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jlgrif03
07-17-2008, 12:20 AM
I have a 1972 Stars and Stripes. When I try to start the motor it seems like the battery is going dead and the motor doesn't really want to turn over. I have replaced the starter, starter solenoid, battery, altenator, coil, plugs and checked points. I have had this problem for three years and cannot figure out what the deal is. I have even hooked up a batter charger for extra cranking power and still the same problem. Once started it runs great but just doesnt want to turn over. Does it in and out of water. Worse in water though.

JimN
07-17-2008, 12:27 AM
Check your timing. If that's OK, it could be that the exhaust manifolds have become clogged.

Remove the spark plugs and see if it wants to crank. if water shoots out, your manifolds are probably shot.

TRBenj
07-17-2008, 03:44 PM
Bad battery cables or dirty connections.

jlgrif03
07-17-2008, 09:23 PM
if water was gettin in the combustion chambers it wouldnt start at all right? what is the difference betreen an auto starter and a marine starter?

jlgrif03
07-17-2008, 09:23 PM
definetly not the battery cables either

Chicago190
07-17-2008, 09:40 PM
Check the timing. I had a problem this year where the boat would crank, pause, crank, pause, crank and then fire. It seemed like the battery/starter were dying, but it turned out the timing was too advanced. Both JimN and Vince@skidim diagnosed the problem and sure enough it was the timing.

watkins27
07-17-2008, 09:55 PM
starter for auto is rh rotation,and if your boat is lh it will turn the motor the wrong way. and can really mess stuff up

WTRSK1R
07-17-2008, 11:03 PM
what is the difference betreen an auto starter and a marine starter?

Biggest difference between an Auto starter and a Marine starter is when it is marinized it is sealed to prevent sparks and explosions if you have gas fumes in the bilge. They are pricey by comparison, but IMHO cheap insurance compared to the alternative of an explosion.

:twocents:

JimN
07-17-2008, 11:37 PM
"If water was getting in the combustion chambers it wouldn't start at all, right?"

If it gets in enough cylinders, it won't turn over because you can't compress a liquid. If enough water gets into a cylinder that has both valves closed, it won't turn and this is called 'hydraulic lock' or 'hydro-lock'. Removing the spark plugs and cranking it will blow any water out and then, you can re-install the plugs to try starting it.

By any chance, does it experience 'run-on', regularly? If it does, it will often finish by turning in reverse, which causes water to be sucked in through the exhaust ports.

jlgrif03
07-18-2008, 01:18 AM
i don't know what run-on is. please explain. i have an auto starter on it right now. i don't think its the timing because while turning the motor over i adjusted the distributor and it didnt' help. i'm thinking about running to batteries. anyone ever do this? my diesel has to batteries to help with start up and it works very well. bad idea?

JimN
07-18-2008, 01:59 AM
If you have ever seen a car or truck that kept running when the key was turned off, that's 'run-on'. It can be caused by several things. Among them are spark plugs of a temperature rating that's too high, carbon deposits, hot and dry climate/extremely high operating temperature. Mercruiser has had many years of trouble with this issue and water getting into the cylinders is one result, which then causes hydraulic lock, fried starters and batteries.

jlgrif03
07-18-2008, 09:59 AM
Had a feeling thats what you were talking about. No it doesn't get run-on at all. It's just really weak turning over and when its warmed up its worse. the starter side of the solenoid is getting 12v so its not a voltage drop. Is the dual battery a bad idea? Maybe a gear reduction starter? I mean the motor is old and I have replaced the head gaskets. Maybe from having the heads replained caused the motor to have more compression and thats why its so hard to turn over especially when warmed up?

JimN
07-18-2008, 10:16 AM
If you have a 351, there's absolutely no reason you should need two batteries just to crank it.

Check the basis- battery load test (not just voltage), starter/starter wiring and solenoid, timing, exhaust manifolds and carb. Remove the plugs and crank it- if it's still slow, either the battery, starter, solenoid or wiring has a problem. If it cranks freely, they may be fine, but it's a good idea to load test the battery, since it has cranked hard, which stresses a battery and starter. If water shoots out of the spark plug holes, look into the manifolds. If that checks OK, look at the carb. If gas drips out in certain positions or when it's hot, it needs work- either a rebiold or replacement.

Because it has cranked hard for three years, it's possible that the battery cables are bad. If you can substitute a good set of jumper cables and crank it and it returns to normal, you'll know the cables are suspect.

Process of elimination is the only way to find this, but it has to be done.

kingu
07-18-2008, 10:22 AM
What size battery did you install?

Kevin 89MC
07-18-2008, 11:11 AM
Just a shot, but what kind of battery are you using? If you're using a deep cycle or marine battery, that may be part of the problem. My boat never used to turn over very fast, and would often leave me stranded when trying to start it when fully warmed up. It would barely turn the engine over once or twice, not enough to start it. After ~half hour, it would then start up. I put in a regular automotive starting battery, biggest one I could fit in the bin, and now it starts great, hot or cold. I've been running a Kirkland (from Costco, they're cheap) battery for 2-1/2 years now, no problems. I was surprised how much faster the auto battery would spin the engine.
Good luck,
Kevin

cbryan70
07-18-2008, 11:23 AM
There are marine batteries that have 1000CCA's which is PLENTY to crank over ANY gas engine

Kevin 89MC
07-18-2008, 11:32 AM
There are marine batteries that have 1000CCA's which is PLENTY to crank over ANY gas engine

You're right, as long as it is a marine starting battery. My point was to make sure it was not a deep cycle battery, as that was what was in my boat originally, and gave me trouble until I got a starting battery.

skidancin
07-19-2008, 12:39 AM
I have a 1972 Stars and Stripes. When I try to start the motor it seems like the battery is going dead and the motor doesn't really want to turn over. I have replaced the starter, starter solenoid, battery, altenator, coil, plugs and checked points. I have had this problem for three years and cannot figure out what the deal is. I have even hooked up a batter charger for extra cranking power and still the same problem. Once started it runs great but just doesnt want to turn over. Does it in and out of water. Worse in water though.

I feel strangely confident that you'll find the lovely white/green corrosion IN the Negative Battery Cable starting where it attaches/grounds to the Engine Block. Replace the whole length of Cable From Battery Negative to Block Ground. That ought to take care of it for a decade at least. It proved to be the case for me with identical symptoms on my '86 Powerslot.

JimN
07-19-2008, 02:12 AM
"I was surprised how much faster the auto battery would spin the engine."

Being an auto engine, it should crank well. The problem is, too many boat dealers didn't/don't understand the difference and sell "Marine" batteries simply because it's going to be used on a boat. If it was a "boat" motor, it would work, but.....

In a '70s model boat, I would be surprised it one or both cab;es weren't badly corroded inside the jacket. Also, the mating surface of the block/starter is where the starter gets its ground, so that is a very likely source of cranking issues, along with battery termianls and cables.

If the battery cable clamps have been replaced, I can almost guarantee that the ends are toast and if that's the case, the cables should be replaced. It's not very expensive and can mean the difference between killing the starter and getting a few more years out of it.

jlgrif03
07-19-2008, 05:29 PM
Ok I'm going to try some things out this weekend. Due to an overwhelming workload I haven't had anytime this week to do anything. I'll post some stuff once I've done some trouble shooting I really appreciate all the help.

TMCNo1
07-19-2008, 07:50 PM
Could it be that the timing is off, we've seen several of those this summer and i don't believe it will be the last, 6 to 10 degrees BTDC for reference.