posts on Nailing and understand that it is apparently a case of the fuel injected into a cylinder exploding all at once. The possible causes appear to be many, and all seem to be injection related. What I did not find was a suggested course for dealing with the problem. My instinct is to start at the inectors replace or rebuild) and work towards the cylinders instead of the other way around. Has anyone succesfully dealt with this?

Have you tried checking the 'start of fuel delivery' ? You take off number one injection tube and substitute a cut off one with a curve pointing toward the engine... then you set it for one drop per second... at a specfied place.. I have not been too specific because you need to use the manual to do it right. Be sure this is correctly set before worrying about other stuff...Greg

PEH:

The easiest and cheapest is a full bottle of RedLine or similar in a full tank of fuel. If the problem gets better, then returns on the next tank, you have an injector problem, most likely. You don't have to take anything out, etc. for this.

Next best is a nozzle replacement (or just switch injectors around) -- if the knocking is gone, the nozzle was bad, ditto if it moves to another cylinder. While you are at it, check for a broken ball pin or bits of burned out injector in the prechamber -- either will cause injector knock, as will installing the seal upsidedown or putting a new style seal on top of an old style seal (I don't think this is the case, your car is too new). There is a faint chance that a burned out glowplug is lowering compression some, too -- the Champion plugs I took out of the Volvo had a hole in the end were the filament separated from the steel tube, making them hollow.

If that doesn't do it, compression check and leakdown test are in order. You will probably find a compression leak of some sort on that cylinder, and repairs will be determined by what is wrong.

If compression is fine, leakdown indicates no problems, your IP is bad. Might only be a leaking pressure valve holder, might be a plunger/sleeve problem, if new pressure valve seals don't fix it, it's Bosch injector service time.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Hey, Peter. First time I have been accused of having a car too new for anything.

I may be asking for you to walk me through switching injectors around this weekend. I use Redline or PowerService with each tank, so I will move on to inspecting injectors and glow plugs. All GP test strong at relay, but I will visually inspect as well. Thanks for the directions.

Try a whole bottle in a tank, not just the two ounces or so. It raises the cetane index more, and increases the ignitibility of the fuel. This will reduce or eliminate knock if it is due to poor fuel spray or a carboned up injector.

To have the old style injector seals you would have to have something as old as 1972 or so, and they would have to be either original or so badly stuck they couldn't be removed -- that is why I still have one in the 220D -- I can't get it out. they go into the hole at the top of the prechamber, not just on top of it like the new ones. If you get the new ones upsidedown, they leak, and you have low compression.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

I think low compression will cause nailing, which is pre ignition.

I don't think your IP is out time though, unless it is loose and has moved.

ALSO, a strected timing chain will cause a change in timing, enough to cause nailing, usually on #1 cylinder for some reason...

Why is that?

__________________
Ed
1981 300CD (Benzina)
1968 250 S (Gina) 266,000 miles!
1983 Alfa Romeo GTV6 (Guido)
1976 Jaguar XJS-saved a V-12 from the chevy curse, what a great engine!
1988 Cadillac Eldorado (better car than you might think!)
1988 Yamaha Venture (better than a Wing!)
1977 Suzuki GS750B
1976 Yamaha XS 650 (sold)
1991 Suzuki GSX1100G (Shafty Gixser)
1981 Yamaha VX920RH (Euro "Virago")
Solex Moped
1975 Dodge P/U camper


"Time spent in the company of a cat, a beer, and this forum, is not time wasted!"

Ed:

I noticed you saved a Jag V12. I was always under the impression that there were serious fire problems with the fuel system on that engine -- I've heard I don't know how many stories about dead Jag v12s -- wonderful when it ran, but usually inert. Glad you have it running! The XJ6 was otherwise a very nice car.

A stretched timing chain gives late injection timing and quieter operation. More smoke a speed.

Only lowers compression if late enough to change the valve timing significantly (won't show up in a cranking compression check).

Diesels CANNOT pre-ignite unless fuel is added to the air -- there is no fuel in the combustion chamber until the injector fires, and if injection timing is so fast as to cause pre-ignition (20-30 degrees before top dead center) the engine will not start. Only if there is ether, propane, acetylene, or some other atomized or vaporized flamable material in the air will pre-ignition occur. Sever engine damage will result almost instantly.

Injector knock is LATE combustion, with the prechamber filling with atomized fuel before ignition occurs, so that the fuel all burns at once rather than as injected. This is why a serious knock won't hurt anything much -- the piston is going the other way.

The fuel is injected rather slowly to make the engine as close as possible to a Carnot cycle engine -- that is adiabatic expansion (no temperature or pressure change during expansion of the hot gasses).

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Hey, Peter, I was with you until that last paragraph. All I can say to that one is - what??? Can you please re-explain that as if talking to a distracted-drowsy-ADD two year old. If you can swing that, I might catch some of what you're talking about. What is a Carnot Cycle engine?

Re: 12 cyl. Jag. Tuned and running it is one of the finest experiences you may ever have. Tremendous responsiveness and a vibration that feels like it is in tune with the cosmos. That peak is hard to acheive and much, much harder to maintain. Many have burned. I think that possibly some people have torched their V-12's when they discovered what a huge and terrible task lay ahead when all they had to do was remove the valve cover.

My father had a v12 jag. I drove it one day when I was 14 and home for the summer. Boy was I lucky and boy do we laugh about it now. I have never felt a stronger force than that engine. It was similar to a jet when it takes off only smoother and quieter.

I have picture somewhere of his car floating down the street during "THE PERFECT STORM" on October 31 1991. We lived on the ocean in North Hampton NH. What a sight, his jaguar and our neighbors Porsche bobbing in the waves down the street. He later had it cleaned, dried, and sold.

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83 300TDT BROWNBENZ
04 Sprinter

It's a bit off the Diesel topic but I still have a V-12 that I've owned for 15 years. I think the reason they burn is that the engines run very hot (something about a bad design that wrapped the water jackets too far down the exhaust stream) and with all the plumbing very few owners bothered to replace their fuel lines as they dried out. Couple that with the fact the carbs are located right over the exhaust manifold and it's an accident waiting to happen unless you're dilligent about the maintenance. All this kind of makes you appreciate the engineering the Mercedes guys put in.

__________________
LRG
1987 300D Turbo 175K
2006 Toyota Prius, efficent but no soul
1985 300 TDT(130K miles of trouble free motoring)now sold

mccan:

Otto cycle engines are gasoline engines -- all the fuel burns at once and the resultant hot gases expand to drive the piston down. Since they expand without any further input of heat, the temperature and pressure drop rapidly as the volume of the cylinder increases with piston movement. Much of the heat gets absorbed by the cylinder walls or goes out the exhaust -- heat and noise out the tailpipe.

Carnot cycle engines are theoretically adiabatic -- no temperature or pressure change as the piston moves down and the cylinder volume increases. This is achieved by continuously injecting fuel as the piston moves down, continuously increasing the amount of hot gas in the cylinder. The result is less heat loss due to free expansion and less heat and noise goes out the tailpipe.

This would be great if you could inject variable amounts of fuel over a fixed injection period, but what really happens is that the amount of fuel per millisecond is about the same while the duration of injection changes as more fuel in injected.

True adiabatic diesel engines have been built as research projects, but they have a single rpm and load combination at which they are truely adiabatic. Laboratory curiosities.

Hope this helps. It's rather complicated. Basic physics, though!

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Thanks, Peter. So the goal is the most efficient use of the explosion. More space in the chamber would mean more fuel in the space. And the perfect coordination of diesel/air increase with the space increase yields the explosion that drives the piston with the least waste of heat and noise (friction and vibration).

Can you breakdown the term "adiabatic"?

Irg

You are very correct about owners not replacing their fuel lines when they get old. This is the reason for the fires.

There is nothing wrong with British engineering versus German engineering, just that British, as well as American companies, do not sweat the details like the Japanese and German companies.

The main reason the V-12 engine was switched out for Chevy V-8's was that they quit running! And their owners couldn't diagnose the problem, and neither would the indies. To put it simply, the amplifier for the ignition was located smack in the middle of the V, and literally cooked itself to death. The factory fix for this was to remount the amps in front of the radiator, and from then on, there was no problem. My fix was to purchase a kit from Crane Ignition which includes an optical pick up for the distributor which replaces the Hall effect pick up. It runs sweet.

The other problem which haunted this particular car and had me going in circles!! was the "roll over switch" was being tripped by closing the drivers door too hard! Therefore the fuel pump would not work. (the power to the pump is routed through this safety device) Trouble was, I could not find this switch! It was very unclear where it was from looking at the wiring diagram.

While trying to get a restart at a restaurant in Gilroy (garlic capitol of the world!) on a busy street, I just happened to spot it as I was getting out of the car. There it was, right at the door jamb/kick panel. Apparently it is a very sensitive switch and is conveniently located so the driver can reset it.(just push the button on the top of the switch, and hey presto!)
I bought a beautiful Alfa Spyder this way once. No one could figure out why it would crank, but it wouldn't start! $500!
Sold it the next day for $4500. Pushed the button!

This engine is carried around in an XJ-S, not the sedan, and therefore has a very cramped and hot engine compartment. The fuel lines get so warm, that the factory actually circulates the fuel line through the A/C system to cool it down!!! And therefore, the A/C is required to run it's pump all the time, which contributes to the truly miserable fuel mileage of these beasts. < than 10!!!

But I will tell you what gang, This car handles brilliantly while having a magic carpet ride at the same time. The only other car that does this magic trick are my two 123's.
So there you have it. Jags are not what I thought they were. They are beautifully engineered and constructed cars, which were cheaper than MB's when new. Overly complex and troublesome and expensive for casual owners, which led to early retirement.

I love working on my Benz, hate working on the Jag!

__________________
Ed
1981 300CD (Benzina)
1968 250 S (Gina) 266,000 miles!
1983 Alfa Romeo GTV6 (Guido)
1976 Jaguar XJS-saved a V-12 from the chevy curse, what a great engine!
1988 Cadillac Eldorado (better car than you might think!)
1988 Yamaha Venture (better than a Wing!)
1977 Suzuki GS750B
1976 Yamaha XS 650 (sold)
1991 Suzuki GSX1100G (Shafty Gixser)
1981 Yamaha VX920RH (Euro "Virago")
Solex Moped
1975 Dodge P/U camper


"Time spent in the company of a cat, a beer, and this forum, is not time wasted!"

a-(not)-dia(two)-batic(tempurature) or little or no change in temperature.

No internal combustion engine runs on explosions! Fuel is BURNED in a controlled way to produce heat and expanding gas. Explosions in a cylinder are DETONATION -- on gas engines this results in broken spark plugs, melted and blown out pistons, blown head gaskets. On diesels, started with too much ether or propane or acetylene, the head bolts usually fail in addition to severe piston melting/fracture. Not pretty.


Believe me, if you actually hear detonation in an engine, you will never mistake it for anything else!

Fuel burns in a Otto cycle engine all at once. In a Carnot cycle engine (diesel), at full throttle it should burn all the way down the power stroke. Too much fuel or too long an injection, and the exhaust valve opens or the oxygen runs out, and excessive soot is produced. Extra long injection will increase torque some, but horsepower usually drops fast as the soot increases.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Sorry to jump in here.

The word "adiabatic" comes out of the Greek word "adiabatos". Adiabatos means "impassable."

In thermodynamics, an adiabatic process refers to a process in which there is no heat exchange (a system does not receive or lose heat).

The temperature can still change in an adiabatic process. No heat exchange does not necessarily mean there is no temperature change as temperature can still be changed by changing the pressure and volume of the system.

A Carnot cycle consists of two adiabatic processes and two isothermal processes. An isothermal process is a process in which temperature does not change.