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  #1  
Old 07-07-2002, 01:08 PM
brandoncrone
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617 Diesel Engine, strange sounds

Ok, I've read a lot of posts about engine noise due to clogged injectors, timing, etc.

My engine has about 3-4 degrees of timing chain stretch.

This noise I have sounds like a gas engine pinging on acceleration, like a spark knock sound. This engine is a replacement used engine for my original one. My first engine (the original) had this very same sound, I tried on the original engine adjusting the fuel timing and that had some change but never eliminated it. This engine (the replacement) has the same sound, no smoke that I can see in the rear view mirror, when backing up I can see a whiteish colored smoke, but that is it. No black smoke on acceleration.

I tried checking the IP timing when I adjusted the valves, but when you remove the check valve all the fuel runs down into the injection pump when it is at 24 degrees BTC. I use the hand pump to pump it up only for it to run back down into the pump.

This is what I want to know:
Does there have to be a certain amount of fuel in the tank in order fuel to stay in the pump??

3-4 Degrees of t-chain stretch, is that normal?? What is the MB spec on that???

If you take the injectors apart, can they be reassembled without affecting the opening pressure???

And, does the 3-4 degrees of stretch affect the cam timing enough to cause that noise??

Thanks in advance!
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  #2  
Old 07-07-2002, 06:36 PM
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Location: Evansville, Indiana
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If the fuel is running down out of the IP, check the fuel return line on the side. There should be a restriction or a spring loaded valve in there to hold pressure in the IP. It is the thread as the inlet, and I've heard of them being swapped. That would account for injector noise, as the amount of fuel being injected could vary somewhat at idle.

There are a number of causes of injector knock, not the least of which is being a diesel engine. You will always have some diesel noise (least on the TDI or CDI engines). A hard "snap" rather than a rattle is an indication of a problem.

Injectors can be taken apart and reassembled without pressure testing, but I don't recommend it. Too much chance of more trouble than you started with. If you want to have them tested, pull them and take them to a diesel shop, they will test them for free. The opening pressure is set with internal shims, so you must have a test bench.

A broken ball pin in the prechamber, bits of burned out glowplug tips, and incorrect IP timing will all cause the same symptoms as a bad injector. So will a bad chain tensioner, as chain slap sounds a lot like injector knock. Low compression also caused injector knock. You will have the other symtpoms of low compression if this is the case, though.

You can test for a bad injector by sequentially loosening the injector cap nuts while idling -- each cylinder should give the same amount of idle speed reduction and increase in vibration. If the knock goes away when you loosen a cap nut, that injector is bad. Ditto if the idle doesn't change as much for that cylinder as for the others.

One last thing to check is for good seals at the pressure valve holders. Leaking seals will allow fuel to leak back in the injection lines, causing all sorts of noise and running problems. Seals are easy to replace. This was the case with my 87 and gave the following symptoms: serious knock on #4, poor performance until the turbo kicked in, some knock on #2 and #3, all of which dissapeared on loosening the cap nut. Rough idle at all temps, but no starting problems. No smoke, at low or high speeds. Slightly low compression on #4.

Turned out that someone had been in the pump, and failed to properly torque the pressure valve holders. New seals fixed everything.

Peter
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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!
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  #3  
Old 07-09-2002, 08:45 PM
brandoncrone
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Thanks so much for your response!

I'll check those pressure valve holders, I'm assuming that those are the metal valves under the fuel injection line fittings on the IP. The strange thing about this whole thing is that this started w/in 1500 miles, the first 500 miles I had the engine in the car there was nothing, actually now its getting pretty bad.

Are there any other filters part of the IP besides the 2 main filters??

When I had the #1 Valve out of the IP, the fuel in there was not very clean. I had trouble awhile ago with some dirty fuel. Maybe the injectors are plugged. Both filters are new, I changed them recently, actually it seems to be around the time this noise really started to pick up.

I have a fuel injector pressure tester, a special tool I inherited from some GM stuff that was going to get pitched.

Do you know where I can find the opening pressure of the injectors??

One last thing...what is considered excessive t-chain stretch??

Thanks again!
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  #4  
Old 07-09-2002, 09:40 PM
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Location: Evansville, Indiana
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Yes, the seals are under the fitting that the injection line screws too -- I think the are under the actual valve in yours, so you will have to take out the spring, valve, and valve holder. The seal is the little copper washer underneath. Put on new 0-rings, too.

If you had dirt in the pressure valves, I'd guess you managed to get dirt past the filters (very bad sign-- unless it is varnish from crappy fuel, in which case a good blast of Diesel Purge or several treatments with RedLine or similar should take car of it). Very much grit in there will kill the IP for sure.

I believe opening pressure is in the 1700 psi range, but I've been wrong before.

Certainly, if you have an injection tester, pull the injectors and at least check them for spray pattern. It should be a fine mist, conical, and even around the pintle. Any unevenness, sputters, drips, or solid stream will indicate a bad nozzle ($50 or so each on FastLane). You should also be able to get the nozzle to "buzz" and it opens and closes with slow application of pressure. I think it takes some practice to get them to do that, but it shows that the nozzles are working properly.

Any crud in the nozzles with give bad spray patterns, high or low opening pressure (depending upon whether they are stuck open or closed!), and intermittant operation.

Chain stretch of 8 degrees or more indicates replacement is needed. More than that, and you risk serious trouble, usually a broken chain.

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!
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  #5  
Old 07-10-2002, 05:35 AM
brandoncrone
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Ok! I'll give this stuff a shot this weekend, I'll let you know what I find!
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  #6  
Old 07-11-2002, 07:23 AM
brandoncrone
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psfred!

I have a question!



Ok, back to the pressure valves on the IP, I see the copper sealing rings that you are talking about, but no o-ring. Is it possible that my car does not have any??

I pulled the valves out of my old injection pump from the original engine and those don't have any o-rings either.

Do they disentegrate in there??

Let me know!
Brandon
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  #7  
Old 07-11-2002, 10:52 PM
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Location: Evansville, Indiana
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Brandon:

The O-rings go on the pressure valve holder (the part that screws in) to seal the pump -- without them (or if they are bad) the pressure valve holders will leak out the threads and dribble fuel. They fit in a slot toward the bottom, at least on mine. Have a care not to cut them on the threads putting new ones on.

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!
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  #8  
Old 07-12-2002, 05:40 AM
brandoncrone
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Thanks Peter,

I think this car doesn't not have the orongs. There are no slots in the threaded part on the IP.

I think I'll go simple for now, checking the injectors. I found that they are stamped 115bar on the side next to the Bosch part number. That works out to 1668psi. So I am assuming that is the opening pressure of the injector.

We'll see!
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  #9  
Old 07-12-2002, 10:32 AM
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Join Date: Jul 2001
Location: Old Lyme, Connecticut
Posts: 3,596
brandoncrone,

I just pulled my manual for the engines OM 615-617 and it specifies 115 to 123 bar for new injector nozzles and 100 bar for used injector nozzles. Hope this helps, Jim
__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)
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  #10  
Old 07-12-2002, 12:14 PM
brandoncrone
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Well, in that case they are all opening around 1500 psi, which is about 110 bar, but, the spray is off to one side and there is a thick stream coming out of the center. (Well thick enough to noticed beyond the atomized fuel. And sometimes they don't spray at all right away, but they have that same stream coming out before the atomized fuel gets out!

So I've come to the conclusion that the injectors are tired, and I will had to save my pennies to buy a new set.

I wish I could find someplace that sells the pintle and body to rebuild the injectors, since I can set up the opening pressure.

It just seems weird that this came on so fast...Oh well, I hope the fuel spray, (since basically its pushing raw fuel into the prechamber) doesn't affect piston temps or anything. Or, hopefully it won't have any long term affect on the enigine.

My old engine in the car did the knocking for about 30K miles, I could never figure it out before, but I also didn't have this forum then!!

Thanks Peter for all your help, I'll let you know how I make out.
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  #11  
Old 07-12-2002, 12:43 PM
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Join Date: Sep 2001
Location: central Texas
Posts: 17,277
I suspect that lots of people have fuel mileage issues, smoking, noises, and other stuff which comes from either a bad spray pattern or from holes in the prechambers being clogged...but I seldom hear of anyone wanting to pull the prechambers to clean and inspect...it does not help to have a perfect spray pattern that is messed up by clogged holes in the prechamber.. they both have to be right to have things right at combustion time.... Greg
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  #12  
Old 07-12-2002, 01:02 PM
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Join Date: Jul 2001
Location: Old Lyme, Connecticut
Posts: 3,596
Brandoncrone,

I am not sure if MB still offers just the nozzle assemby (body and pintel) anymore, but they used to sell them for under $20 apiece. Check Fastlane. They went by the name "nozzles" and they came in matched sets (pintel and body). Jim
__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)
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  #13  
Old 07-12-2002, 02:34 PM
brandoncrone
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I'm not really over concerned about the noise, I am more worried about longevity. It needs to go another 85,000 miles before I get rid of it, and I drive 550 miles a week.

I drive from an altitude of 3000feet to about 100 feet on my commute to work. I noticed that the injector knock is consideably less in the lower altitude. Just thought I'd mention that.

I'm not real sure Greg if I want to buy the necessary tools to remove the prechambers....they are fairly expensive if I remember correctly.

I checked with MB, I can get injectors for $41 ea, cheaper the performance products, they want $61.

So I guess I'll leave it at that for now.
Thanks Guys!
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  #14  
Old 07-12-2002, 03:10 PM
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Join Date: Sep 2001
Location: central Texas
Posts: 17,277
The screw out one is very expensive... but I think you can get a slide hammer type reasonably.. or rent the screw out one... ? If you were going to do that... when you had the injectors already out sure seems like a good time,,, and anyway.. how do you know if things look good between the combustion chamber and the injector if you don't pull them ? It would be a shame to have brand new stuff on top and be squirting into only half the holes that were designed to disperse that fan spray.... I would think that the bad spray.. or the streaming of the fuel would raise the probablility of their being combustion products left from faulty ignition if the fuel has been entering the area as a stream rather than mist.... But I am just guessing..... greg
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