Few quick questions now that my 1970 is finally running.

[traumadoe]

Hi Guys,
After a long and spendy battle my1970 250c has finally been roadworthy for about 1000 miles. I have been driving it almost everyday and I love the car. I am new to these cars and I have a few lingering questions.

1) after 1000 miles should I still be getting a little spit up out of the radiator overflow hose everytime I drive it? It dosen't have anything to catch it, should it? Everytime I check the coolant level it seems okay.

2) According to the speedo it shouldn't shift into 4th gear until 80mph but my car doesn't really like to go over 55. Am I paranoid or am I correct that it sounds like it's working really hard to go over 55?

I appreciate any and all advice.
Thanks!

[wbain5280]

Originally Posted by traumadoe

1) after 1000 miles should I still be getting a little spit up out of the radiator overflow hose everytime I drive it? It dosen't have anything to catch it, should it? Everytime I check the coolant level it seems okay.

The car did not come with a catch basin. Replace the radiator cap.

2) According to the speedo it shouldn't shift into 4th gear until 80mph but my car doesn't really like to go over 55. Am I paranoid or am I correct that it sounds like it's working really hard to go over 55?

The marks on the spedo are the maximin speed in each gear. When you say that it doesn't like to go over 55 what do you mean? These cars have a low final drive ratio and the engine rpm is higher than you may be used to. You can expect 3000 - 3500 rpm at 60 mph. Unless the engine has a knock, you have nothing to fear. These engines are like fine watches, smooth as silk. If the engine is loud, the exhaust pipe gaskets need to be replaced. Check the engine and transmission mounts, they may have collapsed and the engine is touching the crossmember. Also, the front subframe bushings, there are 4 of them, may also need to be replaced.


Your carbs may need to be adjusted or averhauled. You may also need to replace the distributor cap, rotor, wires spark plugs etc. The valves may need to be adjusted. There is plenty of information here and on other forums.

[Skid Row Joe]

Originally Posted by traumadoe

Hi Guys,
After a long and spendy battle my1970 250c has finally been roadworthy for about 1000 miles. I have been driving it almost everyday and I love the car. I am new to these cars and I have a few lingering questions.

1) after 1000 miles should I still be getting a little spit up out of the radiator overflow hose everytime I drive it? It dosen't have anything to catch it, should it? Everytime I check the coolant level it seems okay.

2) According to the speedo it shouldn't shift into 4th gear until 80mph but my car doesn't really like to go over 55. Am I paranoid or am I correct that it sounds like it's working really hard to go over 55?

I appreciate any and all advice.
Thanks!

That mark @ 80 mph represents the maximum that 3rd will produce in speed. At 80 mph, and above, you should have it in 4th.

I am familiar with that vintage/era since my Father bought a new 1969 220D automatic in 1969. I drove it on occasion - what a treat!

[Stretch]

Originally Posted by traumadoe

... Am I paranoid or am I correct that it sounds like it's working really hard to go over 55?

I appreciate any and all advice.
Thanks!

My guess is that you are being careful - do you have a tachometer or any way of rigging one up? You'd then have a better objective idea of what is happening.

[traumadoe]

Thanks everyone for the quick responses!

I will try a new radiator cap, it is likely the only part of the cooling system that has not been replaced! Thanks!

I don't have a tach in the car, it just sounds to me like it's working really hard. It may be that I am not used to what the car can handle. Everything above the engine block itself is new and professionally installed so I assume it is all as it should be. The car doesn't knock or rattle, it just sounds like it's really wound up. What kind of RPM range can a W114 SOHC handle?

[wbain5280]

Originally Posted by traumadoe

Thanks everyone for the quick responses!

I will try a new radiator cap, it is likely the only part of the cooling system that has not been replaced! Thanks!

I don't have a tach in the car, it just sounds to me like it's working really hard. It may be that I am not used to what the car can handle. Everything above the engine block itself is new and professionally installed so I assume it is all as it should be. The car doesn't knock or rattle, it just sounds like it's really wound up. What kind of RPM range can a W114 SOHC handle?

The engine will easily handle 6000 rpm.

You might consider having a pressure check done on the cooling system and take the radiator to a shop to make sure there are no leaks.

[traumadoe]

Thanks again Warren.

[Pooka]

Your car may not be shifting out due to a faulty or mis-adjusted vacuum modulator.

These are easy to check...

Locate the modulator on the back of the transmission and pull off the vac line from the vac port and see if transmission fluid drips from the hose. If so you need to replace the modulator. If not then replace the hose as it might have a small crack in it somewhere.

They are easy to replace...

There is usually just one bolt securing a flange. After removing the flange the modulator just pulls right out and the new one just pops right in.

They are murder to adjust....

When you buy a new one you get a little 'key' with it for adjustment purposes. This is almost an art and is best left to someone who has been there and done that.

Therefore I would recommend checking for a fluid leak and, in any case, replacing the vac hose that runs from this to the vac source on the engine. If the modulator needs replacement then find a transmission shop that works on Mercedes and let them do the replacement and adjustment.

[traumadoe]

Thanks, I'll peak at it in the morning.

[mercmad6.3]

The radiator is not spposed to be filled to the top. There should be a gap of 1" between the top of the water and the filler neck. This is to allow for heat expansion. When you stop after a run,the heat from the exhaust mainfold is soaked into the engine( heat soak) and this heats the water. because there isn't any airflow over the radiator core,the water temp rises along with the pressure and the excess is spat out the over flow.
Your best bet is to make sure the engine doesn't go over 175 F when driving.
The top speed of your 250 should be 120+ mph. There is something wrong if it is struggling at 55MPH. Is it a C or CE ?

[D&W]

I'm always quite surprised as to the top speeds some guys are getting on here.

In my 68 280se Inline 6 I have been up to 93mph in it. it felt quite 'exciting' and there is no way I could drive it that fast for more than a few seconds.

The freeways in CA are pretty terrible and jittery though too.

What top speed should I expect in my car?

[Maki]

The engine in my 250 would often show heat soak in warm weather -- enough to make a mechanic who specializes in vintage Mercedes comment on it. He suggested installing an electric auxiliary fan like the ones available from Summit Racing or JC Whitney and setting it up so it can run after shutdown and cool the engine bay. I never did it, but I probably would have if I lived in Arizona.

As for RPM, I've driven my car regularly at a steady 75-80 with the engine singing away. Enjoy the chat! And I think your transmision is in top gear. (Doesn't it start out in 2nd?)

[suginami]

I've had my 280SE 4.5 up to 110-115 mph, and it cruised quietly and effortlessly.

The car is not particularly fast 0-60, but if you punch it when you are going 70-80 mph, it will knock your head back.

The suspension is tight, and the steering wheel has absolutely no play in it.

At the time, I felt like I could maintain that speed all day long.

[D&W]

Originally Posted by Maki

The engine in my 250 would often show heat soak in warm weather -- enough to make a mechanic who specializes in vintage Mercedes comment on it. He suggested installing an electric auxiliary fan like the ones available from Summit Racing or JC Whitney and setting it up so it can run after shutdown and cool the engine bay. I never did it, but I probably would have if I lived in Arizona.

As for RPM, I've driven my car regularly at a steady 75-80 with the engine singing away. Enjoy the chat! And I think your transmision is in top gear. (Doesn't it start out in 2nd?)

Yea I can drive 75-80 comfortably on nice roads, engine sounds great and is responsive. feels stable.

Yep its starts in 2nd so its in top gear from about 30-40mph upwards

Its not a big concern considering I should really only go 65 legally. an extra 10-15mph suits me fine

[mercmad6.3]

Originally Posted by D&W

I'm always quite surprised as to the top speeds some guys are getting on here.

In my 68 280se Inline 6 I have been up to 93mph in it. it felt quite 'exciting' and there is no way I could drive it that fast for more than a few seconds.

The freeways in CA are pretty terrible and jittery though too.

What top speed should I expect in my car?

My First mercedes was a 280SE which was 4 years old when i got it.I was picked up on radar at 125MPH and it wasn't working hard . I drove it at those speeds all the time in those days because it was built to do it and I did it.
I've had my 6.3 flat to the floor a couple of years ago for 2 hours (130-140MPH) when I was rushing to meet a boat ,again the cars were meant to drive at those speeds.
In both cases the cars were easy to drive that fast and in the second case I had never driven on those roads before.
If your car feels unstable at high speeds there is problems with the suspension.