W123 Rear Muffler
 

My 84 300D needs a new rear muffler. Can anyone tell me if this is a pretty easy DIY? Do I need to remove the rear wheel?? All replies greatly appreciated.

Thanks,
Harry

Hi Harry,

I'd put it in a DIY category so long as you have the tools. Working on exhausts can be a right pain in the backside though - often literally.

If you are fit and agile you can get the exhaust on and off without jacking up the vehicle. If you want some more space raise the rear of the car - chock the front wheels - and support the rear end on axle stands.

Support the middle section of the exhaust before you start to remove the back end. You can use bricks / wood for this if you don't have a jack that will fit under the car. The exhaust is not so heavy that it will crush / crumble bricks etc - a car is!

You will find that the rear section of the exhaust is held in place with four rubber doughnuts at either end of the muffler. Replace these if they show any signs of cracking.

But before you remove these bits undo the clamp that joins the rear muffler to the rest of the exhaust - see if you can move the rear muffler away from this pipe - you might be lucky. If not you're better off cutting the exhaust. Cut the section you are going to replace. An angle grinder is the tool of choice for this job => 125mm ideal.

Once you've cut the pipe / pulled the exhaust muffler pipe away from the joint you can unhook the rubber doughnut things and do your best to lift this rear section up and over the axle.

If you've had to cut the pipe the hardest part is often getting the remaining bit of stuck pipe out of the join with the rest of the exhaust. Be careful removing this bit. The edges of the exhaust are likely to be sharp and aggressive. I've seen many a nasty cut from exhausts - combined with exhaust soot this doesn't half itch. Not nice.

Another thing I'll mention is that working under a car even on a decent lift is always a bit nasty - things can easily drop into your eyes. Wear goggles if you have them.

Harry, those exhausts are nasty dirty old things. Chances are you need a whole new system, and by the time you get the muffler off, you will see it too. If it is original from the factory, the whole system is welded together. If your rear muffler has holes in it, I would advise putting a complete system, although the down pipe from the engine to the first connection usually lasts much longer. I would say you should look at putting on two mufflers and the connector pipe and you might be surprised at the good quality ones that can be found in the pick and pull yards. Get a complete system from a junker that somebody replaced a couple of years ago. Until that time, run it. It will make a little more noise and it probably won't pass inspection if your state requires inspections.