Engine just clicks but no start

[Harveyf22]

I have an 87 Mercruiser 165 io engine. When I go to start it, it either just clicks or just barely turns over. It has a new battery and connections to it look fine. Any other ideas on what could be happening ?

 

[QBhoy]

I have an 87 Mercruiser 165 io engine. When I go to start it, it either just clicks or just barely turns over. It has a new battery and connections to it look fine. Any other ideas on what could be happening ?

Yeah. Almost odds on (if admittedly a little pessimistic of me to say so) that it’s hydro locked or out of shape, from suffering the far too familiar failures. Water pump and overheating and/or head to block interface compromised. Allowing water into the cylinders. Or perhaps even a cracked exhaust or riser doing similar as a result. Pull the spark plugs out her and turn her over. Hopefully I’m wrong and there isn’t water evident on the plugs or pumping out like a fountain

 

[Lou C]

Even if the connections look fine you have to find out if the main lug terminal on the starter is getting 12v with the battery switch on and the red/yellow wire terminal is getting 12v when the key is turned to start. If not you need to go thru all the connections including the engine ground cable/stud. There is an additional assist solenoid to prevent voltage drop that will cause this as well. If voltage checks are good might have to remove the starter & test it. If worried about water intrusion hydrolock remove spark plugs check for water/rust

 

[Scott Danforth]

I have an 87 Mercruiser 165 io engine. When I go to start it, it either just clicks or just barely turns over. It has a new battery and connections to it look fine. Any other ideas on what could be happening ?

Start at the battery and work your way to the helm cleaning every connection and clean them with 150 grit. They need to be clean and shiny enough the queen would eat off them

Pull every one, one at a time. It will take the weekend

 

[Bondo]

I have an 87 Mercruiser 165 io engine. When I go to start it, it either just clicks or just barely turns over. It has a new battery and connections to it look fine. Any other ideas on what could be happening ?

Ayuh,..... Welcome Aboard,..... Looks can be deceiving, so unless you take 'em apart, 'n clean 'em as Scott says, they can still be a problem,....
'n don't forget the Grounds,....

 

[Lou C]

Also forgot to mention a connection can be good enough that you can measure voltage present BUT not good enough to allow enough amperage to flow for the starter to engage & turn the engine. If those battery cables are original they could have all green corrosion up inside the insulation. When I got my boat (1988) in 2002 the cables were trash I had new cables made up with Ancor Marine wire & installed a dual battery system at the same time.

 

[dubs283]

a connection can be good enough that you can measure voltage present BUT not good enough to allow enough amperage to flow for the starter to engage & turn the engine.

As in acceptable vs. unacceptable continuity of a part of/entire circuit. Most easily measured in voltage drop with a load applied

I also agree with Q's mention of possibility of hydro lock.

My common experience with 470's is they are either pristine one owner fully maintained gems or absolutely destroyed left in the back 40 rhubarb trying to get it running free boat. Very little in between

 

[Lou C]

This has fooled me 2x with oxidized old fuses that read 12v but didn’t allow enough amperage to flow to make the component work.
Remember how many amps it takes for a starter to crank over an engine. It’s not simply 12 volts!

 

[Scott Danforth]

inrush current on the old direct drive starters on the mercruiser 470 is 57 amps to pull in the solenoid and about 350 amps to get the motor starting to turn. then the solenoid amperage drops to about 5 amps to hold and the motor amperage drops to about 200 amps.

 

[Lou C]

good to know that Scott, was going to measure with an amp clamp myself. Just curious....

 

[Harveyf22]

Regarding hydro lock, this seemed to start last year and my marine mechanic was able to start it up fine and winterize it. Seems like he would’ve mentioned it if he saw it.

 

[Scott Danforth]

The 470 is a heat-exchaned full system. Other than the one hose to the heat exchanger to drain what did your mechanic do?