Water in cylinders

[PAMeyer]

Johnson 3-cylinder 1976 75 HP 75ELR76. When I winterized the engin last Fall I fogged the cylinders. Today I planned to start the engine for this season. I pulled the plugs and they are still wet with oil. I have the gearcase off for seal replacement but I thought I could start the engine by connecting the garden hose to the tube in the leg. I cranked the engine (without gas yet) and it spins fine. I added gas, turned on the water and attempted to start. The engene turned about 1/2 revolution and stalled. I pulled the plugs and all 3 cylinders had water in them. I turned off the water, cranked the engine to expel the water, reinstalled the plugs and started the engine and it ran fine. After 1-2 minutes I shut it down. I restarted it without problem and the turned on the water. It seemed to run fine. I shut it down with the water still on and, after 1 minute, it wouldn't crank - water in the bottom cylinder. I got the water out of the cylinder, started it to "dry it out" and did a compression test: 140, 138, 140 which is identical to last summer's test. I would appreciate your suggestions for repair - what are the most likely causes?<br />Thanks for your help.

 

[mikeyzx2]

Re: Water in cylinders

I'm wondering about that.....if you had a bad gasket then it would be obvious with compression. I don't think these motors have an exhaust tube like those old tiny motors do, cause it sounds like water is being forced into cylinders through exhaust ports. Probably not the case but the way they're designed you would think that

 

[mikeyzx2]

Re: Water in cylinders

What I was meaning is that if it had the exhaust tube like the OLD Neptunes and 1hp motors then I could see the hose being hooked to the wrong tube and water being forced into cylinders through the exhaust ports when they were exposed

 

[ledgefinder]

Re: Water in cylinders

Sounds like one of the two gaskets in the exhaust box. Check the surface flatness (block and exhaust box) when you have it apart to change gaskets. Leaks are not uncommon on the triples, particularly in the are of the middle cylinder. They can be a result of local overheating, so be real sure your carbs are clean (not gummed up internally), and consider jetting a bit richer, and/or a thicker head gasket.

 

[R.Johnson]

Re: Water in cylinders

With that hose connected to the water tube, you have water going every where. When the engine is on the down stroke, you are pulling water into the cylinders through the exhaust ports. Put the gearcase back on, and hook up the water properly. If you still have water in the cylinders, look for a leak in the exhaust cover gaskets

 

[mikeyzx2]

Re: Water in cylinders

from what R.Johnson is saying that's the probably the main reason you'll hear or read that with the muffs on you only need to turn the water on enough to get a trickle from the muffs, if it's spraying out from the muffs then the water's on too much.

 

[PAMeyer]

Re: Water in cylinders

Thanks to all for your suggestions. I don't have the gearbox reassembled yet, so I plan to check the exhaust cover gaskets. Can I do this without removing the powerhead? I have a factory service manual but it only describes complete disassembly - nothing about removing specific sections.

 

[ledgefinder]

Re: Water in cylinders

40-60psi (house pressure) is quite a bit higher than the 5 or so psi the pump normally runs. I'm not sure an intact exhaust gasket setup in perfect shape would hold house water pressure. Ideally, you want to renew that gasket, since it has developed a leak path. But if you're in a pinch, try running it with the lower unit back on & see if you get leakage. <br /><br />Again, it is not unusual for the triples to develop leaks at the exhaust box and/or the head. That's a very highly tuned motor (75hp from 50 cubic inches), and there were factory service bulletins discussing methods to lower the temps in the middle cylinder - jetting & timing. <br /><br />It'll be easier to pull the powerhead - not that big a job by the way. Make sure you get the nut in the middle of the back of the powerhead before you go to lift the powerhead off.<br /><br />I don't think there's a path for water to be getting into the exhaust box, without a gasket leak. Has to be a exhaust box gasket leak, or possibly a tiny head gasket leak that still allows good compression readings (unlikely). The whole midsection would have to fill up with water, and that's not going to happen with the lower unit off.

 

[PAMeyer]

Re: Water in cylinders

Thanks, ledgefinder. How do I get copies of the factory service bulletins discussing methods to lower the temps in the middle cylinder?

 

[Joe Reeves]

Re: Water in cylinders

Forester.... It's simply possible that with having a hose attached to the copper water tube that some of that water is being sprayed outside of the tube straight up towards the exhaust ports. Now, that'll load the cylinders with water quite quickly.<br /><br />However, I'd suggest that you wait until you have the gearcase back together and once again assembled to your engine, preferably with a new water pump installed. Then.......<br /><br />Double check the compression, after which (if compression is the same) start the engine. If the water problem is now non existent, the hose scenario as above would pertain.<br /><br />If water still enters the cylinders, first remove the cylinder head to inspect the head gasket and sealing surfaces of the head and block. If all is as it should be, install a new head gasket, torque the head bolts to 18 to 20 foot pounds in the sequence of: Center left bolt, center right bolt, drop down to the next lower right bolt, then in an ever widing circle.<br /><br />Test run the engine again. If the water is still entering the cylinders, the usual cause (the only cause I've ever encountered) is a warped center exhaust baffle plate located on the port side of the engine (the smaller inner plate). If this is the case, and you have a problem locating the plate, I have a couple left in my remaining stock but try here at "iboats" first.<br /><br />Note... On a flushette, always have the water pressure on full blast as per OMCs recommendation. You do not want that water pump sucking air which would lead to further problems. The smaller engine (9.9hp, 15hp, 25hp etc) would need less pressure but the larger engines require the full pressure amount.

 

[DHPMARINE]

Re: Water in cylinders

Joe,Well said.I'm guessing you were a tech rep with OMC.? ?<br /><br />Your replies are well thought out and precise.<br /><br />DHP

 

[PAMeyer]

Re: Water in cylinders

Joe, you make an excellent point about the water possibly spraying into the exhaust ports, and this may allow me to avoid a tear-down. <br /> This site is fantastic. I greatly appreciate everyone's help - even when I'm just reading other posts.<br /> Have a great day!