Merc inline 6 - possible water intrusion?

[Chris1956]

I removed the hose from the lower crank case bleed valve and I get a few drops of white liquid. It smells like gas and soaks into a rag like gas, and could be the remants of the white grease I used to install the rod bearings mixed with fuel. It could also be water mixed with 2 cycle fuel.

Question: If it is water, can it be from a leaking inner water jacket cover or baffle plate? Can water travel through the combustion chamber and past the rings? Or is it likely I have a bad lower crank seal?

 

[jimmbo]

Re: Merc inline 6 - possible water intrusion?

Mercury doesn't reccommend using white grease during engine assembly. They do specify one of their greases. It probably has to do with making sure the grease will dissolve in gasoline and wash off so the oil can do its job.
Get some of the grease you used for assembly and put in a container with some fuel and mix it up. Does it look like what you saw coming out of the recirc line?

 

[Chris1956]

Re: Merc inline 6 - possible water intrusion?

Jimmbo, Thanks for the reply. What does Mercury specify for engine assembly? The grease was white-colored marine grease BTW.

 

[jimmbo]

Re: Merc inline 6 - possible water intrusion?

In my service manual(official merc) it states Quicksilver Multi purpose Grease. It also stated NOT to use Quicksilver 2-4-C beause it wouldn't disolve in gas. Merc has discontinued the Multi Purpose grease but have new grease
http://www.mercurypartsexpress.com/...02868Q+1&store=Accessories&compName=&compSKU=

 

[Chris1956]

Re: Merc inline 6 - possible water intrusion?

Thanks for the update. I didn't know that there was a grease that didn't disolve in gasoline.

Hey Clams, do you want to weigh in on the original question about water working it's way into the crankcase from the exhaust cover of baffle? Ever see this in your travels?

 

[jimmbo]

Re: Merc inline 6 - possible water intrusion?

Resistant to washing away by gas/oil might be a more accurate description.

I guess if the waterjaket gasket were to leak some water might get into the cylinder thru the exhaust ports. It would take bit of water to fill the cylinder enough to spill out of the intake port and into the crankcase.

Water will mix with gear oil and turn milky but I've never seen it do that with gas-oil mix..

 

[Chris1956]

Re: Merc inline 6 - possible water intrusion?

Jimmbo, Thanks again for the info. I also thought it would be remote that water from the water jacket could make it into the crankcase, but welcome the agreement.
Obviously I am hoping that the milky stuff is just residual grease and not water, but I am having a hard time getting that cylinder to fire consistantly, and am trying to learn why. I think I will check out the carb, since the #6 plug is usually wet.

 

[Clams Canino]

Re: Merc inline 6 - possible water intrusion?

Yes... you can get water intrusion via exhaust plates, but that will usually manifest as a wash off, de-oiled, destroyed, piston. Lower crank seal is more suspect. But if you just had it apart I TRUST you replaced the lower endcap seals - right???

Replace the hose with a clear one and watch it for a while.

-W

 

[Chris1956]

Re: Merc inline 6 - possible water intrusion?

Clams, I had the motor apart twice last year. Once to replace the lower crank seals and once to inspect the baffle and inner exhaust cover. The last couple of days I am getting a more consistant firing of #6 cylinder. It is not 100% though, and I am still searching for the reason. When I run at 3500RPM, within a few seconds, I hear #6 start to fire. When I go to WOT, it is hard to tell if it is firing all the time or sometimes, due to wind noise. I have checked the fuel pump, rebuilt it last year, seems OK. I have also checked the fuel inlet on #3 carb, seems OK.

I think I am down to removing the carb to check for any blockage, loose main jet...

Thanks for the assistance.

 

[Laddies]

Re: Merc inline 6 - possible water intrusion?

Chris, I have not really followed your thead but I think I would be checking for loss of spark with a induction type meter at speed. I have seen switch boxes that worked fine at idle miss at higher speeds, even a coil os ciol wire can give you fits if it only acts up at running speed

 

[Chris1956]

Re: Merc inline 6 - possible water intrusion?

Laddies, If I understand what you are implying, it is that a miss can occur at higher speeds. I presume that this miss would be on all cylinders since the motor is distributor type, with a single switchbox. When I look at the plugs, all but #6 have that burn(carbon) mark across the gapless plug insulator. I assume that means they are firing. The number six plug is usually quite clean, hence my search for water intrusion. Since the plugs are fairly new, I also assume the cleaness of the #6 plug could be due to unburned fuel, washing the plug.

 

[Laddies]

Re: Merc inline 6 - possible water intrusion?

I thought the engine was a 84, sorry for the bad info. I still wonder about spark, a bad wire, plug or even a cap or rotor. I sounds like lack of ignition you have covered most of the other bases. If it were at idle it could be a reed but after 1500 they are wide open all the time so it's not that. a restrictor effects idle not mid range up. You have replaced seals and exhaust plate gaskets , a carb would effect 5&6 so that gets you back to compression that don't come and go or spark which can. Good Luck, its hard at times to not loose ones mind working on these things, try to take your time and reason it out--Bob

 

[Clams Canino]

Re: Merc inline 6 - possible water intrusion?

Also.... if the bottom carb is overflowing at all... it could flood foul the #6 plug and not #5 (think gravity). But for giggles replace the #6 plug wire and plug 1st. Also make sure the inside of the dist. cap is clean.

Water intrusion will usually destroy a piston before it kills the running of the cylinder. Also because of the steam effect at the exhaust #6 is often cleaner than the rest of them.

-W