Checking/setting ignition timing

[Vronsky]

How much time does it take to check and (if wrong) set the ignition timing? Want to have an idea how much I can be charged.
Called the local MB shop today: guy over the phone mentioned something about reading the diagnosis system aswell: that doesn't say anything about the timing, does it?

Thanks!

[Duke2.6]

Checking the timing takes about as long as hooking up the timing light and pointing it at the tab. In most jurisdictions that require emission testing, checking and recording the base timing is usually part of the test.

It looks like you have a 124 with a 102 engine. Not sure about your engine, but the 103 engines of that vintage do not have adjustable base timing, and I suspect yours is the same. The complete timing map is controlled electronically by the EZL ignition module using the TDC #1 pulse from the magnetic pickup sensor on the front torsional damper as a reference signal.

Reading the diagnostic memory is a couple of minutes of buttom pushing, but if you don't have a "check engine" light, there are probably no stored fault codes.

What makes you think there is a problem?

Duke

[Vronsky]

Thanks Duke,
Engine basically starts/idles/runs very smoothly, but it always starts to 'roar' from 3500 rpm and upwards. Everything else seems to be okay, so I was thinking to have the timing checked. From what you write, however, perhaps there's no point in doing that as the timing is electronically controlled, except for the vacuum line.

What do you think?

[Duke2.6]

When the temp hits 100C and the thermo clutch on the fan tightens (or the electromagnetic fan clutch engages on some engines) you will hear "fan roar" at over 2-3000 RPM, which is normal.

Also, four-cylinder engines are noisier than sixes because their unbalanced second order vertical shaking force can produce a low frequency audible noise at medium to high revs.

If this noise is something new, I would verify proper operation of the fan and have the motor mounts inspected by a competent Mercedes tech.

Duke

[Vronsky]

Éngine has an electromagnetic switch controlling the cooling fan.
I read lots about fitting a electrical cooling fan. In fact, in front of the radiator there's already an electrical fan for extra cooling due to the airco condensor which has been installed later.
Would replacing the belt-driven fan by another electrical one be a good option to reduce roar?

Appreciate your help a lot!

[Duke2.6]

My erstwhile '84 190E 2.3 had an electromagnetic clutch on the engine driven fan rather than the thermoclutch as is the case with my 2.6. It sounds like they stuck with the electromagmetic clutch on the 102 four-cylinder engine in later years.

I feel you might trying to fix a "problem" that doesn't exist. Assuming you live in Europe you had an unusually warm summer and the fan was probably engaged a lot.

On my 2.6 when the temp reaches 100C, which is not often in my driving conditions, I can definitely hear fan roar at and above about 2000 RPM when the thermoclutch tightens. When the car gets hot more air flow is required through the radiator, and the only way to achieve this at low speed is with fans, and fans make noise. It's the nature of the beast.

The only thing you need to check is the electromaganetic clutch. I expect that if they fail they would fail open and the fan will not engage though it's possible that they fail closed. If the system is designed such that energizing the clutch disengaged the fan this would be a better failsafe design as failure of the clutch or control system would keep the fan engaged all the time and prevent the car from overheating. The fan should spin freely when the engine is cold, and this should be checked both with the engine off and on, but cold. If the fan is engaged with the engine cold then you will need to troubleshoot the clutch and control system.

Assuming the system is operating normally as we progress into fall and winter, your fan roar issue will go away with the cooler temperatures.

Duke