OMC Ford 2.3 Exhaust Problems? Wet Exhaust?

[papayadialog]

From the begining:

I bought an 89 Bayliner with a "blown engine". 2.3L Ford Inboard and OMC Cobra Outboard. Popper the valve cover off and one of cylinder 3 rockers was off and just lying around. I put it back in place and it fired right up. Awesome. Ran it on earmuffs and it ran for a while (minutes) at around 2000 RPM and stalled. It also stalled at lower RPMs where you'd want the idle. I put it in the water to see how it acted and once off the trailer it simply wouldn't fire up. Wanted to, had spark and fuel but wouldn't fire up. Eventually it stopped wanting to turn over even though the battery was fine. Put the boat on the trailer and pulled it just out of the water and it fired up in a matter of seconds. Backed it into the water and it stalls. Eventually it blew the overpressure cap off the water pump.

Get it back to the shop and pull the exhaust expecting backpressure to be causing the slow turning over and pressure build up and the water passages were swamped with rust and barely flowing. I get it all cleaned out and notice that the #4 exhaust valve has a little surface rust, #3 a little less and #2 and #1 clean. Did plugs and wires next. Took exhaust apart back to the prop and made sure nothing was stuck in there. I guessed water was jumping across the riser/manifold joint and into the cylinders starting from the back to the front. I ended up machining the surface as flat as I could, putting a bunch of exhaust RTV on the surfaces and then putting it back together. Fired right up and also ran in the water! Got it back to the shop to button some stuff up, put it on earmuffs to warm it up and boom stalled. Back to the beginning. Won't turn over, one rev every few seconds. After 30 minutes sitting it fires right up. This sounds a lot like trying to compress an incompressible fluid in the cylinder.

So here is the question:
What are my options? Does it soud like this thing needs head work? Is water just leaking and it needs exhaust? This engine wasn't very popular so there aren't a lot of options for buying a new manifold and riser. Can I pull the thermostat housing, make a flange that matches the back and run the water out of it's own tube out the back to separate the exhaust and the water? I'm not really seeing why they need to be in the same double walled cast iron tube. Can a real machine shop weld the flanges and machine them perfectly and will this solve the problem? There seems to be meat between the actual manifold walls but the flanges are a bit janky.

Thanks for any help. Sorry for all the words.

 

[Scott Danforth]

Welcome aboard

if you get a chance, fill out your profile a bit. helps us to know a bit about you

acetone test the manifold. could be cracked.

did you have a proper gasket between the manifold and the elbow? you mention the flanges are iffy, post a few more times and you can upload pics. do the surfaces clean up enough with a large flat file and a belt sander?

manifolds are a wear item that gets replaced every 5-10 years in salt water. usually not in fresh. the fact that the passages were full of rust flakes makes me think these have seen salt water and are at the end of their life needing replacement

exhaust needs to be water cooled to not start the boat on fire. the rubber exhaust hoses have a max temperature of 250 degrees. so the 1100 degree exhaust needs to mix with water prior or it literally burns the rubber hose off the motor

kenny nunez any additional thoughts?

 

[Keyboardman]

I would suspect the exhaust manifold is shot. Acetone test it to be sure, but sounds like it could be leaking back and hydro locking up a cyl. I just swapped an automotive 2.3 over to marine use and was able to find a new aftermarket manifold but it was $600. Also found a good freshwater used riser for $150. Used manifolds are out there but still pricey. I wouldn't trust one with a new engine. I have two used ones laying around that were junk.

 

[Bondo]

I bought an 89 Bayliner with a "blown engine". 2.3L Ford Inboard and OMC Cobra Outboard.

Ayuh,...... Welcome Aboard,.... Donno what to say, other than, Ya got exactly what ya paid for,......