Engine turns slow but doesn't start

[Mark Brandly]

Hi everyone
I took my 20" Searay out of storage. I noticed the engine turning very slow, too slow to start. There is heavy resistance somewhere.
I eventually jumped the engine directly at the starter to eliminate possible bad wiring..no improvement. I changed the one year old staerter with a new one.
it tuned slow till the NEW starter began to produce smoke...so I stopped.
Could it be the outdrive?
Engine : 350 Merc ,Rebuilt (1 year ago), oil clear, starter new.Ran great.
Outdrive: originlal pre alpha, never made noise or dripped oil (external oil reservoir still half full)
Batteries : New and fully charged.
Any ideas ?
Thanks
Mark

 

[SSSuper83]

Re: Engine turns slow but doesn't start

Pull the spark plugs. Check for any evidence of water or any other junk in the cylinders. Crank the engine and have a helper watch underneath the manifolds. If water comes out, you have a larger problem with your exhaust system.

If not, I would suspect your "new" starter has a problem. If it's relatively easy, remove it and take it to a Napa or similar to have it tested. And unless the outdrive is stuck in gear or jammed somehow, I highly doubt thats your issue.

 

[tigerfishes]

Re: Engine turns slow but doesn't start

be interested in finding a solution as i have a similar issue... no smoke from starter and haven't replaced it... yet..
good luck! please post if you figure it out. did you see the thread on how to diagnose starter problems? it's great... it's below...

 

[tractorboy]

Re: Engine turns slow but doesn't start

Interested too. My boat was winterized and not use for 5 years. Im the New Owner but engine is TIGHT!! Could barely turn engine by hand.

Not stuck in gear
starter rebuilt and was new

Im thinking of pulling plugs and putting some drops of oil in the cylinders to loosen in all up. and maybe turn it over a bit with out the plugs in. Will that bet the oil pump to pump a little oil around??????

motor is very TIGHT. Thinking without the plugs there will no compression and maybe the oil will get moving around abit...any ideas? are these good and bad??
thanks

 

[legoman67]

Re: Engine turns slow but doesn't start

it tuned slow till the NEW starter began to produce smoke

you burnt that starter out, starter motors overheat very quickly(within 30 seconds of continual cranking) if you just held it trying to crank over a motor that obviously wasn't cranking easily, it would have overheated very quickly, and if you kept it going it would get hot enough to start melting components, hence the smoke.

 

[180shabah]

Re: Engine turns slow but doesn't start

Seriously doubt the drive is your issue - you can turn it by hand, so the starter won't even know it is there - unless it is in gear and half of your cover is all knotted up around the prop......

Removing the plugs and spinning the engine manually is good advice - then you'll KNOW how hard it is to turn.

When you replace the starter this time, look for a gear reduction unit, they are a little less demanding on the electrical system...

 

[Mark Brandly]

Re: Engine turns slow but doesn't start

Thank you guys for all the great sugestions.
It isn't the starter for sure. Both old and new where tested on the bench. There is also no water present...... It is just that a tight engine. I will remove the plugs again and feel the the resitance by turning it manually.
Why is it tight though ???....I never had that happen to me.

 

[tractorboy]

Re: Engine turns slow but doesn't start

Sitting and lack of oil/lubrication. When things sit.....Things happen. Surprised like that after only 1 winter. Mines been sitting 4-5years so Im not surpised.

hopefully they will free up.

keep us posted on yours and I will mine. again tonight putting some oil in the cylinder to lube the rings and what not.

 

[JustJason]

Re: Engine turns slow but doesn't start

Funny thing about starters and most other electrical equipment. The smoke is magical smoke, and once you let the smoke out of the box you can't get it back in.

1. Your starter is probably junk at this point.
2. Your engine isn't starting because your cranking rpms are to low
3. Google "voltage drop test", and do it on your starting system. Do it point to point, if you have a battery switch don't forget that, and don't forget the slave solenoid. 1/2 of your starting system probably has rotted wiring.



It doesn't matter if you have a little 4 cylnder or a monster V8, all these engines should crank over just as fast as your car cranks over it's engine. And with every engine, unless your just pulling this thing out of storage or something, it should fire right up after 3 to 4 seconds of cranking max, course that's if your following the correct starting procedure. (ie-if you have a carb, priming the engine etc). If they don't start up after 3 or 4 seconds then you have a problem, and cranking the crap out of the starter motor doesn't fix that problem.

 

[tractorboy]

Re: Engine turns slow but doesn't start

and if you are pulling it out of storage? whats the best course of action there. I agree its not spinning fast enough to start. have had wd40/marvel mystery oil sitting in the cylinders but nothing yet....how long should it take to get this thing moving again??
Todd

 

[180shabah]

Re: Engine turns slow but doesn't start

Have you isolated the the cause of the increased resistance???

 

[Mark Brandly]

Re: Engine turns slow but doesn't start

I didn't have time yet to work on it but will this weekend.
Again thanks to all.
I will post my findings.
Mark

 

[Mark Brandly]

Re: Engine turns slow but doesn't start

The verdict
I finally had time to look at the motor.
Again, thanks for all the helpful hints.
The news is good and bad.
The culprit was water..fresh water thank god but nevertheless
4 out of 8 cylinders had rust on the plugs.
I will do a compression and leak down check tomorrow but I am fairly convinced that it is not the head gasket. Heat was never a problem.
That leaves the riser/manifold gaskets. They are Sierras and less than one year old, so are the manifolds and the risers.
Whatever lead up to the problem, the motor will survive.
wd40 worked wonders on the tightness.( it now spins at normal speed in the starting mode)
If there is one suggestion I would make to my fellow tight engine sufferers, then it would be to disconnect all the water supply hoses, remove the plugs and spoil the engine with wd 40.
It should turn despair into instant gratification.
Yours
Mark