Injectors?

O.K. Time to deal with the Nailing in #1 cylinder. From what I've learned here over the last few months, I need to check:

1.) the injector nozzle, and

2.) the timing chain for stretch.

Questions re: nozzle. When I pull the nozzle, what pieces and parts do I need to be aware of? As in, are there seals or gaskets or grommets? Do I need to have replacements for any of these on hand? Once the nozzle is out should I try a basic solvent cleaning and then put it back in and test?

The chain comes later.

Thanks, guys.

[Billybob]

For your 617.950 engine, MB #601 017 00 60 Seal Ring, AKA Heat Shield, is a washer that goes under the injector/nozzle holder is supposed to to replaced each time you R&R an injector.

Thanks, Billybob. I'll get the part before I pull the nozzle.

[autozen]

Mccan,

A friend and I just picked up an exquisite 1980 300SD in San Francisco as a project. It allegedly had a bad engine and wouldn't start. To make a long story short,I adjusted the valves, replaced a leaking hand pump, and replaced a clogged fuel filter. The car ran great except for the nailing in /#2 cylinder.

I've been a professional MB mechanic for 30 years, and my first inclination would be to install rebuilt injectors. My partner who grew up as a farmer from the midwest,I say that because I can't spell Missouri, said he'd just take em apart and clean em. Well the nailing is gone. I now have to agree. You can disassemble the nozzles and clean all the crud that makes them hang up. I offer a couple of tips: don't forget to clean the tiny holes in the pintle, and torque on assembly. Cracking pressure is determined by little washers in the injector. Do not lose them in the process.

Good luck,
Peter

[elatu]

My '85 300CD's #1 and #5 injector look like they are leaking....could this just be the seal???? This is the first time that I am getting into fixing up an MB by myself and would like some advice. Thanks! You guys are wonderful!

[autozen]

elatu,

99% of the time what looks like an injector leak is really the 3.5 mm fuel return hose or in the case of #5 possibly the end plug.

Peter

Peter,
Great stuff. Only problem is i don't know from 1.) a pintle, 2.) cracking pressure. Can you help walk me through the disassembly, cleaning, reassembly procedures? Or does your dude from the Show Me State have pictures.
Thanks.

[Billybob]

I've got a 126 CD that has the info for a 617.951 engine, it's in the 617 engine manual 07.1-135 Testing and 07.1-137 Cleaning, your 617.950 shouldn't be too different.

P. S. I just sent you an e-mail with the procedures as attatchments in case you can use them now.

[surfblau]

I am still a junior member and otherwise new dieseler, but how do you know which cylinder is nailing?

I think I can identify that the engine is nailing, but how do you know which specific cylinder?

Sorry if this is somewhat elementary...


:p

It is nothing more than a slightly-educated guess. The noise is like a ballpeen hammer hitting a cannon ball; I assume that is nailing. The noise is way forward in the engine but short of the timing chain. The archives of this forum indicate that nailing will take place most often in the #1 cylinder. So I assume #1 cylinder. Maybe not the most exacting of empirical data upon which to base my speculation, but it's a start.

After reviewing the specs. graciously emailed by billybob, I may pass this job onto someone with more tools and experience.

[autozen]

Blue Surf,

Mccan is pretty much right on. To put it another way, if you drive up in a diesel and nobody really notices, that's normal. When you drive up and they ask. "What's wrong with your car"? That is nailing.

Mccan,

Don't be overcome by the special gage and cracking pressures etc. Remember my friend the farmer. Just take them apart, clean them and reassemble them. This is one of the few places I observe torque specs. I also torque head gaskets, steering box bolts, valve bodies, and brake calipers. This procedure is not by the book, but it will probably work fine. I don't mean to undermine procedures followed by professional mechanics. They follow accepted proceedures to insure the client has no problems after the service. Let's face it we're cobnobbing here to save money so it's ok. Go for it.

Good luck,
Peter

O.K., Peter, I'm feeling inspired. I really do want to see what makes these things tick. Literally.

[h2odiesel]

Guys,
A quick way to isolate a nailing cylinder or faulty injector is to lossen each injection line at the injector one at a time while the engine is running. Each time the engine speed should decrease by a similar amount. If one make less of a difference or the nailing stops you've got the bad one. Remove and clean that injector.

I've got the Bosch test unit on my bench at home, what I need is a supply of the shims to set pop off pressure. Anyone who comes up with a fist full gets a set of nozzles cleaned and balanced for free!

Bob,

I'll be going back to the salvage yard in the next week or two. I'll pull as many injector nozzles as I can find. I'll be happy to send you some shims. What size deep well socket do I need?

Re: loosening the injector line. Do I loosen the injector line at the pump or at the nozzle? Does it matter? And will there be some diesel coming out of that line when loosened? I am assuming so.

[leathermang]

To keep from bending the metal fuel lines you should loosen them at both places... If you get near a front injector line for a 300 engine I need one.... I took this one off to make a "start of fuel delivery tool" for my other car.... now I need it replaced.... Greg