Mercedes-benz w203 timing chain tensioner replacement – (2001-2007) c230, c280, c350, c240, c320 pelican parts diy maintenance article quadcopter gas motor


The timing chain tensioner is responsible for keeping the proper tension on you timing chains. It does this by keeping constant pressure on the guide rail. If you are starting to get chain noises from the engine, especially on cold start ups you should inspect or replace the tensioner right away. Failure to maintain constant tension can lead to the timing chain jumping a sprocket and then catastrophic engine failure.

The first step in replacing the timing chain tensioner is to disconnect the battery. You are going to have to remove several components to get to the tensioner including the alternator and you will be working around live electric wires here. If you happen to touch the lead going to the alternator against something, you can cause permanent damage to the electrical system if the battery is hooked up. Be smart here and disconnect it. Please refer to our article on battery replacement for more info.

You will need to remove the two air inlet ducts as well as the front engine cover to get access to the coolant temperature sensor on the front of the engine. Remove each duct by compressing them towards the engine and slipping them off the air inlet. With the ducts off remove the front engine cover. It pulls up and away from the engine. The cover is held on by five clips and will easily come off with hand pressure.

Next, use an E10 (reverse Torx socket) and driver. Locate the tensioner and using the Torx driver turn the nut on the wheel counter-clockwise 45 degrees. You can now slip the belt off the tensioner. There is a picture below that shows you the routing of the belt that you can use when you reinstall the belt.

You can also lock the tensioner into the open position if you need both hands to install the new belt. Turn the tensioner all the way counter-clockwise and insert a retaining pin between the rotating part and the tensioner base. If you do not have a retaining pin you can use a 5mm Allen key.

Located on the engine block between the upper mounts for the alternator is the tensioner. Use a 27mm socket and unscrew it. Note: make sure you have the socket flush to the block as it is at an odd angle and you do not want to strip it. The tensioner has almost 2 inches of threads on it so just keep unscrewing until it comes out. There will be a little oil that comes with it so be prepared. Clean around the block and make sure the new seal is on the new tensioner.

Comments: Seems like the WIS manual says that reverse steps to install and does not mention priming the tensioner. But is it advisable to prime the tensioner before installing it? Some sources on youtube point out to priming the tensioner before installation. Anything wrong if I prime the tensioner before installing it?

Comments: I have a 2003 c240 v6 which is misfiring on all cylinder occasionally. The engine still runs but very poorly and won’t accelerate. It also idles rough although when under normal acceleration works fine. When the misfiring starts the engine light comes on and stays on and the only way to stop is turning off engine and restarting. The problem seems to reset and goes away for a day or less before reoccurring.. The engine has 240k km and I have replaced the fuel filter, plugs and wires.

Comments: I have a Mercedes E200 2011 Model.There is a noise like something loose when I am about to stop the car or sometimes when accelerating after stoping. The fan that usually came on even if the engine is off does not come on anymore and i suspect that this noise might be associated with this am I correct or is there other problem. There is no noise when starting the car

Comments: Hi I have a 02 c240 with only 124k. When I start itcold, the engine is quiet and runs like a dream, however once warm and idling the chain rattles. I have taken the serpentine belt off and run the engine, to make sure it wasn’t anything associated with that, however it still rattles. Im hoping its just a tensioner? What are your thoughts? Thank you.

Comments: Have a C180 w203, it started making a rattling noise then the engine check light appeared. I got two mechanics to look at it. 1. said the camshaft gear needs replacing, but the engine is running smoothly no timing issues. the 2nd said the guide on the tension belt needs replacing. what could be the most likely cause???

Followup from the Pelican Staff: Could be either. Remove the drive belt, does the noise go away? if so, it is the drive belt and not the timing components. be sure to run it only long enough to confirm the noise is gone. – Nick at Pelican Parts

Comments: Hi, I have just replaced the E and A camshaft gears and timing chain kit for my c200 M271 engine, it now make a rattling sound for few seconds when starting the engine. So what could be the cause of the rattling sound. But it drives ok and there is also an engine light.

Comments: I have w203 07 MB c230. Recently had some plug fouling/carbon buildup in the piston/bores on the bank same side of motor as timing chain tensioner too high compression that side also. Currently doing internal engine cleaning and replacing oxygen sensors….I know about the balance shaft failures associated with this engine. Thinking a bad tensioner could be a precursor to a balance shaft failure and heard once that someone had valve issues on the side of the engine as the tensioner first, prior to balance shaft failure. Seems hard to check tensioner without hearing the chain. Any thought whether a bad tensioner could lead to balance shaft failure and described right bank issues and the possibility I could be on that path with issues described? Thankd

Comments: Sorry about that it’s a 2001 S430 starting to make noise what the tensioner but don’t know if I could just pull it out and put the new one back in do I need to set the timing and any certain place or crank or Cam Shaft whatever it is I’d like to shut the motor off let it cool and take it out and put it back

Comments: I’m having some engine noise I was told that I could take out the tensioner disassemble it clean it and put it back in that will tighten the tensioner but I was told that you have to put them over at 20 degrees I just don’t know if it’s 20 degrees intake of 20 degrees exhaust

Followup from the Pelican Staff: You didn’t mention what vehicle you are working on. if removing the tensioner for the vehicle covered in this article, follow the instructions. TIming locations is always the crankshaft, not the camshafts. – Nick at Pelican Parts

Comments: Nick 99 CLK 320 there is too much inside pressure on the new timing chain tensioner, and the piston is extended all the way out. When inserting the new tensioner, the piston end touches the chain guide and it seems very difficult to push it in and start any threads at the same time. Is there oil inside the new tensioner in addition to the spring? is there a special installation tool? Thanks

Comments: guys, some help needed, I had just replaced the head-gaskets water leaking into oil and now started to re-assembly the engine. mine is a W202 M112 1998 C280. I am willing to use the same tensioner car has roughly 100K kilometers so I believe it to be still good, however I noticed it has to be pre-loaded or re-set to minimum extension for it to be screwed back in place. This tensioner looks not obvious how to do this, any ideas?

Comments: Hi there I have the same problem with my Mercedes, I have took everything off apart from a bolt that is on the right hand side from the inner side of the timing chain cover, it is bloody difficult to get to that screw, is there a way of doing it without taking the camshaft and the cilynder block off. Unfortunate I don’t have a photo to show you at the moment but if requested I’ll probably take one. Kind regards if you know anything about this busters bolt