Water in the cylinders?

CCBMBB2 · Jan 7, 2003

Guys, I have a mid 1980's series Yamaha 15 HP outboard the had degenerating low speed performance. Recently, it has refused to idle or run at low speed. I noticed a "white-ish" tinit to the exhaust. When I was checking everything later at home, when I pulled the spark plugs, I noticed water on them. Also saw evidence of water on the tops of the pistons. I have secured a compression guage, but I'm not sure how much good it will do me. Could this be a bad head gasket or a cracked head? Or is the most likely culprit a bad block and a subsequent search for a new motor will ensue? Thanks to all. Bayou Fisher

DJ · Jan 7, 2003

Re: Water in the cylinders?

Bayou Fisher, My bets would be on the head gasket or exhaust cover gasket. Both easy fixes.

CCBMBB2 · Jan 7, 2003

Re: Water in the cylinders?

djohns19, Is there a diagnostic process or do I just remove the cylinder head and the cover plate and inspect the gaskets upon removal? Thanks Bayou Fisher

DJ · Jan 7, 2003

Re: Water in the cylinders?

Bayou Fisher, A compression check may or may not verify this. It will tell you something if the two cylinders are significantly different in the readings. Sometimes, you can introduce a bit of air pressure into a cylinder that is on the compression stoke and listen for air escaping into the exhaust leg. You will have to hold the flywheel to do this. Are both cylinders ingesting water? Both plugs show water droplets? If so, I would retorque the cyl. head first and see if that helps.

dkondelik · Jan 7, 2003

Re: Water in the cylinders?

B.Fisher., Sorry, don't know your motor BUT,.... in most cases it is fairly easy to remove exhaust cover(s) and when applicable, the head. My first guess would be the exhaust cover. If this is the source of the leak, chances are that there will be evidence. Regardless, the cost of a couple of gaskets (e-cover & head) is substantially less then a new motor. Goog Luck Have FUN!

CCBMBB2 · Jan 7, 2003

Re: Water in the cylinders?

djohns19, I will be running the compression check in the next couple of days. One question - Is the presence of this water a symptom of the root cause of my engines poor (or nonexistant) low rpm performance? Thanks Bayou Fisher

DJ · Jan 7, 2003

Re: Water in the cylinders?

Bayou Fisher, Absolutely! Your low end performance would be the worst. The water is cooling off the combustion process. Until you get this fixed, I would suggest you keep the cylinders lubed with some fogging oil (WD-40) would be OK). We don't want any rust to develop in there.

NathanY · Jan 7, 2003

Re: Water in the cylinders?

Have your run it in saltwater? Did not see if you mentioned it. If so, if it has not been properly maintained, and there is not eviedence of head gasket or ehaust cover, check the cylinder walls to see if there is any integrity loss due to corrosion. Had this happen to me, not a good day.

CCBMBB2 · Jan 8, 2003

Re: Water in the cylinders?

All, The motor has been used in fresh and brackish water by me. Unfortunatly, I'm not the first owner. I have only had the motor for a little over a year. It has always got me home, but frankly, it has always been problematic. Bayou Fisher

CCBMBB2 · Jan 13, 2003

Re: Water in the cylinders?

OK, time for an update. I ran a compression test on the engine. 130 lbs for the top cylinder, 126 for the bottom cylinder. I had previously cleanned the fuel tank, fuel line and the fuel lines inside the engine cowl and flushed the carb. Since the compression was good and the fuel source was eliminated, I decided to check the exhaust cover. Eight broken bolts later, there is no evidence of gasket failure or water passing thru the exhaust plate. There is some discoloration of the cylinder head (from gray to black) around the top cylinder. There is also a tremendous amount of water in the cylinders. Could the head be cracked? Could the head gasket be causing this even though I have very respectable compression numbers? Or, should I fear the worst? Thanks all. Bayou Fisher

DJ · Jan 13, 2003

Re: Water in the cylinders?

Bayou Fisher, Your head and/or gasket is certainly suspect. You'll be able to tell more, once removed.

CCBMBB2 · Jan 13, 2003

Re: Water in the cylinders?

djohns19, I agree. I spoke to the mechanic at the nearby Mercury/Mariner dealership and he told me to clean the exhaust plate and inspect it thoroughly. It is apparently the weak link and they are known to go bad. He also said that the flaw or crack can be minute and very hard to locate, so I'll check that out before I start cracking cylinder bolts.

G DANE · Jan 13, 2003

Re: Water in the cylinders?

Hi Bayou Fisher Get someone who can TIG weld to weld a nut to the broken bolts and you can unscrew them. Get a price from him, not a big job. I wouldnt recommend to drill and ezout - you will for sure ruin some of the threads.

CCBMBB2 · Jan 14, 2003

Re: Water in the cylinders?

All, I have started removing all of the crud from the inner exhaust cover and the outer exhaust cover. So far, nothing is jumping out at me as a potential root cause of water in the cylinders (both), but I am astonished at just how much water is in there. I have been told that I may have a cracked cylinder wall. How would the water get in both cylinders if that was the case? Anyway, still cleaning and inspecting the exhaust covers and preparing for the eventuality of a cylinder head removal (boy, those frozen bolts are pesky!). Thanks to you all for your time and expertise. I am very grateful. Bayou Fisher Can't wait 'til spring topwater fishing!

CCBMBB2 · Jan 16, 2003

Re: Water in the cylinders?

OK, I have removed the power head from the leg. Between the power head and the leg is a gasket and 3 orange "O" rings. The "O" ring that goes over the water inlet into the power head had a 1/8" thick coating of a semihard jelly-like substance on it. The other 2 "O" rings had some of this also, but not nearly as much. There was no obvious path through the base gasket to the exhaust ports, but the gasket came off in more than 1 piece, so I can't be sure this is the problem. I inspected the inner exhaust cover and there is a flaw in the surface of the aluminum (a pit large and deep enough that I can put the point of a finnishing nail in it). I did an ambient temperature leak test on the inner exhaust cover and the part passed the test. This pit may open up when the engine is running due to the heat of the exhaust, I just can't tell. At this point, I'm thinking that the compression test that I did was affected by the water in the cylinders, so my actual compression levels in the cylinders may not be that high. A mechanic that I spoke to last night said that he has experienced leakage in the powerhead-to- leg gasket causing this water intrusion and he thinks that is my problem. If he is right, would there be a "smoking gun" (some evidence of this condition)? As always, thanks for your time. Bayou Fisher

DJ · Jan 16, 2003

Re: Water in the cylinders?

Bayou Fisher, Not necessarily. I've had many gaskets leak that did not show any obvious signs. If you're worried about that hole/dent, fill it with JB Weld.

CCBMBB2 · Jan 22, 2003

Re: Water in the cylinders?

Thanks to all! Decided to remove the cylnder head, mostly out of curiosity. Found 4 bolts loose, 3 I could turn with my fingers. That's the good news. the bad news is that I found serious corrosion damage to the cylinder head and block. There are also 11 bolts that the heads sheared off of during removal. They are essentially welded into the block. We have tried everything and have had no luck with removal. Based on both of these conditionsd, we have determined that repair is not economically feasable. I have located a used block and a cylinder head that an experinced mechanic will clean and hone for a total cost of $150. My internal parts appear to be usable, so for an additional $100 (gasket set and misc. parts), it looks like I can get this thing back on the water. Thanks again to all of you for your assistance. Good luck to you all in future and enjoy the great outdoors. Bayou Fisher

Still hanker'in for that topwater bite!

Water in the cylinders?

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