Rusty Spark Plug (X2)

[foresteronw]

I have a 1989 Sunbird Eurosport with a OMC 5/7L. I recently was going throught the ignition system to figure out a higher rpm problem and came across two spark plugs with rust on them. At the end of the season I had water under my valve covers but nothing in the oil pan. The engine ran fine, except for the higher RPM sputtering, but that has been figured out. In the past two years the boat has been ran less than twenty hours. I have heard everything from moisture in the engine from sitting and to just keep running it. All the way to a cracked head. Anyone know what it could be???????PLEASE HELP???

 

[ob]

Re: Rusty Spark Plug (X2)

Were the two plugs that had the rust on adjacent cylinders?If so,possibly head gasket.If not, maybe condensate through intake valves.

 

[foresteronw]

Re: Rusty Spark Plug (X2)

no they weren't. when looking at the engine it was the one on the right side in the back and on the left side it was two back.

 

[ob]

Re: Rusty Spark Plug (X2)

I'm guessing that those two intake valves were open fully and what your seeing is condensate.Has motor sat idle for a spell during weather change?

 

[foresteronw]

Re: Rusty Spark Plug (X2)

yes it did. i just bought the boat at the end of the summer and the guy i got it from had it for almost two years and didn't use it more than 10 hours. he said it sat a lot. He also had the heads re done before I bought it.

 

[ob]

Re: Rusty Spark Plug (X2)

Heads being redone adds a new twist to the equation.Hoping they were seated and torqued in proper sequence and to proper torque.Wouldn't hurt to retorque heads and test run engine ,then reinspect.

 

[foresteronw]

Re: Rusty Spark Plug (X2)

ok. sounds easy enough. Let me ask you this though. Say all that checks good, were should I go from there. That there is nothing else wrong. How can I tell If I have a cracked head? Or there is a problem with the riser/manifolds. Could this actually be a blown head gasket. (Thru hull exhaust "steams" a little.) Oh yeah thanks for all the help so far. Oh and one more thing, why the water only be under the valve covers and not in the oil pan?

 

[ob]

Re: Rusty Spark Plug (X2)

Without removing and installing new head gaskets the only way you'll be able to verify whether water intrussion is a factor is to clean plugs after retorque and test run.In order for water to get into crankcase you would indeed have to have a cracked block or enough intrusion into cylinders to get by the piston rings.Without physically seeing I'm only imagining how much water we are taliking about.If it was a head gasket leak during operation that was entering cylinders,after test run plugs on those cylinders would either wet foul or appear clean as new from atomization.Since you say you don't have presence of water in crankcase and water would surely sink to it if you had a substantial leak I'm still guessing condensate pending the outcome of run test. Valve covers are more open to atmosphere than the crankcase for condensation ,however I'm betting that the crankcase as well has some condensation just from setting idle.As engines cool,even from ambient temps outside air,and its moisture content, is drawn in to intake and crankcase vent passages.That coupled with the aboard boat application of the engine makes it a candidate for laden moisture if not run regularly.

 

[foresteronw]

Re: Rusty Spark Plug (X2)

Thanks a lot for all the info. I really appreciate it. I will take your advice and retorque the heads and most likely through new plugs in it anyway. Hopefully it works. I don't know if this had anything to do with it, but I know that the engine runs very cool. And obvisouly i should change the oil a couple of times huh.

 

[ob]

Re: Rusty Spark Plug (X2)

I too hope it is just a condensate issue.Post back after you have some time to service it and run test.Good Luck