Smoke at Idle -- Getting Picky - PeachParts Mercedes-Benz Forum

floydla1 · #1 07-01-2011, 12:21 PM

I have light, black smoke at idle that is more pronounced when the A/C is on. Is this normal?
I have replaced the injectors (twice), adjusted the valves, checked the compression twice (all within 400-410 psi cold engine), removed the EGR valve, ALDA bango bolt clean, diesel purge (twice), changed air filter (twice), checked stretch on the timing chain, timed using the drip method, then timed using a Kent-Moore Tach-N-Time / strobe (13-14 BTDC @ 750 rmp), done the Italian tune-up. The engine runs fine at idle, and cruises great, 0-60 in about 13s. The old gal uses no oil. Gets 25mpg on the road.

leathermang · #2 07-01-2011, 12:33 PM

Put new valve stem seals on. cheap parts, DIY labor just tedious....

floydla1 · #3 07-01-2011, 12:40 PM

I would have expected to observe blow-by and oil consumption to be symptoms of the seals. No?

floydla1 · #4 07-05-2011, 12:03 PM

OK. I have the stem seals and a valve cover gasket on order. Are there any special tools required? Thanks.

leathermang · #5 07-05-2011, 12:11 PM

Basically what is needed to set your valves once you have put the seals in .....
and you really really need to have a mental picture of the workings of the crank and pistons...
AS they are USED TO HOLD THE VALVE from DROPPING INTO THE BORE...
a nightmare situation ...
Since you are doing so much stuff to it.... and it would be a safety feature also.... I would pull the precombustion chambers ( AFTER PULLING THE GLOWPLUGS TO KEEP FROM DE CAPITATING them )... so that you can see that the piston is up to support the two valves you will be working on..
Anyway.... those 7 or so tiny radial holes which the fuel atomizes out of the bottom of your precombustion chamber.... if your pintle is in place and they are clean... are the heart and soul of the operation of your engine... so they need to be clean... and would be a shame to have 99 percent of the rest of the car in great shape... and that critical item ...which is almost NEVER checked... be affecting your fuel and power adversely....
So the pullers and stuff for them I would suggest renting from the rental forum on this site....
And for myself.... I would never have my engine all the way down to the stem seals and not renew the valve rotators... cheap and very good for engine longevity... if your engine only has them on the exhaust you can add new ones to both I and E... I would also never do that without putting new valve springs in... they are kinda important, cheap , and there would be NO extra labor putting them in since the old ones would be out on the bench already... just be sure to know which side of the springs goes Down...

You really ought to have the FSM in SOME form to do this stuff... all the warnings are posted there... which seldom get mentioned on forums...

floydla1 · #6 07-05-2011, 03:01 PM

Well, it seems that this is developing into a sweet little project! The valve rotators threw me a bit. Looks like I will be going to the dealership for the rotators and the springs. I have attached an exploded diagram -- if you could identify these rotators by reference number, that would be most helpful. As long as I set each valve at TDC, and cam lobes free, I would like to forgo pre-injector stuff for now.

You did not mention the stem seal mandrel, 617 589 00 43 00. In your opinion, can I get by without this tool? Thanks.

leathermang · #7 07-05-2011, 03:06 PM

I can not actually tell from that drawing..let me check my FSM...
but whatever the pictures.....
OK... they are below the springs when installed....
from the side perspective they are below the new valve stem seals because the valve guides stick above the block part way inside the springs..
Remember that some of the seals on the precombustion chamber are one time use... so you need new ones going back together...
In the FSM it uses #69 for the rotators....

When you get through with all this stuff.. you should be able to drive it with only minor regular maintenance for years...

floydla1 · #8 07-05-2011, 03:52 PM

Attached is a pdf file that shows a valve lifter cross section. I have marked what I believe to be the rotator. Can you confirm? A pdf print of the 2006 referenced thread is also attached. You identified the rotator as a #69 in this thread as well. Thanks again.

leathermang · #9 07-05-2011, 03:57 PM

Yes, that is correct....same view is used several times in the FSM.. nice they use the same numbers consistently.... LOL

leathermang · #10 07-05-2011, 04:00 PM

The only addition to that thread.... some engines only have them on the exhaust valves... the turbo's have them on both... but all engines can have them installed on both...

floydla1 · #11 07-06-2011, 09:46 AM

OK, parts on order from dealer:
Cap, Roto, PN 000-053-12-35, $13.00/ea
Valve spring, PN 615-053-01-20, $6.60/ea
The former is coming from Germany, so I have a little time to research pre-combustion chambers -- something I do not completely understand.

leathermang · #12 07-06-2011, 09:55 AM

Thanks for those parts numbers.... very helpful...
need to do this to my engine but can't get to it...
check PM's...

dieseldan44 · #13 07-06-2011, 11:51 AM

Im a little confused - if the OP is seeing no oil consumption - why would replacing the valve stem seals make a difference with smoke-at-idle?

Wouldn't it be better to check the pre-chambers first? Or the ALDA?

I have a similar issue with my donor engine so Im trying to learn here as well.

leathermang · #14 07-06-2011, 11:56 AM

Did you see how much stuff he had already done to the fuel part of his car ? I was going for the next most logical .... to me.... item...
and one often left off of even large restoration jobs... like vatting the engine when rebuilding... ever seen that mentioned here on the forum... by someone doing a rebuild ?

AND as I have said before..... the seals are cheap.. only tedious labor involved..but clearly DIY category...

AND it goes along with taking out the precombustion chambers perfectly , to make sure the piston is up to hold the valves while doing the seal job, to see that they are clean and the pintle in place...

dieseldan44 · #15 07-06-2011, 12:11 PM

leathermang,

i hear you - the two jobs do go well together. the OP's vehicle has only 145k and isn't seeing any oil smoke or reporting oil consumption. now i know stem seals have a lot to do with time as well as miles, but Im just saying.

im just trying to find out is there another logical place to go since i fear i may be going there soon. and stem seals with no benefit is a depressing thing to do.

for example what about the fuel pump pressure, or fuel pressure relief valve on the engine side of the IP that regulates fuel at idle? im just guessing - but im trying to think of other less labor intensive things to check.

floydla1 - are you running biodiesel or regular diesel? is this enough smoke that only you would notice or is it a lot?