C250 Sport - No oil change in 6 years and 50K miles.






You still have to watch out for the timing chain.
It’s just a simplex chain with a propensity to stretch and jump timing.
This alone could cause major damage to the engine.
Worst case would be a timing chain breaking apart and causing even worse damage to the engine.
For further info just google search for “m271 timing chain stretch”.



You still have to watch out for the timing chain.
It’s just a simplex chain with a propensity to stretch and jump timing.
This alone could cause major damage to the engine.
Worst case would be a timing chain breaking apart and causing even worse damage to the engine.
For further info just google search for “m271 timing chain stretch”.




The Best of Mercedes & AMG
Last edited by dol4er; Apr 18, 2019 at 04:38 PM.



Torque specs and pattern
All parts ordered are here and reusable parts are cleaned and prepped. Ready to start the build
Head gasket and exhaust gasket placed. Zip ties are being used to temporarily align and hold in place the exhaust gasket.
Head placed and aligned.
New head bolts placed on their holes. Hand tighten until snag.
A 3 step torque is required to torque the head bolts:
1. The first step is torque to 45 N-m following the pattern on spec above.
2. Wait 10 minutes then then torque each bolt 90 degrees further following the same pattern again for step 2.
3. Wait 10 minutes then then torque each bolt 90 degrees further following the same pattern again for step 3.
* torque is set for 45.4 N-m because my torque wrench has a tolerance of +/- 1%.
Last edited by azblk; Nov 7, 2019 at 09:48 PM.



Second and third step head bolt torque involves turning the bolts 90 degrees following the torque pattern above. Wait 10 minutes between both torques.
Next attach the exhaust manifold by screwing lightly a few of the head bolts or studs.
Cut/remove the zip ties used earlier to align/hold in place the gasket.
install all 8 bolts/studs and torque to spec. MAKE SURE you coat the bolts with anti-seize before installing them !!!.
Head and exhaust manifold installed and torqued to spec.
Next I will install the cam housing. There is an RTV gasket between the head and the cam housing. I used Loctite 5900 which MB also uses.
Before applying the RTV thoroughly clean the sealing surfaces. I used a razor blade to scrape the surfaces and used a lint-free cloth soaked in acetone to wipe away any oil and dust. When surface was clean and dry, I traced the RTV path with a sharpie and then applied the RTV silicone.
I did not take any picture of the applied RTV as it starts to cure quickly. Anyway after aligning and installing CAM housing. I clamped the front and the back to apply pressure and I will leave the clamps(vice grips) on overnight.
Last edited by azblk; Jun 20, 2019 at 06:29 PM.










While waiting for the RTV to fully cure I reinstalled the timing chain guides and pins.
I also reinstalled the cam lifters and rocker arms. Since i decided right away that I was going to re use these i kept track of where each came from and I returned each to the same spot. I used sandwich bags marked E1/I1 for exhaust 1/ intake 1 and so forth.
Apply assembly lube to the cam cradles. Be generous since it will dissolve in the engine oil and the engine will start dry before oil makes its way up.
Both cams installed. Make sure the correct cam goes to the correct side. Not sure if you can swap them anyway.
Lube the cam cradles on cam housing covers with assmbly lube and then reinstall
reinstall the cover bolts and torque to spec. The torque spec and pattern attached below.
Torque spec for cam housing
Next I will set the timing and reconnect the timing chain. When that is completed it will be down hill from there.
Last edited by azblk; Jun 19, 2019 at 11:45 PM.
I hope you don't sell this car to some poor kid down the road.....






