Mercruiser Spark plug broken

[liusigou]

Today I tried to do the cylinder pressure testing and usded the 15mm socket and failed, the head of spark was broken. To ensure the spark can be get out, what kind of socket should be applied.

Really I cannot find the serial No. and I only can know it is 185hp. also what kind of manual should I follow?


Before I did a cylinder pressure testing with my socket for my 2.5L 120HP mercruiser. Could somebody help me to solve this issue?

 

[Scott Danforth]

Spark plugs are NOT metric
5/8"

 

[liusigou]

Spark plugs are NOT metric
5/8"

Thank you Scott. Tomorrow I will buy one socket of 5/8''.

How can I identify the seral NO?

 

[Scott Danforth]

If you work on a boat, you should have a toolbox full of tools

 

[liusigou]

If you work on a boat, you should have a toolbox full of

I know. But there are thousand if tools in store and I even do not know which tools box I should have. Would you please suggest what I should buy?

 

[Fun Times]

Search online spark plug socket... As mentioned, you'll need 5/8.
Also Wobble Socket Extension Set, https://www.harborfreight.com/wobble-socket-extension-set-9-pc-67971.html

What year is the boat? 2- or 4-barrel carburetor?

Look in the area of the engine starter for a aluminum tag with the serial number on it..., https://www.perfprotech.com/blog/articles/mercruiser-serial-numbers#

 

[tpenfield]

This is my go-to tool set. Crescent 100 piece tool set.

 

[liusigou]

Done. I have bought a tool set with 5/8'' and have tested all the cylinders preesures. They are 130,140,130,130,120,120. It seems that battery is shortage of power, So the fifth and sixth should be higher.

 

[liusigou]

If you work on a boat, you should have a toolbox full of tools

Hi Scott Could you please help me solve another issue in another ticket.

Where can I find the oil filter?

Currently my alighment tool show the witness mark is that bottom touch the coupler more(See the pits of up and down). Why is my understanding different from achris? Achris mentioned following in my another thread as following, /************************/* No, the engine is LOW if the bottom of...

forums.iboats.com

The issue is the propeller spinning while I tried to start the motor.

 

[ScottinAZ]

Judging from your writing, English isnt your first language, so you likely live in a country that uses the metric system. Not a bad thing, but your engine is USA made, and will have a mix of SAE standard and metric fasteners in it. You will need to invest in a tool kit that has both to easily wrench on the engine.

As for the prop spinning, the issue is going to depend on HOW FAST it’s turning…. If it’s just creeping around, that’s no biggie, just parts moving in the viscous oil, if it’s SPINNING at engine driven speed, you are in gear, and either need to adjust your shift cables properly if the helm is in neutral, or your neutral switch is not working and you are starting in gear.

 

[Lou C]

This is my go-to tool set. Crescent 100 piece tool set.

View attachment 382092

very nice Ted how much if you don't mind my asking?

 

[Dubed]

very nice Ted how much if you don't mind my asking?

I am in the habit of carrying a full compliment of tools on the boat. If I use a tool for a repair, I try to keep it onboard.
Back when I raced motorcycles, I was always in the habit of only using the tools I carried in my pack for all repairs. That way if there was any failure, it could be repaired on the trail.

 

[tpenfield]

very nice Ted how much if you don't mind my asking?

IDK . . . I think they used to be around $100. Probably more now.

 

[matt167]

fwiw 5/8” is exactly the same as 16mm. If you notice some sae and metric kits only have one or the other and usually not both. That’s why

 

[Lou C]

There are a few sizes like that; the other is 3/4” & 19mm

 

[ScottinAZ]

There are a few sizes like that; the other is 3/4” & 19mm

the infamous always lost 10mm and 3/8" along with 13mm and 1/2"

 

[markhodges78]

Ok I'll bite 7mm and 1/4 , 8mm and 5/16, 11mm and 7/16 14mm and 9/16