Calling all 8.1 Gurus (running rich)

[SeadawgVB]

That is a first for me. I have seen thousands of plugs missing parts but never one that broke off that way. Are those the original plugs and how did the other plugs look? I'm curious if the original rich issue is on this plug or somewhere else.

I feel your pain on this. Tearing down an engine at the beginning of the boating season for a spark plug is heartbreaking. If the base of the plug is seized in the head....it probably is best to have a machine shop handle it or get a new head.

I've busted a lot of plugs over the years but none in this way ever. Unfortunately YouTube has many many videos on this exact issue. I really did not want to expose the cylinder walls to the atmosphere.... Going to attempt to pull the head this afternoon.

 

[SeadawgVB]

I would pull the head. The risk is far too great getting a single shaving that scores the cylinder wall and takes a $2k problem and turns it into a $20k problem. Right now he has two days of work and $1,200 for a new head. If the machine shop can fix it for a $200, he is ahead of the game. The manifold leak is the other issue to resolve. Then we can get back to the original issue of what caused the engine to run rich.

I would take the time to look closely at the injectors since he has to pull the intake manifold. That said, the spark plugs would definitely show a "rich" issue and point him to the injector to look at.

I'm planning on doing the work on this. The motor is in very good condition and has very little visible corrosion, I'm hoping all the bolts come out. While the head is out and in the shop, I plan on sending the injectors off for cleaning / flow testing. The plugs all looked good, and the wire showed no signs of arcing.

This tune up has taken on a life of it's own.

 

[SeadawgVB]

SO, all the head bolts came out without issue. Machine shop removed the plug remains (and broken extractor). I was able to re-use the Cylinder head bolts..... (Just kidding, these are torque to yield bolts and should never, ever be re-used.)

Torquing the head was a little challenging due to the need to use a torque angle gauge down in the engine room, so close to the batteries and holding tank. I cut the heads off of a couple of the old head bolts and used them as guides as I was the only one available to lower the head down on to the block and the cast iron head must weigh over a hundred pounds.

Used the same trick on the exhaust manifold (cut off bolts as temporary guide studs), it's lighter than the head but a very difficult angle, holding it up with my knee while trying to start threading the bolts.

To wrap up this story of the hardest "tune up" ever, everything went back together smoothly. (Although the whole time I was waiting for something else to crop up and become an insurmountable disaster like breaking a head bolt or ripping some threads out.) The shakedown run went well, holding my breath the whole time. This past weekend I made a club cruise that was two and a half hours out, on a plane almost the whole time and in some of the worst seas I have been out on in this boat. The ride back was completely uneventful, no leaks (coolant, sea water, nor oil) and temperatures seem normal.

However, the original symptom of spots of petroleum product in the exhaust still exists. I'm thinking of sending the fuel injectors off for servicing. I can pop those babies out in about 10 minutes now....

 

[PlayDate]

Dave,

Great work!!! I'm sure it was a knuckle buster but it is good to hear that all the pieces went back together without incident. I'm not a huge fan of torque to yield bolts. I use ARP bolts as a replacement and use their process which is easier.

In regards to excess fuel.....did you see anything on the plugs you pulled that looked different? Generally, if any injector is leaking at idle.....the plug will be wet with fuel. It doesn't hurt to get the injectors serviced.