0M 603.971 Cold Starts, right up Then: - PeachParts Mercedes-Benz Forum

Uncle Benzz · #1 10-22-2018, 07:57 PM

Idles smooth for 25 -30 seconds then runs not so smooth. Then smokes. I removed the air intake from front of turbo saw some oil film on turbo inlet. EGR is connected. Zero blowby off oil cap and breather hose. The idle sounds like a trotting horse.

I want to install new injector nozzles. Thoughts

tjts1 · #2 10-22-2018, 09:14 PM

Disconnect the EGR.

Uncle Benzz · #3 10-22-2018, 09:20 PM

Quote:

Originally Posted by tjts1

Disconnect the EGR.

My Understanding is this will have issues on the w140 with computer.

wwii · #4 10-24-2018, 09:47 AM

Quote:

Originally Posted by Uncle Benzz

My Understanding is this will have issues on the w140 with computer.

I can't confirm but I also had this impression. I must have gotten that impression by reading something either in my manual or in a forum (maybe in the w140 forum at benzworld.org - not many diesel ppl over there but there are some). What I recall is that when the computer asks the egr valve to operate it expects to see a change in intake pressure and if it doesn't it thinks there is something wrong with the boost pressure (P2) control loop and dumps the boost pressure - or maybe something more sinister like if you mess with the egr we're not going to let you have boost. I haven't tried it yet, it's near the bottom of my priority list, but if I can find where I read that I'll add a post.

Quote:

... simple thing to pull the plastic tube out of the EGR valve and heat the open end of it until it melts closed...

I've also seen posts of putting a bearing/bb/steel ball in the tube to block it.

If you try it please post your results.

dieselbenz1 · #5 10-24-2018, 09:52 AM

Quote:

Originally Posted by wwii

I can't confirm but I also had this impression. I must have gotten that impression by reading something either in my manual or in a forum (maybe in the w140 forum at benzworld.org - not many diesel ppl over there but there are some). What I recall is that when the computer asks the egr valve to operate it expects to see a change in intake pressure and if it doesn't it thinks there is something wrong with the boost pressure (P2) control loop and dumps the boost pressure - or maybe something more sinister like if you mess with the egr we're not going to let you have boost. I haven't tried it yet, it's near the bottom of my priority list, but if I can find where I read that I'll add a post.

I've also seen posts of putting a bearing/bb/steel ball in the tube to block it.

If you try it please post your results.

I can confirm that for you all boost will be lost exactly as you described no change in MAF.

wwii · #6 10-24-2018, 09:58 AM

Quote:

Originally Posted by dieselbenz1

I can confirm that for you all boost will be lost exactly as you described no change in MAF.

AHA!!
I've wondered how hard it might be to fake the computer out so you could delete the egr - probably start by taking a bunch of measurements.

R.Diesel · #7 10-31-2018, 07:37 AM

Quote:

Originally Posted by wwii

I can't confirm but I also had this impression. I must have gotten that impression by reading something either in my manual or in a forum (maybe in the w140 forum at benzworld.org - not many diesel ppl over there but there are some). What I recall is that when the computer asks the egr valve to operate it expects to see a change in intake pressure and if it doesn't it thinks there is something wrong with the boost pressure (P2) control loop and dumps the boost pressure - or maybe something more sinister like if you mess with the egr we're not going to let you have boost. I haven't tried it yet, it's near the bottom of my priority list, but if I can find where I read that I'll add a post.

I've also seen posts of putting a bearing/bb/steel ball in the tube to block it.

If you try it please post your results.

What about crankcase pressure and blowing out oil seals?

Diseasel300 · #8 10-31-2018, 10:03 AM

Quote:

Originally Posted by R.Diesel

What about crankcase pressure and blowing out oil seals?

EGR is Exhaust Gas Recirculation. It has no effect on crankcase pressure since exhaust gas doesn't route through the crankcase (except for blowby gasses obviously, which are routed through the breather system).

Smeans92 · #9 10-22-2018, 10:30 PM

This is sounds similar to what my om603.96 does.
It most likely idles smooth for the first 30 seconds or so due to your afterglow then when the glow plugs turn off you get poor combustion.
What is your oil consumption? Have you done a compression test? What color smoke? What's it smell like? Does it continue to smoke when its warmed up?
Common things that cause cold start smoke are, valve stem seals, head gasket leak at cylinder 1, bad injectors and low compression on one or more cylinders

Uncle Benzz · #10 10-22-2018, 11:07 PM

Smoke is a puff of bluish,but smells like unburnt diesel, not oil. She will emit on occasion. When I removed the air intake from the turbo the impeller had no play but oil was there in a small line about an 1/8th of an inch in width by the impeller travelling out.. The wild thing is that the idle tends to lope, But she runs nice out with not alot of smoke on the highway,just usual haze. Shes using about quart every 700-800 miles. Coolant is clear. Temp stays around 80C/hair over. I'm in the Northeast and heat is hot, and AC is ice cold. My cylinder head is a #18. I know she sat a while before I got her,possibly coked up?. I believe a set of new injector nozzles are due. Only has 112k on her. I love this 140. I'd like to put an 606 super in her. IF my wallet will allow.

Quote:

Originally Posted by Smeans92

This is sounds similar to what my om603.96 does.
It most likely idles smooth for the first 30 seconds or so due to your afterglow then when the glow plugs turn off you get poor combustion.
What is your oil consumption? Have you done a compression test? What color smoke? What's it smell like? Does it continue to smoke when its warmed up?
Common things that cause cold start smoke are, valve stem seals, head gasket leak at cylinder 1, bad injectors and low compression on one or more cylinders

g-wizz · #11 10-23-2018, 04:09 PM

run it hard see if that changes anything. some oil in the compressor housing? or does it look like its flinging oil?
can you inspect your timing chain slack?
the injectors should more or less last the lifetime of the vehicle with maybe an overhaul or two. i wouldn't replace them. they are not spark plugs.

should only haze on the highway if your floored.

you can either disconnect the egr or block it off and leave it connected. basically YOU DONT WANT IT TO FUNCTION regardless of what the computer thinks is happening. never has it been a good idea for an engine to ingest exhaust gases or oil vapors.

Uncle Benzz · #12 10-24-2018, 12:30 AM

Can you recommend a block off plate source that will fit correctly? I'm all for it. The engine fires immediately. Timing may be an issue. As well as idle smoke. She rolls up to 100 mph quite well with that nice sounding 1/2 dozen sound. Pump timing/Timing chain slack may be off too. WHY? I can hear a miss once in a while in the exhaust. I ran a diesel purge twice. Lots of carbon in the purge liquid. Almost zero smoke and idle was smoother. I really love this barge. It is in great shape. I just have to get the MB HEX off her.

Quote:

Originally Posted by g-wizz

run it hard see if that changes anything. some oil in the compressor housing? or does it look like its flinging oil?
can you inspect your timing chain slack?
the injectors should more or less last the lifetime of the vehicle with maybe an overhaul or two. i wouldn't replace them. they are not spark plugs.

should only haze on the highway if your floored.

you can either disconnect the egr or block it off and leave it connected. basically YOU DONT WANT IT TO FUNCTION regardless of what the computer thinks is happening. never has it been a good idea for an engine to ingest exhaust gases or oil vapors.

vwnate1 · #13 10-24-2018, 12:58 AM

It sounds like you're on the right track here, it's a simple thing to pull the plastic tube out of the EGR valve and heat the open end of it until it melts closed, then shove it back in....

Loping idle can be many things, unless you run a diesel purge and get clear fuel coming back into the purge jar there's prolly still some crud in there ~ I like to set up the purge jar and drive the car using various speeds & loads so the rack gets fully opened and closed when purging .

Often a loping idle is simply a drooling injector ~ most Indie Mercedes Shops can pop test your injectors cheaply if you carry them in .

dieselbenz1 · #14 10-24-2018, 10:42 AM

On my 92 if you disconnect the MAF it resorts to full boost as required and maintains the over boost protection. Others and I'm not sure of the vechile years have said disconnecting the MAF did nothing.

vwnate1 · #15 10-24-2018, 11:02 AM

Dang computers ! .

It's another simple thing to buy a $15 1-1/2" fuel pressure gauge that goes to 15 # and connect it to the intake manifold to see what happens when you block the EGR's vacuum pipe .

My old Mercedes has no computers in the fuel injection so I use the added gauge to keep an eye on what's happening with each change I do .

Now up to 13.4 PSI boost and tweaking the ALDA in 1/8 to 1/4 increments, boy howdy do I have more power, better off idle acceleration and 5.5 more MPG's the last fillup .

Just blindly tweaking things isn't wise .