MOTOBRICK.COM
TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: gabe92 on June 15, 2015, 08:00:04 AM
-
Hello all, I have searched the forum, but haven't found any issues like mine.
History: My 1992 K75 sat for about three years because I couldn't get it started. This spring, I invested several weekends and several hundred dollars in parts to get it fixed. I replaced (in this order) the fuel filter, fuel pump, all hoses in the tank, crank case breather hose, external fuel lines, spark plugs, spark plug wires, fuel rail, and fuel injectors. Turns out the biggest issue was the fuel pump was inoperative, the spark plug wires were bad, and the fuel rail/injectors were full of rust and gunk.
During the fixing process, I would crank the bike to see if it would start. I didn't know that the injectors were evidently stuck open, allowing fuel to drain past the rings and into the crankcase, diluting the oil with fuel. When it finally did start after changing the fuel rail and injectors, it would run great until it warmed up, then it would start to sputter and die. It wouldn't start again until it cooled down. After some brain racking, I couldn't figure it out, so while continuing to ponder the situation, I decided to change the oil. To my surprise, then I pulled the drain plug, oil (and fuel) the consistency of water poured out, and continued pouring out well past four quarts. I would estimate that there were eight quarts of fluid in the crankcase. I then develop a theory that as the fluid heated up, it would expand, choking the engine and causing it to die. After changing the filter and adding the prescribed amount of oil, the bike started and ran beautifully, without ever dying.
Problem: However, a new problem surfaced. I know the cause, but don't know how to fix it. The engine leaks very badly. I believe that the oil/fuel mix that sat in the crankcase has compromised the gaskets and seals of the engine. Question, is this reasonable and if so, are there specific gaskets/seals that I can change without removing the engine, or is an engine pull in my future? What do you suggest changing?
-
Where is it leaking? By that I mean is it an all over leak, or a specific area.
-
If it's just the rubber seals, then you'll need to replace those. Luckily they're not SUPER expensive, but there's quite a few of them.
-
Last night I went to take pictures. I realized that the leak was not oil. It was fuel coming from the back side of the engine, between the engine and the air box. The fuel mixing with the oil residue on the engine made the fuel "oil colored". This makes me happy as now I assume that fuel is leaking from the fuel regulator connections, a relatively easy fix. As you can tell by the pictures, I still have oil leaking, but it is not the bad leak I thought it was. Any ideas where the oil on the block is coming from?
-
Looks to me like the oil in the 1st picture is coming from the weep hole at the bottom of the bell housing. Not uncommon for oil to leak there when you have leakage from the clutch nut o-ring, and/or rear main seal.
Go ahead and fix your fuel leak, but beyond that clean up the bottom of the engine real good and ride it with your fresh oil and see if the rear weep continues.
If you had the engine overfilled with that thinned out oil, more than likely it leaked out past the clutch nut o-ring/rear main seal.
It may possibly stop leaking now that you have the thinned out oil out of it and at the proper level.
There may be some residual oil internal to be bell housing that may drip a bit till it dries up.
If the leak continues(and from there) it will require you to remove the transmission to repair. More than likely it will be the clutch nut o-ring as it ages and breaks.
-
Thanks so much for your insight Scott! I will fix the leak, clean it up, and go for a nice, long "test ride" this weekend.
-
I fixed the fuel leak last night. The vacuum hose that runs to the bottom of the fuel regulator, the one covered by a wire spring, was split in half where it made a sharp bend going into the bottom of the regulator. I cut the hose back an inch or so, reinstalled, problem solved! I ordered a new one this morning since I have little faith in the integrity of the remainder of the hose, but it should be good enough for my long test ride ;) Now on to identify the oil leak...