tuna_man
Regular Contributor
"Ive just rebuilt my 1988 SB 3
"Ive just rebuilt my 1988 SB 350, which is actually a "260 Mercruiser", dead stock, no mods. Rochester 4 barrel, Flame Arrestor type air filter, Thunderbolt 4 electronic distributor. Its in a in a 23 ft carribean boat.
When I started it recently, it over revved and broke an #7 inlet pushrod. Pulled the inlet manfold and rocker cover off, Inlet valve #7 is locked solid, cant move it. removed valve spring and retainer, used oxy and vice grips to free it. Its not bent. All this black goo came out of valve guide when i applied the heat, looked in all the other inlet ports and its coated everywhere. What is this stuff? Its black, shiny, a little sticky and disolves with WD or petrol. In a valve guide it works like super glue.. I removed all 8 inlet valve springs, stuck same on odd side only. 2,4,6,8 fine free as. (why dont these engines have guide seals?). Valve guide clearence seems same on both sides (each head).
Engine only 50 hrs since reco 2 years ago. Recoed it myself, new rings, bearings, re-use same pistons, hone cylinders by local re-bore shop, Heads recoed by local head shop, inc knurling of valve guides to prevent sticking. (ha).
I think it may be;
1/ crankcase ventilation from each rocker cover goes straight into top of carby, thru flame arrestor, fumes causing black goo?
2/fuel additive i use (Flashlube). its supposed to provide valve lubrication for unleaded fuel in leaded engines.
3/cheap oil i used for running in engine (still in it) causing excessive fumes?
4/Rich mixture from dirty flame arrestor. It was dirty, but clean when i re built engine.
Maybe this goo is normal and I just have to use the boat more often....
Any advice appreciated. Mark."
"Ive just rebuilt my 1988 SB 350, which is actually a "260 Mercruiser", dead stock, no mods. Rochester 4 barrel, Flame Arrestor type air filter, Thunderbolt 4 electronic distributor. Its in a in a 23 ft carribean boat.
When I started it recently, it over revved and broke an #7 inlet pushrod. Pulled the inlet manfold and rocker cover off, Inlet valve #7 is locked solid, cant move it. removed valve spring and retainer, used oxy and vice grips to free it. Its not bent. All this black goo came out of valve guide when i applied the heat, looked in all the other inlet ports and its coated everywhere. What is this stuff? Its black, shiny, a little sticky and disolves with WD or petrol. In a valve guide it works like super glue.. I removed all 8 inlet valve springs, stuck same on odd side only. 2,4,6,8 fine free as. (why dont these engines have guide seals?). Valve guide clearence seems same on both sides (each head).
Engine only 50 hrs since reco 2 years ago. Recoed it myself, new rings, bearings, re-use same pistons, hone cylinders by local re-bore shop, Heads recoed by local head shop, inc knurling of valve guides to prevent sticking. (ha).
I think it may be;
1/ crankcase ventilation from each rocker cover goes straight into top of carby, thru flame arrestor, fumes causing black goo?
2/fuel additive i use (Flashlube). its supposed to provide valve lubrication for unleaded fuel in leaded engines.
3/cheap oil i used for running in engine (still in it) causing excessive fumes?
4/Rich mixture from dirty flame arrestor. It was dirty, but clean when i re built engine.
Maybe this goo is normal and I just have to use the boat more often....
Any advice appreciated. Mark."