manifold question

[spartanpele]

1994 Four Winns; 3.0L GS, OMC/Volvo<br /><br />Since I'm in the process of having my manifold replaced, I have a simple question.<br /><br />How does water get into the oil if theres a crack in the manifold? Are there oil passageways in the manifold? Does the water get mixed with the intake mixture and then leak past the pistons? <br /><br />I'm just trying to think of the scenario where the oil and water could come together.

 

[TilliamWe]

Re: manifold question

The water that "jackets" the exhaust manifold leaks into the exhaust part of the manifold through the crack(s). It then enters the cylinders through open exhaust valves, when you shut the engine off. Once in the cylinder, it leaks down past the rings and into the crankcase.

 

[spartanpele]

Re: manifold question

Thanks, Till...<br /><br />If its a small leak, would it be a subtle change in oil color (water mixing with oil) over time? <br /><br />And if its a major leak, wouldn't it lead to hydro lock? <br /><br />I would think water would be present when taking out the plugs if checked immediately after running, correct? But if you checked hours/days later, would the water be gone, already leaked down to the pan?

 

[KaGee]

Re: manifold question

The smallest of leaks will cause a frothy foam to develope. Another sign is one or more of the spark plugs will look clean... sometimes shiny. Water droplets are normally visible. If the engine has set a few days the plug may be rusty.<br /><br />A major leak can cause a hydrolock. Your engine will usually run crappy first. A hydrolock can damage internal engine parts, starters and flywheels, so that is a scenario you want to avoid.<br /><br />An extreme amount of water in the oil pan might indicate more serious internal engine problems like a cracked head, cracked block or bad head gasket.