W126 Monovalve eliminator – part 4

I have now completed the installation of the Movovalve elimination kit on my 560SEC. So far so good. Most importantly, I don’t have heat when I don’t want it, but it is available when needed. In the last installment, I completed the routing of the cooling hoses. From there I installed the radiator and ensured the cooling system didn’t have any leaks. The final step was to set up the vacuum solenoid so it could control the heater valve.

The very rough diagram below outlines how I adapted the kit for the W126. Note the diagram is not to scale […]

Installing a W126 radiator

Today’s job was installing a W126 radiator into my 1987 560SEC. I had previously sorted out the cooling hoses as part of my monovalve eliminator install. I was just waiting on a few extra parts I had ordered to begin this job.

Firstly I decided to replace the coolant reservoir tank. My current one is not leaking, but the plastic was quite discoloured and looked a bit white around the hose entry. Genuine Mercedes coolant reservoirs are still quite inexpensive, and you never know how long that will continue. Best to change it now. I was already planning to replace […]

Replacing W126 cowl covers

I had previously removed the W126 cowl covers to clean the drains. Now they are clean and I have replaced the ABS module bracket, they were ready to be re-installed.

Before I did so, I had some new parts to install. The first were the rubber boots that cover the windscreen wiper shafts. On most W126 cars they are almost non existent. On my 560SEC, I had the remains of one, and the other was completely gone. The picture below shows the two new boots along with the remains of what was left on my car.

Second was the rubber […]

Cleaning W126 cowl drains

As part of the installation of the Monovalve elimination kit, I needed to remove the ABS controller bracket. The bracket was in the way of the coolant hoses. I order to remove it, I needed to remove the W126 cowl drains cover. This is great opportunity to inspect this area and clean it. Cars that have parked outside often have debris here that causes rust.

In order to remove the W126 cowl drains cover, the seals at the firewall and windscreen must first be removed. In the photo above, I have removed the seal on the firewall but not the […]

W126 Monovalve eliminator – part 3

I have been working on a project to eliminate the monovalve from the climate control system in my 560SEC. In the last part I had almost completed the cooling hoses required for the job. I had mostly worked out hose routing I was looking for – which was combining the dual outputs from the heater core into a single hose where I could place the new heater valve.

Looking further my design wasn’t going to quite line up. Once I put the elbow piece on the end, it was too long and the hoses were bent too much. I didn’t […]

W126 low pressure hydraulic hoses

My 560SEC has been leaking from the power steering and self leveling suspension. In both cases, it is obvious that (at least some) of the leakage is coming from the low pressure hydraulic hoses. It is possible there are additional leaks in the steering, but fixing this obvious one is a good place to start.

I had looked at doing this job a couple of months ago. I quickly saw it was quite fiddly and as I was planning to use the car the next day, I decided to put it off. Once I realized I would be removing the […]

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 […]