I recently installed 2 electric puller fans on my m103 2.6 and I'm having a bit of a problem, not sure if its wiring or what, but here is what I did and how I have the relay set up:

#30 - Fused to +12VDC disrtibutor block
#85 - one prong on coolant temp sensor, other prong on cts is grounded to engine block.
#87 - +positive wire on fan, -negative wire is grounded to chassis
#86 - +12VDC acc. source.
#87a - Not used.

So my m103 and an unused spot on the next to the original cts, maybe 2 inches more towards the front, so I unscrewed the plug and put in another cts. Using jforgione's idea for the Cool Harness, I ran a 1.1kohms resistor across the terminals so that the fans turned on at 92C. Well, the car gets up to about 80C and the fans turn on. So I removed the resistor and the same thing, fans turn on at 80C. I disconnected the wiring temporarily from both cts on the engine and tested them both with cold engine the resistance was about ~3.45 ± on both. Then I warmed the engine up and they both dropped resistance about the same values so this rules out a faulty cts as far as I'm concerned. So what can I be doing wrong? If I let the car idle for a good while (30-45mins) the needle will eventually make it to 87C mark and sit there for quite a while before temps slowly creep up. Thermostat is fully functional as well.

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1990 190E 3.0L