New owner of antique boat

[Sonoran Heat]

Hey all, first post on here but wanted to give quick intro - names Craig, purchased 78 invader with merc 140 I/O. Runs decent and have learned to change impeller, thermostat and other small projects from many of the posts on here. Problem I am having now is on water yesterday had 2 spark plugs rattle loose and seems much motor oil spattered out. Noticed obvious loss of power and popping sound. Torqued plugs back down but still have some bogging and loss of power at higher throttle. Any help would be appreciated.

Novice mechanic but always willing to learn

 

[KRH1326]

Re: New owner of antique boat

What did the plugs look like? Are they gapped right? Did you try to see if you are getting spark at each?

Maybe what seemed as spatter could have been some unburnt fuel mixed with residue oil from unfiring cylinders.

You can take the plug and hold it against ground to see if there is spark, but there are little testers that are a little safer.

Alot of folks are going to suggest that you check your wires, to make sure that none are crossed. Also to do a compression test.

Welcome to the forum.

 

[Sonoran Heat]

Re: New owner of antique boat

Compression good, cables are new, all cylinders firing. Was running fine until those spark plugs came loose. Is it possible to lose a significant amount of oil from around those plugs? I did an oil change earlier in week but am pretty sure everything tightend back down. just found good amount of clean oil in bilge and that power loss. Just fired it back up and power seemed to be back but noticed small amount of smoke coming from #1 plug. Could that be oil residue burning?

Thanks for your reply

 

[P 0 P E Y E]

Re: New owner of antique boat

Sounds like the tune up mechanic may have left a couple of plugs finger tight and they shook loose.

You say the engine is now running up to speed? 4200 rpm max?

Check for oil leak and recessive blow by...see if the breather hose is connected. Look at the oil filter for leaks.

 

[danond]

Re: New owner of antique boat

There is no oil behind spark plugs. Not enough to count, anyway. That's where the air/fuel combustion takes place.

If you have oil in the bilge and on the engine, something else is leaking. Tighten your plugs properly and move on to finding the oil leak.

 

[Alumarine]

Re: New owner of antique boat

Antique???

I wish I had a boat that new.