water on spark plugs

[tfret]

1984 5.7L Mercruiser. I have no.5 and no.7 plugs with water on them when I pull them right after running the engine on the muffs. I pulled the risers and manifolds in the Spring. I replaced the risers as they were badly rusted. The manifolds looked good and I leak tested them over night with isopropanol and found no leaks. Does this mean I likely have a bad head gasket?

 

[joewithaboat]

Re: water on spark plugs

maybe,
next step... compression test and/or a leakdown test?
Are you confident the gaskets sealed well on the manifolds?
A mercruiser mech will be along shortly, they will know best based on most common thing to fail.

 

[tpenfield]

Re: water on spark plugs

Yes, do a leak test of the cylinders. Check the oil for water as well

 

[tfret]

Re: water on spark plugs

Could be the riser gasket gasket I guess, I'll check for tightness. No sign of water in the oil. I just had the valve cover off on that side and didn't see any sign of water there either. A compression test is a good idea.

 

[bruceb58]

Re: water on spark plugs

You replaced with a new riser gasket right? Were the mating surfaces perfectly flat and clean including no paint?

 

[Don S]

Re: water on spark plugs

Look at your manifolds and make sure the gasket surface is in good shape. Normally when the risers go, the manifolds are done too. The manifold itself seldom leaks, it's the gasket surface that fails and causes water in the cylinders.

 

[muc]

Re: water on spark plugs

Could be the riser gasket gasket I guess, I'll check for tightness. No sign of water in the oil. I just had the valve cover off on that side and didn't see any sign of water there either. A compression test is a good idea.

Leakdown test would be better.