4.3 L Mercruser

[kulle]

Hello,

Installed new spark plugs, dist cap & rotor , fuel/water filter. Might just be imagining , but thought the engine was vibrating a little more than I thought it did last season. read that possible cylinder misfires could contribute to this? Is the easiest way to check for misfire to unplug each cylinder plug at the distributor until no change is noticed? Might just be wasting my time but its in my head and feel i need to check. going to take it out on a run tomorrow. Only thing that was recently done, is the shop said they "lifted" the engine to install a core plug that popped out...assuming they needed to remove from engine mount, maybe that didnt go back exact?

 

[alldodge]

Was engine alignment checked?

Did you recheck the firing order?

What is your engine serial number?

 

[achris]

... to install a core plug that popped out...

Oh, that's not good. The only reason a core plug will pop out is if there was water in the block and it froze. And in that case, a slight vibration will be the least of your problems...

Chris....

 

[kulle]

Was engine alignment checked?

Did you recheck the firing order?

What is your engine serial number?

Serial#- 1A340702 - I was told the shop checked alignment, i had them put on a new transom kit because i noticed my lower shift boot bellow had a tear in it. I retraced each spark plug cable on distributor cap to the correct cylinder ( firing order i found for that boat is, facing towards the stern, right side is 1, 3,5 and left is 2,4,6. Maybe it's nothing and me being paranoid. I dont know what a misfiring engine sounds like.

 

[kulle]

Oh, that's not good. The only reason a core plug will pop out is if there was water in the block and it froze. And in that case, a slight vibration will be the least of your problems...

Chris....

yeah i know! - i must not have used the wire enough or forgot in that drain plug area. No water in oil or any other leaks are present. the shop had it out on lake for around 30 mins after they repaired it and said all seemed fine.

 

[alldodge]

OK SN shows TBV ignition and TKS carb
Yes you can remove wires one at a time to see if there is equal change. If one cylinder shows more change then others, I would do a compression test first.

May not be a problem

 

[kulle]

OK SN shows TBV ignition and TKS carb
Yes you can remove wires one at a time to see if there is equal change. If one cylinder shows more change then others, I would do a compression test first.

May not be a problem

Lake test was successful, was able to achieve 4500 RPM WOT, engine sounded good, no water in bilge. Guess im all good, dodged a bullet with the core plug popping out ?

 

[Scott06]

Lake test was successful, was able to achieve 4500 RPM WOT, engine sounded good, no water in bilge. Guess im all good, dodged a bullet with the core plug popping out ?

yes dodged a bullet, my neighbor had the same thing happen to his mastercraft a few years back. He got lazy it frooze then he winterized... core plug popped out. Intially he was ok but after 3-4 hard uses he started getting water in the oil. Bottom line just keep an eye on the oil for milkyness and increase in level hopefully you are ok.

 

[kulle]

yes dodged a bullet, my neighbor had the same thing happen to his mastercraft a few years back. He got lazy it frooze then he winterized... core plug popped out. Intially he was ok but after 3-4 hard uses he started getting water in the oil. Bottom line just keep an eye on the oil for milkyness and increase in level hopefully you are ok.

appreciate the heads up. will the milkyness show up only after its warmed up/in use...meaning if it sits for awhile , i probably wouldnt notice anything
- what was the result of your friends issue??

 

[Scott06]

appreciate the heads up. will the milkyness show up only after its warmed up/in use...meaning if it sits for awhile , i probably wouldnt notice anything
- what was the result of your friends issue??

My neighbor had a cracked block after seeing a freeze plug pushed out. The point I was trying to make was I think in his case it took a couple of usesages of the boat (engine gettting hot and staying hot then cooling off) before the crack opened from water jacket to the crankcase.

Im not trying to scare you just watch what the oil looks like - it will get white pretty quickly and the level will rise on the dipstick as water gets added to the oil. It is not uncommon if someone isnt watching this the water will build up in the crackcase until it comes out the top of the valve covers which makes a mess.