hesham78

Hi Guys,

i had rough idle issues, after looking into O2's voltage reading on the OBD2, i've noticed that reading aren't correct, i suspected my O2's are bad, although no codes were showing,

I replaced all 4 O2's, car ran better, butt still had rough idle

the same day of my replacement, i filled some gas 95 octane, went back home

after maybe 7 hours of sitting, i turned on my car, and it blow a big puff of white smoke !!

within few sec's, it stoped smoking, and nothing came after, tried to rev car to see if there was signs of smoke, nothing

next day, i started the car, a little puff came out !

and the puff will come out anytime car sits for several hours


last thing i noticed p0422 and p0432, and cylinder 7 misfire

oil level is ok though ,,

any suggestions ?

M5 LOL

mine does that maybe once twice a year. from what Ive read through searching its more less nature of the beast.

chassis

White smoke and rough idle is consistent with coolant in the combustion chamber, for example from a failed head gasket. Tests to diagnose failed head gasket:

- coolant pressure test
- cylinder compression and leakdown
- exhaust gas test in coolant
- sweet smell from tailpipe
- white smoke or steam from tailpipe
- bubbles in coolant
- coolant consumption (level dropping in reservoir)
- "washed" piston crown
- "washed" spark plug
- spark plugs with significant differences in color from one another

Do you have any of the above diagnostic information?

decorily

..... and froth in or around oil filler./ dipstick (if you have one)

hesham78

What scared me out, that it never smoked, and it only happened after o2's been replaced

I forgot to mention my engine is recently re built

I noticed one of the breather hoses, the one that fits into the air box is too lean, could it be a reason ?

hesham78

Umm, i didnt check if there was any bubbles, plus i dont have issues with water level / consumption.

If was too scared that i didnt take my time to realize the smell.

It was something toxic maybe mixed with sweat ?

Anyhow, i forgot to mention my engine is recently re built, it only have 6k kms on it till now.

hesham78

Hii,

I didnt understand what did you mean ?

decorily

Sometimes with a head gasket damaged coolant/water can get in to the engine oil.
A sign of this can be a frothy, creamy substance showing inside the oil filler cap.

Yuille36

Basically your oil will look like a milkshake, and this is bad. Do need drive your vehicle and have this issue addressed immediately.

chassis

@hesham You need to do some diagnostic work. Do the inspections listed and post your findings here. If the engine is recently rebuilt, it is entirely possible the mechanic made a mistake and there is a coolant leak somewhere. It would be unfortunate, but it's in the realm of possibility.

decorily

Why was the engine rebuilt?

hesham78

Check oil cap today all is good, no milk shake signs, even inside the reservoir no oil signs.

hesham78

Umm, ill try to do a compression test

From obd2 readings what possibly could be wrong it

Bank 2 LTFT is high nevative ( - 18 )

And on WOTs it gose to 0.

​​​​​and from tail pipe on start up its a white puff of smoke only at startup


And i recently notice obd emission test

I have incomplete o2 + cats + secondary.

hesham78

Bad piston ring

hesham78

Update

So i opened my airbox filter, i noticed some oil on breather hose on the top of the cover valve + oil sludge on the back of the cover valve + some on the top of the coil packs + the pcv hose that is connected to the airbox has oil + y pipe

Engine has some blow by from filler cap, looks mostly like oil vapor but it dosent have pressure

Flipped the oil cap it was standing still

And from the backside pcv it had cutted blow by (vapor)

Any suggestions ?

hesham78

Update

Did a compression test,

Plugs were in good condition, not oily

Cylinder 1 had 60psi
Cylinder 2 had 105 psi

Others were all around 145-140 psi

Cylinder 4 was 175 psi

Could it be a head related issue ?

chassis

Cylinder 1 not good
Cylinder 2 questionable
Cylinder 4 strange

The M113 should be 10:1 compression ratio, correct? This means 150 psi or so.

Seems like there is high crankcase pressure from poor compression in cylinders 1 and 2. Based on not oily spark plugs and no pressure in valve chest.

What does the white smoke smell like? How does the engine idle?

Have you started reading the warranty document for the engine rebuild work?

Seems to me like a piston ring(s) or piston(s) issue(s). If it was a head gasket issue there is a high probability of coolant leaking out of the engine or into the crankcase. You said you don't see chocolate milk/milkshake. The rings could have been installed incorrectly, they have an up/down orientation and they need to be staggered/clocked. They could have been damaged by overstretching in the installation process. They could be the wrong dimensions/tolerance. A ring could have been forgotten. They could have been damaged during reassembly into the cylinder bore.

Is the shop you used a widely recognized expert in rebuilding Mercedes engines?

Have you done a coolant pressure test? Any bubbles in the coolant reservoir? Any combustion smell in the coolant reservoir?

hesham78

Hii, thanks for the reply

Yeah 1, and 2 have a bad compression

To be honest i though 140 - 145 is low too, a friend of mine said lowest psi they should have is 120.

A mechanic told me it should be 150, and a guy i know that re built his engine said , he's engine was around 180..


Anyhow, yesterday i took the car it stayed maybe 24 hours without starting, i didnt see any smoke on startup

Today morning i started the car, no smoke too

But i noticed that since last time you told me to check coolant level, it had a slight lose of coolant, i topped it maybe with 10 - 25 ml only.


Today, it was lower than last time maybe it need 20 - 30 ml

hesham78

Forgot to mention, idle is okaay, engine is slightly shaking, plus i dont have misfire codes on obd2

I remember my last engine when it had a bad piston ring, it was shaking and engine noise was weird + smoke out of tail pipe + oily rings


​​​​

chassis

@hesham78 Agreed that there are some cylinders with low (bad) compression. You added new information about coolant loss. This is sounding more like a cylinder head to engine block sealing problem. This can be caused by a failed cylinder head gasket or by a warped cylinder head or, less likely, by a warped or damaged engine block deck surface.

hesham78

Thought the same that it might be a head related jssue than block, the guy who did the compression did mention that mostly when 2 cylinders near to each other have a bad compression it could be a head issue, other said if its i bad head gasket both cylinders will have same pressure,

Anyhow, will update you guys on whats new.