R107 sl suppressed engine response, play in gas pedal, temperature issue

[Viajero]

Hi all, hopefully someone might be able to help with the following problems I'm having with my 1986 300SL:

1. Driving at speeds above 40 miles per hour the car starts to resist further acceleration - it almost feels like the brakes are pulsing on and off, and the car feels quite heavy, resistant and unwilling to accelerate. The power seems to 'pulse' in and out and seems a bit choked and suppressed. I did have all the brakes checked for binding and the tires are moving freely so perhaps the problem is arising in the engine or transmission? any thoughts would be most welcome.

2. The gas/throttle pedal has play in the sense that it feels quite soft when starting from rest, and I have to press it around an inch before the car actually responds. Again, starting from rest the car feels quite heavy/restrained and unwilling to move. This lack of crisp response makes city driving annoying. Can I remove the play as a DIY or should i take it to a garage?

3. Unrelated to the above, but I was driving in central london yesterday and during a long wait at a traffic light the temperature gauge starting creeping quite close to the red line. It came back down to normal a while after the car started moving again, but I'm now concerned about driving it in heavy traffic. The radiator fan is running and the coolant seems to be topped up. Any advice on why this may be happening?

Many thanks in advance for any thoughts on the above problems.

 

[millo777]

Related to point 3, that sounds like the clutch isn't engaging. I assume it's a viscous clutch rather than an electric fan? If the temperature starts to cool down when moving the coolant is circulating through the rad and the thermostat is opening, which leaves the fan clutch. When the fan engages you should hear it with a roar, which will then bring the engine back to it's normal temperature.

Even though it may be spinning, it not be fully engaging. If when the temp is creeping up you can stop the fan with a folded up newspaper then you need to consider changing it.

If the fan is electric, try shorting it out and seeing if it starts, if it does the temp sensor needs to be changed.

It's worth checking the coolant strength with a couple of quid tester from hellfrauds and replacing as necessay and flush the rad at the same time. The antifreeze also raises the boiling point so a good strength is equally important for summer driving.

 

[Viajero]

Hi millo777, I checked the fan yesterday and you are right it is a viscous fan. I let the engine idle for around an hour at the end of which the temperature gauge was slightly above the mid-way mark (it stays around the quarter mark when driving at reasonable speed); I was unable to get the car any warmer, but the fan had not automatically switching on up till that point - I could stop it turning with some folder paper. I'm thus guessing that it's likely the fan not automatically turning on and needs replacement. Separately though I will flush the radiator as house keeping as well. Many thanks for your advice on this.