Further Down the Rabbit Hole

October, 1955 issue

I am deep into mechanical work on the car now and I haven't been taking many photos. This is for three reasons. 1. I am too busy working on it to remember to take pictures of the process, 2. My hands are too greasy to want to touch the camera, and 3. Any photos would be of engine and brake parts and probably not all that interesting to look at. So, because a blog post is always more entertaining if there are pictures in it, I am including vintage 190SL photos that I found on the web.

You never know how much trouble you are in for when resurrecting an old car. I got a new brake master cylinder but it is not exactly the same as the old one. The exact one is not available, apparently. Here is the possibly boring story.

1955 was the first year of 190SL production. That first year did not have a brake booster so the master cylinder was designed to work without one. In 1956, the year of our car, they started using brake boosters and a different master cylinder. For two years, 1956 and 1957, the brake light switch, which operates on brake fluid pressure, was attached to the end of the master cylinder. In 1958 they moved the brake light switch to the brake booster. The hole in the master cylinder where the switch used to go is now sealed off. The only master cylinders available now are designed for 1958 and newer cars. So we have to find somewhere else to put the switch.

To do this so that it matches the way Mercedes designed it requires the purchase of more parts. There is a "Y" fitting that costs $45. But this fitting is pretty thick so I would have to buy the hollow bolt that mounts it ($28). Then I would have to get a different switch because the mounting holes are different sizes. I can't even find that part.

What I think we will do is just put a generic pressure switch in the brake line that goes between the master cylinder and the brake booster. This will work fine even though it is not the way the car was originally put together.

A rendering from the 1957 190SL dealer catalog

The carburetors are another rabbit hole I am falling down and don't know how far it will go. This car has its original Solex carbs. I am SO glad I have these! To buy new ones would cost an unbelievably huge amount of money. Fortunately I don't have to buy new ones. The ones I have are leaking from the bottom though. Perhaps it's just a couple of gaskets?

I checked a diagram of the carb. It is not a couple of gaskets. What is leaking are the accelerator pump diaphragms. Maybe the cover plates just need to be tightened. I will try that next time I work on the car. If  the diaphragms are bad they will have to be replaced. A pair of new ones costs $320. Ouch!

I am missing all except one of the gaskets for where the air intake plenum (190SL folks call it an air log) attaches to the carburetors. They are paper gaskets and aren't that expensive but even cheaper is to make them myself using gasket material. That's what I will do. I will use the one that I have as a template and cut three more and it should be good.

On the assembly line in February, 1958

There are two carburetors linked together on this engine. The fuel lines are a bit complex. The one that connects to the rear carb needs to be replaced. Unfortunately I cannot just buy that piece. I would have to buy the whole assembly which is $350. I think we will try to make just the piece we need and not replace the whole assembly.

When looking closer at the carbs we noticed paper stuck in two of the ball and cup linkage fittings. This must have been because they were popping out due to wear in the fittings. I am sure the paper won't last long so I will have to order some new ones. Fortunately these are not expensive.

We pressure-washed the underside of the car this afternoon. There was a lot of oil, grease and dirt under there. We got it mostly clean and then put it up on the lift to inspect it all. There are about 30 grease fittings!  Every moving part of the front and rear suspension had one or two fittings. We greased them all so they should now be good.

Not everything is bad news on the way down the rabbit hole. We discovered that the center link tie rod was loose and, fortunately, it was just a big nut that needed tightening. A super easy fix. We discovered that the differential is not leaking gear oil. What we thought was gear oil was just old grease that had broken down. We also inspected a rubber boot that often goes bad on the rear swing axle. It turns out that it was replaced with a new one back when the car was being worked on in the early 80's. It is in perfect shape.

This truck is awesome!

The drain plug on the oil pan is all rounded off so I am going to order a new one. Lucky for me it is inexpensive and not hard to get. The valve cover gasket also needs replacing. It's not super cheap but it's not expensive either. Only about $30.

I have been working on this car for about a year and a half now in my spare time. It is starting to feel sometimes like it will never get done. There is so much left to do! But every time I work on it some small bit of progress is made so I suppose, at some point, I will actually get in the car, start it up, and drive around. Between now and then, though, I am sure there will be plenty more discoveries both pleasant and unpleasant.

Will the accelerator pump diaphragms need replacing? Will we get a brake light switch to fit the way we want it to? Will I be able to successfully get the brake booster back together? Will the brakes even work when the whole system is fully assembled? Stay tuned!

This pic is from the 1957 dealer catalog