Why water can intrude through crankshaft lower seal of 77 mercury 1150?

[tavacska]

Hey guys,

My #6 spark plug still has a little grey fluid, no as dark as other spark plugs. I checked the history of forum, some said it's normal, some said it's water milky.

I installed the new exhaust plate, water jack cover, with every new gaskets and silicone black. But the #6 still a little grey color. How can I check if water intrudes inside the chamber?

I did replace the crankshaft lower seals (2 of them) and the O ring seal. There does have a groove on the lower seal contact position.

I am now considering to repair that grove with the repair kit, (forgot the name, "speed-??")
But how can water intrude from below? It's all sealed around by the gasket and silicone. There should be no water around the seal position.

Please see the picture. All the red lines are sealed. This is not the picture from my motor.

 

[racerone]

First tell us what you think the bottom oil seals do on the crankshaft !

 

[jimmbo]

A little lesson on 2 stroke theory would be needed to understand what the seals do


It's called a speedi-sleeve

 

[Chris1956]

Water will usually show as small droplets on the spark plug. The crankshaft seals keep crankcase compression in and water out.

A lot of times there is room for 3 seals in the endcap. That changes the position of the seals, usually bypassing the groove in the crankshaft.

 

[tavacska]

I did a lot research on this seal. I know it's to seal air and water out. I am just trying to figure out where the water come through to the chamber, from crankshaft or from exhaust cover leak, or from a corroded power head?

For right now, it only idle runs with water muff, not sitting on water. So I believe no water come gathering around the oil seal. So there should be very little chance that water come through the oil seal to the cylinder.
I need help to confirm the assumptions to figure out where the water is coming from.

But if Chris says there is often some water drops on spark plugs, there is a release in my mind. But the water drops come from the gas tank or where? Anyway, I ordered a endoscope and will have a deep check this weekend.

 

[racerone]

When an outboard is running the cooling water is dumped into the exhaust to cool it.----So there is a lot of moisture in the exhaust !!-----That lower seal is exposed to that exhaust.-----But if the seals are new and properly installed the leak is elsewhere.

 

[Chris1956]

On the picture you posted, the top compartment is filled with pressurized cooling water, from the waterpump. If the gasket between it and the crankshaft leaks a bit, water will be pressurized against the crankshaft seals, possibly leading to leakage.

 

[Faztbullet]

The bearing housing/seal area is not pressurized by water...The reason water enters lower cylinder is usually due to hardened crankseals or pinhole eroded in bearing housing. Water climbs the driveshaft at at low RPM and is sucked(crankcase vacuum) thru the bad seals into lower cylinder. 90% of the time it will not show on muffs but submerged in lake/barrel. If your getting water in cylinder on muffs its possible it has cracks between alum block and sleeve on exhaust port. Also be sure its water, install new plug and runs for min of 15 minutes and remove. Inspect reside for water droplets and let air dry. If water is present it will cause a light rust to form around electrode.

 

[tavacska]

Thanks guys, you are awesome.

I did the crankshaft seal twice before. First push a new oil seal in with the old 2 seals. The second time with 2 brand new seals only, but didn't deal with the grooves.

I did the exhaust very very carefully. 3 Times repeat doing that, and finally using a almost new exhaust and water covers.

All these done and there is still water-like color on the 6# spark plug. I am afraid I have to replace the power head if it's the corrosion leak because it does have a lot corrosion. It drives me mad.

I will redo the test this Sunday, running on water muff for half hour. And I will show the pictures. Thanks.

These are old pictures. Exhaust Cover and Water Cover already replaced. The spark plugs picture is from half year before. The #6 shows water intrusion?

 

[racerone]

You are referring to the rust on the outside of the sparkplug ??-----If yes that maybe the water jacket cover is leaking around the sparkplug area.

 

[tavacska]

Today, I run the motor with water muff for 30 minutes.

Here are the pictures before the run. The 6 cylinders all have corrosion after the 2-3 months sitting. The #6 looks better because the piston reaches the top.

 

[tavacska]

After the 30 minutes running. The 4-6 turns to lighter than the 1-3.

 

[tavacska]

The #6 piston seems to be black, not water flushed. Maybe the clear/whity is just the lean fuel?

Anyway, it seems to run and idles good. Just one problem is it cold starts very hard. Maybe because the lower seal is not good enough. It started very well before when it has three oil seals and now I replaced them with two brand new seals.

I will run it on the water next week.

 

[racerone]

But I believe only the top 2 carburetors have choke flappers on them so # 6 and the bottom seals do little until the motor starts !

 

[tavacska]

But I believe only the top 2 carburetors have choke flappers on them so # 6 and the bottom seals do little until the motor starts !

Thank you for pointing out.

 

[tavacska]

Anyone knows what size or part number of the speedi sleeve is for the 1977 mercury 1150 crankshaft?

 

[tavacska]

Updates:

Ok, it turns out to be water in cylinder or exhaust.
The power head is pulled out today.
Messy grey milky in exhaust. But it seems to be around 3-6 cylinder looking inside.
No idea where the water is coming from.
Any suggestions?

 

[tavacska]

Updates:

It's not leaking. There's no water intrusion. It's just oil and non burned gas causing it milky.
I pulled out the power head, hanging it upside down, pouring water in water jack, it holds one night, with no water leaking.
I poured oil on lower seal ring, no leaking with cranking.

It turns out to be the sync and link. The first pick up got 20 degree misaligned! What a mistake I made.
The water tank test is perfect now. Idle 850-900 neutral and 650-700 engaged. Will put out to lake for final mixture tuned.
The 6th spark plug turns out to be brown, no milky any more.


Thanks everyone for your precious suggestions.


Edit: I did some deep thinking about this. The timing belt is correct. The first pick up is set to be advance 20 degrees, the max advance is 21 deg. That means, when it idled, it idled at max advance, but with no throttle open. There's a lot gas not burned efficiently, which makes the exhaust milky.

 

[Chris1956]

Primary pickup timing should be 4-6* BTDC. If yours was set to 20* BTDC, I would expect the motor to idle real high, or maybe not idle at all.

Hopefully you are correct about the water jacket not leaking. Milky fuel is usually water.....

 

[tavacska]

After changing the lower crankshaft seal, lower powerhead gasket, and also replacing a defective check valve.
Here is the what looks like for the spark plugs after running 15 minutes.

Seems still milky oily on the sparks #5 and #6. #1-#4 all good.
The motor idles good, the check valve works good.

1. Can I confirm there is water leaking?
2. If motor runs good and can reach WOT rpm, what will be the bad results if I keep running it?
3. I did a good seal installation on baffle and water coverage. If there is still water leak, it could be the inner plate or the body. Could there be any other reason? I read a Johnson guy with milky oil fuel extract from bottom balance tube. It turns out to be the problem of carburetor.

Thanks.