Hello and thanks for any info for this ignorant but great mechanic-neighbor-having boater...
Engine Info (transom ID) A177296
Mercruiser v6 4.3l with TKS
Serial #: 1A335597
August 2008 4.3 TKS
Family 8M9XM 04.32VC
W.O.T - 4400-4800 (this is what the RPM should max out to).
Ignition Timing: 10 degrees Before Tap Dead Center
SHORT VERSION
Was having engine not starting / cutting out / power problems.
Having just replaced the distributor and rotor
-the motor seems to stay running, but seeing multiple issues around low RPM's and power, and a 'chuh chuh chuh' poor engine sound at low rpms when it's not running well; it occasionally gets up to about 4000 rpm WOT, but that's a good 6-800 low... We think this is definitely some bad spark plugs
-idle had been around 1100 before, should be closer to 650; with the new distributor, it's at least below 1000, seems to be more like 800
Current questions:
-what spark plugs are right for my 2008 V6 4.3l Mercruiser? (quite sure at least 1 or 2 are bad)
-what would cause engine to still be idling at ~800 instead of 650?
-Is an adjustment to timing necessary?
-engine says 'special ignition timing'; what timing adjustments need to be made after installing new distributor?
LONG VERSION / OTHER INFO
Boat history:
A couple years back, TKS system was failing (sticking maybe?) and was still putting fuel in even when warmed up; neighbor (long time mechanic) disabled that.
Over the past few years, have had a couple episodes of distributor problems causing sporadic engine start failures, even after already warmed up and running, etc. Diagnosed as condensation and moisture the first couple times.
Had sporadic engine start problems, spark plugs getting fouled, RPM / power issues.
Replaced a couple spark plugs here and there.
This year, just started again with similar issues; not starting, stumbling and stopping when in idle or between shifts, etc.
Found water and damage in the distributor again, points covered with rust, hairline crack in the distributor, etc.
One thing we realized is that after the engine lid cushion went bad, water was going right through a hole (by design, no idea what it's there for) through the engine compartment lid, and splashing all over the engine (rainwater collected by and passing through the cushion). That may have been the root cause for a lot of these issues, more than just condensation... Adding all that water directly and then also keeping that much moisture in the engine compartment...
We just replaced the distributor and rotor; the rotor wouldn't slip off, it was basically stuck on due to rust on the shaft... Had to pry the dang thing off! Then we had to sand down the shaft enough to be able to get the new rotor on!
Now it's starting fine, and not dropping out in idle or when shifting.
My own post from 2016 on earlier power problems that were spark plug related primarily, but also early distributor issues
https://forums.iboats.com/forum/eng...4-3l-alpha-2008-stalling-surging-rpm-oddities
June 2020
-replaced distributor cap & rotor (crankshaft had rusted, had to pry rotor cap off, sand it down to fit new one on)
-likely missing one or more cylinders
-idle seems to have dropped below 1k rpm (supposed to be 650), closer to 850/9
The tach: WOT (wide open throttle) should be 4600-4800rpm.
(I’m barely getting to 4000 in ‘good’ times…)
Engine Info (transom ID) A177296
Mercruiser v6 4.3l with TKS
Serial #: 1A335597
August 2008 4.3 TKS
Family 8M9XM 04.32VC
W.O.T - 4400-4800 (this is what the RPM should max out to).
Ignition Timing: 10 degrees Before Tap Dead Center
SHORT VERSION
Was having engine not starting / cutting out / power problems.
Having just replaced the distributor and rotor
-the motor seems to stay running, but seeing multiple issues around low RPM's and power, and a 'chuh chuh chuh' poor engine sound at low rpms when it's not running well; it occasionally gets up to about 4000 rpm WOT, but that's a good 6-800 low... We think this is definitely some bad spark plugs
-idle had been around 1100 before, should be closer to 650; with the new distributor, it's at least below 1000, seems to be more like 800
Current questions:
-what spark plugs are right for my 2008 V6 4.3l Mercruiser? (quite sure at least 1 or 2 are bad)
-what would cause engine to still be idling at ~800 instead of 650?
-Is an adjustment to timing necessary?
-engine says 'special ignition timing'; what timing adjustments need to be made after installing new distributor?
LONG VERSION / OTHER INFO
Boat history:
A couple years back, TKS system was failing (sticking maybe?) and was still putting fuel in even when warmed up; neighbor (long time mechanic) disabled that.
Over the past few years, have had a couple episodes of distributor problems causing sporadic engine start failures, even after already warmed up and running, etc. Diagnosed as condensation and moisture the first couple times.
Had sporadic engine start problems, spark plugs getting fouled, RPM / power issues.
Replaced a couple spark plugs here and there.
This year, just started again with similar issues; not starting, stumbling and stopping when in idle or between shifts, etc.
Found water and damage in the distributor again, points covered with rust, hairline crack in the distributor, etc.
One thing we realized is that after the engine lid cushion went bad, water was going right through a hole (by design, no idea what it's there for) through the engine compartment lid, and splashing all over the engine (rainwater collected by and passing through the cushion). That may have been the root cause for a lot of these issues, more than just condensation... Adding all that water directly and then also keeping that much moisture in the engine compartment...
We just replaced the distributor and rotor; the rotor wouldn't slip off, it was basically stuck on due to rust on the shaft... Had to pry the dang thing off! Then we had to sand down the shaft enough to be able to get the new rotor on!
Now it's starting fine, and not dropping out in idle or when shifting.
My own post from 2016 on earlier power problems that were spark plug related primarily, but also early distributor issues
https://forums.iboats.com/forum/eng...4-3l-alpha-2008-stalling-surging-rpm-oddities
June 2020
-replaced distributor cap & rotor (crankshaft had rusted, had to pry rotor cap off, sand it down to fit new one on)
-likely missing one or more cylinders
-idle seems to have dropped below 1k rpm (supposed to be 650), closer to 850/9
The tach: WOT (wide open throttle) should be 4600-4800rpm.
(I’m barely getting to 4000 in ‘good’ times…)
