Bad W126 window regulator

Another long standing to-do list item on my 300SE was the passengers side window. Over time, the window would slip down so there was half a centimeter gap at the top. It would also make a clunking sound at the top of the window travel.

I had purchased a good used W126 window regulator a couple of years back. Yesterday I decided to try and fit the regulator. To get to the W126 window regulator, the door card must be removed. To do so, there a few screws holding it in place. Two holding the little chrome embellisher near the […]

300SE cowl drains

Last year, while I was fitting the monovalve elimination kit to my 560SEC, I cleaned the drains under the cowl covers. I also fitted a new upper seal and new shaft seals for the windscreen wipers. The condition of those seals was even worse on the 300SE, so today I finally got around to doing the same job on that car.

I was especially keen to do this on my 300SE as water would get into the passengers foot well in the rain. This would only happen when the car was parked nose up on an incline. My theory was […]

W126 Outside temperature LCD screen repair attempt 1

The W126 outside temperature display was standard in all Australian delivered series 2 models. The little LCD screen is not really compatible with the Australian sun as most of them start to bleed and become unreadable. My 300SE and 560SEC both have unreadable LCD screens. The 560SEL, which was garaged all its life still has a good screen.

Buying a used one is not really a good option. They are not particularly cheap, and even if a cheaper one from the USA can be sourced, it would be in Fahrenheit. There is somebody in Europe who is selling replacement LCD […]

W126 Radio and USB sockets

When I bought my 300SE about four years ago, it came with an early 2000s era Kenwood CD player. At the time, I assumed I would need to replace it, as it wasn’t working. Turned out the plug had come out of the back and it actually worked fine. It wasn’t a bad unit, as it could play MP3 CDs, display track information and so on. My main problem with this radio was that it would occasionally cut out, and only work again if I removed and plugged the face back in. The W126 radio is a DIN unit, so […]

M103 Oil Pump catastrophic failure

My 1986 300SE is now back in business with good oil pressure.   Turns out the reason why the oil pressure was low was a catastrophic failure of the oil pump itself.  In the last part, I had narrowed the problem down to most likely being the pump.   I assumed that something was either blocking the screen or the pressure relief valve was stuck.    At this point it was time to take the car to a professional mechanic to have a look.

On the M103, the engine has to be raised to remove the one piece sump.   Once the sump […]

More M103 low oil pressure troubleshooting

As a recap, my 1986 300SE started showing low oil pressure. I tried changing the oil and filter, replaced the sender and checked with a mechanical gauge. Still low oil pressure. I decided to do some final oil pressure troubleshooting before I took it into a mechanic to lift the engine and remove the sump.

I was advised on the ozBenz forum that another possible cause was the oiler tube for the camshaft coming loose. The oiler tube is held down by a couple of bolts that if overtightened can strip the threads. Since I don’t have a lot of […]

Testing M103 Oil pressure with a mechanical oil pressure gauge

In my last update, I had ruled out the sender unit when it came to the low oil pressure readings on my 300SE. My intention had been to take the car to a mechanic to test it on a mechanical oil pressure gauge. Two things changed that. Firstly, my area of Sydney went into lock down. Secondly, most mechanics are on holidays until after the new year. I therefore purchased my own mechanical oil pressure gauge off eBay.

I hooked up the gauge and sadly the results were much the same as the dashboard gauge. The mechanical oil pressure gauge […]

M103 Oil pressure sender

A few weeks ago my 300SE started to show low oil pressure on the gauge. It happened all of a sudden while on a drive. At the time, I surmised that I had a dead M103 Oil pressure sender. They are apparently a common fault. I ordered a new one and fitted it today.

The M103 oil pressure sender can be found on the side of the oil filter housing at the back of the engine. Most of the threads you’ll find on the various forums are referred to the W124. Apparently on the W124 space is tight and it […]

300SE low oil pressure gauge

Today I took my 300SE on a Mercedes Club Pop up drive. The Pop up drives are short notice mid-week drives. I normally take the other cars to club events, but the 300SE had not been on a decent run for a while and the weather was terrible. The drive was down through the Royal National park to Mt Kembla, Mt Kiera and then back.

The other cars on the drive were rather varied. There was a Ferrari 458 Spider, an Audi SUV, a race prepped Toyota Yaris and a couple of other Mercedes including a C63, C250 and E400 […]

W126 Klima Relay

A week or so ago, I diagnosed that the likely cause of my non functional A/C in the 300SE was the W126 Klima relay. The second generation W126 went to a Klima relay to control the A/C compressor.

The W126 Klima relay is more of a control unit than a simple relay. It has multiple inputs that determine if the A/C compressor should not engage. These include:

During full throttle When the engine is very hot Invalid compressor speed (e.g slipping belt) Not enough coolant in the system

This additional functionality makes these relays more sensitive than the little silver […]