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Charles, Marine Mechanic
Category: Boat
Satisfied Customers: 3977
Experience:  US Navy (Ret) Certified Mercury Marine Tech with over a decade of repair experience.
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Starter is struggling to turn flywheel. This is a

Customer Question

Starter is struggling to turn flywheel. This is a fresh-rebuild built 100% to speck by the schematics and manual. I have compression I can feel it when I manually turn the flywheel. But when I hit the starter it is a very sluggish womp.......womp.......womp..... Then my negative terminal starts to smoke. I have two 380$ batteries from cabellas that are fully charged with a brand new starter solenoid. Starter is the same original one but it has always worked fine up until now. Starter will free spin great with plugs out. But will not spin with compression in the cylinders
Submitted: 1 year ago.
Category: Boat
Expert:  Charles replied 1 year ago.

Hello, my name is***** will assist you today.

To find the issue here, I will need your serial number please.

Do you have a multimeter to do some testing?

Customer: replied 1 year ago.
I do have one
Expert:  Charles replied 1 year ago.

Great, what was the serial number on the engine?

Customer: replied 1 year ago.
I don't have it on hand at the moment.
Expert:  Charles replied 1 year ago.

that will be ok. Are you near the boat and ready to start?

Customer: replied 1 year ago.
Expert:  Charles replied 1 year ago.


First test the voltage right at the batteries. both not cranking and while cranking. You may need an assistant.

Then do the same test at the starter solenoid red lead. The neg lead of the meter can go to a clean engine ground. These two readings should be really close to the same. Let me know what you have here.

Expert:  Charles replied 1 year ago.

Just a quick touch base with you before I log off for the night. i will be in the shop until after 6 PM CST tomorrow, then i will come back on line. We can continue with your question then. There is NO additional fees.

Customer: replied 1 year ago.
I was unable to preform this test at the moment. 2am and 20 degrees makes for a difficult start. As long as this thread will not be discarded and we can continue this discussion on Friday. This inquiry was more so to get a fresh opinion on what it may be seeing as I have tried quite a few things. I can get you the serial number / model # ***** but will be away from the engine for a couple days.
Customer: replied 1 year ago.
Let's say this is not electrical. What other possibilitys could it be. This engine is again a fresh rebuild so mechanical failure internally I would rule out seeing as i saw the piston and cylinder walls and all ports two days ago and all was perfect: I guess that would only leave electrical.
Customer: replied 1 year ago.
I will preform the tests this Friday when the temp comes up a little more.
Expert:  Charles replied 1 year ago.

Friday is good. I will be on after 6 PM CST. On the weekends, I log on after 10 AM and stay here until around midnight.

Customer: replied 1 year ago.
Since I already paid but fixed my original problem without assistance I will just ask you a new questionI put my head on and I have water coming out of it. Is it possible to over tighten. The head? And would that cause it to leak under the water pressure? I put on about 45 to 50 lbs ft. Which is 450 inch pounds it calls for 240 inch pounds. Is this why it is leaking? Why does the tightness of bolts determine a leak if it is too tight.?
Expert:  Charles replied 1 year ago.

Hello again,

What was the cause of the prior issue?

Are you leaking around the actual cylinder head of the water jacket cover?

if you put 45Ftlbs on each bolt, that is actually 540 Inlbs. The bolt tightness will leak when over-tightened due to the gasket being forced out of place and the metal rings on the cylinders being overly crushed. To get Inlbs from Ftlbs, multiply by 12.

Customer: replied 1 year ago.
I meant 540 I know the conversion, prior issue was caused by a thin film of corrosion on the positive eye connection to battery. Took little drimil to it to reduce the eye back to shiny metal and the starter turn As it was supposed to. By water jacket do you mean the "face" of the head there are two parts one touches the deck of the block and then on top of that is the "face" . It is coming out of the head gasket itself I believe in fear of leaking into cylinders I haven't cranked again after I saw that. But it is I am 98% sure coming from between the deck of he block and head where gasket is at. But for S&G what would be the fix if it was the water jacket
Expert:  Charles replied 1 year ago.

Since the water jacket (face) is metal to metal, you can apply a very thin layer of a gasket sealing compound to just the outer rim of it.

If it is coming from the head, you are going to need to remove it, make sure that all surfaces are very clean, check the head for any warpage using a straight edge. Then replace the gasket and retorque it to the block. Be sure that you start in the center of the head and move outwards.

Customer: replied 1 year ago.
would that be the reason it is leaking? this will be my 4th gasket i have installed on here. all surfaces were refaced by machine shop (outboard clinic) he stands by his work saying there is no warpage and is completely straight. i have over torqued it and did not start in middle when torquing down. could that be the reason for leaking?
Expert:  Charles replied 1 year ago.

Yes that very well could be the reason that it is leaking now. The head is really sensitive to the torquing process. Run all bolt up until snug, but not tight, then go back over them with the torque wrench set to the proper torque.