Mercruiser 4.3 water on starboard spark plugs

[Malibu-m1700]

I'm having a issue with my 2000 4.3l mercruiser, it has 50 hours on the engine & 150 hours total on the boat. The engine block was replaced after it had froze. I bought the boat off a buddy he couldn't remember what was all replaced but it was a $5800 repair. The boat was used for 2 years after being repaired (with no issues). The boat was not being used & I purchased it. The unit ran good the first couple times out, it then lost a bit of power, I found the exhaust flappers had come apart, I replaced them & made a few more trips. I did notice after a long high speed/rpm run that the buzer would go off, if I pulled the throttle back about 1/8-1/4 throttle the buzzer went away. Oil pressure, rpm were good but the temp was a touch high & the starboard manifold (it has the 1piece manifolds) was hotter than the port one. While winterising I noticed water on all the starboard spark plugs, while running on the flush hose the water out the starboard exhaust was aerated. I checked compression (all good on both sides), I did a leak down test (5-8% on all cylinders) the only bit of leakage seemed to be coming out the crankcase breather. I removed the manifold & ran water through the cooling inlet, no water came out the the exhaust port side of the manifold only out the bull horn side. Any tips or advice would be great. I was thinking head gasket, or possibly cracked head but I think that should of showed up in the leak test?

 

[Bt Doctur]

manifolds are bad, replace them with the 2 piece setup

 

[Malibu-m1700]

That's what I was leaning towards initially but wouldn't i see water coming out of the engine side of the manifold when I put water through the cooling port? Is there a better way to test them, they are sitting on the bench in my garage as we speak? With the engine running wouldn't the exhaust pressure push the water back the other way instead of allowing it to run into the engine?

 

[Malibu-m1700]

I don't know if it matters but the boat has never seen salt water.

 

[Bt Doctur]

The one piece bat wings were a designers wet dream. There not even made as replacements

 

[Bondo]

The one piece bat wings were a designers wet dream. There not even made as replacements

Ayuh,.... I couldn't agree more,... I've seen 'em Destroy a few 4.3l motors,...

You could try pressurizin' the block with air to test for head cracks maybe,....

Either way, whatever turns out, get Rid of the batwings,....

 

[Malibu-m1700]

K I will look at replacing, are there lots of issues with these manifolds even in fresh water? Are there replacement options or conversion kits for these manifolds? Where is the best place to find a replacement set for a fair price? Could this manifold cause the aerated water out the exhaust as well as the high temp buzzer once in a while?

 

[Watermann]

If it's been ran for 2 or 3 years since the water pump in the lower was replaced I would start there when it comes to over heating.