ADKoutboard
Cadet
- Joined
- Jun 14, 2010
- Messages
- 19
I'm working on a 1988 Century Resorter w/ a 5.7L comp ski inboard, raw water cooled.
Owner's son-in-law overheated the motor & (wait for it...) "Revved the engine to blow it out." Raw water pump was shot, so we replaced it. Took it out and it ran great but once it reached WOT it slowly lost power. Found port exhaust hose loose and leaking onto spark plug leads & re-clamped them. Couldn't test boat again before owner took it. Now, it runs good and cool up to 2900 rpm, but around 3000 rpm and higher it lacks power. Won't get to WOT (4000-4400rpm) only gets 3200-3000 rpm max. Temp gauge rises @ idle to aprox. 150 degrees, but @ higher rpm gauge drops to bottom of the scale and engine smells hot. I did notice that the port side riser is cooler than the starboard side. Motor sounds almost like an outboard w/ the throttle plates advanced too far. (if that makes any sense to anybody) kind of hard to put into text the sound it's making.
-new water pump.
-new fuel filter.
-new spark plugs.
(part of spring start-up)
Could it be possible that a head gasket is blown? or am I barking up the wrong tree?
Are there any tests short of pulling the heads?
I have mercruiser manuals (i.e.; #17 5.0L /5.7L)
Any help would be appreciated. I'm more of an outboard guy.
Thanks.
Tarren
Owner's son-in-law overheated the motor & (wait for it...) "Revved the engine to blow it out." Raw water pump was shot, so we replaced it. Took it out and it ran great but once it reached WOT it slowly lost power. Found port exhaust hose loose and leaking onto spark plug leads & re-clamped them. Couldn't test boat again before owner took it. Now, it runs good and cool up to 2900 rpm, but around 3000 rpm and higher it lacks power. Won't get to WOT (4000-4400rpm) only gets 3200-3000 rpm max. Temp gauge rises @ idle to aprox. 150 degrees, but @ higher rpm gauge drops to bottom of the scale and engine smells hot. I did notice that the port side riser is cooler than the starboard side. Motor sounds almost like an outboard w/ the throttle plates advanced too far. (if that makes any sense to anybody) kind of hard to put into text the sound it's making.
-new water pump.
-new fuel filter.
-new spark plugs.
(part of spring start-up)
Could it be possible that a head gasket is blown? or am I barking up the wrong tree?
Are there any tests short of pulling the heads?
I have mercruiser manuals (i.e.; #17 5.0L /5.7L)
Any help would be appreciated. I'm more of an outboard guy.
Thanks.
Tarren
