W126 radiator removal

As part of the work I have been doing to the 560SEC, I have removed the radiator. The radiator was leaking from the top tank and appeared to be original. It was an IMI unit which was one of the OE suppliers and had a 1987 date code on it. W126 radiator removal is fairly straightforward.

Fist step is obviously draining the coolant, and there is a drain valve at the bottom of the radiator. The coolant will drain must faster if the radiator cap is off. I am really happy with how clean the coolant is, and how little […]

W126 Monovalve eliminator – part 2

My 560SEC had been leaking coolant and giving me heat when I didn’t want it. Last week I started the repairs for these problems. As the Bosch and Mercedes W126 Monovalve repair kit was no longer available, I have been installing the Klima Design Works monovalve elimination kit.

In the first part I removed the W126 monovalve, auxiliary water pump and other hoses. This gave me the room to give the area underneath the heater hoses a good clean. There were some leaves and other detritus. Its important to remove this stuff it can cause rust. The mud stays wet […]

W126 Monovalve eliminator – part 1

My 560SEC has been having a couple of problems with its cooling system. Coolant has been weeping out of the top tank of the radiator. In addition, the monovalve has failed, causing unwanted heating at idle. The radiator looks either original or replaced very early in the cars life. As these radiators have plastic tanks, I have purchased a new one to replace it.

It used to be possible to purchase a monovalve repair kit from Mercedes or Bosch. The supply of these has now dried up. There is a kit from a company called MTC but all the Mercedes […]

560SEC stone chip touch up

Over the years my 560SEC has acquired quite a lot of stone chips on the front of the car. I understand the previous owner was in semi-rural Queensland so there may have been some gravel or unsealed roads in there. Today I applied a stop gap fix until I can address the problem properly. Most of the stone chips were in the front panel under the headlights. These panels are removeable, so eventually when I have the rust under the rear screen fixed, i’ll have this panel repainted too. That repair will be a couple of years away, so today’s […]

W126 Antenna grommet

One of the things that had been bugging me about my 560SEC was the missing W126 antenna grommet. Over time, they perish and instead of replacing it, the previous owner had used household sealant. This is an odd bodge as the part is inexpensive and easy to fit. The household sealant was making the SEC look like a real jalopy, and while that might be the name of this site, I don’t actually want the cars to look like jalopies.

It is quite easy to fit the new W126 antenna grommet. The power antenna must be dropped down. It […]

Repainting the W126 cladding

The W126 was the first Mercedes to feature plastic cladding. I’m not sure this is the best feature of the W126, but it started a trend that would continue for many years. The W126 cladding is attached to the car with a series of clips and consists of eight peices (four on each side) along the line of the bumper bars. The cladding is not the same colour on each car. Before 10/88 it was a contrasting grey, and after 10/88 it was generally a darker shade of the body colour.

This page (in German) provides all the colour codes, […]

W126 SEC auxiliary fan replacement

Once I got the air conditioning working on the 560SEC it was apparent the auxiliary fan was not working. As can be seen in the wiring diagram below, the W126 SEC auxiliary fan can be triggered either by high coolant temperature or by refrigerant pressure. The diagram is for 1986-1990. In 1990, the W126 went to a dual fan setup. The fan can operate at two speeds based on a resistor.

My fan would not work even when fed 12v directly. I struggled to find a replacement fan from a brand I trust. I wasn’t that keen on a […]

560SEC Climate Control repairs part 1

When purchased, my 560SEC did not have working climate control. Not only did the A/C not work, but the heater had a mind of its own, occasionally bursting in to life and turning on full heat. Curiously for a car that has been in Australia since the early 2000s, the car had not been converted to R134A.

My first step was to see if the system could work. Overseas readers may not know that in Australia it is illegal to sell freon to the general public. R12 has not been available for many years. Therefore, I booked the car into […]

KE Jetronic EHA Adjustment

I discovered at the MBCNSW Dyno day that my 560SEC was running dangerously lean. Lean enough to cause damage to the engine. While I was in the USA for work, I went to the Mid Florida Auto show. I met Pierre Hedary there (who runs an independent Mercedes workshop), who suggested that I should start by testing my fuel pressures and that he had a couple of videos on youtube to help. The first video was on checking KE Jetronic Fuel Pressures. The second video was on KE Jetronic EHA adjustment.

As I own two KE Jetronic cars and one […]

MBCNSW Dyno Day

The MBCNSW held a tech day at a dyno equipped performance shop today. I was keen to attend as I wanted to understand how much power my ECE 560SEC is making. Geting dyno time independently can be expensive, but through the club day it was very affordable. The tech day was held at SR Performance at Wolli Creek.

On the Dyno, the following cars were tested:

CLK350 C209 C63 AMG 1974 350SL 1972 280SE 3.5 1987 560SEC 500SL R230

While my primary reason for attending the day was to find out how much power my engine is making, A […]