Front crank seal replacement

[bestill]

Hi there guys. I want to replace the 40x55 oil seal in my haflinger that's located behind the crank pulley. Any ideas on getting the pulley off? Mine wont budge! In the parts book the pulley looks like it is held on with a threaded nut. Is this a left hand thread? Also is the pulley splined? and does it have to go back in exactly the same spot on the crank shaft. I cant see any timing marks on it? Any help would be appreciated.

[AustHaflinger]

I really cannot answer any of your questions other than the the pulley closest to the engine does have a single small notch in it that is the timing mark.

Here is a pic of mine with the notch highlighted in white lined up with TDC on the fan housing. My assumption is that the crank pulley is slotted to the crankshaft to ensure timing is correct.

Garry

[bestill]

Thanks Gary

[Adam]

I’ve been waiting for this moment where I might actually be able to help someone out!! Pulley has a key way to align mark with tech. But is a standard thread, normally super tight. I had to use heat with a heavy rattle gun. No other tricks, my pulley was still reasonably tight on crankshaft after but was removed, but should basically slide off and then replace seal.
Good luck, Adam

[Adam]

TDC sorry, not tech!!

[AustHaflinger]

TDC - top dead centre. Is where the piston is at the top of its compression stroke in the firing cycle - both valves will be closed.

However because of the time it takes for the HT charge to get from the coil, through the distributor then to the plugs, fire the plugs and the flame front builds up, most engines fire the plugs before the piston gets to TDC - the term is Before Top Dead Centre (BTDC) this means the spark plug fires before the piston gets to the top on the compression stroke so that the fuel is fully alight and expanding as the piston goes over TDC and on the way down on the power stroke.

Most cars measure this firing point as °BTDC but for some reason Puch measures it as mm (0-2) before TDC. So when you time the engine with the timing light you want the mark on the pulley to be about 2mm to the left of the mark on the fan housing. I have found this equates to about 3°BTDC and I have a centre punch mark on the fan housing so I dont have to guess this 2mm distance - see my pic above - if you zoom in you will see 3 dots - the closest to TDC is 2°BTDC, the next dot is 5° BTDC and the furthest is 10°BTDC - the little stroke between 5 and 10 is 7°BTDC. I have a modern timing light and just dial into the light the setting I want (say 10° BTDC) and then adjust the distributor so the pulley mark and the static TDC mark align and my timing is set.

Most engines can handle static timing of up to 10°BTDC without issue if running on good fuel but the engine will run a little hotter but develops a little more power - at 10°BTDC and above you need to be wary of pre-ignition where the engine is firing too early and this can damage the piston or burn a hole in it.

If you move your timing into the After TDC (ATDC) position, generally the flame front is trying to catch up with the piston moving down so you loose power and if the fuel mix is still alight when the piston goes up on the exhaust stroke much of the unburnt fuel can just go out the exhaust increasing emissions, fuel consumption and loosing power.

Here endeth the lesson

Garry

[heinkeljb]

Set the points gap on TDC. Then set the timing at which ever BTDC unit you have chosen. As pointed out above, firing point can vary and various people will tell you it should be this exact figure or that. In truth, it can vary by quite a lot and still the engine will run perfectly well. THe only real way to get the ignition point absolutely correct would be to measure the composition of the exhaust gases using O2 sensors like modern cars - not really very easy on a Haflinger engine, so best way is to use a good timing light once you have set the static timing and play with the position of the distributor until you get a nice even running state in both idle and at full revs. (It's all a compromise).

John

[bestill]

I’ve been waiting for this moment where I might actually be able to help someone out!! Pulley has a key way to align mark with tech. But is a standard thread, normally super tight. I had to use heat with a heavy rattle gun. No other tricks, my pulley was still reasonably tight on crankshaft after but was removed, but should basically slide off and then replace seal.
Good luck, Adam

Thanks Adam, I knew someone on here would know! Cheers!