83 Merc 115 hard to turnover

[mikel2k]

Hey folks i have purchased an 83 merc 115 that was in storage for 3 years, upon doing a compression check i sprayed the cylinders and ran the check all 6 were at 125lbs. When i put the plugs back in and try to start it turns over slowly twice then stops, I have tried another starter from my 89 115 as well as two fully charged batteries and it still does the same thing. Again i pull the plugs hit the switch and it turns over easy.....What would be causing it to strain with the plugs in? Would it help to pull the lower check the impeller then try to turnover? Thanks for your comments in advance.

 

[wavebuster1]

Re: 83 Merc 115 hard to turnover

check the exhaust ports and work your way back to the motor there may be a blockage some were not allowing the exhaust gas out. depending on the storage conditions theres no telling what may have gotten in there . but a blockage will cause the compressed gasses to stay in the motor and "lock it up" when you remove the plugs you provide an escape route for the exhaust

 

[CharlieB]

Re: 83 Merc 115 hard to turnover

Grab your trusty battery jumper cables and jump directly to the starter motor, by-passing the starter solenoid, does it turn O.K. now?

A poor contact anywhere between EITHER battery post and the motor will allow NO-load RPM yet fail once LOADED.

 

[mikel2k]

Re: 83 Merc 115 hard to turnover

I did try bumping it over with the jumper cables onto the starter and it did the same thing. Im working to replace the powerhead on my 89 115 with the 82 powerhead and while looking at it the newer 89 has a few wires mounted beside the top spark plug where the 82 does not im trying to find out what that controlls because i would like to keep the controls and electronics from the 89 vs the 82 one main reason is that the tilt/trim is diffrent. Also on the 89 it has a small hose coming out of the rear under the 4th spark plug where the 82 only has a cap and no hose, again not sure what thats for on the 89 vs the 82. Thanks for all the help

 

[JB]

Re: 83 Merc 115 hard to turnover

What CharlieB said. Classic poor connections symptoms.

Do the jumpers and let us know what you find.

Good luck.

 

[Maxz695]

Re: 83 Merc 115 hard to turnover

Remove the spark plug wires from the spark plugs. With the plugs still in try to turn the engine over. If it turns fine try checking your firing order. if not then I would think on checking the first reply. could be a bad starter. lose connection Timing out of wack just a few suggestions. removeing the LU if it turns over good without plugs in it is not nessecary if it was the LU it would turn hard with the plugs removed

 

[jeffersondodson561]

Re: 83 Merc 115 hard to turnover

Remove the spark plug wires from the spark plugs. With the plugs still in try to turn the engine over.

I agree remove the plugs and turn over by hand (disconnect the battery first) flywheel should turn over by hand with relative ease. If not could have a bad bearing, etc.

 

[mikel2k]

Re: 83 Merc 115 hard to turnover

I have tried another starter and tried starting it straight from the starter still the same issue. I did pull all the plug wires off and tried, still same thing. Acts like it maybe builds two chugs of compression then stops. Pull the plugs out and it turns over great even by hand.

 

[jeffersondodson561]

Re: 83 Merc 115 hard to turnover

That is usually a sign of bad compression on a cylinder check compression with your two pulls

 

[Maxz695]

Re: 83 Merc 115 hard to turnover

did you try several times toallow all gas to escape when doing the test witout wires connected to the park plug this could take several trys before the cylinders are clear. remove plugs turn the engine over for several turns so anything in there will be forced out replace the plugs and try again without the wires connected this should release any gas in the motor also disconnect any fuel source from the engine. if this is a 4 stroke to me it sound like a broken cam stuck exhaust vave, broken valve spring etc

 

[mikel2k]

Re: 83 Merc 115 hard to turnover

With the plugs pulled it turns over great not the case with the plugs in although i can wait 10-15 mins go back and it will turn over like it does the first round, seems like its building compression to a point then not able to turnover anymore. Im going to pull the lower unit and check all exhaust etc.

 

[CharlieB]

Re: 83 Merc 115 hard to turnover

i can wait 10-15 mins go back and it will turn over like it does the first round.

You tried another starter? Was that starter off a RUNNING motor?

I still suspect poor brush contact in the starters.

Test battery voltage while cranking, then test voltage at the starter while cranking, if it is the same (good #s) clean the startr commutator and brushes.

 

[mikel2k]

Re: 83 Merc 115 hard to turnover

You tried another starter? Was that starter off a RUNNING motor?

I still suspect poor brush contact in the starters.

Test battery voltage while cranking, then test voltage at the starter while cranking, if it is the same (good #s) clean the startr commutator and brushes.

Yes I tried another starter from another motor that was running. Voltage was 12.48 on the battery and to the starter, dropped to 12.11 when trying to turn it over

 

[daveswaves]

Re: 83 Merc 115 hard to turnover

You tried another starter? Was that starter off a RUNNING motor?

I still suspect poor brush contact in the starters.

Test battery voltage while cranking, then test voltage at the starter while cranking, if it is the same (good #s) clean the startr commutator and brushes.

Im with Charlie on this one too. I just overhauled a starter for my inline 6, symptoms...exactly like yours. Solution, clean and re oil bushings, polish and undercut commutator, smooth brush surface or replace brushes. Results, 350 rpm cranking speed with 150 PSI all six.

 

[daveswaves]

Re: 83 Merc 115 hard to turnover

Yes I tried another starter from another motor that was running. Voltage was 12.48 on the battery and to the starter, dropped to 12.11 when trying to turn it over

See my other post, you have poor contact inside the starter. That voltage drop is not low enough to indicate good connections in the starter.

 

[mikel2k]

Re: 83 Merc 115 hard to turnover

Took the starters and had them checked and tested they are both fine.

 

[CharlieB]

Re: 83 Merc 115 hard to turnover

WHO tested them?

How? Sticking them with 12 volts and seeing that they turn is NOT a valid 'test'.

What is the amp draw?

Did Superman look inside with his X-ray vision to tell you they are 'fine'?

 

[daveswaves]

Re: 83 Merc 115 hard to turnover

Took the starters and had them checked and tested they are both fine.

What were the LRA readings (locked rotor amps)? Im still with charlieB on this one.

 

[mikel2k]

Re: 83 Merc 115 hard to turnover

WHO tested them?

How? Sticking them with 12 volts and seeing that they turn is NOT a valid 'test'.

What is the amp draw?

Did Superman look inside with his X-ray vision to tell you they are 'fine'?

One was just rebuilt 4 months ago and the other was on the replacement engine that wont turn over good, I have tried both starters on the other 115 that has the bad cyl and they both turn it over with ease....I took both starters back to the rebuilder to check and test they were both fine but he did replace the springs since they were apart.

 

[Big flop]

Re: 83 Merc 115 hard to turnover

When you did your cranking voltage check
was your volt meter on the battery
or on the starter?