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.
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.
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.
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.
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.
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?
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!
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.
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.
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.
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.
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.
Changing out worn shocks might be most effective and cheapest fix that can transform the ride handling of your car for the better. My S600 had very noticeable up and down wobbling when driving over bumps and a quite large body roll making in tight corners. It was becoming a bit boat like there at the end. The S600 is a very heavy car and needs good handling when going fast. A flatter ride in corners also makes for a more comfortable drive overall, so your passengers don’t wake up from their naps.
Changing the shocks will reduce wear on other more expensive suspension components like bushings and tires, while overly worn might damage the suspension. Changing the shocks is in your interest to be an economical DIYer.
The front suspension uses normal a McPherson setup with separated gas shocks detached from the springs and can easily be removed. The rear suspension on the other hand uses the more complicated SLS leveling suspension setup and don’t use shocks at all. Instead it uses hydraulic rams along with pressure spheres. More effort and money is needed when doing maintenance on the rear suspension than the front. The SLS however normally lasts a lot longer if you remember to change the fluid once in a while.
When changing the shocks you should also use the opportunity to inspect/change some other wear items easily accessible in the front suspension. This could be sway bar links or the brake rotors and pads. The sway bar links wear down faster than the other suspension components due to their tiny ball joints and should be replaced whenever cracks appear in the sleeves or any slack starts to be noticeable. Worn sway bar links can make annoying sounds for you and your passengers. We all know expensive cars are known for being the most squeaky cars around, let’s change that!
You should expect to use around half day to a day on this job, depending on your skill set, the amount of rusty bolts and your tools at disposal. It’s something you can do easily on a weekend. When doing the job I was even under time pressure since I had to catch a flight the same day. I managed to catch the flight and get the job.
If you want to bundle more front suspension jobs while doing the shocks, I recommend removing the front wheels and inspect the suspension such as the sway bar links, brake pads and rotors as well as the tie rods. Any more advanced jobs than that you will will require a lot more time invested so be sure to plan accordingly. Usually large front end jobs require a re-alignment of the suspension, but is not required here.
Parts needed (as described in the article):
2x front shocks. I recommend premium brands such as Bilstein or Meyle
1x Left front sway bar link
1x Right front sway bar link
I ended up using quite a tool collection because of rusted bolts on the sway bar links, but this might not be the case for you. I think this collection of tools goes into most home car mechanics tool box, but there might be a couple of them you should consider getting. Always better to be prepared than sitting there stuck without finishing the job.
Jack and 2 jack stands
Long breaker bar
A set of long spanners
High quality hex sockets
Pin punch driver
Long Hex keys
Propane blow torch (super handy when things are stuck)
Start by raising the front of the car and remember to use the E-brake together with wheel stops. Place the front on jack stands. I also like to keep the jack in the up position as redundancy on the side I’m working with. You can lift the w140 with the jack on the rubber jacking pad and place the jack stands more towards the center of the car under the sub frame.
The shocks can be removed when the calipers are in place, but to remove the sway bar links, both the calipers and the brake rotors need to be removed to access it. I will first describe how to replace the shocks since it is a much easier job. Then I will describe how to replace the sway bar links.
Start by removing the lower bolt. Use a long breaker bar and a large spanner to break the bolt loose. Then move to a ratchet to get the nut off. Use the jack to lift the lower suspension arm a little bit to relieve some tension in the bolt through the bracket hole. Then use a punch to smack out the bolt with a hammer. Be careful if the bolt catches too much, then try to relieve more pressure before continuing. Most shocks do not come with replacements for the lower bolt and nut, so try keeping these in good shape.
When the bolt is loose, open the hood and locate the top nut. The top part of the damper can look different from each other. You have to keep the strut bar still with a hex socket or flat pliers while using a spanner to unbolt it. There exists a special tool to do this with a socket, but is frankly unnecessary except if you’re addicted to tools. This locking nut always comes with a replacement nut and you should throw away the old one. When the locking nut is off you can easily remove the old damper.
Before installing the new damper, push it completely down a few times to relieve tension. The installation orientation has no influence if the brand does not specify it. Start by installing it with the top part and the top locking nut. When installing the new damper you must take of not letting the damper shaft rotate while turning the locking nut. Keep it secured while fastening the locking nut. This is to reduce the risk of breaking the internal seal of the damper so it will start leaking. The nut does not need to be extremely tight, but do tighten it until you feel it is secure. It is very important to make a re-tight after the car is on the ground. I will remind you of this again shortly.
Now you will probably notice that the new damper is quite shorter than the old one when you took it out. You therefore have to compress the spring by jacking up the lower suspension arm until you can align up the bolt hole. This might be a bit tricky and use a hammer to punch the bolt through since it is nearly impossible to align them up 100%. Again take care of not ruining the threads on the bolt. The lower bolt and nut should be torqued to 80Nm.
Front sway bar links
Now on to the more fun part where you can expect to meet more of a challenge. First you need to turn the wheel you’re working on all the way out to get access on the backside. Start by removing the caliper, it is held by two bolts. You may require some force to break them loose. Prepare some method too hook the calipers up in the spring to relieve tension on the flexible brake hoses. Never let them hang freely. I used long zip ties here and I could just to cut it off when done. But a simple S-shaped hook would have been even easier!
The caliper might be difficult to get off if the brake rotor has a lip on the edge. Use a pry bar or the back side of a hammer to press in the outer brake pad by using the rotor for leverage. Be careful not to damage the pad material. When the caliper is loose, secure it up onto the spring.
When the brake caliper is loosened you can start remove the break disk rotor. It is secured by a tiny hex nut, but you might find this lost or broken. Mine was broken off on the right side, but the left one was fine. Loosen the nut with a hex socket. If the brake rotor is sticking to the hub, try hammering gently on it with a plastic hammer. If it does not pop off, it can be quite frozen due to rust and you’ll need heat to loosen it. Ignite up your blow torch and heat the area just around the hub. This should expand the rotor just enough so it will pop off with a light hammer blow. Over heating the hub might make the hub grease melt and run out, so be careful with the heat.
Now it’s the time to locate the outer sway bar link nut. Cross your fingers for no rust. It is located right under the brake rotor. The locking mechanism is not the best engineering, since you’ll need either a special tool or trying to combine a socket with some magic tricks. I used a socket, secured it with locking pliers and then used a hex key sticking through it. After some fiddling I managed to get the nut off. You can usually loosen the bolt the first few turns by using just the socket normally.
The upper nut should be the easier of the two to get off, since the lower one usually gets all the rust and is easier to round off the hex bolt head. Soak it thoroughly with rust penetration fluid and let it work for 15 minutes. Then use a hammer and whack that nut good a couple of times.
I got lucky with one side, but the other side I had to drive in an over sized XZN socket with a hammer so it’s surely stuck in there. Then I could get enough torque to loosen the rusted nut. This will obviously destroy the part, but it’s thrown out anyway. Unfortunately I did not get any pictures of this process since I was struggling a bit and running out of time.
Now you should be able to remove the sway bar link. Go fetch the one that fits depending on the side you are working (hopefully you order the correct ones). Fit the top side first, then you move on to the lower side. It can a be a bit tricky to fit the lower side onto the sway bar again. Get a long bar or a long spanner and wedge it between the spring to get leverage to push down on the sway bar.
It is not necessary to tighten the sway bar links very hard, just snug with enough force so they sit on. Remember these will probably rust tight faster than you can say cheese and the hex bolts will round off again.
Caution: Before assembling the rotors, make sure you brush off any old rust off the hub face and the inside of the rotor. This is to prevent rumbling while braking and that the rotor sits on straight! You can use a steel brush and a rough pad to do this. Also brush off any surface rust on the front side of the rotor where it meets the wheel.
The front caliper bolts need a layer of blue thread locker on them since there are no shims or similar. Use 115Nm torque when tightening the caliper bolts.
It can be a bit tricky to mount the wheel if the little rotor locking nut is missing, so a replacement might come in handy here. Otherwise you have to align the hub with the rotor first and then with the wheel when sticking in the bolts.
Now I hope you will take on this task without paying stupid amounts of hours for mechanics to figure this out at a workshop. Go do it yourself!
Part 1.5 of valve adjustment of Mercedes M110 Engine. Stuck valve adjusting nuts require a DOHC valve compressor tool, which is hard to obtain for this engine.
Christmas came early..
Notice the part 1.5 nonsense, what is that all about you might think to yourself? Have I gotten mad over New Year’s? It’s rather just because of the half usefulness of this article. Since you readers are mostly DIY mechanics and Mercedes enthusiasts, I want to convey a story of the journey toward valve adjustments of such an old engine. In this way we share the ups and downs, the challenges and successes, and maybe learn something on the way.
Remember in Part 1 https://mercbenz123.com/posts/valve-adjustment-m110-engine-part1/ where I ended with 4 different options listed with increasing price and pain? Well since Christmas came early (2018) I ended up somewhere with a solution in the middle of option 1 and 2. After trawling the used car tool market, mostly ebay, I managed to find a seller which sold a late 70s vintage Mercedes valve compressor kit for DOHC engines. Although not specific to the M110 engine it is close enough, that with a few modifications it might just work. Let me just say it was the most expensive vintage tool I have ever bought. Lets hope it can come to good use!
I almost did not buy due to the high asking bidding price, but after the deadline was reached it was still for sale. I decided to go for it as a Christmas present for myself and bid on the tool for a little less. Chance happened that we compromised and reached a fast deal. Two weeks before Christmas it landed in the mail box.
It comes with 4 different valve compressors, although I’m not sure if any of them fit right out of the box. I might need to adjust one of them. The lever bar has a simple screw on attachment to swap out the compressor ends. The Hook is not attached, but can be placed in different grooves. I might also need to adjust the arrangement here as well.
Under I have tried to visualize how the tool is operated on the valve head. The idea is to compress the valve just enough so I can slide off the rocker arm. Since the valve clearance adjusting nuts are so tight we need a socket over the nut which is naturally blocked by the rocker arm.
I’m excited to see how the tool can be used in real life, but since it’s winter and the car is hidden away, this have to wait until spring. I’ll keep you posted on the progress in this journey as soon as possible.
Cheers! Robs out
Other news: I tried to sell the S600 in the autumn, but was unfortunately little interest which is hard to believe when regarding the current economics and huge interest in classic cars. Norway is a weird country.. The car is in mint condition with low mileage so I will not give it away for free. I will instead keep it and enjoy it, make some good articles about the w140 and let time mature it into a true classic.
I planned the valve adjustment job to be straightforward and easy, making it a delight to write an article about afterwards, but no! In the end I could not even adjust a single valve out of the 12 in total, and this is why I will divide the so called adventure into multiple parts and share my experience on the topic.
“Mother nature beats father engineer every time..”
Valve adjustments should be done every 15.000 km which means for most people every 2. or 3. year and is important for engine performance and fuel consumption. Neglected maintenance can even end up wearing your cam lobes prematurely if they get too tight!
A story of success
I got all the parts I needed, that is really only a valve cover gasket set. I let the car stay overnight for the engine to cool down. Then I start pulling out the spark plug wires, no need to mark them with cylinder number..haha! I unbolt the valve cover in a breeze, the nuts I throw somewhere neat.
Then I check the valve lobe timing, oh see that the first one is perfectly aligned already so I can start adjusting the first valve immediately. I find my valve feeler gauge easily from the toolbox and it’s not rusted together at all. I adjust the first valve and since my memory is faultless I can easily keep track of all the valves I have adjusted and the ones who are left. The crank is so easy to turn by hand and I don’t need to remove the radiator shroud or anything silly like that. I get everything done in under a less hour and bolt everything together with the new valve valve gasket and I’m now already on my way to the race track with 40 more HP.
This is all however a big lie.
Sometimes wisdom words are painfully true: “Mother nature beats father engineer every time..”. The real struggle you can follow below.
So before starting you should take care of a few things. In theory a valve adjustment is easy and requires little preparation and engine know how. You need a new valve cover replacement kit, since your old one is probably leaking oil and a new one is very cheap. The valve adjustment can be made either when the engine is warm (just after driving) or cold (20°C). I really recommend the latter since you will not burn your fingers and get better results since the engine is not cooling down slowly. Ideally it should be at ambient summer temperatures in the shade. You have to leave the car overnight to properly cool down after driving so this have to be planned in advance.
The tools you need is just really a spanner and some feeler gauges for the adjustment and a socket for turning the crank over, but as we will see here this is not the case for my case.
I start by removing the air filter housing to access the valve cover freely. Then I mark every spark plug wire with a number on a piece of tape. Usually the spark plug wires are different length, but it’s so much easier to plug them in afterwards. Then I take out the spark plugs.
Now I can start removing the valve cover bolts and place them somewhere safe. I note that the middle ones have a copper shim which I can keep, but the new valve cover gasket comes with replacement ones. It’s always nice to keep bolts, nuts and shims if they are in good order.
NOTE OF CAUTION With the valve cover off is is extremely important to not drop anything into the engine like a nut or something, since this will cause catastrophic engine failure. Also keep dirt away and exercise hospital level cleanliness while the engine is open. Cover it always when not working on it, like lunch break etc..
I then go in the the toolbox to find my gauge feeler blades and realize they have rusted together and end up throwing them. I go in my dad’s old toolbox and luckily find some that are in a bit better shape. With a cold engine the inlet valve clearing should be 0.10 mm and the exhaust 0.25 mm. I draw a diagram over the valves so I can mark them after every adjustment, it will be very hard to keep track of otherwise. Just try remembering 12 boolean positions for reference!
Of course none of the valve lobes are pointing directly vertical for any of the valves after opening the cover, that would be too easy! So I go ahead and try to turn the crank, but come over a problem. The fan shroud is too tight to engine for me to get any socket tool and ratchet to the crank. Loosening just the fan shroud is not helping either since the fan is sitting tight to the shroud. Then I loosen the fan and I can just get enough room for the ratchet and finally being able to turn the crank.
I align the first cam lobe and is ready to check the valve clearing. I expect most of the valves to be to bee way too tight, and the first one is as expected. I grab my spanner to start adjusting, but the valve adjusting nut is not moving at all. In fact I’m starting to slightly round off the nut. I stop before I ruin it. Then I quickly check a few other valves, they are all tight as expected, but also here the valve adjusting nuts are super tight. I am totally stuck.
After searching the Internet for similar issues it seems this is a common scenario for these aging engines. The nut material is quite soft and can easily be rounded off when they are tight. The solution is to remove the rocker arms to access the whole nut so you can get a socket over it to exert more force.
Seems easy right? To remove the rocker arm you need to depress the valves somehow. They are under very high pressure from the valve springs and a special compressor tool is needed. There are many different DOHC valve spring compressor tools on the market, however the M110 engine have very tight space between the cams and the engine walls where the spring compressor have to fit. And the valve is at an angle so the tool need to be just for this purpose. There is such a speciality tool for the M110 engine, but I can’t find it on a single place on the internet. It turns out it is in fact out of production. Fuck!
I am stuck and have to abandon my job and put everything back together. This was a waste of time! (But in the back of my cynical mind I think it can be turned into an article at some point..)
Here is a diagram over the valve assembly to illustrate the point better.
The valve compressor tool is like a leverage bar with a hook for the cam axle and a crow foot depressor at an angle that can slide between the engine wall and the cam axle down on the top of the valve. It looks like this:
how to solve the tool problem
I have considered some options below and ranked them from easier/cheaper towards more expensive options.
Obtain the tool
I have really tried to find this on the internet, but with no success. I think I will not be able to obtain it. Not sure if Mercedes has one , but I am scared of even asking, it’s probably super expensive.
Make the tool myself
I know how it looks like and roughly the sizes. I can easily obtain some steel, and a crow foot. I have a welder so I can make the tool. However I expect it to take some time to assemble. Definitely worth looking into.
Take the car it to a workshop
I can just take it to a workshop and tell them to adjust the valves, but they are going to run into the same problems like me and they might end up ruining the valve nuts unless I explicitly tell them the problem in great detail. Remember these days no cars require manual valve adjustment and only the more experienced mechanics have done this. If you want things done right, better do it yourself.
Contact Mercedes on how the fuck….
This is my last option and will consist of asking if they have such a tool, and if the tool is not for sale (or out of production), if they can at least adjust the valves if they can send a tool from Mercedes Classic in Germany to their workshop. Problem is that is going to be very expensive for a simple job. Not likely I will venture down this path. Also would turn into a dreadfully boring article for you DIY people!
More on this adventure when we return in Part 2 of the valve adjustment nightmare… soonish