how to fix m276 engine rattle on startup
This is a walkthrough of how to fix the timing and engine rattle on mercedes Benz m276 series engine.
When this vehicle came into the shop after sitting long enough to let the oil pressure bleed off it would rattle on startup until oil pressure built back up. It also had a code for bank 1 intake timing deviation from specified value.
With scan tool connected monitoring the variable camshafts we found that bank 1 intake wanted approximately 45 degrees of timing and it was only achieving 42 degrees of timing. The other three camshafts were all bang on. So we knew before even opening the engine we had to pay extra close attention as to why we were out of timing by 3 degrees.
Now Mercedes Benz has multiple technical service bulletins on these series of engines regarding rattle on startup. Make sure you acquire all the information you will need.
Check your engine code as some minor differences are present between different versions of the same engine. Some differences are simple things like the size of the bore for the engine check valve you will have to install. if you have the wrong sized one obviously you will encounter problems.
Make sure to acquire the most current tsb for the engine version you have regarding rattle on engine startup.
Now you are ready to start tearing into your engine and completing the tsb service procedure for installing updated timing chain tensioners and check valves.
Well you are in there make sure to check you're variable valve camshaft actuators for failing. In my video we have a bad camshaft actuator as well as the tsb work to complete.
Good inverted torx set
T100 socket for camshaft actuator
Check valve installer tool
Rags and gloves
(as shown in my video if you are crafty enough you can do this job without purchasing the t100 socket and the special check valve installer they say you need)
Tsb only approximately 1 to 2 hours
Tsb and camshaft actuator 4 to 5 hours
Mercedes Benz check valves and tensioners
Mercedes Benz variable actuator