M272 Camshaft position sensors

When you own a modern Mercedes-Benz, you seem to be playing constant whack-a-mole with the check engine light.   I’ve written before how silly I think the check engine light is, but we’re stuck with it.   Personally, I would just drive older cars, but this is not for everyone and my wife has a 2007 E350 Wagon.    There were two codes this time.

The first set of codes were complaining about the correlation of the camshaft and the crankshaft on one bank.   I had previously changed the magnetic actuators, which temporarily fixed the problem.    If the car didn’t sit outside the engine numbers with the soft balancer shaft, I would have probably assumed that this was my issue.

The second set of codes were about the tumble flaps in the intake manifold.   They are made from plastic and the hot engine makes them brittle and fail.   Mercedes will try and sell you a whole new intake manifold, but there are aftermarket solutions to replace the plastic with metal.   You would have thought Mercedes-Benz would have learned by now about brittle pastic on their engines.   I didn’t want to tackle this one myself, so had it done by a professional.   While the car was there having this and the front suspension rebuilt, we checked the codes.    The various camshaft codes were there, but the actual values of the camshafts seemed correct.

That got me thinking that perhaps it was the sensors sometimes giving bad readings.   I probably should have changed them at the same time as the magnetic actuators.   In any case, the M272 camshaft position sensors are not particularly expensive and very easy to change.

M272 camshaft position sensors
As the M272 is a DOHC engine, there are four sensors.   The right hand sensors are slightly harder to change, but each one can be done in less than five minutes.   The new sensors came with o-rings, which was good as the old ones were very hard.     I don’t know what it was, but there was some kind of residue on a couple of the sensors.   I doubt it was impacting how they worked, but at least the new ones do not have it.

M272 Camshaft position sensorsAfter replacing all four sensors and re-setting the codes, I was able to drive for 15 minutes without the check engine light.   It’s been a long time since that was possible.   The proof of the fix will be if the light is still not illuminated after a couple of weeks.   It was worth trying as four M272 camshaft position sensors are not expensive and the time to change them is negligible.

15″ AMG ‘Penta’ wheels for my 450SLC

I’ve been on the lookout for a different set of wheels for my 450SLC.   It is currently running a set of W126 second generation alloy wheels.  I like these wheels, but they are not quite right for the 450SLC.     My 560SEL uses these same wheels, but they are in need of refinishing.   Instead of having some of my spare W126 wheels refinished, I thought I would get a different set of wheels for the 450SLC and use the refinished W126 wheels on the 560SEL.

I thought of a few options for the SLC.

  1. Standard 14″ Steel wheels with colour matched hubcaps.   These were the original wheels that came on my car.   The proper 14×6.5 wheels with the fins to cool the brakes are still available, although getting harder to find.   The tyre selection on this size of wheel is quite lacking.
  2. W126 15×7 Steel wheels with colour matched hubcaps.   The colour matched hubcaps were available in 15″ for special orders, ambulances etc, but are now very very expensive.   Still, there are much better tyres in this size.
  3. Standard 14×6.5 Fuchs alloy wheels.   These are the standard alloy wheels for the period.   I have a set of copy wheels in this size, but I’ve never liked this wheel and they have the same tyre availability issues as the 14″ steelies.
  4. Period AMG wheels.   These came in both 15 and 16″ and a few different styles.   The most well known are the AMG “Penta” five spoke style.   I think these look great on the 107 SLC.

After considering all these options, I decided to start looking out for an original set of 15″ AMG Penta wheels.   I think the 15×7 size work much better on the 107 SLC.  They keep the ride and look better.   I am not a fan of big wheels on classic cars.    These wheels were not actually called Penta by AMG, but one of the popular replicas had that name and it stuck.

I found a set that had been refinished not so long ago on facebook marketplace.   They were exactly what I was looking for.   The only downside was they didn’t come with lug nuts or centre caps.    As they were in Melboure, it was just as well they didn’t have tyres.   It would have made the freight too expensive.

AMG Penta

Lug bolts shouldn’t be a problem as it looks like I can use the bolts that go with the 14″ factory alloys.  I have a set of these.   Centre caps were a bit more of a challenge.   Unlike some of the copies, the original AMG wheels use a much narrower centre cap.

Surprisingly, even though they date from before AMG was acquired by Mercedes-Benz, they are still available.   The part number is H WA 201 400 01 25.   They are not cheap, but I was able to grab a set of five from the classic centre.

AMG Penta

The next step is to choose the tyres.   This isn’t a simple as it sounds, so will be covered in the next episode.   I think they are going to look great on the car.

BM2 Battery Monitor

A couple of months ago a friend showed me his BM2 Battery Monitor installed on his 420SEL.    It is a bluetooth enabled battery monitor that connects to a phone app.   The app lets you monitor the battery in real time, run some tests and download history from the battery monitor device.

I already have various battery testers which are useful for standalone battery testing.    However, I didn’t have a good way of checking the overall charging system of the cars.    In particular, I have seen some strange behavior with the radios in my 250SE and Citroen DS that may be related to over or under charging.

I ordered the BM2 Battery Monitor devices a while back, and they finally arrived yesterday.   I had the E-Type at my house this week, so thought I would try out one of the devices.

BM2 Battery Monitor

There are two apps you can choose from.   The free app, that lets you connect to one Battery Monitor at a time, and a paid one that lets you connect to four.   I started with the free app.     You don’t connect your phone directly to the BM2 battery monitor bluetooth, you start the app and give it permission to use the bluetooth device.

When I first connected the phone, it showed the current status of the battery in the car.   As expected the battery was fairly low.   The last drive was quite short, in the rain and dark.

BM2 Battery Monitor

When I started the car, I was able to use the cranking test which passed (as expected).   Next, I tried the charging test.   This is where the unit somewhat fails on older cars.   According to the BM2 Battery monitor, the car wasn’t running, so I couldn’t start the test at idle.   Its not really surprising as modern cars have very large alternators that provide plenty of amps even at idle.    The E-Type has a 43 amp alternator.   It doesn’t produce a whole lot at idle.    I was only able to start the test holding the revs above 2000. I imagine it would have even less luck on an older model equipped with a generator.

BM2 Battery Monitor

In any case it showed that once the revs were up, the alternator created plenty of current.   This was even more apparent during normal driving where the Alternator was putting out plenty of power.  I was seeing a regular 14.5-14.6 volts while driving.

BM2 Battery monitorI did get an alarm at idle when the cooling fan was running and I switched on the headlights.   Once I took off again there was plenty of power.   The E-Type has pretty low power needs.   During normal driving only the fuel pump, the ignition system and sometimes the cooling fan are drawing power.

I think this will work well to test the charging system of the 250SE and Citroen DS.   I may even get a couple more to keep them on the older cars.     It would be good if the app could be put in a mode where the screen does not turn off, as it could function as a temporary voltage gauge.    The range is quite good as I was able to connect to the device from outside the garage.

560SEL front suspension rebuild

This week I got my 560SEL back from having a front suspension rebuild.   This wasn’t something I really wanted to take on myself.  My SEL drove well, but there was some looseness in the front end.   As I plan on keeping the car long term, it made sense to rebuild the front suspension to restore an as-new ride.

The front suspension rebuild included new upper control arms and associated bushings, lower control arm bushings and sway bar bushings.    I went with genuine for the upper control arms and Lemforder for the lower control arm bushings.   The genuine parts are expensive, but they are inexpensive compared to the labour required and I am confident they will last the distance.

As well as the sway bar bushings at the front suspension there are also a set on the firewall.   Replacing these was a big job.   One of them is under the battery tray which is quite easy to get at.   The other required the removal of the brake booster and fuse box.    Having removed and replaced the brake booster on my old W111 250SE, I’m glad I didn’t have to do it on the w126.

While I was having this work done, I also had the brake hoses replaced.   I had experienced brake fade on a long downhill stretch, and I wasn’t sure how old they were.   I am glad I had them replaced as they were swollen inside. The picture below shows some of the old parts.

front suspension rebuild

At the same time, I also had a couple of o-rings replaced in the transmission.   This was the cause of a transmission leak.    After all this work you can tell the front suspension is far more supple.   Since I re-installed the rear self-leveling suspension, and not fixed the front suspension this car rides really well.

Prior to this work being carried out, I also had the flex discs replaced.   I had noticed some minor cracking in the discs when inspecting the underside of the car.   I probably could have left them for a while longer, but it is better to be safe that sorry with parts like this.   There are plenty of stories of major damage and accidents from failed flex discs.

flex discs

My 250SE is now repaired and better than ever

After the impact with a Kangaroo, my 250SE Cabriolet is back on the road and better than ever.    While the damage didn’t look that bad at first, the repairs required were extensive.   Unlike when you hit another car, A Kangaroo is ‘softer’ damage that isn’t as apparent to the naked eye.   It would be the same for hitting a Deer or other medium sized animal.

As outlined in the article linked above, there was a fair amount of body work required on the car.   In addition, we required a good used headlight, the grille repaired and re-chromed, a NOS grille mesh and new chrome strips from the Classic Centre.   During the repair there was evidence of previous minor accident damage which is now better than before.   These cars were very solidly built, so there was nothing that couldn’t be fixed.

250SE repaired

Obviously as well as the repair work the front part of the car needed to be repainted.  All Classic Car restorations, who did the work did a great job.  I actually got the car back a couple of weeks ago, and was planning to take a few nice photos.  However, we’re back in COVID-19 lockdown here in Sydney.  The best I can do is the car parked, ready to be used again in a couple of months. I have taken it on a few short drives to buy essentials, but that is all.

While the car was in the shop, I had them fit rear lap/sash seatbelts so my kids can ride in the car.   Despite what I was told, there were original mounting points for the shoulder belt hiding under the trim.

250SE repaired

Of course, one of those short drives resulted in a flat tyre, so I hope any back luck I have with the car is now behind me!    I don’t think its related to the crash, but I am still trying to work out the cause of a stutter or miss that the car sometimes has.   Plugs are fairly new, although it would have been started and moved around the workshop a bit when it was being fixed.   A few good long drives might even sort that one out.   I hope I can still display the car at the MBCNSW event later this year.  Unfortunately, it’s looking less and less likely.

250SE repaired

Bleeding W126 brakes with a Motive Power Bleeder

I recently changed the flexible brake hoses in my 1986 300SE.   I wasn’t sure how old they were and they are a wear item.  The next step was obviously bleeding the brakes.  Bleeding W126 brakes is really no different to any other car.    I recently purchased a Motive Power Bleeder to make this job easier.

I’ve bled brakes many ways over the years.   The traditional two person method of pumping the pedal; various one man systems such as vacuum pumps or valves.    So far I had found the vacuum pump system the best.  However I had ruined two vacuum pumps by getting brake fluid in them.    The Motive Power Bleeder looked promising.

At first, it looked like it was going to be much harder than the videos suggested.  I couldn’t get the system to hold pressure.   There was a hissing sound, and it appeared that it was coming from the cap.   I tried to bleed the brakes anyway, and got one wheel done before fluid started gushing out of the reservoir.

Bleeding W126 brakes

Turns out the little rubber grommets above the fluid level sensor had gotten hard and were letting fluid through.   They were still available and quite cheap.   The reservoirs were also still available, an updated version without the grommets.  I got both, as I didn’t want to find the grommets didn’t fix the problem and have to wait another couple of weeks to get the reservoir.   Also in my mind was having a spare reservoir on hand given how little interest Mercedes-Benz has these days on suppling youngtimer parts. The picture above shows the reservoir with the grommets removed, and below shows with the new ones installed.

Bleeding W126 brakesOnce I had the leak fixed, Bleeding W126 brakes with the Motive Power bleeder was a cinch.   It took longer to get the car up in the air and take the wheels off.

I needn’t have put that old tee shirt around the reservoir to catch any overflow, as the new grommets did their job.   There was enough vacuum to do all four wheels.   This may not be the case if starting from scratch, as I had done one wheel last time.

Bleeding W126 brakes

Instead of buying the motive catch cans, I used an old coke bottle with a hole drilled in the lid.   It worked quite well. I drilled hole in an oval shape so it held the hose but let air get into the bottle.

Bleeding W126 brakes

Due to COVID lockdown, I didn’t get a chance to test drive the car.  The pedal felt firm so I am confident that all is well.    I also noticed that I have a miss matched set of wheels on the car, so I want to change some of the tyres so I have a set that match on this car and a set that match as my spare set.

Now I have the Motive power bleeder, I will probably do regular fluid flushes myself.  I don’t think I’ll be that keen to take on the replacement of the hoses though.

W111 Cabriolet rear seatbelts

I’ve always been a little surprised that my W111 Cabriolet rear seatbelts were lap only.   Mercedes-Benz were such pioneers of safety at the time that it seemed odd that they wouldn’t have fitted lap/sash seatbelts.   It hasn’t been a problem for me as I so rarely had passengers in the rear of the car.

That has started to change as my kids are getting old enough to want to ride in the back of the car.   I wasn’t so keen in a convertible with lap only belts.   I mentioned this when my car was at All Classic Car restorations being repaired from the ‘roo damage.   They said that if I removed the rear seats, they would take a look and were confident they could fit seatbelts.

I took out the rear seat and couldn’t see any obvious seatbelt anchors.   I removed the trim at the bottom of the parcel shelf where the soft top folds.   There was nothing obvious there.   Stranger still, was that there were factory anchors at the bottom, but my current lap belts were not using them.

I went on various forums, Facebook groups and checked pictures of cars for sale.  I found a couple of cars that had been modified during restoration to take inertia reel seatbelts, but as far as I could tell the W111 Cabriolet rear seatbelts were lap only.

On closer examination, my car did have rear anchors for lap/sash seatbelts.   They were covered up by some trim.   On the Cabriolet, there is a bulkhead between the parcel shelf and the rear seat.   On each corner of this bulkhead there was a seatbelt anchor.   They very much looked like factory anchors as this bulkhead section is not accessible from the boot or from the parcel shelf.   Adding the anchors later would have left evidence of cutting and welding into this bulkhead.

W111 Cabriolet rear seatbelts

Incidentally this bulkhead section is one of the many reasons why a coupe shouldn’t be ‘converted’ into a Cabriolet.   Not only is a beautiful coupe being vandalized, but the structures are quite different.

Getting the rear seats in and out of the Cabriolet is much easier than it was on my 450SLC.   Space is cramped on the SLC.   On the Cabriolet, you can mostly open the roof and stand up.   I found the easiest way was to make sure the bottom of the seat was below the level of the armrests and push it towards the bulkhead rather than sliding it down from the top.

W111 Cabriolet rear seatbeltsThe set back illustrates another difference between the coupe and the cabriolet.   The top of the seat back is narrower on the cabriolet to clear the soft top mechanism.

Getting the seat bottom in is fairly straightforward, but don’t assume you need to keep pushing it in to line up.   I had actually pushed it in a little too far on one side.  Pulling it back out 1cm meant the screw slid in no problem.

W111 Cabriolet rear seatbeltsI’m pretty happy with the result.  I now have W111 cabriolet rear seatbelts and I didn’t need to modify the car in any way.   I’m not fussed about not having inertia reel belts as they will not be used often.   But now when my kids ride in the back of the car, I’ll have a lot more peace of mind.

W111 Cabriolet rear seatbelts

W126 brake hose replacement

I’ve been meaning to change the brake hoses on the 300SE for a while.   I have no history for the car, so I don’t know how old they are.   As I also wanted to change the brake fluid, I thought it made sense to do both jobs at the same time.   I had noticed a slight pull to one side on hard breaking.   It may not have anything to do with the hoses, but they are a good place to start.   Brake fluid really should be changed ever two years.   Most people don’t do it that frequently, but regular changes are still important.   Probably even more important on cars that don’t see much use.

I recently had the hoses changed on my 560SEC.   I was originally planning to do this job myself, but when I inspected the hoses under the car it seemed apparent they had not been changed since the car was imported from the UK in 2005.   After seeing this, I decided no to tackle this job myself and I’m glad I didn’t as the old hoses put up a good fight.    I figured since the 300SE was an Australian delivered car, the job would be much easier.

W126 brake hose replacement requires different hoses depending on the model.   Based on my 86 300SE and 87 560SEC and SEL, these were the required hoses.


Front: 129 428 00 35

Rear: 126 428 03 35


Front: 129 428 00 35

Rear: 126 428 01 35

I haven’t looked but I suspect the rear hose difference on the 560 models is due to the anti-squat suspension geometry.    I found that the attachments to the caliper were easy to remove, but I was only able to get one of the connections to the brake hard lines off easily.   Even after letting the other ones repeatedly soak in penetrating oil, they still wouldn’t move.   I was using the correct flare nut spanners but I still couldn’t get them to budge.

In the end I had a mechanic from up the road help me and we only got them off with vice grips.   This is not ideal, but the only way to get them off.    Cutting open the old hoses didn’t show any restrictions, but they were very hard and were starting to get some minor cracking on the outside.    I think next time I will not tackle W126 brake hose replacement myself and just send the car into a mechanic.

With the new hoses installed, the next step was to bleed the brakes.   I had bought a new vacuum bleeder a few months ago and this would have been its first use.

W126 brake hose replacementThe power bleeder is quite easy to use, however I ran into another problem.   I couldn’t get my system to hold pressure.  At first I thought it was just a minor leak from the cap.   It turns out the rubber grommets on top of the housing for the fluid level were leaking quite badly and fluid poured out when I tried to bleed the brakes.    I’ve ordered a new set of grommets but also a new fluid reservoir in case there are more leaks.

As so many W126 parts are going NLA as Mercedes-Benz loses interest in the model, it will be good to have one on the shelf even if I don’t use it today.   The new housing is an upgraded part and it looks like it doesn’t need the rubber grommets.

In the short time I used the bleeder before I noticed the leak, I found it quite easy to use – the best system for bleeding brakes I’ve used so far.  I am confident it will be quite a simple job once I get the parts in I need.

W126 brake hose replacement

300SE fuel pump replacement

When inspecting the SLS in my 300SE, I noticed that the fuel pump was seeping fuel.    It wasn’t enough to smell fuel, so I am not sure how long it had been like that.   I’ve owned the 300SE for about four and half years and have not done the fuel pump replacement job.

300SE fuel pump replacement

As I keep a spare Bosch fuel pump and filter, I figured I should change it ASAP.   In my view, it makes little sense to change out the pump and not do the filter at the same time.   I changed the filter when I did the accumulator about four years ago, and it was very dirty.   I think my car sat for some time, so the tank is probably a bit dirty.

My 300SE is an 86 model, so it has the single pump setup.   Obviously the first thing I did was disconnect the battery before working on the pump.   This job is not difficult but hard to do without spilling fuel everywhere.   I own some fuel line clamps, but of course I forgot to use them and sprayed myself with fuel.   This was rather uncomfortable as it soaked into my socks.    Its important not use vice grips here, as they will chafe the fuel lines.   I was able to push the handle of my ratchet into the fuel line to keep the stream of fuel at bay.

fuel pump replacementI am glad that I decided to change the filter.  After four years and about 12,000km, it was filthy.  I think this is also the reason why my fuel gauge flickers at lower levels.   I suspect after sitting for a while there is debris in the fuel tank.   This filter was not as bad as last time though.   Its also not been bad enough to affect the running of the car.   In my old 1988 560SEC, I ran out of Petrol.  The didn’t run properly until I changed the filter.   Given the debris in the bottom of the 300SE tank, I shouldn’t ever let it get too low.

fuel pump replacementFuel pump replacement is one of my least favourite jobs.   I’m glad its sorted out, but I really don’t enjoy doing this one.   I’ll probably be doing the filter again in a couple of years to see if there is still debris in there.

W126 Self-leveling suspension adjustment

On a recent drive with a few friends I noticed my 560SEC was sitting a bit low at the rear.   I had it parked next to a 380SEC, which I am pretty confident is at the correct height, and my car was lower.   Based on that, I started reading through the section on W126 self-leveling suspension adjustment to work out why.

The length of the control rod that links the height corrector to the sway bar impacts the ride height.   However, the manual is quite clear that this adjustment is not there to compensate for the standard ride height (without load) being off.    When the car is sitting on the ground without load, the height corrector should be in the neutral position and this is baseline adjustment.

W126 Self-leveling suspension adjustment

After reading this, I wanted to see the adjustment of my cars.   I can only keep two cars at my house, so as it happens I had the 300SE and 560SEL at home.   While on the ground, the 560SEL was in the neutral position.   The 300SE on the other hand was set up in a very strange way.   And to insult to injury, my fuel pump was seeping fuel.

W126 Self-leveling suspension adjustmentI had replaced the control rod a few years ago, but I had just put it back where it had been before.   Based on the workshop manual, this was clearly not right.   The manual outlines a procedure where you can lock the car in the neutral position and then lower it back onto the ground.   This establishes the standard ride height without any SLS adjustment.

The manual then goes on to suggest the length of the rod should be set based on this neutral position with the car on the ground and no load.   I used a small drill bit as a substitute for the special tool that locks the height corrector in place.

W126 Self-leveling suspension adjustmentThere are two holes for the control rod.   The outer car is for cars without anti-squat suspension geometry.   This is basically M117 cars, excluding some USA models.   My 560s both use this hole.   The inner hole is for other models that do not have this suspension, i.e. all fives, sixes and M116 cars.   At the 300SE is a six, that is where it goes on this car.  On my car I had to shorten the rod about a centimeter.

W126 Self-leveling suspension adjustmentAfter this adjustment, the car seemed ever so slightly higher at the back.   I didn’t measure it first – probably should have.   Based on my W126 self-leveling suspension adjustment, I have not noticed any change in how the car rides.   I did hear a slight groaning noise on hard acceleration though, something to check.    I also don’t know the long term impact of my height corrector running with the arm backwards for so long.

While I was under the car I also changed the fuel pump and filter.   Luckily I had both on hand.   This will the subject of a separate article.

I will have to do some further tests on the car to ascertain the correct operation of the SLS.