My super c 123 engine is burning oil. I checked the compression dry and all read close to 120 dry and 160 wet. After running it a few minutes the blue smoke builds in the exhaust and I have a steady slow running stream of oil dripping through the exhaust manifold gasket. The oil is bleeding at the center two ports and runs down the motor behind the carb. I had the head and valves redone. I assembled it with a new head gasket and copper spray. Any ideas whats wrog? I just removed the valve cover and with a flash lite looking through the valve spring I noticed where the valve stem passes through the head and valve guide there isnt any type of rubber boot on any valve stem. Is there suppose to be? Thanks! Sorry this is so long.
- Thread starter kelsh
- Start date
Janicholson
Well-known Member
From the factory they have no Valve seals (I like them, but I know that others do not. Perfect Circle style Teflon seals go on my rebuilds.
There may be a crack in the head from an oil gallery to the exhaust port. (bad news if so) The head shop should have crack checked the head as a normal procedure. Taking the manifold off might show the location if it is. The plugs should show dramatic oil fouling where the problem is if it is in the cylinder/s, and not a cracked head. The crack may ne all the way to the outside, leaking in that spot. If the manifold was put on well, and flat, it should not leak oil from any place (nor exhaust) Does the oil look burnt when it druels down the block? JimN
There may be a crack in the head from an oil gallery to the exhaust port. (bad news if so) The head shop should have crack checked the head as a normal procedure. Taking the manifold off might show the location if it is. The plugs should show dramatic oil fouling where the problem is if it is in the cylinder/s, and not a cracked head. The crack may ne all the way to the outside, leaking in that spot. If the manifold was put on well, and flat, it should not leak oil from any place (nor exhaust) Does the oil look burnt when it druels down the block? JimN
The oil stream looks like a black carbon thick fluid. When I pulled the head off tonight all cylinders had a small amount of oil on top of the pistons. The center two ports on the exaust manifold were oil saturated and all the plugs were wet with oil. When the shop rebuilt the head they manifluxed it and reported no cracks.
Janicholson
Well-known Member
Was it surfaced to flat?
Was the gasket in the area of the oil passage to the valve gear stained and looking like it did not seal there?
Are the edges of the pistons (2-3) clean and oily like oil is coming from the ring area, and getting to the piston top?
What was the condition of the engine prior to head work?
An oil leak still seems probable to me. JimN
Was the gasket in the area of the oil passage to the valve gear stained and looking like it did not seal there?
Are the edges of the pistons (2-3) clean and oily like oil is coming from the ring area, and getting to the piston top?
What was the condition of the engine prior to head work?
An oil leak still seems probable to me. JimN
I've got to ask. What was the condition that caused you to do the valve job? Jim is right, a leak seems likely, but if you had oil consumption before, a valve job can only aggravate it. I am kind of inclined to suspect rings as an equal possibilty here. I would start with very close visual inspection. If the intake ports and valves are dry, that for the most part eliminates the intake side. Another thought...even though the head was magnafluxed, you still may want to have it pressure checked. We are talking about a 50 to 60 year old casting here that has been hot and cold a number of times so fatigue may come into play.
Wayne in MN
Well-known Member
That much change in compression from dry to wet readings tells me the rings are in tough shape.
Many times if you just do a valve job it will cause the rings to go from bad to worse.
I think you are in need of a complete overhaul.
To know more accurately if the rings are worn, get a cylinder leakdown tester and see what percent of the compression loss is past the rings.
Many times if you just do a valve job it will cause the rings to go from bad to worse.
I think you are in need of a complete overhaul.
To know more accurately if the rings are worn, get a cylinder leakdown tester and see what percent of the compression loss is past the rings.
I bought this tractor with the motor already torn down. The head was also disassembled with valves and springs stored in a small box.This is why I took it to the machine shop to reassemble it. I put the motor back to gether and this is when I noticed the smokeing and the leaking black oil from the exhaust manifold. The oil was running on top of the head gasket to the two center ports. The gasket does have an oil stain on top where the two small holes are above the center exhaust ports. The pistons did have oil on top of them and yes all four plugs are oily. The oil from the number two cylinder was running on top of the gasket to the exhaust ports. I will try to senda photo of the gasket after I tore the engine down . Thanks again!
Janicholson
Well-known Member
I would have the head checked for flatness, and if not within .002" I would have it surfaced.
The block can be checked as well. Check for cracks at the oil passage location. Clean it well, shiny, then heat it with a propane torch. If a line of oil bubbles up, it is cracked there.
The gasket looks bad in the location of most interest. The gasket might have been good, but not pinched enough to seal. Spray copper coat spray on both sides of the gasket, let almost dry, then assemble. JimN
The block can be checked as well. Check for cracks at the oil passage location. Clean it well, shiny, then heat it with a propane torch. If a line of oil bubbles up, it is cracked there.
The gasket looks bad in the location of most interest. The gasket might have been good, but not pinched enough to seal. Spray copper coat spray on both sides of the gasket, let almost dry, then assemble. JimN
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