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  #1  
Old 12-29-2020, 10:11 AM
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Location: Marrakech, Morocco
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new nozzles made clacking louder

Well, it's all there in the title. I may have been a bit of a chump and taken bad advice here in morocco from an injector test firm which told me all my injectors were bad, so fittted new nozzles to all of them.

But the 'clacking' is actually worse now. To be precise, it sounds bad between 1000 and 2000 rpm and then after that seems to quiten.

Is it POSSIBLE that an injector which was tested ok on the bench with the compression contraption can UNDER perform once fitted?

The reason why i ask this is because a so-called mercedes mechanic here examined the car and was pretty sure that number one injector was the problem.

Any thoughts, advice welcome. Failing that, I'm ready to call the Samaritans.


MJ in Morocco


Last edited by Beirut Brit; 12-29-2020 at 10:26 AM.
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  #2  
Old 12-29-2020, 12:06 PM
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You can have a metallic clanging sound up to 200 or so miles. That is air in your system. Injectors are pop tested on the bench.
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Old 12-29-2020, 12:08 PM
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Also, new nozzles could have a frozen pintle which is very common. The tech should have ensured the pintle and nozzle spins like a bearing before install. If it got “jammed” then you might be stuck rebuilding that injector. No pun intended
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  #4  
Old 12-29-2020, 12:31 PM
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im putting all my hope on this. There's no way it can work its way free, at higher revs, over many days? Does it have to be taken apart again and checked? The technician did seem to reassemble them in record speed.

Of course, i could just swap injector 1 with injector 6 to see if the clacking relocates, no? this would def confirm that its the injector.

thanks






Quote:
Originally Posted by greazzer View Post
Also, new nozzles could have a frozen pintle which is very common. The tech should have ensured the pintle and nozzle spins like a bearing before install. If it got “jammed” then you might be stuck rebuilding that injector. No pun intended
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  #5  
Old 12-29-2020, 12:43 PM
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If you can, I'd send them to Greazzer to check rebuild them correctly. His website is: https://dieselfuelinjector.guru

I used UPS to ship to him from London and it got there in 3 days and cost £25.
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  #6  
Old 12-29-2020, 11:04 PM
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The air will work it’s way out. The pintle may spin itself free; however probably not. I generally spin it a number of times to ensure it spins like a bearing. If there is any “friction” of “snags” and I go ahead and pop test it anyway I can bet myself that it will not pop correctly and I won’t see the proper repetitive popping. Rather it pops poorly and you’ll get a weep eventually. I just run the nozzle and pintle through another ultrasonic cycle.
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  #7  
Old 12-31-2020, 10:49 AM
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Now it has become worse and its really a very loud knock. I can't think what the technician has done in the workshop in rebuilding the injectors, but he's ruined my new year spirit.
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  #8  
Old 01-02-2021, 02:10 PM
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The easiest way to verify the noise is due to a particular injector or cylinder is to loosen the tube nut on top of each injector, one at a time, while idling. I recall that is a 17 mm wrench. You normally don't need to secure the injector since it is in much tighter. Loosen just enough so you see fuel dribbling out. That will disable that injector. If the noise goes away, it was due to that injector or cylinder. It will also help sweep any trapped air bubbles out of the high-pressure tubing.

My 1985 300D had a strange knocking or rattling sound around 2006 when driving 30 mph, about 5 years after I bought it. I pulled over, popped the hood, and the noise went away. It sounded like something was rattling around inside the engine. Maybe a year later, it happened again and a bit louder. I didn't make it home as the engine got weaker and died when I lifted the pedal when rolling down a hill. Couldn't even turn the engine over after that. Towed it home and pulled off the head. Something had beat up the #1 cylinder, leaving round depressions a few places in the top of the piston, like a small round bearing. I first suspected a turbo-pump bearing, but it has only solid bronze bushings. No idea what that was or how it got into the cylinder. I found several pistons with chunks of aluminum missing around the ring grooves and some cylinder walls scored. That was at 330K miles, and explained the low compression (~250 psig) and needing a block heater to start on <45 F mornings. I swapped in a used engine which had perfect compression.

I hope your fast-working mechanic wasn't so erratic to drop something into the engine while the injectors were off, but would have to be small to make it thru the pre-chamber holes. If you pull out the injectors, fish around in there with a small magnet for steel parts, plus look close with a good light or USB endoscope. As I recall, a 1985 engine has a straight view down to the glowplugs, whereas earlier engines have a neck which obscures the view, but maybe vice-versa. Sometimes the end of a glow-plug breaks off to rattle around in the pre-chamber.

Marrakech sounds exotic, but perhaps just residue from the Beatles days. More likely a poor-man's version of Southern CA, with more history.
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  #9  
Old 01-06-2021, 02:44 PM
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Wow Bill, that’s a scary story.

I had a mid rpm clatter in my 240d. It would make a loud clatter at 2000 rpm. It would go away at 2500. I solved it by pulling the injectors and cleaning them out in my ultrasound cleaner. Later the sound came back and I rebuilt the injectors with new nozzles that didn’t have pilot holes. I noticed the tiny holes were always clogged when I pulled the injectors. The issue never returned.

It is really easy to introduce dirt when building injectors if you’re sloppy. The tolerances are tight.
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  #10  
Old 01-10-2021, 03:27 AM
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Thanks for all that. I followed this procedure of isolating which pots were clacking - which the next day became worse and actully started knocking - and discovered that it was fault NEW nozzles. Two of them were factory rejects. Can you imagine?

Then after that, adjusted the IP and quitened it entirely.

But i still have a loud clack-clack-clack on start up for a couple of minutes.

Im assuming that my prechambers need a look at,

hope that helped someone. Moral of the story is that new nozzles can't always be trusted to be A1

MJ
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  #11  
Old 01-13-2021, 12:29 AM
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Quote:
Originally Posted by Beirut Brit View Post
But i still have a loud clack-clack-clack on start up for a couple of minutes.

Check your glowplugs. They can measure in the correct resistance range and still heat, but heat at the shaft instead of the tip.

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