Have new injectors made your car quieter? - PeachParts Mercedes-Benz Forum

jbach36 · #1 05-11-2020, 12:38 PM

My car got louder about 2 years ago when possibly a bit of dirt got into the injector area while changing the O-rings. Despite everything being cleaned with molly lube and having the injectors taken out and cleaned, it has always seemed louder than it should be. It'd be interesting to see how loud this car was when brand new so I'd have something to compare it to. Maybe it's as quiet as it should be.

All my 3 of my filters are clean, the pre-filter, filter, and tank filter.

I read some threads where people got new injectors and in some cases it helped and others it didn't, meaning their injectors didn't have a problem after all. Have new injectors helped any of your cars to be more quiet?

jeff 1991 300d 230k

ah-kay · #2 05-11-2020, 12:57 PM

In your mind, yes. In practicality, no. This is my experience. Assuming the injectors were all balanced to start with.

Diseasel300 · #3 05-11-2020, 01:11 PM

If the injectors are worn out or dribbling, then yes, new nozzles will help immensely. If the delivery valves are worn and no longer seating properly, they'll actually make it worse, especially if you raise the pop pressure. An OM602/603 with the updated "inclined" injection and "moose horn" combustion chamber design should be very quiet at idle if everything is right. If the hood is closed, you shouldn't even really be able to tell it's a diesel.

oldsinner111 · #4 05-11-2020, 01:15 PM

not really,a small amount of cooking oil,like one pint to 24 gallons fuel, will make motor sound like a m104

jbach36 · #5 05-11-2020, 03:18 PM

Quote:

Originally Posted by Diseasel300

If the injectors are worn out or dribbling, then yes, new nozzles will help immensely. If the delivery valves are worn and no longer seating properly, they'll actually make it worse, especially if you raise the pop pressure. An OM602/603 with the updated "inclined" injection and "moose horn" combustion chamber design should be very quiet at idle if everything is right. If the hood is closed, you shouldn't even really be able to tell it's a diesel.

When you say "updated", is that an aftermarket thing or are you talking about a later model 602 engine? How would I know if mine has that?

Diesel911 · #6 05-11-2020, 03:27 PM

No one has mentioned the Fuel Injection Pump and camshaft timing.

In the past Dr Bert was one of those that recommended advancing the timing from 24 BTDC to 26 BTDC. When I did that acceleration was slightly more peppy but it was noisier. So I decreased the advance in the timing and the noise went back to normal.

It will also nail if your timing is too retarded.

Valve timing, fuel injection pump timing, pop/opening pressure, condition of the Nozzle and compression all effect the combustion and having the fuel burn well and at the right time is what reduces the noise.
I have to let those that have had delivery valve issues speak for that. But before I changed delivery valves I would be sure to make sure the 2 timings were within spec.

ah-kay · #7 05-11-2020, 07:42 PM

Quote:

Originally Posted by Diseasel300

If the hood is closed, you shouldn't even really be able to tell it's a diesel.

Really, keep dreaming. New diesel is much more quieter but you can still notice it.

Diseasel300 · #8 05-11-2020, 09:11 PM

Quote:

Originally Posted by jbach36

When you say "updated", is that an aftermarket thing or are you talking about a later model 602 engine? How would I know if mine has that?

1990 was the update year for the 603. The 602 had some earlier updates, but should be the same from 1990 onwards. The inclined injectors thread into the prechambers, the "vertical" injection of the early engines thread into the prechamber collars.

Quote:

Originally Posted by ah-kay

Really, keep dreaming. New diesel is much more quieter but you can still notice it.

I own one that's well maintained. If the engine is warm, about the only thing you really hear is the "click" of the delivery valves. It's nothing like the pre-1990 engines. If the hood's up, you can tell pretty easy that it's a diesel, but the hood closed is another story.

jbach36 · #9 05-13-2020, 12:43 AM

I just talked to the Seafoam rep after reading an article where someone said he used it in his MB and it quieted the car down.

The rep said he used it on a W124 and it pepped the car up and quieted it down. He recommended using Seafoam in 3 places.......

1) in the fuel tank. One oz. per gallon of diesel fuel

2) in the screw off fuel filter. I forget how much he said to put in there but he said screw the filter off, dump out some of the fuel and pour in some Seafoam, but I figure putting it in the tank,it will ultimately reach the fuel filter just the same.

3) in the oil crankcase. He said pour some in your oil, 1 oz. per quart of oil. Drive the car for 300 miles and then do an oil change. He said putting it in there will loosen up a lot of old burned oil, helping the car to run better.

Diesel911 · #10 05-13-2020, 01:10 AM

[QUOTE=jbach36;4045657]I just talked to the Seafoam rep after reading an article where someone said he used it in his MB and it quieted the car down.

The rep said he used it on a W124 and it pepped the car up and quieted it down. He recommended using Seafoam in 3 places.......

1) in the fuel tank. One oz. per gallon of diesel fuel

2) in the screw off fuel filter. I forget how much he said to put in there but he said screw the filter off, dump out some of the fuel and pour in some Seafoam, but I figure putting it in the tank,it will ultimately reach the fuel filter just the same.

3) in the oil crankcase. He said pour some in your oil, 1 oz. per quart of oil. Drive the car for 300 miles and then do an oil change. He said putting it in there will loosen up a lot of old burned oil, helping the car to run better.[/QUOTE]

I can't agree with this one. Using proper diesel Oil should take care of it especially if you use full synthetic oil.

Note the additives that increase the cetane tend to quite down the fuel knock on older engines. Never driven a new car with a new diesel engine in it so can't comment on of the additive would quite it down a little.

Clemson88 · #11 05-14-2020, 06:31 PM

Quote:

Originally Posted by ah-kay

In your mind, yes. In practicality, no. This is my experience. Assuming the injectors were all balanced to start with.

...and went to ridiculous trouble to get them to pop at nearly exact same pressure. After putting them in it became obvious that the 617 ran exactly the same.

I console myself by thinking I need a spare set of perfectly operational injectors and ignore having bought new nozzles a pop tester and enduring a learning curve which is too embarrassing for description here.

ah-kay · #12 05-14-2020, 08:07 PM

Quote:

Originally Posted by Clemson88

...and went to ridiculous trouble to get them to pop at nearly exact same pressure. After putting them in it became obvious that the 617 ran exactly the same.

I console myself by thinking I need a spare set of perfectly operational injectors and ignore having bought new nozzles a pop tester and enduring a learning curve which is too embarrassing for description here.

Glad that you concur with me. The only thing that can quiet ithe engine down is running veggie oil. However, that is frowned upon by members here. By the way, a diesel is a diesel, you can't disguise it as gas engine no matter how quiet it becomes.

rocky raccoon · #13 05-14-2020, 10:01 PM

A quiet OM617 is one that needs a valve adjustment.

R.Diesel · #14 05-16-2020, 06:24 PM

I’d recommend driving them a few thousand miles before you decide to do anything else. In my experience injectors need some time to break in some brands more than others.

Diesel911 · #15 05-22-2020, 03:30 PM

When I first got my Car it was nailing. I already had a pop tester and knew how to rebuild the Injectors.

Pulled some injectors and looked at them and tested them and the nozzles were shot.

I rebuilt the Injectors with some brand X Italian Nozzles (this like back in 2008). The seller said they were made bye 7 Diesel. They quieted the Engine down.

After a few years I replaced them with Monark Nozzles because I wanted better quality nozzles. I don't remember any issues caused by the 7 Diesel Nozzles.

I did not retime my Fuel Injection pump for several years after I got my Mercedes. As I mentioned previously that timing is something else that can cause nailing.