50 HP Mercury turning over slow

Rich-ard

Cadet
Joined
Jul 12, 2002
Messages
8
This "good deal" on a boat for $600 is turning out to be a ripoff. Supposedly, the boat was started last year, the gas was drained and it was stored under it's custom cover. The boat, motor, trlr. appear to be in fairly good condition. It came from Montana (not in salt water). It still has Montana regis. After charging the battery and testing for 12 volts I could only get it to turn over slowly by using jumper cables to the starter. The starter had a lot of slop (wear) in it so I found a brand new one for $110. Still turns hard. I pulled the plugs and put transmission fluid down the cylinders. At this point I won't have much to loose by trying something risky. I want to put the old starter back on, hook up two weak 12 volt batteries in series to jump the voltage up to around 18 volts, put enough starting fluid into the cylinders to get it started. If successful in starting the engine it may free it up, or blow it up. Watch for sale on parts. Has anyone out there ever had this problem with a motor turning hard after not being run for a long time?
 

Rich-ard

Cadet
Joined
Jul 12, 2002
Messages
8
Re: 50 HP Mercury turning over slow

With the spark plugs out the motor turns over okay, but you can barely pull it over by hand with a rope with the plugs in. I can't imagine what would cause that, rust maybe? Anybody ever had this happen
 

RandyJ

Master Chief Petty Officer
Joined
Jun 13, 2002
Messages
808
Re: 50 HP Mercury turning over slow

With the plugs out you should be able to spin the flywheel very easily by hand. If you are having difficulty doing this I would suggest squirting some wd-40 in the cylinders and spinning it over a few times. It kind of sounds to me like you got battery cable corrosion problems. You can substitute another set of cables just to eliminate that possibility. Too, there is always that stupid one in a million chance that you exchanged a bad starter for a bad starter. I've got a pile of 50 hp Merc's from 1968 to 1978 and all are pretty good motors. Old merc's are notorious for having gawdawful deteriorated wiring.
 

Rich-ard

Cadet
Joined
Jul 12, 2002
Messages
8
Re: 50 HP Mercury turning over slow

The motor turning over slow is not the wiring or the starter. Something in the engine itself is making it turn hard. Has anyone ever had this problem? I really don't have the time to take it apart to find out. On Monday I may try hooking up two batteries to it and see if it turns over fast enough to start.
 

tmcalavy

Rear Admiral
Joined
Aug 29, 2001
Messages
4,005
Re: 50 HP Mercury turning over slow

Well, if you only paid $600 for the pair you don't have much to lose...if the boat is solid. If you blow up the powerhead, check the lower unit (for water in the case) and email me...I may want to buy the lower unit from you.<br />Hey RandyJ, do you have a lower unit for a 73 vintage Merc 500 laying around? Need a bolt on and go replacement for mine. Seals are shot. If so, post back and we'll swap emails.
 

Rich-ard

Cadet
Joined
Jul 12, 2002
Messages
8
Re: 50 HP Mercury turning over slow

Did not try anything else to loosen up the motor yet. Usually a motor either turns over too easy or not at all when something's busted or worn out inside. Guess I will have to tow the thing to a boat repair place and see if they can figure it out. This thing has me stumped. Thanks anyway tho -
 

ehenry

Commander
Joined
Jan 6, 2002
Messages
2,393
Re: 50 HP Mercury turning over slow

You never said if the engine spins easily with all the plugs out. If it spins easily with the plugs outkeep working with it yourself before you start paying a shop to look at it for you.
 

grandx

Petty Officer 1st Class
Joined
May 21, 2001
Messages
383
Re: 50 HP Mercury turning over slow

A lead acid battery registering 12volts is dead, need to show at least 12.6 V or more, and more importantly whats the voltage after trying to turn it over, if it drops well below 12V its no good. Get a good well charged battery (jump it off your vehicle while running, this would be better than two "bad" batteries in series). Don't use starting fluid cause it lacks lubrication, use premixed gas(2 cycle mix) through the carbs - crank bearings need lube as well. Use heavy duty jumper cables, can get some voltage drop through cheap thin ones. After you've done this, let us know what you've found.
 

petryshyn

Commander
Joined
Oct 3, 2001
Messages
2,851
Re: 50 HP Mercury turning over slow

grandx is right......check the voltage at the starter while cranking. You should have more than 9.6V. If you don't, you have a battery-solenoid-wiring issue.<br />
starter.gif
 
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