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Re: if cylinder base gasket leaks will it cause excessive...
Hi, LeeA I would really love to help you but due to the magnitude of yesterday's solar flare the batteries in my crystal ball are dead and my mental telepathy headset circuitry was melted. I need the year, make, and model of your motorcycle please click on the word "COMMENT" below and provide this information in the box that will open and then click on the green comment box in the bottom right-hand corner after it posts I will receive an "ALERT" icon that will allow me to respond to your information.
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If your machine is truly spraying fuel oil out of the dipstick tube, you most likely have some severe engine damage, most likely originating from a leaky (dripping) fuel injector/nozzle. The fact that fuel oil is present in the crankcase leads me to believe that at least one cylinder has been overfueling, causing wash-down of the cylinder walls and resultant piston ring and cylinder wall (or liner) damage. Enough raw fuel is getting (first) into the cylinder and (second) into the crankcase to wash the normal oil film off the cylinder walls, resulting in excessive ring and cylinder wear. In all likelihood, you now have excessive crankcase pressure due to the damaged rings and cylinder walls, as compression pressure is being lost into the crankcase..
Have this engine evaluated by a professional, as a tear-down and rebuild is very likely necessary. At the very least, the fuel system -- injectors/nozzles specifically -- must be investigated and repaired...
Go tell your mechanic that he doesn't know what he's talking about. I own a 1994 FXDWG and the only thing it does is seep a bit of oil on the rear cylinder base gasket. Your '94 model Evo engine is what we call a "head breather" in that the crankcase pressure is vented into the air filter through hollow "union bolts" that go into each head. If you or someone else has changed these bolts to eliminate the "breathing" effect, crankcase pressure can build in the engine causing it to blow the gaskets. Another thing that could be wrong is that your breather gear in the crankcase may have a broken tooth on it. This is the rotating "valve" that allows your crankcase to evacuate the oil into the cam chest so that the oil pump can pump it back to the oil tank. The gear is made of plastic and the teeth on the gear will break off. When this happens, the "valve" will either stop turning or become out of time with the crankshaft causing excessive pressure in the engine. Also, when installing the new seals, the middle and upper rocker box covers must be aligned properly to ensure the seal is not squeezed out or pinched.
In 1993, Harley went to the "head breathing" crankcase breathing system. The crankcase pressure is vented into the air cleaner to be routed though the engine and burned. This was a requirement mandated by the EPA. Prior to '93, the crank case vent was down behind the oil pump and a pipe directed the crankcase pressure up to the air cleaner. If you have the "head breather" heads, you'll have a large hollow bolt going to each head from the air cleaner assembly. If whoever did the top end job on your engine left the umbrella valves out, installed them upside down, or put the center plates in wrong, it could be causing your problem. If they replaced the head gasket and did not replace the base gaskets, the base gasket are going to leak. Whenever you take the torque off the head bolts, you must replace all gaskets. Additionally, if the cylinder studs on your engine have not been replaced, they are probably stretched and not holding the torque like they should. In 1996, Harley came out with an improved replacement stud for the Evo engine. The large diameter part of the stud is at the lower end of the stud rather than at the top end like the older model was. If you can't get those, Colony Fasteners makes an excellent set of studs that cost about the same as H-D parts. Blue or black smoke out of the exhaust usually indicates a rich fuel mixture.
if it is coming from up top it is in all probability the valve cover-check to be sure your PCV valve is not plugged and the crankcase is properly vented as excessive crankcase pressures will cause oil leaks from what would normally be good gaskets.
Without seeing the bike, I would guess that this is the crankcase vent. Originally, the crankcase vent tube came up from behind the oil pump and went to the backside of the air filter. A lot of owners changed the routing of this hose due to oil being blown into the air filter. They simply remove the metal part of the tube and replaced it with a short open ended hose running back and ending just forward of the rear tire.
As for the oil blowing out of the tube, it depends on how much oil blows out of the tube. If it's just a mist that will sometimes coalese into a droplet, this is about normal. But, if it's a steady drip or flowing oil, this is not right.
If the mist is heavy, this could be caused by excessive blowby on the rings creating high crankcase pressures. The use of synthetic oil should not increase the blowby unless the rings are in poor shape, then it will. The use of synthetic oil seems to aggrevate any minor leak turning it into a much larger leak.
If the oil is coming out in a steady stream or pumping the oil out of the engine, you proabably have sheared a key in the scavenge gears of the oil pump and it's not pumping the oil back into the oil tank.
Now there is a vent hose on the oil tank but it should be routed to a fitting on the crankcase that is located just above and slightly behind the top of the oil pump.