Force 125 water in #1 cylinder

[pnwboat]

I recently purchased a 1988 19 foot Bayliner Corbra. Used it 4 or 5 times this summer with some minor problems. Hard to get started, but once started no problems. Runs at about 5500 RPMs 38 - 40 MPH. 13 1/2 X 17 prop. I was going over the motor just to make sure all was in order. Re-built carbs, floats were set too high. I think this was why it was hard to start. When running the motor with muffs, I noticed that #1 spark plug had some water droplets on it. Compression was 125 on #1, 135 on #2, 140 on #3, and 140 on #4. I also noticed evidence of water leaking around a couple of the head bolts too. I figured that the head gasket was bad. I replaced the head gasket twice. It stopped the leaking around the head bolts, but not the water droplets in #1 cylinder. I replaced the water pump impeller, the impeller housing and the drive shaft seal in the housing. I noticed a significant increase in the water coming out of the two exhaust holes in the upper rear portion of the motor. Used to just spit water with muffs, now two solid streams of water coming out. Unfortunately this seemed to aggravate the water problem in #1 cylinder. Also #1 plug was clean as a whistle, while the others showed light carbon deposits. I dissasembled the motor and took the bare block and head to a machine shop. They had to take off about .015 off the block, and .007 off the head to true things up. I also noticed that the stainless steel baffle plate under the exhaust cover was severly warped. Could this be a source of water leakage too? If it was leaking, can water get into one of the cylinders? The stainless steel baffle plate seemed kind of thin. It measured .029 thick. I have a piece of .046 stainless steel that I plan on using to make another plate with. The thickness shoudn't cause any problems should it? I also wanted to mention that I have new rings. Figured this would be a good time to eliminate any issues there too? Anyways, just wanted to bounce a couple of concerns off of anyone out there before I put the motor back together again while I'm waiting for engine gasket set and seals to arrive.

 

[Frank Acampora]

Re: Force 125 water in #1 cylinder

That SS plate is not a baffle per-se. It forms one wall of the exhaust cooling passage. It is stainless because exhaust gases will eventually corrode away and perforate aluminum. There is always water on the other side of it while the engine is running. This keeps exhaust heat from melting the aluminum parts of the passage. Because it always gets the direct exhaust, this plate always warps. A thicker one won't hurt anything but I'll bet it will warp also unless you fabricate it from something thick like 1/4 stock. Then, of course, you will need to use longer bolts. By the way: the factory uses an odd length of steel bolt. I like to replace them with slightly longer SS bolts and I slather on the anti-seize because no matter how good the gasket, there is always some water migrating through to the bolts causing corrosion and rust.

By #1 cylinder, you do mean the top cylinder, don't you? There is not usually a leaking water problem there. The bottom cylinder, however is prone to water leakage because that SS plate is sandwiched between two identical gaskets and these gaskets have their thinnest section right at the bottom near the front of the plate. It is easy to kink them at this point during installation and develop water leaks.

If indeed it is the top cylinder you are calling #1, then look for either gasket to be defective in the top area. Either that or the bolts holding the cover are not properly tightened. Either will cause a water leak since as I previously said, there is ALWAYS water in this part of the jacket while the engine is running (assuming the water pump is working) Also check the block casting to be sure the gasket sealing surfaces are not nicked or cut.

And of course, a cracked liner will admit water into the cylinder--But we won't even think about that right?

While you have the exhaust cover and SS plate off, look at the water passages. Upon close inspection you will note that water is always circulating through the exhaust cavity and passages. It comes up from the bottom of the block through the front passage and circulates around and also through the cover. That's why the SS plate has several small weep holes in it and the inside of the aluminum plate has some holes drilled in it or cast in (depends on which plate and engine year) To a small degree, it is also circulating around the cylinder bores while the thermostat is closed (thermostat has a weep hole in it). When the thermostat opens, water is fully admitted to the head and more also flows around the cylinders.

 

[pnwboat]

Re: Force 125 water in #1 cylinder

Thanks for the reply Frank. Yes I'm referring to the top cylinder as #1. I thought about a cracked cylinder liner too. Did a visual inspection but could not see any evidence of a crack. That's not to say that there isn't one. The eyes aren't quite as sharp as they used to be. Hopefully that's not an issue. I'm surprised that the motor ran as well as it did. Maybe that says something about it's ruggedness. Yes I noticed that the exhaust cover bolts were something like 1 1/8 inches in length. Not something you find easily. I'm replacing all the bolts on the exhaust cover with stainless steel ones too. Thanks for your advice. This is a very useful forum.