Engine Only Starts if Hand Cranked

[DangerMouse1]

I have a Mercruiser 5.7 V8, and I'm having an issue with starting. I couldn't find a similar issue to this on the forum.

The engine had been running fine all summer, and I changed the outdrive mid-summer (alpha one gen 2) and had no issues. Now all of a sudden I am having issues starting. It makes a loud click noise, no cranking. I cleaned the starter relay solenoid connections (the one on the top of the engine block, not on the starter itself) and also all the battery terminals, connections and ground on the engine block. I got autozone to test the battery and it is good.

So I still couldn't get it to start. I decided to crank the crankshaft by hand and turned it a little, and the engine then started up immediately when I turned the ignition. I stopped it and it started up fine a few times after that. Then after 15 minutes I thought I would try again, and again the click noise when ignition on, no cranking/starting. Again I turned the crankshaft by hand, and it then started no problem.

Not really sure where to go from here. Anyone had anything similar or any suggestions. Thanks in advance.

 

[alldodge]

Need a serial number?

Most likely its corrosion or bad connection. There is not enough voltage at the coil or other to get a good spark. So when its cranked by hand more voltage is available to start.

Sure wonder how your cranking a V8 by hand

 

[GA_Boater]

Pull the spark plugs and see if any liquid comes out when the motor is cranked. How are you turning the motor manually?

 

[DangerMouse1]

Thanks for the replies. I am only moving the crankshaft pulley using a socket wrench, and only moving it around 1/4 rotation at most (yep it is hard to move!). Serial is 0w332827

I don't think any fuel would come from spark plugs as it is only clicking not cranking. It only starts and keeps running if I first move the crankshaft by hand a little first.

-- I replaced the ignition coil in August so don't think it is this, unless it is getting less voltage all of a sudden.

 

[nola mike]

Thanks for the replies. I am only moving the crankshaft pulley using a socket wrench, and only moving it around 1/4 rotation at most (yep it is hard to move!).

First, don't do this. You can shear the crank bolt.

Second, are you turning it by hand, and then turning the ignition to the "start" position, and then the starter motor kicks in?

GA_Boater is talking about water coming from the plug holes, not fuel. After 1/4 rotation, your exhaust valves might open on the affected cylinder(s) and allow the water to escape.

 

[harringtondav]

It may be that slave solenoid on top of the engine. Since it clicks your key switch seems OK.

The safest way to test the slave solenoid is to borrow either solenoid from you power trim, assuming it works. ...all three are the same p/n. But caution. The trim solenoids are direct wired from the battery +. So the feed to the solenoids will be hot. Disconnect the battery + cable before removing a solenoid.

If you're willing to take a risk, jump across the two heavy gage wire terminals on the solenoid and see if the engine cranks. Be absolutely sure the engine compartment is completely vented and no fuel is leaking. This will cause a spark.

 

[DangerMouse1]

Thanks nola mike I didn't know that. Won't do it anymore.

When turning by hand I don't have the key in. I then insert the key and turn to start position and starter motor kicks in and engine starts no problem and keeps running.

 

[DangerMouse1]

It may be that slave solenoid on top of the engine. Since it clicks your key switch seems OK.

The safest way to test the slave solenoid is to borrow either solenoid from you power trim, assuming it works. ...all three are the same p/n.

If you're willing to take a risk, jump across the two heavy gage wire terminals on the solenoid and see if the engine cranks. Be absolutely sure the engine compartment is completely vented and no fuel is leaking. This will cause a spark.

I put a jump wire on the two heavy gauge wire terminals on the slave solenoid and it didn't crank. A spark and the same click but nothing more.

 

[alldodge]

I put a jump wire on the two heavy gauge wire terminals on the slave solenoid and it didn't crank. A spark and the same click but nothing more.

Then you not jumping the terminals Mike is talking about. One side of the slave relay is a direct connection to battery via 50 amp breaker, and the other goes straight to the battery

 

[Furbird]

I think this is something mechanical related. From what you are describing, it sounds to me like either the starter is failing and not engaging the flywheel or it is misaligned and when you're having this issue the starter gear is not engaging with the flywheel correctly. By you physically moving the crankshaft, this frees the mechanical issue up as now it's past that "bad" spot where the problem is occurring. It could be a bent tooth on the flywheel or on the starter gear, but for some reason it seems that the starter gear is popping up to it's position on start but jamming and not turning. My absolute best guess is that you have a failure on the starter nose of some sort, probably the mechanism that extends and retracts the starter gear to engage the flywheel. More than likely it's coming out at a weird angle and engages sometimes then jams on others.

That's a long winded way to say you've got to pull the starter. This will give you the opportunity to rotate the engine and visually inspect the entire tooth range of the flywheel to determine if it's that or the starter itself.

 

[DangerMouse1]

Then you not jumping the terminals Mike is talking about. One side of the slave relay is a direct connection to battery via 50 amp breaker, and the other goes straight to the battery

Just took a picture of the starter relay solenoid and the terminals that I connected a wire between to bypass the solenoid. Are these not the right terminals?

 

[alldodge]

Just took a picture of the starter relay solenoid and the terminals that I connected a wire between to bypass the solenoid. Are these not the right terminals?

Yes those are the right terminals, and looks like Furbird has the answer. The starter is hanging, and moving the motor allows the solenoid to release and can make contact again.

You can have the key OFF and jump those terminals and the motor will crank. If it doesn't crank then its the starter and or its solenoid

 

[Bt Doctur]

That is the "slave solenoid" jumping the 2 large lugs should spin the motor

 

[DangerMouse1]

That's a long winded way to say you've got to pull the starter. This will give you the opportunity to rotate the engine and visually inspect the entire tooth range of the flywheel to determine if it's that or the starter itself.

I think you could be right. Everything is pointing to mechanical, but want to explore all options before pulling the starter.

 

[DangerMouse1]

Furbird thanks for the advice. I look/remove the starter and solenoid. I was thinking it could be voltage drop, but seems unlikely given it starts once I manually rotate the crankshaft?

 

[achris]

Pulling the starter motor is a 15 minute job, just get in and do it. Sounds much like you're missing teeth at the point where the engine stops (Engines stop at specific points, not random points)...

If you are missing teeth, then pulling the starter motor is the least of your problems.

Chris......

 

[GA_Boater]

Missing flywheel teeth causes a whirring starter and no crank. I think it's a starter issue, possibly the bendix isn't retracting and is jamming on the flywheel. But it has to come out to look at it. And pay attention to the starter bolts. They like to loosen and break off which can **** the starter.

I think gas and water are both liquids. Am I wrong?

 

[DangerMouse1]

Missing flywheel teeth causes a whirring starter and no crank. I think it's a starter issue, possibly the bendix isn't retracting and is jamming on the flywheel. But it has to come out to look at it. And pay attention to the starter bolts. They like to loosen and break off which can **** the starter.

Thanks GA_Boater I was thinking the same that if the starter was working on missing teeth I would hear something else like grinding or whirring due to no contact. Going to pull it tomorrow, will update everyone on the progress.

 

[Furbird]

I've seen this on a GM truck before (which is the same engine as a boat for the most part) and fortunately the flywheel wasn't damaged. Maybe you'll get lucky like that guy did and it be confined to the starter itself. But like the warning above, check the bolts and also the threads on the block to make sure it's not an issue there.

It's funny this popped up as just this weekend I was diagnosing my truck that has an intermittent starter issue. Sometimes it's like the power just goes away for a split second almost like the engine is hydrolocked or a dead cell in the battery. Turns out the previous owner never fully tightened the battery cable to the starter solenoid and sometimes it was getting full power and other times not. But yours definitely leans more towards a mechanical failure than electrical with what you describe. If the starter was hanging up on the flywheel and not retracting then you would most assuredly hear that bendix spinning until the starter just exploded as it cannot handle that kind of RPM.

 

[nola mike]

Is the click coming from the starter? Wasn't clear...