Merc 170 Possible cracked Ext. Manifold

[jake1z]

Oil is milky, zero coolant missing.. I read some where that the manifolds are prone to corosion which can cause the salt water to get back into the block. boat ran great while driving, i slowed down and it died and would not restart. possible hydrolock? can i take the exhaust manifold off while the boat is in the water or will water run back into the boat?

 

[TiredoleBoy]

Re: Merc 170 Possible cracked Ext. Manifold

Oil is milky, zero coolant missing.. I read some where that the manifolds are prone to corosion which can cause the salt water to get back into the block. boat ran great while driving, i slowed down and it died and would not restart. possible hydrolock? can i take the exhaust manifold off while the boat is in the water or will water run back into the boat?

This just happened to me today. I just got it out of the shop for a check up. They claimed nothing wrong with it. Went roughly 1 mile when it happened. Had to get towed back in to the dock by a few nice bass boaters. But I would like to know as well. But mine is the bilge has a few gallons of water in it as well.

 

[TiredoleBoy]

Re: Merc 170 Possible cracked Ext. Manifold

Ok so I found I had a leaking bellows for the shift cable. But still hav no clue why water is in the oil. I found out this motor has a sealed coolant system and the river water only circulates through the stern drive and back through a pipe at the exhaust and then back out into the river. So this one is confusing.
Now the only other thing it could is rain.Rain running into the flame arrestor on the carb.

 

[solar7647]

Re: Merc 170 Possible cracked Ext. Manifold

If the issue is the manifold you will have water in your cylinders and head.

The only way you can be sure that no coolant is missing is to drain the entire system and see how much you get. The system should hold 11qts.

There are many places for antifreeze to mix with the oil but only a few for water. You will need to go through the system to find the issue.

You can remove the manifold in the water but i would recommend that you pull the boat from the water. The work will cause fluids to drain from the engine and you dont want to get them into the water.

 

[jake1z]

Re: Merc 170 Possible cracked Ext. Manifold

i put the boat on craigslist... i really dont want to deal with it. the ext manifold is like 700 bucks - rediculous. everthing was fine... i had the ext bellows off to change the heat exchanger gaskets could i have messed some thing up there?

 

[TiredoleBoy]

Re: Merc 170 Possible cracked Ext. Manifold

i put the boat on craigslist... i really dont want to deal with it. the ext manifold is like 700 bucks - rediculous. everthing was fine... i had the ext bellows off to change the heat exchanger gaskets could i have messed some thing up there?

Yep. Sometimes these leaks are hard to find. I had to really seek mine out. I actually used a flashlight and a mirror. Once I though I saw a crack I used a hose at low pressure at the area.Sure enough water was running in as a spray.
But off to my issue at hand. I strongly feel the water was spurting into the bellows and since the compartment was closed it sucked water into the carb. Oddly enough with high RPM carbs will operate with water injected into them. This is how we used to clean valves. So now to figure out how to change this damn oil!