How do you go about pressure testing the crankcase.Do all saws have the impulse line as stated in this thread to vaccum test ????
Hi milkie62; Not all saws have an impulse line. To connect the saws that do not have impulse lines you have to come up with a fitting that screws into the sparkplug hole. There may be a fitting that can be purchased with a hose barb fitting already on it but I made mine from a old spark plug . First break out the white porcelain insulator material,a couple cracks with a hammer works well, then clean up the area where the porcelain meets the metal base. Take a hose barb, the ones I use are made of brass ,and with a little filing or a lite grind make it fit into the base where the porcelain came out and then just solder together, use flux and 50/50 solder and any torch to just melt the solder and it will join tightly. Once done you have a fitting to connect your hose up to.For pressure testing you can just run a line from a compressor or any air supply but you will have to reduce the pressure to a couple of lbs as you don`t want to blow anything apart . I have a regulator from one of my paint guns that will regulate down to zero and set it for 2-3 lbs then apply air and then check for leaks .If you have a good ear you can hear where it is leaking, apply soapy water with a spray bottle to the crank seals ,the gaskets around the carb and spacers or boots ,the crankcase halves and the base gasket under the cylinder or the head gasket if there is one,
if they are leaking it will bubble and you have found your leak.
If you just want to test the crankcase to see if it holds pressure you would also need to have a hand pump,gauge and release valve, these can be bought as a kit and connect to the saw the same as above. Pump up some pressure ,10-12 lbs works for me and see how long it will hold, the longer the better but if it is not all leaked out in 20 seconds the saw will run all right. The vacuum test works better for me as this is what the saw is subject to under operation. If it does not hold vacuum then I apply air to find the leak.
This may answer your question , it is the way I do it, other mechanics may have a different method but it all serves to find one of the most common problems with small engines. Pioneerguy600
, second cup:biggrinbounce2: ,now after a side of AS :hmm3grin2orange: 
