Mercedes vito 112 w638 compression test help needed please

[Dion]

Hello all,im new to the forum and hope someone can help me with some information/help.
I cannot find anywhere in this world,looked hi and low,with no luck.
Does anyone know what readings i should be expecting to read in PSI when performing a compression test on a vito 112 w638 turbo diesel?

Thank you i welcome your help.

 

[Kev555]

Hi Dion sorry somebody didn't answer your question earlier, I haven't been about the forum much lately. i Did a compression test on my OM651 engine a couple of years ago.
https://forums.mercedesclub.org.uk/index.php?threads/om651-not-starting.173065/post-1685902
Not the same engine but might give you an idea if you haven't already sorted the problem.

 

[Mr Greedy]

I tried 18 months ago to find someone local to me to do a compression test on a 2.0L diesel. No one I could find. In the end I sold the car rather than start buying specialist tools to start the fault finding rabbit hole myself.

 

[Dion]

I tried 18 months ago to find someone local to me to do a compression test on a 2.0L diesel. No one I could find. In the end I sold the car rather than start buying specialist tools to start the fault finding rabbit hole myself.

Yes its amazing how this info is not available.
I did a comp test through the glow plug orifice
cylinder 1 ,,,,360 psi
cylinder 2,,,350psi
cylinder 3,,,330 psi
cylinder 4 ,,,330 psi
All brand new Bosch injectors,all new glow plugs,,,but still seems to be over fuelling,,,due to unburned fuel

 

[Kev555]

That test looks strong without knowing the proper psi of that engine/ mileage? now that you've posted the over fuelling issue Dion, some of the indies on here might be able to point you towards what might be causing the issue. Could be something as simple as a temp sensor on the engine faulty. It does seem like some sort of a sensor issue as it looks like injectors and compression ruled out.

 

[Dion]

That test looks strong without knowing the proper psi of that engine/ mileage? now that you've posted the over fuelling issue Dion, some of the indies on here might be able to point you towards what might be causing the issue. Could be something as simple as a temp sensor on the engine faulty. It does seem like some sort of a sensor issue as it looks like injectors and compression ruled out.

Hopefully
4 x new Bosch injectors,,,correct pat number/superseeded
4 x bosch glow plugs
new high pressure pump
new low pressure pump
new rail pressure regulator
new rail pressure sensor
new boost sensor/map
turbo checked ok
compression seems ok from test
you can tell on cold start it does not fire on all cylinders until it warms up,then smooths out when warm
Drives fine but smokes when you stop at lights black/grey
also smokes very fine when driving

 

[LostKiwi]

Have you put it on diagnostics to look at the live values from the sensors?

 

[mattkh]

I did a comp test through the glow plug orifice
All brand new Bosch injectors,all new glow plugs,,,but still seems to be over fuelling,,,due to unburned fuel

I am not suggesting that you buy a new ECU.
I appreciate you have changed a lot of items, but all these things are under the control of the ECU.