Starting then stalling problem, strange. - PeachParts Mercedes-Benz Forum

ubertino · #1 10-20-2010, 06:58 PM

I've searched this pretty well, and not found anything quite like what I'm experiencing.

I've got new glow plugs, the valves are in adjustment (just done) and I've also run a diesel purge, replacing both fuel filters at the same time.

When starting the car (in cold mornings) I cycle the plugs once. Car starts right up, within 3-4 seconds, and runs very smoothly for about 2 seconds, no smoke, no problems. And then, it coughs, the idle drops from 750 to close to 500, belching out grey/blue smoke the entire time, and then stalling. The colder the morning, the faster the stall. If I give it some throttle, just enough to get it around 900 rpm or so, it runs rough, kicks out lots of smoke, and in general hates the world.

But, when the engine is warm, regardless of the external temperature, it runs great. Good power, starts immediately when warm, with or without glow plugs. When it's warm there's only smoke if I open the throttle all the way at highway speeds, and I can only see it at night with the headlights of the cars behind me.

I'm thinking that I might have an injector going bad, so the fuel isn't atomizing properly when it's cold, and going out the tailpipe. When it's warm, even though it's not atomizing properly, it's combusting better because of the heat, so it's not noticeable. Unless it's an injection pump issue, or I really cocked up one of the valves when I adjusted them, and that clearance difference is only a problem with startup. Since I got the car in April, it has always run poor during cold starts, but improved to a normal idle very quickly, in far less then a minute. As the cold has increased, so has the stalling, but I also adjusted the valves around the same time too.

All of that said, if it is the injectors, should I get those bosio nozzles that people talk about, or take mine for a rebuild? I've got, hopefully, 150k on them. Unless the car has a newer odometer, which is always a chance on these cars.

W124 E300D · #2 10-20-2010, 07:28 PM

I'd pull all the injectors and hand them to a specialist injection shop for a full service, all they need to know is the vehicle, or just drive the car to the injection shop and have them do it all, including cleaning the seats and putting in new coppers etc.

If you DIY go to the injection shop FIRST, they will give you a handful of blanks to seal the end of the injector lines and injector holes.

grey smoke is insufficient (atomised) fuel and incomplete combustion.

This
http://www.youtube.com/watch?v=w4MjC1Ywofg
is actually a great video for learning about diesel smoke types.

turn the sound UP, and listen through the stereo, not laptop speakers.. >;^)

ubertino · #3 10-20-2010, 07:42 PM

We have a great shop out here that specializes in rebuilding injectors, so I'll make an appointment with them.

I love solvable problems!

destroy · #4 10-21-2010, 11:51 AM

What else can go bad on these injectors other than the nozzles?

I've had stalling issues on both of my cars when it's cold, but the newer one is a lot nicer than the old and runs quite well, very smooth and responsive with plenty of power. Makes me think this might be it.

destroy · #5 10-21-2010, 11:54 AM

What else can go bad on these injectors other than the nozzles?

I've had stalling issues on both of my cars when it's cold, but the newer one is a lot nicer than the old and runs quite well, very smooth and responsive with plenty of power. Makes me think this might be it.

barry123400 · #6 10-21-2010, 01:19 PM

This is kind of a comment on the modern world. Ask the shop to check the injectors first. They may be fine. Who knows when and if the injectors have been dealt with prior to our aquisition of any car. Unlikely but always possible.

In my opinion if you just ask a shop to rebuild the injectors thats what they might do even if in good condition. In a way I find it sad to post a thought like this. On the otherhand it is obvious from examining several recent garage service bills of other people things are not getting better out there.

barry123400 · #7 10-21-2010, 01:31 PM

Quote:

Originally Posted by destroy

What else can go bad on these injectors other than the nozzles?

I've had stalling issues on both of my cars when it's cold, but the newer one is a lot nicer than the old and runs quite well, very smooth and responsive with plenty of power. Makes me think this might be it.

Amount of fuel available without air and at a reasonable pressure just after starting should be checked carefully first. Otherwise the engine can start and fuel availability is not adaquate or solid enough to give the injectors the amount they should have.A cold engine is more fuel quantity sensitive. So engine dies out if not there.

Easy initial test is to hook up a clear line to the return fitting on the injection pump. Submerge the end in a glass container containing fluid so you can see what is going on. Level of fuel should increase with no air coming through. You need someone to start the car while you observe. A glass food bottle or any other narrow bottle is best for this test.

If the level of fuel does not increase or air is coming through you have good grounds to investigate further. If the level of fuel does not increase. No fuel is coming through. Base fuel pressure in the injection pump is substandard.

ubertino · #8 10-21-2010, 01:47 PM

I'll take it to the diesel shop just to see where the injectors are in their life, that's good knowledge to have. Ill also test the pump, although from all of the yellow paint on each fuel line where it goes into the pump I'm pretty sure that the pump was rebuilt at some point.

I'll post back after tests!

barry123400 · #9 10-21-2010, 02:02 PM

Fuel pressure in the injection pump base is not determined by the injection pump other than the pop off pressure point of the relief/return valve. The relief/return valve can deteriorate with time as well.

Air getting in is of a simular nature. In that it is not dependant on the injection pump either. The injection pump only becomes an issue with air ingress usually on the newer type injection pumps after 1985.

Certainly This area will not be the cause in many cases. It is just so easy and cost effective to check it out first though. These cars are very old remember.

ubertino · #10 10-22-2010, 10:55 AM

I pot some B100 from a local co-op to use in the jar. Since I was there, I got 20 or so gallons of the stuff to run through. Big difference in starting up, power, everything. This bio stuff is amazing!

But, I also discovered that the rear hatch is covered in tiny soot particles (B100 cleaning me out no doubt) mixed with greasy oil. I think this confirms my injector theory- there shouldnt be any oil unless it wasn't combusting properly. Right? Or maybe I found a new problem? This can't be normal for B100.

mach0415 · #11 10-22-2010, 02:17 PM

I just made B100 and the car started doing the same thing. Fuel is very dirty, so I think your theory is correct about this. And the nozzles may need attention, as well.

QS23 · #12 10-26-2010, 04:06 PM

Quote:

Originally Posted by ubertino

We have a great shop out here that specializes in rebuilding injectors, so I'll make an appointment with them.

I love solvable problems!

Where is said shop because I'm thinking my injectors are having issues as well.

Biodiesel300TD · #13 10-26-2010, 04:16 PM

You might also have a clogged tank strainer. Try switching the supply and return lines in the engine bay. This will bypass the tank strainer. Then see if you still have the issue. Swappying the lines is a troubleshooting technique, don't leave then swapped indefinetly.

ubertino · #14 10-26-2010, 04:42 PM

Quote:

Originally Posted by QS23

Where is said shop because I'm thinking my injectors are having issues as well.

Diesel injection services, just south of grand rapids. Prices don't seem too bad, $5-10 to test, $45-55 to rebuild, and $180 to have them do the labor of taking out and putting back in the injectors.

ubertino · #15 10-26-2010, 04:45 PM

Quote:

Originally Posted by Biodiesel300TD

You might also have a clogged tank strainer. Try switching the supply and return lines in the engine bay. This will bypass the tank strainer. Then see if you still have the issue. Swappying the lines is a troubleshooting technique, don't leave then swapped indefinetly.

I'll do that tonight! Still need to do the clear hose and jar test. If it helps any, the clear hose that goes from the ip to the fuel filter assembly has on air in it. When I put in new filters there was air in the line that went away when I primed the pump, this is what makes me think that there isn't any air in the system.

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