spark plugs and water moisture

[sogud]

5.0 Liter Mercruiser Engine on a 2001 SeaRay Sundancer.
Automatically shut down due to overheating.
Would not fire up again.
Replaced mangled impellar, did a tune up with dist cap, rotor button, plugs.
Engine will now fire and start and run. But....after shut down, engine will not start back up.
A few spark plugs have moisture from water - not fuel.
From what I've read, there's a gasket that needs replaced.
Which gasket should I start with?

Thanks

 

[Bt Doctur]

Re: spark plugs and water moisture

Head gaskets for a start,

 

[sogud]

Re: spark plugs and water moisture

The problem happened right after getting fuel. What is the possibilty of water in the fuel causing the moisture...do you think I should replace the fuel filters before the head gasket? Thx

 

[littlebookworm]

Re: spark plugs and water moisture

BT Doctur said it all: blown head gasket. Probably caused by the engine overheating. Check the head for warpage - possible result of overheating and blown gasket. Hopefully you got all the water out of the cylinders right away so that you won't have a rust/salt problem. Change the oil and oil filter; they may have some water in them. If you have a closed cooling system, you may have to change the coolant because of contamination from engine oil. Good luck. Hy

 

[rbh]

Re: spark plugs and water moisture

Like the guys said it is most likely your head gasket, but you mentioned possible water in your fuel?
have you checked your water seperator/ fuel filter?

rob

 

[TowRoper]

Re: spark plugs and water moisture

personally i would start with changing the fuel filter and clearing out the f/w separator and even drain the carb and fuel lines and then a compression and leak down test b4 pulling the head if your sure its water on the plugs and not fuel, the reason i would do this is i got a 50/50 mix of fuel from a bad station one time and it had me convinced it was a head gasket but that was my experience i hope you got lucky and just got the bad fuel good luck

 

[Maclin]

Re: spark plugs and water moisture

While I agree the head gasket is one of the first things to go in an overheat please do not go after the head gasket yet, perform a compression test on the engine first, it will show a head gasket problem.

Also, if there is a head gasket problem it could be due to the head warping and the gasket blows out where it is not clamped good. In that case you need the head resurfaced AND a new gasket.


I have a couple of questions though on what exactly is going on when the engine will not restart.

Do you have water hooked up to the engine when trying to start? If so, when you say the engine does not start after it has been running, do you mean the starter motor turns the engine over but the engine does not fire up and run? Or do you mean the engine does not turn at all when trying to start?

If the engine does not turn over until you take the sparkplugs out then it may be ingesting water from the riser/exhaust manifold connection, there is a gasket there. Also either of those components could be failing internally and letting water get into the cylinders thru any open exhaust valve. There would be a LOT of water coming out of the spark plug hole if this was the case though.

 

[sogud]

Re: spark plugs and water moisture

I will definitely run the compression test. We had only been on the water for 15-20 minutes before the alarm sounded and it quit so I'm hoping there is nothing warped.

Yes, water is hooked up. the starter turns over but there is not enough fire to make the engine run....if the plugs are wet. The theory is that after the engine does start and runs for a bit - then shuts down - this is when the little bit of water is spewed onto the spark plugs - which will cause it to not fire up again, until the plugs have dried out.

I have another engine that is running A-OK so I would think if it was a water in the fuel issue, this would be happening on BOTH engines.

I think I'll start with the fuel filter f/w separator.
Then the compression test.

I'm new to these types of engines on a boat...and I'm a girl....and I don't wanna get ripped off....so I really appreciate all of your help!!!!

 

[Maclin]

Re: spark plugs and water moisture

Yes, water is hooked up. the starter turns over but there is not enough fire to make the engine run....if the plugs are wet. The theory is that after the engine does start and runs for a bit - then shuts down - this is when the little bit of water is spewed onto the spark plugs - which will cause it to not fire up again, until the plugs have dried out.

This could happen from a blown head gasket, but could also be from a cracked exhaust manifold or riser or the gasketed joint between them. The exhaust manifolds have two chambers, one for exhaust and the other for raw water that is exiting from the cooling system. This raw water gets mixed ito the exhaust flow at the riser. If there are any cracks in the manifold or riser or gasket problems on the manifold/riser then water can run back down the manifold and get in via open exhaust valve.

DO THE COMPRESSION TEST FIRST even before the fuel filter check.....if no head gasket leak is indicated then the next suspect is in the exhaust system.