454 Mag Tracking Down Water in Starboard Cylinders Only
03-04-2021, 11:44 PM
#1
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454 Mag Tracking Down Water in Starboard Cylinders Only
I have a 454 Mag EFI. Low hours. After medium run I anchored and shut off motor. Felt a big of lag at 4400 RPM so didn't push. Wouldn't start again. Got towed back and found water in Starboard cylinders. Dried out and added oil and then ran again just fine until a 30 minute run and then again same thing but just a little bit of water.
1) Replaced impeller - starboard riser 40 degrees hotter than Port but within spec for Mercruiser. Been that way for a while but started getting worse.
2) Replaced all 8 plugs as they were black. Wires and distributor newer. Oiled cylinders.
2) Checked oil (fine not milky) and did oil and filter change (it was time anyway (30 hours) and will send to Blackstone)
3) Pulled starboard riser and manifold and flaps looked good per marine mechanic.
Motor runs fine on hose in all RPMs. Haven't done water test. Not excited about taking it out again and getting towed again so working on in depth diagnosis. Boat is run in brackish water but spent early life in Salt water.
What other sources of water intrusion are there into cylinders but only on Starboard side? Heads or Valves? Trying to track down where its coming from. Started with simple stupid.
1) Replaced impeller - starboard riser 40 degrees hotter than Port but within spec for Mercruiser. Been that way for a while but started getting worse.
2) Replaced all 8 plugs as they were black. Wires and distributor newer. Oiled cylinders.
2) Checked oil (fine not milky) and did oil and filter change (it was time anyway (30 hours) and will send to Blackstone)
3) Pulled starboard riser and manifold and flaps looked good per marine mechanic.
Motor runs fine on hose in all RPMs. Haven't done water test. Not excited about taking it out again and getting towed again so working on in depth diagnosis. Boat is run in brackish water but spent early life in Salt water.
What other sources of water intrusion are there into cylinders but only on Starboard side? Heads or Valves? Trying to track down where its coming from. Started with simple stupid.
Last edited by Lafuerza; 03-04-2021 at 11:55 PM.
03-05-2021, 04:54 AM
#2
I have a 454 Mag EFI. Low hours. After medium run I anchored and shut off motor. Felt a big of lag at 4400 RPM so didn't push. Wouldn't start again. Got towed back and found water in Starboard cylinders. Dried out and added oil and then ran again just fine until a 30 minute run and then again same thing but just a little bit of water.
1) Replaced impeller - starboard riser 40 degrees hotter than Port but within spec for Mercruiser. Been that way for a while but started getting worse.
2) Replaced all 8 plugs as they were black. Wires and distributor newer. Oiled cylinders.
2) Checked oil (fine not milky) and did oil and filter change (it was time anyway (30 hours) and will send to Blackstone)
3) Pulled starboard riser and manifold and flaps looked good per marine mechanic.
Motor runs fine on hose in all RPMs. Haven't done water test. Not excited about taking it out again and getting towed again so working on in depth diagnosis. Boat is run in brackish water but spent early life in Salt water.
What other sources of water intrusion are there into cylinders but only on Starboard side? Heads or Valves? Trying to track down where its coming from. Started with simple stupid.
1) Replaced impeller - starboard riser 40 degrees hotter than Port but within spec for Mercruiser. Been that way for a while but started getting worse.
2) Replaced all 8 plugs as they were black. Wires and distributor newer. Oiled cylinders.
2) Checked oil (fine not milky) and did oil and filter change (it was time anyway (30 hours) and will send to Blackstone)
3) Pulled starboard riser and manifold and flaps looked good per marine mechanic.
Motor runs fine on hose in all RPMs. Haven't done water test. Not excited about taking it out again and getting towed again so working on in depth diagnosis. Boat is run in brackish water but spent early life in Salt water.
What other sources of water intrusion are there into cylinders but only on Starboard side? Heads or Valves? Trying to track down where its coming from. Started with simple stupid.
I suspect risers. the risers if pin holes exist it can do this. Did you look into the manifold when problem occurs, by removing riser and see puddles in the manifold floor? if so that would eliminate the intake or head gaskets as the culprit, Do a compression test? valve problems can cause reversion. On another note, what year? if its a 1998/99 ish there where intake gasket problems....this usually causes water in oil as Ive seen on these years though, but bad int gask. could put water in cyls....
