Starboard engine is toast

[Gag_Halfront]

Well, 3297 is my first boat. I bought it in May knowing that it needed fuel tanks but not knowing much else about it. It had sat in a yard for several years on the hard. After struggling with a bad cooling pump on the port engine, then a bad port fuel pump that failed and pumped 4 gallons of fuel into the block via the weep tube on the fuel pump (kinda a long story) then working through all the gear like a bad nav light, bad horn, rebuilding the head pump, exhaust manifolds, risers and elbows on the starboard engine, replacing the chart plotter and radio, and more, we finally got to take the boat out.

We got about 30 total miles and our season ended. The starboard engine is Tango Uniform. I can’t say exactly what order the failures happened, but we were WOT crossing the river headed for the reef to do some fishing when we started to suspect a problem. After a few minutes we noticed the temp gauge on the starboard engine was pegged. We shut it down and limped out to the reef on one engine and dropped anchor so we could at least fish until tow boat got there.

Once we were back in our slip, I tried to start the starboard engine and it was cranking really slowly. The first thing I found when I opened the engine room hatch is that the brand new alternator/water pump belt had jumped off and was ruined. I started pulling spark plugs and when I pulled the #5 plug, about a pint of water poured out. The first thing I did was put my air compressor on #5 to do a leak-down test. It held 100# of air no problem with no obvious leaks. Compression tests showed 160,120,120,160 on the even side of the engine. I put the compression guage on #5 and got 0#. When I took it back off, more water poured out.

The boat is raw water cooled. I shut off the raw water to the engine and disconnected the hose to the exhaust manifold, cranked it a few times and water blasted out of the odd side of the engine all over my fuel tank. It looked like it was from #3 and #5. Upon closer inspection, several spark plugs looked like they might have evidence of water. My theory at the time was that when the engine overheated, the head cracked or warped letting water into the cylinder. Hydraulic lock might have broken a rod and with the piston not moving I got 0# but water still leaking in. The borescope showed pistons and valves moving like they should which blew that theory. Time to pull the thing apart.

When I pulled the exhaust I found evidence of water in all the exhaust runners on that side. Time to pull the head. When I pulled the head the gasket looked good. I found lots of water in all 4 cylinders and the #3 exhaust valve has a bite taken out of it. I’ve seen lots of valves fail over the years, but never quite like this.

I’m still not sure exactly what all failed. The obvious common links between the 4 cylinders are head gasket, intake and exhaust. If it was the intake, the way the split-plane manifold works, I would have expected two cylinders on each side to have water, not all 4 on one side. The water in the engine in the pictures is from after turning the raw water off, cranking it a bit and then sitting a couple days so it almost certainly rules out the (brand new) exhaust manifold as the culprit. Anyway, the upshot is, my engine is toast. Time to build a pair of new engines and hope for a full season next year.

PS. Before anyone mentions the single host clamp on the fuel line, all the OEM fuel lines are threaded fittings. The barbed fitting was for the test run. A whole set of new lines with proper threaded fittings will be part of the new setup.

[Viper]

Ouch, sorry to see that.

[bud37]

Too bad there, did you drain the water from the block before pulling the head ? Anyway good idea to pull and do it right, as it looks like it has been wet for a while, the other side seems to show moisture in the intake runner for what looks like #8.

I would make doubly sure you check the new exhaust stuff for the right parts before putting them on a new build. My guess here is it had sat for too long and just gave up, that valve could have been stuck and the first start up from sitting stressed it. , one thing I always enjoyed was building engines.....good luck with yours.

[tomschauer]

You mention its raw water cooled. If its not a cracked head or block due to freeze, its good chance the manifold was leaking water into the cylinders. Especially in a salt water application. They don't last very long in salt.

[Gag_Halfront]

I really do agree that the manifold or riser could be the culprit on the water issue. The broken exhaust valve could be a coincidence. The exhaust on that engine was brand new, but “new” doesn’t always equal “good”. I’m thinking I should make some block-off plates and pressure test the exhaust before I install it on a new engine.

I didn’t drain the block because I had seen evidence of water all across the odd side of the engine so it seemed like being super worried about some leaking in when I pulled the head bolts was a lost cause. The pictures were taken as soon as the head came off, so clearly that water had been there a while. Maybe a little of it was from the water jackets in the head.

Apart from pressure testing the exhaust I’d love to hear if there were any troubleshooting steps you all might have done that I missed ( for future reference)

[mjk1040]

I have a set of used 1986 long blocks if your interested. Starboard has a bad #1 rod bearing.