When I was unable to time my 6kw Onan generator with a timing light I
eventually found that the timing Marks on the flywheel do not coincide with
TDC on the engine. True TDC occurs about 20 to 30 degrees behind that
indicated by the markings. I've already torqued the heads so am not sure of
the exact numbers. Has anyone else had a similar experience?
How I got to here is a long sequence of events. While we were in the Black
Hills last week I developed a leak in the exhaust pipe. I then stopped at
the local auto parts store and wrapped the pipe in an exhaust bandage
thinking that I was again on my way. The generator started and ran just
fine but it sounded odd when it started. Apparently the starter bracket had
chosen this time to break. When I pushed the generator back into it's
compartment the starter fell off shorting out the batteries in the process.
This burned the terminals off of one of the house batteries, this was the
only good luck that I had since it probably prevented a fire. The resulting
short also left the engine alternator under a short condition, which I
didn't figure out until we stopped later. We were in the middle of nowhere
on the road to Devil's Tower with no power and no AC. (A hose on the dash AC
had blown earlier) While we were moving the cab temperature stabilized at
114 degrees.
When I got home I found that the starter bracket was cast iron and had been
repaired before so I decided to make one from steel which should prevent a
similar problem in the future. The generator had also been acting like it
was running too hot. I found the heads particularly the forward one were
oily and dirty. I'm not sure of the cause but a couple of the fin passages
were nearly completely blocked. While I was down this far I decided to pull
the heads and decarbon them. They were heavily carboned. The crud was so
baked on the fins that I resorted to oven cleaner to get it off. I don't
like doing this to aluminum but didn't see much choice. The worst head also
didn't have much torque on its bolts so I suspect the problem could have
been seepage around the bolts but I'm not sure of this. Torqueing the heads
stripped one of the studs requiring a heli coil. This then led to putting in
new points then being unable to time the engine with a timing light.
OBTW The battery cable to the generator happened to pick today to open up.
I'm running on a jumper cable right now and will trouble shoot that one
later. I'm starting to believe this machine is a jinx. everytime I fix one
thing two other things go wrong which are only tangentally related. On this
same trip the gasket under the heater riser blew out requiring an emergency
stop at a local car parts store then about a hundred miles later tha gasket
under the EGR valve did the same thing. These gaskets have been in there for
twenty three years without a problem. Why did the pick my vacation to blow?
Dick
eventually found that the timing Marks on the flywheel do not coincide with
TDC on the engine. True TDC occurs about 20 to 30 degrees behind that
indicated by the markings. I've already torqued the heads so am not sure of
the exact numbers. Has anyone else had a similar experience?
How I got to here is a long sequence of events. While we were in the Black
Hills last week I developed a leak in the exhaust pipe. I then stopped at
the local auto parts store and wrapped the pipe in an exhaust bandage
thinking that I was again on my way. The generator started and ran just
fine but it sounded odd when it started. Apparently the starter bracket had
chosen this time to break. When I pushed the generator back into it's
compartment the starter fell off shorting out the batteries in the process.
This burned the terminals off of one of the house batteries, this was the
only good luck that I had since it probably prevented a fire. The resulting
short also left the engine alternator under a short condition, which I
didn't figure out until we stopped later. We were in the middle of nowhere
on the road to Devil's Tower with no power and no AC. (A hose on the dash AC
had blown earlier) While we were moving the cab temperature stabilized at
114 degrees.
When I got home I found that the starter bracket was cast iron and had been
repaired before so I decided to make one from steel which should prevent a
similar problem in the future. The generator had also been acting like it
was running too hot. I found the heads particularly the forward one were
oily and dirty. I'm not sure of the cause but a couple of the fin passages
were nearly completely blocked. While I was down this far I decided to pull
the heads and decarbon them. They were heavily carboned. The crud was so
baked on the fins that I resorted to oven cleaner to get it off. I don't
like doing this to aluminum but didn't see much choice. The worst head also
didn't have much torque on its bolts so I suspect the problem could have
been seepage around the bolts but I'm not sure of this. Torqueing the heads
stripped one of the studs requiring a heli coil. This then led to putting in
new points then being unable to time the engine with a timing light.
OBTW The battery cable to the generator happened to pick today to open up.
I'm running on a jumper cable right now and will trouble shoot that one
later. I'm starting to believe this machine is a jinx. everytime I fix one
thing two other things go wrong which are only tangentally related. On this
same trip the gasket under the heater riser blew out requiring an emergency
stop at a local car parts store then about a hundred miles later tha gasket
under the EGR valve did the same thing. These gaskets have been in there for
twenty three years without a problem. Why did the pick my vacation to blow?
Dick
