How to change the oil pan gasket in the M110 engine – W123 and W126

This has to be the most common oil leak area except for the valve cover on these engines. The gasket here is not rubber, but made of some sort of compressed fiber and they tend to start leaking after a few years. The leak from the oil pan will make oil spill from the front of the engine and oil will fly pass the whole length of the engine and on to the transmission, making oil seem leaking from everywhere. The MOT inspection might not like it either, although they usually will have more forgiveness towards classic cars. However you should not enjoy leakage from the front of the engine.

The leaking oil pan is usually not enough to drip on the ground while parking only for a day, but is surely noticeable after parking on the same spot over a longer time (like your garage). The M110 engines are notorious for some natural amount of oil consumption while driving, but a leaking oil pan will make this oil consumption seem worse. You should put a habit on inspecting the oil pan gasket for leaks every time doing an oil change. The chances are 100% likely that it needs replacing if you have never done it before.

I have noticed that simply changing the oil pan gasket without the proper procedure will make the oil gasket seem to leak after just a short while. This is usually due to lack of thread sealer on the pan bolts and improper torque. Sometimes the thin oil pan is bent slightly (due to bumping into rocks on a gravel road) and proper sealing is impossible to achieve, then you will need a new oil pan. Replacing the oil pan is something you might need to consider if you see clear scratches on the bottom side or noticeable dents.

The details on the specific oil change procedure for the M110 engine can be found in this article: How to Change Oil and Filter in the M110 Engine


You cannot do this procedure without doing an oil change, so try timing it to your next oil change otherwise you will need to replace that new oil of yours.

Parts and supplies:

  • Oil pan gasket
  • Thread sealer (not the same as thread locker)
  • 6.5L oil + oil filter
  • Brake cleaner
  • Lots of shop paper/rags
  • zip ties


  • Jack + Jack stands or ramps
  • Socket tools
  • Hex bits
  • Spanners
  • Low range torque wrench
  • Oil drip pan


Start with warming up the motor to operating temperature and raise the front of the car for better access. Drain the oil from the oil plug and let it drain until the dripping stops. Then you can start the process of removing the oil pan.

draining engine oil
Draining the engine oil

After the oil is drained you can start loosening the oil pan bolts with a hex socket. There is a lot of them so be patient. And not all of them are the same length! There are a couple of bolts with longer length at the right front corner which also holds a bracket to an oil cooler line.

M110 engine oil pan
Disgusting oil pan with caked oil from leaking gasket.

Take care of holding the pan horizontal when you remove the last bolt, because there is still a lot of oil left in the bottom. Carefully lower it and then pour out the remains. There is most likely some sludge and debris left. Now the time has come to inspect the bottom of the oil pan. The leftovers in the bottom of the oil pan can tell the condition of the engine and if it has been properly maintained.

Bottom of M110 engine oil pan
Bottom content of M110 engine oil pan

A common denominator is that silicone or RTV debris are to be found due over use in valve gasket sealing. I do not blame them since the M110 engine is notorious to leak after a few years, but still this debris can clog the oil pickup and damage the engine. Also the engines tend to leak more if they are not used on a regular basis, sounds funny right? But it is the sad truth. Long time storage of these engines without usage will dry out the seals and the engine will leak more oil.

My engine (the whole car) had been parked for 1,5 years and only started intermittent and not driven. So the oil in the lower oil pan was very sludgy and you can notice that moisture has started building up, which can be seen from the white color. This is not good for lubrication obviously, and was the reason I did this job in the first place.

sludge in bottom of oil pan
Heavy sludge in bottom of oil pan due to long time parking.

Use break cleaner and clean the oil pan thoroughly so it is dust free inside. Also clean the outside so you can notice new leaks id they appear. If you have some small strong neodynium magnets you can attach them in the lower edge of the oil pan, otherwise the filter will catch most of the debris anyway.

Cleaned oil pan for the M110 engine
Cleaned oil pan for the M110 engine.

After the oil pan is cleaned, there is another matter to tend to. Grab the oil pickup strainer and pull it off. It is probably very clogged from debris and gunk, so you better clean it now or never.

Underneath the M110 engine
Underneath the M110 engine. Notice the oil strainer.

Whatever you do do not spray oil cleaner oil solvent into the lower engine since it can damage the rod bearings!!! Use only some paper or cloth and clean off the lower engine housing then pull off the strainer and use brake cleaner on your work bench.

Oil strainer M110 engnne
Very dirty oil strainer indeed.
Dirty oil strainer for M110 engine
Dirty ass oil strainer, must be cleaned! So black you cannot look through it even.
Clean oil strainer M110 engine
Cleaned oil strainer, you can actually see the mesh here.

After cleaning the strainer, put it back into the lower engine and start assembly of the parts! Put on the new flimsy gasket, since it will not stay n place use 3-5 zip-ties to secure it in place for assembly. After mounting the oil pan with some bolts on you can cut the zip ties.

New oil pan gasketf for M110 Engne
New oil pan gasket secured with zip-ties

Prepare the bolts with the thread sealer, start with two bolts, one on each side so the oil pan will stay in place.

Assembly of oil pan M110 engine
Assembly of oil pan. Fasten two bolts then cut the zip ties.
Oil pan assembly M110 engine
Cut and remove zip ties after some oil pan bolts are in

Put thread sealer on each bolt yo inert, all the bolts should be tightened to 11 nm. Remember that the two front right bolts have a different light than the rest due to a bracket with and oil lines.

Long oil pan bolts
Longer oil pan bolts due to oil cooler brackets
Torque oil pan bolts
Torque all oil pan bolts to 11nm. Don’t forget to use thread sealer otherwise they will leak.
M110 engine oil pan
New oil pan gasket installed!

After torque of all the bolts this job is well done. Hopefully it will not leak in a few years, well done!

Robs Out!

How to Change Oil and Filter in the M110 Engine

Changing engine oil is usually an straight forward procedure on most cars, however the location of the oil filter housing for the inline six cylinder M110 engine, makes the job a bit more messy and annoying than necessary. Now these cars with M110 engines are starting to get pretty old, which means more often oil changes with the increased mileage. My 280CE is of now 38 years old and I do regular oil changes at every 5000 km. This might seem often, but the little amount of actual kilometres this car is seeing it is usually only once per year.

If the car is parked for long periods, moisture will build up inside the block and the oil will eventually turn milky white, which can be noticed if opening the oil filler cap. If you are doing the oil change yourself, you will get a clear indication of the health of the engine. This you won’t get at a workshop unless it is a special workshop for classic cars. Who can afford that anyway?

This is an article long overdue, but since I did a lot of work on the W123 laterly the opportunity presented itself. Also got inspired by writing this since I already had an article on changing oil in the big brother M120 engine:

More articles on W123 coming up soon too!


You will need a few supplies and tools before starting on the job. Also it is best to change the oil when the engine is warm since this will let the oil drain easier. So make sure you take a short spin just before changing the oil. Changing the oil can be done in any season, so no need to wait until summer for this one. Just do it!


  • 6.5L Synthetic Motor oil with viscosity for your climate and use: A good all-rounder could be 10w-40.
  • Good quality oil filter. I recommend getting a filter from Mann, since it will come with all new washers and gaskets.
  • Paper towels or rags to clean up oil
  • Brake cleaner


  • Torque wrench
  • Sockets
  • Oil drip pan
  • Ramps or jack stands


Make sure the engine is warm and drive the car upon ramps or raise the front of the car upon jack stands. The car is usually high enough just by itself to drain the oil without raising it up, but in order to reach under to the oil filter, you need the space to crawl under it.

280CE upon ramps
280CE upon ramps for the oil change

Draining the old oil

Normally you would open the oil filter can before draining the oil, but since this will literally spilling oil everywhere, you must drain the oil pan first. Open the oil filler cap to let the oil drain out easier. So grab your cleaned oil drip pan, or dirty if you do not care for inspecting the oil afterwards. It is your call. Grab your trusty 13mm socket and crank open the oil drip plug.

open oil filler cap
Open the oil filler cap before draining oil. Notice the white oil inside the valve cover due to moisture buildup. It is not because of coolant mixing with the oil. This ca has been parked for over a year due to reasons.
Draining oil from the M110 engine
Draining oil from the M110 engine

When the oil have stopped dripping, you can move over to removing the oil filter housing. If you have never seen it, it is a large aluminium canister located underneath the left side on the engine towards the back. See image below:

Oil filter housing location on the M110 engine
Oil filter housing location on the M110 engine. Mine says MANN on it, but it might not be the case for you. It is held in place with a single bolt.

The oil filter is held in place with a single bolt, but be prepared for oil splashing when you start removing it, try balancing the filter into the upright position since it will be completely full with oil. So be prepared to get oil everywhere and keep you mouth closed. After the oil housing is removed, clean the mating surface and the area around.

oil filter removed from M110 engine
Oil filter removed from M110 engine. Clean surfaces and area around.

Replacing oil filter and washers

Pour out the old oil in the filter housing and notice the orientation of the old filter and washers. Take out the oil filter and throw it away. Now clean out the old gunky oil from the oil filter housing. Use some break cleaner and get all that gunk out and dry clean.

Mann Oil filter for the M110 Engine
Old and new filter. Mann filters are high quality and comes with gasket and new washers.

Hopefully your new filter has some new washers in the pack. Replace the lower washer on the oil filter bolt which goes on the outside of the filter housing (this not a copper washer). There is a spring and a spring retainer inside the housing below the filter, keep this in the same orientation before inserting the new filter. Place the new filter with the narrow hole down and the larger hole upwards. The side for up usually has a little handle on it. Do not forget to replace the new rubber gasket around the edge of the filter housing.

If you notice in the oil filter kit that there is an additional large copper washer there with an unusual shape. This washer is for the large bolt which holds the oil pressure relief valve right next to the oil filter housing. However this only needs replacing if you see oil seepage from the area. No need to replace this every oil Change. The torque for this bolt is 41 Nm.

Lower washer on the filter housing bolt
Replace lower washer on the filter housing bolt
Reinstall oil filter housing bolt
Reinstall oil filter housing bolt and place in spring and retainer before inserting the new filter.

Before reinstalling the oil filter, make sure you top up the oil filter completely with new oil. This will reduce the wear at the first startup after the oil change since more oil will be available for circulation right away. This is not possible in all engines, but here there is an opportunity in the M110 engine.

New filter inserted into the oil filter housing
New filter placed into the oil filter housing. As a last step top up the filter with new oil until the brim.

Reinstall the oil filter carefully not trying to spill out the oil from the new filter. Hand tighten so you can feel you do not ruin the threads. To tighten you will need to use a torque wrench and torque it to 35 Nm. This is pretty tight and will prevent leakage through the housing.. Too tight however and you will ruin the filter housing. Use a rag to clean up the filter housing and area completely so you can inspect for oil leaks later.

Reinstalled oil filter on the M110 engine
Reinstalled oil filter and torqued to 35 Nm. Cleaned for residue oil.

Adding new oil

Before pouting in the new oil, you can inspect the old oil and see if there is any residue and metal parts at the bottom of the drip pan. My oil looked alright, not any metal particles or excessive old oil, but because the car have been sitting for so long with only short starts now and then, the oil pan had built up some gunk which came out when draining the oil. Nothing serious, but it was a good time to replace the oil for sure.

Inspecting oil drip pan after oil change
Inspecting the oil drip pan after the oil change. No metal shavings or . Only some gunked up oil residue since the car has been parked for so long.

Then at last replace the copper washer on the oil drain plug bolt and torque it to 41 Nm. Very important to put this plug back before you pour in the new oil. The engine takes 6.5 L of oil, but do not pour in all at once, pour in around 5.5-6 L and start measuring, otherwise you will overfill and have to suck up the extra oil. There is always some old oil taking up some capacity. Remember to use a funnel to avoid unnecessary spills.

When the oil level is up to the minimum mark on the dipstick, pour another 100 ml between each measurement until you are between the minimum and the maximum mark. The correct oil level measurement is only made when the engine is turned off!

Now you can start up the car an let it idle for a few minutes, and while the engine is running, go under the car and check for oil leaks. Inspect the oil filter if it is leaking and the oil drip plug. If everything looks fine, you can lower the car and take it for a short spin.

Go on a short drive just to get the engine up to operating temperature and head back home. Now shut off the engine and re-measure the oil level. If it is between the minimum and the maximum mark, the oil level is good. If the oil level is still under minimum, then add some oil to get it back to the right level. However if the level is above the maximum, you should suck out some of the excessive oil. This might be unnecessary if the level is just slightly above maximum (a few mm), since there is a natural oil usage from the M110 engine and the level will be fine soon anyway.

So DIY you next oil change and become confident in fixing your own cars!

Cheers, Robs out!

Changing the Exhaust pipes in the w123 280CE

There was this annoying hole in the exhaust from last summer. It was the thin sheet under front muffler that had cracked and I had it welded just before the MOT last year. Unfortunately the job was poorly done by the workshop. Another lesson learned on why we should fix our own cars…. The fix ended up costing almost as much as the new pipes, so that was also dumb. On the very day before this summers epic 3000 km road trip of crossing Norway I had to change the entire exhaust system. The pressure was on to get it finished before the trip!

The poorly welded exhaust only got noticeable few weeks before the upcoming road trip, but another car was planned to be used so there was no pressure initially. Then because of circumstances it was decided to use the 280CE after all and the exhaust leak needed to be addressed asap. I decided to swap out all the pipes since some rust was starting to appear in the pipe welds and its easier to just swap the whole thing at once.

I ordered the exhaust less than two weeks before from Germany and it arrived two days before the road trip was starting. Just in time. It only costed me 500$ which I think is a bargain for a classic car! The quality also seems very good as well.

Welded front muffler w123
Poorly welded front muffler. Now junk.

Stage 1 – Getting the car up in the air

You need some good space to wrestle with the large exhaust system under the car. I drove the front of the car up on ramps then lifted the back of the car on jack stands so the whole body was up in the air. I leave the tires on for extra safety and don’t lover the jack either. Also make sure to block the front wheels from rolling on the ramps. I’m a fan of redundancy and here I even placed a couple of jack stands in the front which is kind of unnecessary, but makes it feel somehow safer.

Car on jack stands
Car up in the air. Potentially dangerous and safety should be on your mind. Here I have redundancy by leaving the jack in place and using redundant jack stands. Not recommended to be under the car during an earthquake…

Stage 2 – Removing the old pipes

This is usually the most time consuming job involving rusted fasteners and wrestling with stuck pipes. I was planning to only change the pipes up to the down pipes, since the down pipes are in a really good condition compared to the rest of the exhaust. The issue then become separating the down pipes from the pipes underneath the car.

exhaust clamps
Front exhaust clamps

I started removing the clamps for the front pipes and loosening the system from the transmission mount. Then unhooking the four rubber donuts from the rear muffler. To avoid too much stress on the pipes I placed something under the rear muffler for it to rest on, in this case a tree stub.

rear muffler 280ce
Rear muffler resting on a wood stub

Then the issue with sliding off the exhaust system from the down pipes. They were extremely stuck and you’re not able to twist them since it’s a pair of dual pipes. I was first trying to push them out with putting my entire weight with my legs and kicking. Then I tried heating the outer pipes with a heater torch. After a while struggling with no success and them not moving at all I had to make a drastic decision. I needed to cut them out without damaging the inner down pipes. This would mean the old exhuast would be trash, but it’s old and not worth much anyway.

cutting the exhaust pipes
Cutting the exhaust pipes.

In order to get the old outer pipe off, it needs to be split and then removed. It would be impossible to try pushing them off otherwise. I started by cutting the pipes across a few centimeters before the mating point. Here I used an angle grinder with a thin cutting disk for about half the way, then a manual cutting saw blade for the rest. A bit tedious, but will get the job done. The best would be to use a hack saw which is much safer than an angle grinder and faster than the manual saw. However I don’t have one. Maybe now it’s a time to acquire one?

exhaust pipes cut
Pipes are cut and also a slit is made lengthwise with an angle grinder. Care is taken to not cut all the way through to th einner time.

After the pipes were separated I could remove the old exhaust system. The old stubs of the outer pipes are just as stuck and a slit have to be cut down the middle and care have to taken in order to not damage the inner tubes. The only tool for this is an angle grinder. Watch out for sparks in your face!

Split the pipes
Split the pipes with a sharp punch and drive it in with a hammer. Eventually the metal will split. Use ear protection since it tends to be very loud.

When there is a slit along the length of the pipe I could use a punch with a sharp end and drive it into the slit until it grew larger and eventually the pipe will split along its entire length. Then it was super easy to remove the outer pipe.

Splitting pipes with a punch
Splitting the pipes with a punch. Super easy!

I was surprised of how effective it was, and it was sour that I wasted so much time trying to free the pipes with different methods before I ended up doing this. I was also surprised to find that there was essentially no rust that was binding up the pipes, instead it looked like the metal had expanded into each other and exhaust coke had made this kind of glue between them. Now that the old exhaust was removed, I could mount the new system on.

Stage 3 – Fitting the new pipes

This was the fastest part of the job. It was basically lining up the three exhaust part components, putting on the clamps and tighten them. When the full length is assembled I could slide it under and mount it to the down pipes. Don’t forget to slide on the clamps before joining the exhaust pipes.

Hangers different from old system
Shape of hangers different from the old system.

I found having some help with the assembly part is useful due to the quite heavy and large part that needs to be aligned, but also doable alone if you plan all the moves ahead in time.

The exhaust kit came with four new rubber donut muffler hangers. These rubber hangers crack at an incredibly fast rate due to the heat of the exhaust and they rarely lasts more than 1-2 years before they break.

New exhaust system
New muffler being very shining, almost looks fake.

Stage 4 – Road trip

Luckily I managed to sort it out the evening before and could leave the next day.The road trip went fine and went without issues all the 3000 km. The tail pipes of the new exhaust have a slightly different shape and the heat reaches the rear bumper a bit more making a subtle bluish tint on the chrome which is quite cool.

280CE in Lofoten

I have the habit of doing jobs in hurry lately where I needed to travel shortly afterwards. Unfortunately this introduces a lot of stress and takes the joy out of fixings cars a bit. I need to plan better indeed.

Cheers, Robs out.

Replacing the right side Mirror on W123

The right mirror has been fucked, it was broken while parked in the street and is just hanging on with some tape. It is actually not that obvious, however when traveling at highway speeds the mirror is vibrating by the wind. The angle of the mirror is not right when closely inspected either.

Used electrical right mirrors for coupes are quite hard to find actually, and new ones are very expensive at a Mercedes Benz dealer. So with this in mind I have tried to find a good used one. It is nearly impossible to find those kind of used coupe parts in Norway, too small market I guess, much easier too find used parts for sedans and wagons. Anyway I have been trawling the Internet for a used right side electrically operated mirrors for my coupe, all it took was some great patience and a will for not throwing in the towel and go directly to a Mercedes dealer.

Who would have thought that I found it on ebay in Germany while I studied in Thüringen? Only 130€, or anyway a lot cheaper than new of the shelf by an amount of 300€.

Old mirror hold togehter by tape
Old mirror hold in place by tape

plastic trim for mirror
Just flipping off the plastic trim to get to the mount

W123 mirror mount
Mirror is mounted by a couple of scres and the electric wire

Old and new mirror compared
Comparing the broken mirror, mechanism hold together with copper wire

Mirror 280CE
New mirror, good as new!

This was by far the easiest fix on this car so far, it took me only 5 minutes!