Pulled Spark Plug - Water came out
 

I had an incident on the lake last weekend. Not quite sure of root cause at this point but the boat was overheating. I shut the boat down and got it home. I pulled all the plugs. 7 of 8 of them were perfect and dry. However, once I removed one of the plugs.....water poured out.

Can anyone help me with troubleshooting this? Logical steps to walk through?

Manifold leak !! or cracked head !! ???

I would check exhaust manifold first !:party-smiley-004:

When you say manifold, you are talking exhaust manifold? Same as a "riser"?

The riser is the piece bolted to the top of the manifold.

it sound like you may have done a head gasket.

logical steps,

remove plugs,
do a compression test,
if that is inconclusive do a leak down test. that should identify gasket, piston or valve problems.

if those tests are good pressure test the exhaust and risers.

is this a closed cooling motor?

and it doesn't matter at all right this minute. what you have to do instantly is fill that cylinder w/ wd40 and get the valves oiled down or in the next VERY short period of time, the rings on that piston are going to rust to the piston , the bore will rust and the valve stems will rust to the guide... all of which will take a minor repair right now and turn it into a monster repair by the end of the week.

that is a fact:ernaehrung004:

:eek: CRAP! I was afraid of that. Motor has been sitting for 14 days.

still better go do it. you might be the luckiest person in the galaxy... you never know.

I can personally verify that...I'm about 30 minutes away from having the chain hooked to my engine. I'll be replacing my rings...heads are in the machine shop right now. If all goes well, I'll have it back up & running by the weekend...& I do feel like I was very lucky.
BTW...Both CMI Headers tested perfect with air & water test.

Good Luck...

How long was it sitting? Well, I'm crossing my fingers as I can't get back to my boat until tomorrow. Maybe just maybe the existing oil with serve as a protectant. You guys have me freaked now!!! And I knew better....

Update. I pulled off the manifold today and the exhaust chambers all had very minor surface rust. Nothing to worry about so I'm happy to say that I caught it all in time. I hosed everything down seriously with WD40.

Problem is, now I'm stilling trying to identify root cause. I'm having all kinds of bad luck with this boat. Got a leakdown tester today and sucker turned out flawed. Ticked off. Likely, I'll be rebuiding it entirely but maybe, just maybe I'll have a cracked exhaust manifold.

Guys, I need help theorizing here. So here's what I've done so far.

1) Pulled plugs...passenger side of motor had water in it.
2) Fogged motor to prevent rust & corrosion.
3) Pull off risers. Passenger side exhaust manifold had a ton of water in it. Drivers side a-ok (plugs were dry too).
4) Removed passenger side exhaust manifold. Dryed it out. Plugged water inlet passage and filled with water updside down. No sign whatsoever that water is creeping through the wall into the exhuast port. Anything else I should do to detect a cracked manifold?
5) Compression checked all eight cylinders. #1 thru #8 all ready 165-170 psi. Seems perfect.

What now? Motor appears fine (cross your fingers). I'm going to suck up some oil to see how it appears.

Right now, I was just going to replace the manifold gasket and both riser gaskets. And plumb everything back up & fire up. I'm very afraid though that I'm missing something & might get water into the cylinder.......bend rod! But I can't seem to find anything wrong with her.

The entire event sequenced around a full speed reverse into a massive yacht's wave (yes, dumb as hell & whole reason your friends shouldn't drive). My theory is that it created a massive pressure wave which forced some water all the way up the exhaust into the manifold.....getting some into the heads. All I can imagine at this point. It was easily 100 gallons that capsized over the rear of the boat soaking all 4 rear passengers from head to foot. So not you normal wave.

Thoughts? Other areas to check out prior to firing up? Thought I'd fire it up.....shut it down quickly & pull plugs to check for water?

Are your exhaust flappers in place?

I just had about the same issue... turned out to be a bad riser, not the manifold, that was leaking the water. If you fire it back up and once again find water in the cyclinders, pull the riser off the manifold, depending on the type, if you have more water in the two middle cyclinders- risers leaking.

Could you actually detect a crack in your riser? Or just narrow it down to the riser, replace & back to good?