hi to all 454 gurus
The story so far - 1989 mercruiser 454 with a history of problems with water in the oil. Previous owner rebuilt this engine {reasons unknown] and the rebuilder reported a failed oil cooler that put seawater into the sump on commissioning. he replaced oil cooler and changed oil 3 times and reported all now ok. 6 months later , engine is sounding lumpy and oil is again milky.Crankase vacuum down around 14 psi. Mechanic blames the manifold and headers and changes them out for new Crusader style exhausts. Engine still lumpy but running. 3 months later and around 10 hour run time, oil again milky , changed oil and compression test reveal no4 cylinder low and clean spark plug. Rocker cover off and all valve stems rocker and posts are very rusty on both banks. No 4 cylinder valves stuck and pushrods broken/bent.
The heads come off tomorrow to see how the pistons look. Clearly there is substantial water getting in this engine. Manifolds were looking ok before being replaced but thats no 1 suspect. what ever the cause it seems that the normal fixes are not cutting it here. If not seawater then coolant leak?- there was emulsified oil pooling in no 4 intake and lots of emulsion on the center section of the intake manifold. When the engine was hot & running there was noticable moisture trickling from the rocker cover breather vents.
what are the chances of cracked block ? cracked head ? cracked inlet manifold ?
will do pressure tests where possible - any more ideas - we are scratching our heads here
The story so far - 1989 mercruiser 454 with a history of problems with water in the oil. Previous owner rebuilt this engine {reasons unknown] and the rebuilder reported a failed oil cooler that put seawater into the sump on commissioning. he replaced oil cooler and changed oil 3 times and reported all now ok. 6 months later , engine is sounding lumpy and oil is again milky.Crankase vacuum down around 14 psi. Mechanic blames the manifold and headers and changes them out for new Crusader style exhausts. Engine still lumpy but running. 3 months later and around 10 hour run time, oil again milky , changed oil and compression test reveal no4 cylinder low and clean spark plug. Rocker cover off and all valve stems rocker and posts are very rusty on both banks. No 4 cylinder valves stuck and pushrods broken/bent.
The heads come off tomorrow to see how the pistons look. Clearly there is substantial water getting in this engine. Manifolds were looking ok before being replaced but thats no 1 suspect. what ever the cause it seems that the normal fixes are not cutting it here. If not seawater then coolant leak?- there was emulsified oil pooling in no 4 intake and lots of emulsion on the center section of the intake manifold. When the engine was hot & running there was noticable moisture trickling from the rocker cover breather vents.
what are the chances of cracked block ? cracked head ? cracked inlet manifold ?
will do pressure tests where possible - any more ideas - we are scratching our heads here
