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  #1  
Old 07-15-2007, 09:46 PM
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How forcefully will fuel come out of injector lines

I have a 240D. With the injector lines disconnected from the injectors, while cranking the engine, how forcefully should the diesel fuel come out of the lines at both idle position and full throttle. I have checked it in idle position, idle knob at start position, it comes out one drop per revolution. Is this what is to be expected or should it come out with some amount of force? I am assuming that force would increase if you push the throttle down while cranking. Is that correct? Are there any specs anywhere that states how much pressure should be on an injection line at any given throttle position? If not what is the proper way to test an injection pump?
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  #2  
Old 07-15-2007, 09:50 PM
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Definitely not the right way to test them. I would imagine you'd have a heck of a mess that way. I'm sure Someone will chime in about a better way to test it.
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84 300D Turbodiesel 190K with 4 speed manual sold in 03/2012
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  #3  
Old 07-15-2007, 10:02 PM
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And I hope that answer is not to send it to Bosch or buy a new one. I'm not really worried about a mess, I can rig up bottles to catch the fuel. I got the engine to start twice in the last two weeks by putting oil in the cylinders (has low compression), so I was sure I was dealing with just a compression problem. I tried the oil trick again and it is not starting this time. I was getting ready to pull it into the garage to re-ring it but now, after not starting with the oil, I am no longer sure I am dealing with only the low compression problem.
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  #4  
Old 07-15-2007, 10:05 PM
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Are you sure all your glowplugs are good?
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  #5  
Old 07-15-2007, 10:12 PM
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You must remember, the injector is a MAJOR restriction in flow on the injection system...... Without those, the fuel won't have any pressure.... BUT, we are also talking a miniscule amount of fuel per injection event. One drop per injector line per revolution is about right.........

Sounds like a glowplug issue. I know that my engine, which is in good condition, will not start without glowplugs for anything..... Not even to outrun a car crusher!!
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  #6  
Old 07-15-2007, 11:54 PM
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The only way this car has started in the last several weeks (twice) was to remove the injectors and add oil to the cylinders (has known low cold compression). After finally getting it to start two days ago, I ran it for about 1/2 hours and drove it 4 miles. It ran as good as when it was starting consistently. To discount the possibility of the glow plugs being the problem I turned off the car after running 1/2 hour and immediately tried to restart it: It would not restart. I was told you do not need to use the glow plugs when the engine is hot.

That droplet coming from the injector tube cannot be proof that is has sufficient force to operate the injector, can it? You can force a drop of water up out of a tube with far less than an ounce of force. If fuel comes out of each of the small nipples (overflow?, over-pressure nipples?) on the injectors, with the braided lines disconnected, is that evidence of sufficient pressure to operate the injector? When I spray diesel starting fluid in the engine it cranks slower as though the starting fluid is igniting before TDC because its introduction into the combustion chamber was not timed by the IP, so in a weird way there is evidence of ignition. My crummy manual tells me the IP has to be tested at the dealer but screw that, before I do that I will go to the bone yards, buy the extra injectors tubes and bend one to the right shape so I can attach an injector to it to see if it sprays.

The night before all these problems started I topped off the tank from half filled, but I find it hard to believe that I would have been able to start and drive it friday if the fuel I put in it 6 weeks ago was bad. It is probably a waste of time but I will try running the car on fresh fuel on the off chance that the fuel I topped off with was bad.
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  #7  
Old 07-15-2007, 11:59 PM
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Quote:
Originally Posted by khickey View Post
The only way this car has started in the last several weeks (twice) was to remove the injectors and add oil to the cylinders (has known low cold compression). After finally getting it to start two days ago, I ran it for about 1/2 hours and drove it 4 miles. It ran as good as when it was starting consistently. To discount the possibility of the glow plugs being the problem I turned off the car after running 1/2 hour and immediately tried to restart it: It would not restart. I was told you do not need to use the glow plugs when the engine is hot.

That droplet coming from the injector tube cannot be proof that is has sufficient force to operate the injector, can it? You can force a drop of water up out of a tube with far less than an ounce of force. If fuel comes out of each of the small nipples (overflow?, over-pressure nipples?) on the injectors, with the braided lines disconnected, is that evidence of sufficient pressure to operate the injector? When I spray diesel starting fluid in the engine it cranks slower as though the starting fluid is igniting before TDC because its introduction into the combustion chamber was not timed by the IP, so in a weird way there is evidence of ignition. My crummy manual tells me the IP has to be tested at the dealer but screw that, before I do that I will go to the bone yards, buy the extra injectors tubes and bend one to the right shape so I can attach an injector to it to see if it sprays.

The night before all these problems started I topped off the tank from half filled, but I find it hard to believe that I would have been able to start and drive it friday if the fuel I put in it 6 weeks ago was bad. It is probably a waste of time but I will try running the car on fresh fuel on the off chance that the fuel I topped off with was bad.
Do not ever spray starting fluid in one of these engines as you may seriously damage it.
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84 300D Turbodiesel 190K with 4 speed manual sold in 03/2012
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  #8  
Old 07-16-2007, 12:03 AM
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IIRC, you can get injectors pop and spray tested at most any Diesel shop pretty cheap. Considering you have only 4, it should be really cheap!
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  #9  
Old 07-16-2007, 12:16 AM
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lietuviai,
After 60-70 hours of messing around with this car I am beyond caring. The starting fluid which is labeled "for diesels" will either help get it started or kill it, either way the car will not be wasting anymore of my time, besides, with no way for me to test the IP I have few other options.
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  #10  
Old 07-16-2007, 12:25 AM
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Just in case you were wondering what starting fluid can do, see this thread.
Using starting fluid (ether) in an MB diesel?
I wish you would not quit so easily as you're starting to sound a lot like me. I admit I have wanted to quit on many occasions and the forum members here knocked some good sense into me by offering me some good advice. Don't trash the engine simply on the idea that you can't get it running. If the engine is really worn out, don't try to destroy it completely. There still may be some usable parts left on it.
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84 300D Turbodiesel 190K with 4 speed manual sold in 03/2012

Last edited by lietuviai; 07-16-2007 at 12:33 AM.
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  #11  
Old 07-16-2007, 12:30 AM
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Still check the glow plugs! Also adjust the valves, then recheck compression. Also a diesel with low compression usually needs the glow plugs aftrer the car sat for 30 min or more.
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  #12  
Old 07-16-2007, 12:35 AM
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KarTek,
Believe it or not every shop I talked to referred me to on place in Detroit and when i called the one guy told me they might be able to do my injectors but the only guy who would know for sure was on vacation for the next 10 days. Based of the fact that it ran friday I have to believe the injectors are working, plus while it was running I loosen the injector lines momentarily with the theory that if they weren't spraying correctly or at all the engine operation would not change. I loosen the lines in turn and each made the engine stumble. If one line losing pressure does not affect the others than that test would seem to prove that each injector is delivering fuel and even the lowest compression cylinder is achieving combustion.
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  #13  
Old 07-16-2007, 12:57 AM
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lietuviai,
My problem isn't that I give up too easy, my problem is that I don't give up even when it makes no sense to keep trying. I get obsessed with problems like this and tend not to walk away from them even when, like right now, I have several much more important things I could/should be doing. If I spent the same 60-70 hours on working my business I could have paid for the car three times over, yet here I am spending an unreasonable amount of time on this car instead of just junking it and moving on because it irks me that i got two weeks use out of a $1200 car.

In regards to the starting fluid, what is the concensus on using wd40?
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  #14  
Old 07-16-2007, 12:59 AM
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Evidently it's formula is based on kerosene which relatively safe for these engines.
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84 300D Turbodiesel 190K with 4 speed manual sold in 03/2012
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  #15  
Old 07-16-2007, 01:12 AM
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lietuviai,

Good to know. I will start using WD40 instead. As long as I have some way to introduce an alternate fuel to the engine I don't care what it is. Thanks.
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