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    Rusted clogged cooling lines in the block 5.7 merc alpha 1 gen 2

    Take the hoses off and flush with water. Take the manifolds and risers off and flush them too. If they have a lot of scale and buildup you can soak them in a bucket of CLR or vinegar for a couple days. Flush the engine with water or radiator flush. Inspect the manifolds and risers for corrosion...
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    5.7 omc stalling while shifting

    There are some variations but the idle mixture screws should be in about the same place. They may be hex head as well
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    New rebuilt OMC 3.0l Overcooling no matter what!

    I don't think the thermostat is the problem, since you verified it opens at 175. Are your hoses routed properly? Is the thermostat housing in good shape? There is a controlled amount of water that always flows to the manifold until the thermostat opens. If the flow is too much, the manifold and...
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    OMC 3.0L missfire/ fuel starvation!?

    Well, you're not giving us much info about the powerplant other than it's an OMC 3.0. Engine serial number would be great but year is a good start. Go through the ignition and fuel systems. Put some seafoam or other cleaner in the fuel and see if it helps
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    5.7 omc stalling while shifting

    Set it at 600 and see what happens.
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    Mercruiser 5.7 won’t make power

    17 mph at 2600rpm with a 19p prop and a 1.94 gear ratio (from the 3.0) is 30% slip 17 mph at 2600rpm with a 15p prop and a 1.94 gear ratio is 11% slip. I'm assuming the 30% slip is due to not planing out and not due to a bad prop.
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    1980/90 mercruiser 3.0 140 hp /water in oil/ explosion sound💥

    At the very least you have a bent and stuck valve. You likely had a piston hit that valve and damage the piston. Pull the head and look.
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    Mercruiser 5.7 won’t make power

    Advancing a cam can improve low end torque and retarding can help top end. Some cams have advance built in to the grind. Setting it straight up is generally recommended.
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    Mercruiser 5.7 won’t make power

    I was going to suggest a different prop too, but I see you've tried that. Check the total timing advance and check your tach to see if it's accurate. Did you get a gps speed on any of your outings and compare them
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    5.7 omc stalling while shifting

    500-600rpm in gear (in the water) idle mixture screw should be 3-3/4 turns out
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    Alpha one gen 1

    When the prop turned while the drive was in gear, did the prop drive shaft turn? Or did the prop spin on the hub? If the prop spun but the shaft didn't, you need a new prop or the prop hub repaired. If the shaft turned, either the drive wasn't in gear or is damaged. Make sure the shifter is...
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    Mercruiser 5.7 won’t make power

    Have you measured the timing advance? I would say 32 degrees total advance at 3000rpm. Could be lean. Do you see an even spray of fuel from the boosters? What is the rated flow of the fuel pump? 30gph minimum 40 is better. Can you pump fuel into a bucket and make sure it's flowing well and...
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    Alpha one gen 1

    I don't understand what you are describing. Did you turn the propeller with the drive in gear? If so, the rubbery sound could be the propeller hub breaking loose and spinning, which means your prop is now damaged. The prop nut should be removed before trying to remove the propeller. It sounds...
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    Weak spark

    You said previously that it had 42 psi fuel pressure. Was this not at the fuel rail?
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    5.7 omc stalling while shifting

    Not to sound condescending, but like I said, check your tach, ignition, fuel systems. If it is idling lower than your tach says, it can cause this problem. You can download a free strobe tach for a smartphone. Paint a white mark on the crankshaft pulley and use your phone to determine the rpm at...
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    New rebuilt OMC 3.0l Overcooling no matter what!

    Is this happening on muffs or in the water? Running on muffs can take a while to get up to temp because there is no load on the engine and some cool water always flowing into the engine.
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    Clicking Noise

    Does it only do it when running? Have someone else listen or drive while you listen to pinpoint it
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    5.7 omc stalling while shifting

    I fought similar issues until I determined my tach was not accurate. By ear it sounded right but it wasn't. Once I set the idle speed properly and calibrated the tach, all was well.
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    5.7 omc stalling while shifting

    The esa shouldn't engage when going into gear, only when coming out. Verify your idle rpm with an accurate tach and check for any vacuum leaks by spraying carb cleaner around the carb base and intake. If engine increases rpm you have a vacuum leak. Check ignition timing and set to spec. Verify...
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    Frost Plugs

    Perhaps I've been mistaken about the stainless but none of the exhaust studs I've seen from marine engines dating from 1969 to 1980s to today have been rusted so I assumed they were stainless. Grade 8 possibly (grade 8.8 denotes metric and is equivalent to grade 5 sae)
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