injector service interval question - PeachParts Mercedes-Benz Forum

farmfuel · #1 09-10-2010, 11:51 AM

Hi to all; this will be my first post. I'm very excited to own my first 300D, and I'm a VERY big fan of the OM617 engine. I've been looking for a while for a good deal, and finally made a move on an 84 model 300D turbo that runs and drives for 600. I'm really happy with the car. The interior is perfect, minus a couple of cracks on the dash.

I'm writing my first question with regard to the service interval for the injectors. It seems that I remember reading somewhere about how the injectors need to be shimmed every 70K miles? Does this sound correct? I notice when the engine is cold, that it runs with a hard miss, almost like there's a dead cylinder. When it warms up, it runs really smooth. I haven't cracked the injector lines one by one, but I'm just wonderring if the spray pattern is poor on one injector due to the pop off pressure being incorrect. This almost doesn't make sense though, cause if that were the case, it would do it constantly- cold or warm.

I'd like to hear your opinion on when the injectors need to come out and be overhauled. My odometer has stopped at 154K, and I'm sure it is well past that. I may have another issue, and if you've experienced your engine running rough like I describe, perhaps you know the fix? Thank you for your time.

tangofox007 · #2 09-10-2010, 12:04 PM

Quote:

Originally Posted by farmfuel

I'd like to hear your opinion on when the injectors need to come out and be overhauled. My odometer has stopped at 154K, and I'm sure it is well past that.

In my experience, turbo injectors with that much time in service will be popping in the low 120-bar range and 2 or 3 will be streaming instead of spraying.

farmfuel · #3 09-10-2010, 12:21 PM

I've been quoted 65$ apiece for overhaul. If all 5 were in need of overhaul, that's going to put the bill well over 300$. That's a pretty good chunk of change. Maybe ebay has a better price on them?

I wonder who you would reccomend to overhaul the injectors?

Aquaticedge · #4 09-10-2010, 01:14 PM

C Sean Watts I think does injectors still. chances are the EEK!bay finds are gonna need work or just crappy. you might as well get yours rebuilt and that way you know they work.

C sean Watts did mine and I'm delighted with them.

Diesel911 · #5 09-10-2010, 05:03 PM

Quote:

Originally Posted by farmfuel

I've been quoted 65$ apiece for overhaul. If all 5 were in need of overhaul, that's going to put the bill well over 300$. That's a pretty good chunk of change. Maybe ebay has a better price on them?

I wonder who you would reccomend to overhaul the injectors?

I can not comment on rebuilt Injectors sold on eBay but I can on the so called "running pulls" that are used Injectors supposed to be in good shape. All the ones I bought like that were worn out.

Concerning the miss. If an Injector is not spraying well the Fuel does not burn well. As the Engine heats up the Fuel even the bad Injector will burn better and the symptom may go away.

Do a Valve Adjustment before you start pulling Injectors.

Also the missing symptom you describe can be a Faulty Glow Plug.

DIY Repair Links
http://www.peachparts.com/shopforum/forumdisplay.php?f=82
http://www.peachparts.com/Wikka/DoItYourSelf

Somewhere in the above threads the on concerning injectors there should be one or more of my pics showing the tiny drilled passages in the tip (Pintlel) of the Injector. On my own car and most of the Injectors I have pulled from the Junk Yard those tiny holes were plugged solidly with Carbon. The hole is there to pass the Idle and low amouts of Fuel Through.

Diesel911 · #6 09-10-2010, 05:13 PM

Another issue with buying rebuilts from a Bosh shop or buying Bosch Rebuilt Injectors is that the Spray Nozzles for your model and year are all made in India now. And unfortunately they do not have a go reputation for quality control yet.
So, if you by Bosch Rebuilts you are going to get the Made in India Nozzles.

C Sean Watts also sells the Made in Germany Monark Injector Spray Nozzles for less than you can buy the Bosch ones. You might ask him his price and then ask a Local Fuel Injection Shop how much they would charge to rebuild them with your own Spray Nozzles.

Manual Life · #7 09-10-2010, 06:13 PM

once i get my engine in and running i can let you know if you can have my rebuilt injectors. put bosche nozzles had them pump tested and ran them 300 miles.

if you are interested then pm me, i'm not looking to get much for them, maybe just the cost of the nozzles.

farmfuel · #8 09-10-2010, 08:02 PM

[QUOTE=Diesel911;2542272]Also the missing symptom you describe can be a Faulty Glow Plug.

Thank you so much for the links. I wasn't aware that there was a valve adjustment; I figured they were hydraulic lifters. I'm looking forward to working on this engine.

I was thinking the same thing about the glow plugs, but usually you'd see white smoke due to a bad glow plug in a cylinder, and it's still upper 90's over here in the Dallas area. This makes me think the glow plugs aren't to blame. I haven't noticed any white smoke, but the missfire seems to last a while- well past the point that it would take a cylinder/prechamber to warm up.

If the injectors are indeed a maintenance issue, I might as well go ahead and get it knocked out. I'll be checking into that valve lash adjustment as well; thanks for the reccomendation.

You can't spit without hitting one of these OM617 powered Benz' out here at the wrecking yard, so I might go grab some spare parts this weekend. I wonder how much it costs to overhaul an IP?

Aquaticedge · #9 09-10-2010, 09:18 PM

if you send an IP in to a bosch service center. I'm sure an obscene amount.

Diesel911 · #10 09-10-2010, 09:24 PM

[QUOTE=farmfuel;2542346]

Quote:

Originally Posted by Diesel911

Also the missing symptom you describe can be a Faulty Glow Plug.

Thank you so much for the links. I wasn't aware that there was a valve adjustment; I figured they were hydraulic lifters. I'm looking forward to working on this engine.

I was thinking the same thing about the glow plugs, but usually you'd see white smoke due to a bad glow plug in a cylinder, and it's still upper 90's over here in the Dallas area. This makes me think the glow plugs aren't to blame. I haven't noticed any white smoke, but the missfire seems to last a while- well past the point that it would take a cylinder/prechamber to warm up.

If the injectors are indeed a maintenance issue, I might as well go ahead and get it knocked out. I'll be checking into that valve lash adjustment as well; thanks for the reccomendation.

You can't spit without hitting one of these OM617 powered Benz' out here at the wrecking yard, so I might go grab some spare parts this weekend. I wonder how much it costs to overhaul an IP?

Fuel Injection Pump overhaul is like $1200 and up. But, as you said there is a lot of used Mercedes in your area.

Gillig · #11 09-11-2010, 05:59 PM

There is no service interval for the injectors. Its simply recommended by most enthusiasts to have them physically cleaned and checked every 100k miles. Replace the nozzles as needed if cleaning won't restore a good spray pattern.

Cleaned = Removed from the engine, disassembled and put through an ultrasonic cleaner. "Mechanic in a can" fluids will not clean them thoroughly.