Merc 5.0 Engine trouble

wewefirex2x

Petty Officer 1st Class
Joined
Feb 19, 2007
Messages
267
I have been rebuilding my engine cover for my boat fo the last three weeks. Long Story. The boat has been in storage without engine cover on. The boat has been covered with the cockpit cover and the motor had the flame arrestor on it as well. I was off yesterday and decided to bring the boat home. Test fittef engine cover for proper fit so I can get that thing buttoned up. I replaced the fuel pump two weeks ago and it started right up after getting fuel to the carb. When I was working on it yesterday I went to start it and found out the battery (deep cycle) was dead. I replaced that battery with a marine starting battery and it had a terrible time trying to crank. The motor sounded like it had a dead battery hooked to it. Verified voltage on battery and it was 13.2 volts. Removed spark plugs to check for water intrusion and nothing (dry as a bone). Removed fuel line from carb to check for blockage (nothing). Once I hooked fuel line back up the dam* thing started. After letting it run for about ten minutes on muffs there was steam or some type of vapor coming from the hose that connects the flame arrestor to the valve cover. I have two hoses but steam ? was only coming from one. Could that be condensation from the intake manifold or what in the hel* do I need to look at next???

1989 merc 305 5.0 Alpha one 2 barrel carb
 

jerryjerry05

Supreme Mariner
Joined
May 7, 2008
Messages
18,071
Re: Merc 5.0 Engine trouble

Do a comp test on the motor paying attention to the smokey side.Is the motor an actual 89 ? Blowby can be cause by a couple of things.Bad valve seals,bad ring seal.Head gasket. The motors sometimes set a long time in a boat.They are around a lot of condensation. A motor that old coluld need a valve job. Anything is possible.
Actual steam from the breather hose isn't likley.Jerry
 

danond

Lieutenant Junior Grade
Joined
Jun 11, 2007
Messages
1,118
Re: Merc 5.0 Engine trouble

My 4.3 sat for 2 years. Re-starting it resulted in a fair amount of what appeared to be steam from the valve cover vent hoses. Some of that is normal, but it should go away.

And as suggested, do a compression test.
 

wewefirex2x

Petty Officer 1st Class
Joined
Feb 19, 2007
Messages
267
Re: Merc 5.0 Engine trouble

Will do a a compression check. Anybody want a boat?????
 

Maclin

Admiral
Joined
May 27, 2007
Messages
6,761
Re: Merc 5.0 Engine trouble

Sure, I'll take it!


How long was it stored? Was it stored outside where it could get rained on?
 

wewefirex2x

Petty Officer 1st Class
Joined
Feb 19, 2007
Messages
267
Re: Merc 5.0 Engine trouble

Yes it is stored outside with a boat cover. Unfortunatley I live within a HOA. The boat has been stored since last October 2007. Started for the first time in June 08 after replacing fuel pump and then yesterday 7-7-08.
 

wewefirex2x

Petty Officer 1st Class
Joined
Feb 19, 2007
Messages
267
Re: Merc 5.0 Engine trouble

Just thinking, could the vapor like substance i saw be excess gas that was not burned off possibly from flooding due to pumpinp throttle trying to gas to carb when it would not start.
 
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