How can you effcetive test a diesel injector to see which one is clattering louder than normal? I used diesel purge and my mechanic told me that he thinks that just one injector is bad.
What are your thoughts?

We just crack loose one line at a time. When the noise goes away, that is it. (Watch out for your eyes.))

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Benzmac:
Donnie Drummonds
1992 500E (very soon I hope :)
1981 280GE SWB
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

I am not sure what you mean by crack open the line, can you explain? This is a 1991 300D 2.5.
Thanks.
If you can be as explicit as possible, that would be great.
:)

He means to loosen the fuel supply line to the injector, one at a time, while the engine is running. There should be one supply line to, and one return line from each injector, the supply lines should come from the injector pump.

Be sure to wear safetly glasses, as fuel might spray, since it is under pressure.

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Mike Tangas
73 280 SEL 4.5

Would it be better to loosen the line at the pump or at the actual injector?

Loosen the nut at the injector end. If it quiets down, then your problem is isolated to one cylinder, but you still don't know if it is the injector, pumping element, pre-chamber, compression, etc.

To verify if a specific injector is at fault, tranfer the supposedly failed injector to another cylinder, and see if the problem also transfers with it.

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Jake

Thanks.
I will let you know what happens after I test it.

Ari,

Where is Deezel when you need him?<g> Deezel is our safety officer, and since he has not chimed in, I will do my best to pinch hit for him. This is not a low pressure line that your loosening. In order to overcome very high cylinder pressure, the pressure at the injector is EXTREMELY high. When you loosen the line, a very high pressure stream of fuel could go anywhere. Where safey glasses. It won't really hurt you anywhere else, but a high pressure stream of diesel in the eye could cause very serious eye injury.

How did I do Deezel?

Good luck,

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Larry Bible
'84 Euro 240D, 523K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in
Mercedes automobiles

I guess as a precaution, I will wrap the wrench and line in a large thick rag. It is hard to imagine that just one injector coulkd make such a ruckus. When I start the car in the morning it is very much more quiet, but once I hit the accelerator, the noise increase and does not stop. It is really only noisy at idle, once I hit the gas
the car is as quiet a gas 300.