grober
MB Master
What you need is an old thermostat housing for flushing the system so you can leave the existing housing/thermostat assembly untouched. I agree its a bit naughty of HAYNES not to make this clear but as we all know to our cost they often miss out the odd piece of essential information.
Just tested the thermostat and it works fine so if you are careful you can get them back in the housing,so much for Haynes manual saying don't remove it as you will damage it DOH!
Number_Cruncher
Active Member
If, by mistake, you've had the knock sensor off, you may need to check the re-installation instructions. Some knock sensors are very sensitive to installation torque - this effectively tunes what frequency they "listen" for (typically 4000 cycles per second).
Thanks
Where would I get the re-installation instructions from.
If it has not been installed correctly would it not come up as a fault if not how do you know if it has been installed correctly I don't want to have to remove it again if it is OK it was a bugger to get to and put back.
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Number_Cruncher
Active Member
Sorry, I'm not sure of the best source of data for your engine - for my W124, I use the data available from MBUSA.
>>would it not come up as a fault
No, because electrically, it would still look OK to the ECU.
>>how do you know if it has been installed correctly
If the knock sensor were installed incorrectly, the ECU would not detect knock when it happened, until the intensity of the knock increased to a level higher than normal. Knock can be an engine damaging process, and so, if this were my car, I would want to be sure that I had followed the installation/torquing spec to the letter.
>>would it not come up as a fault
No, because electrically, it would still look OK to the ECU.
>>how do you know if it has been installed correctly
If the knock sensor were installed incorrectly, the ECU would not detect knock when it happened, until the intensity of the knock increased to a level higher than normal. Knock can be an engine damaging process, and so, if this were my car, I would want to be sure that I had followed the installation/torquing spec to the letter.
grober
MB Master
The torque figures I have from MB and Haynes agree at 20 Nm or 15lbf ft-- You will need a low range torque wrench to set that accurately. I'm afraid I don't know enough about knock sensors which I assume are piezo-electric type devices to know if overtorquing them will knock them out of spec?
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Cheers Graeme
As you say 20Nm or 15Ibf ft I did a google on them and you are correct but no info on if they are over torqued.
My wrench goes down to 10lb ft 13.6 Nm but would not like to say how accurate at such a low setting
As you say 20Nm or 15Ibf ft I did a google on them and you are correct but no info on if they are over torqued.
My wrench goes down to 10lb ft 13.6 Nm but would not like to say how accurate at such a low setting
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I have been all morning trying to get a torque wrench on the socket but it is not possible without stripping all the inlet manifold off and I don't think it is worth the hassle, I have tried from underneath and above so I have tightened it up to what I can guess is the correct torque.
Worst that can happen is a buggered up engine but these W202 are worth ****e now anyway.
Worst that can happen is a buggered up engine but these W202 are worth ****e now anyway.
grober
MB Master
Given the circumstances thats probably the right decision. Anti knock sensors are really safety devices to guard against high speed pre-ignition. Pre-ingnition is usually caused by heavy carboning up of the combustion chamber,incorrect mixture, very hot air temperature or most important poor quality fuel. In ambient UK temperatures, a well maintained, normally aspirated engine in standard tune running a good quality fuel of the correct octane is unlikely to need the antiknock facility. Kompressor or Turbo'd engines especially one's that have been "tweeked" might be a different matter.
