zenman63

As above I have a 28000 mile late 2012 engine coming that has seized up.
It had open injector fault that thinned the oil to the point of seized.

Now I intend to put it apart but just thinking how I can turn it over to get the cam brackets on to get the heads off?

Worst can you press the pin out the timing chain

zenman63

I have moved on with this now, chain was not a problem as we removed the cams with the adjuster still fitted.
It had not seized up after all, its hydro locked and bent a rod, engine is other wise mint inside.
New rod coming direct from AMG £154 plus vat.
New bolt set £400!!!!!!! that the full engine and gaskets.

chrisridebike8

So what ended up happening? You had an injector stuck open that hydrolocked the motor? Was there a CEL prior to the engine stopping at all?

zcct04

Congratulations - that sounds like very good news!

I have never pulled down a hydrolocked engine before. Is there any damage to the cylinder wall from the piston being pushed sideways when it locked? Any way to confirm that the crank was not bent?

chrisridebike8

I might be wrong but I think machine shops can inspect the crankshaft to make sure it's true. It seems like labor will be the killer on this job.

CarHopper

It will be. A bent rod means at the very least you have to really break down and inspect everything again. You're basically rebuilding the motor.

zenman63

No damage to the cylinder just a slight bend in the rod and it jams the end float on the crank, as soon as the crankcase was opened up the engine would turn over.
This engine is all done now, every bolt is torque to yield all over this engine and has to be replaced and there not cheap! hours spent cleaning up the parts as they have to be Very clean for the case sealant to stick.

Celicasaur

I can only imagine how much of a PITA that would have been to rebuild ^

Buying all of the TTY bolts can't have been nice...

DavesMeanE's

I wouldn't say it's a "common" issue - but I have replaced about 15-20 M156 injectors for sticking opened and causing drivability/ misfiring. Have also had them hydrolock. I have however never seen one bend a rod - although I have heard of it. It is mostly a issue on early M156 cars. Injectors went through many revisions, and are on Rev.5 at the latest. this is indicated by the "Q" number on your injectors. Q2, Q3, Q4, Q5 - like that... it will be etched in near/under the part number

Generally, Q1/Q2 have been the only ones I've replaced, although I have heard of Q3's failing also. Q4/5 i have never seen or heard of any issues on.

Thanks!

Dave

Vladds

I wonder if theis has anything to do with running or not running injector cleaner.
You can also take the injectors out, bring them to an injector shop and have them ultrasonically cleaned. Those people will determine any possible leaking or onset of this.


You can also take the car to Mercedes, which for around $200 will hook up the car at the rail, through a valve to a cleaning rig that put their solvent/cleaner through the injectors.


Now the downside of too much cleaning with the injectors on the car is that the oxygen sensors can be affected.


But with this factory cleaning rig, I wonder if Mercedes can't inject one at the time and figure exactly how well every injector works.


Star C5 has something to test the injectors, but to me its a crude test where injectors are turned off one at the time and you're supposed to feel the rpm drop.

JimGnitecki

Dropping cylinder output one cylinder at a time on a multi-cylinder engine, and comparing the rpm drop, may sound crude, but I recall only too well that that was the official way that many motorcycle manufacturers years ago told you how to "balance" the 2,3,4, or 6 carburetors on a multi-cylinder bike (By yanking 1 sparkplug wire at a time). It DID produce reasonably consistent results despite the primitive methodology.

Jim G

Vladds

For the 4 cylinder Alfa Romeo engines, (these were boxers with two banks of carburetors, one on each side), the official method, in the 80's was to use a water level vacuum gauge and then adjust the mixture screw based on the readings.
I found that adjusting the idle screw, without the gauge worked at least as good, because the imbalance was at idle, the carburetor idle jets were at different states of jet clogging, but once the engine got going, the main jets were basically not clogged at all.


So anyway, even if the Star stops the injector, it needs to continue the spark, because I guess the point is to see if the injector is leaking. If it leaks, stopping it wont stop the cylinder and the engine won't slow down.


But if the injector DOES work and the cylinder stops, there is quite the jolt.


Because this is a method based on feeling, you have to calibrate your feeling first, so you have to stop all of them so as to get a feel for what the jolt is like and make sure they're all the same.
Then start over, this time for real.


Now these jolts can't be good for the engine, or at least not for the motor mounts.
And that's why I call it crude.


But yes, there were many crude but cool things that we were doing with carburetors.
One was the ad-hoc carburetor cleaning, meaning you did not want to take it apart and clean the jets individually.
Then you revved the engine from the bay and gave it wide open gas with one hand and chocked the carburetor air mouth with the other.
The car would roar and then ..... make a muted sound and hopefully gulp the clog in the jet.
Customers and pedestrians would be freaked out.

Vladds

The injectors never changed part number and in fact are the same part number for pfl and fl.