1999 Mercruiser 5.7 EFI problems

Soo where to start. Had engine hydrolock over the weekend. Immediately took all plugs out turned it over to drain water put plugs in and engine run fine. On Tuesday evening put boat in water and went about 1/4 mile and had alarm come on alarm beeped about every 5 seconds. Engine died for power and shut off. Oil pressure gauge seemed sparatic during this time. Engine wouldnt start until about 25 mins of sitting. Finally got it running went to go again and it shut off again. Suddenly it was hyrdolocked again so once again drained water to get engine running. Engine running again and no water in the oil. Today went about the same distance all in a sudden alarm started going off again and started bogging down and died. Suddenly alot of smoke in engine compartment opened it up and shut off engine. Nothing on fire could not tell where smoke came from. Water manifolds seemed really hot but engine temp was fine. let sit for a while and then finally it started again.. Checked the oil and suddenly there is water in the oil. And to top it off will not shift into gear. Thinking when manifolds got hot they may have melted something in linkage?? Any help on any of the above problems is greatly appreciated.

Re: 1999 Mercruiser 5.7 EFI problems

Welcome to the forum

Is there any oil in your drive lube bottle?
What maintenence has been done to the engine and drive this season?
Is your engine serial number between 0L325977 THRU 0M299999 ?
Sounds like something or things over heated

Re: 1999 Mercruiser 5.7 EFI problems

SillikerW506 said:

And to top it off will not shift into gear. Thinking when manifolds got hot they may have melted something in linkage?? Any help on any of the above problems is greatly appreciated.

Click to expand...

Yes most likely the hot exhaust melted the shift cable either on the inside or outside of the boat. If outside, the exhaust bellows would be melted as well.

Good luck.

Re: 1999 Mercruiser 5.7 EFI problems

so it was hydrolocking and you kept running it on the water without fixing anything??

needless to say....you need to do a compression test. could be a blown head gasket. or maybe the exhaust manifolds are leaking. either way....stop running that boat in the water !!!

Re: 1999 Mercruiser 5.7 EFI problems

Time to get some diagnostics going . . . as stated.

Compression test,

Cylinder leak test,

Cooling system pressure test. . . . These things are best done prior to taking anything apart.

clearly there is a good source of water making its way into the engine, and it seems to be getting worse. Rather than speculate as to the problem, you are better off to run the tests and gather some information from them.