Blackfin27
Contributing Member
Circa 2000 454 Marine Power Vortec 330 HP with 960 light hours.
Engine had run well this past Summer, then some vibration and was laggy, did not push the RPM due to the lag and vibration. Starts were hard and substantial cloud of what I call steam or white smoke that would dissipate after warming.
New plugs, cutlass bearing, PSS shaft seal, oil change, dist cap, raw water pump then went in Summer 2023 and improved, most vibration eliminated, ran WOT to 4800 RPM, short bursts. Was hoping these measures would take care of the major symptoms. But, she was eating coolant and you could smell it in the engine bay, but ran pretty smooth.
Next up, different mechanic ran compression test calling it a 'fail' at 120-130. Elected to tear off the Risers (done and overdue) , replacement was way overdue, manifolds off. Evidence of water intrusion...this a FWC engine. Mechanic said he was concerned about glazing on the cylinder walls, he mentioned possibly lagging due to improper propping, the prop is good and tuned so that's not it.
So, possible poor compression due to water intrusion? Could try a top end rebuild with new pistons/gaskets etc. Labor and parts and still could end up with low compression-
Got quoted a full rebuild price of around $8,000, plus add all the hang ons get replaced, more parts and labor....24 year old engine.
Because she ran strong after the above mentioned work and hit WOT, cant quit wrap my head around it....but. I don't have the time or skills to rebuild myself. Given the labor rates at the yards these days, going with the minimum rebuild and not honing/boring out the cylinder walls and not going all in could still end up with low compression?
Strongly considering a repower, Merc 6.2 320hp, FWC with new gears, engines are on back order. Not many options out there for small blocks V8.
I'm wondering what you mechanics think given the circumstances....give it up and repower, sell the 454w/ gears and move on with fresh power...?
Engine had run well this past Summer, then some vibration and was laggy, did not push the RPM due to the lag and vibration. Starts were hard and substantial cloud of what I call steam or white smoke that would dissipate after warming.
New plugs, cutlass bearing, PSS shaft seal, oil change, dist cap, raw water pump then went in Summer 2023 and improved, most vibration eliminated, ran WOT to 4800 RPM, short bursts. Was hoping these measures would take care of the major symptoms. But, she was eating coolant and you could smell it in the engine bay, but ran pretty smooth.
Next up, different mechanic ran compression test calling it a 'fail' at 120-130. Elected to tear off the Risers (done and overdue) , replacement was way overdue, manifolds off. Evidence of water intrusion...this a FWC engine. Mechanic said he was concerned about glazing on the cylinder walls, he mentioned possibly lagging due to improper propping, the prop is good and tuned so that's not it.
So, possible poor compression due to water intrusion? Could try a top end rebuild with new pistons/gaskets etc. Labor and parts and still could end up with low compression-
Got quoted a full rebuild price of around $8,000, plus add all the hang ons get replaced, more parts and labor....24 year old engine.
Because she ran strong after the above mentioned work and hit WOT, cant quit wrap my head around it....but. I don't have the time or skills to rebuild myself. Given the labor rates at the yards these days, going with the minimum rebuild and not honing/boring out the cylinder walls and not going all in could still end up with low compression?
Strongly considering a repower, Merc 6.2 320hp, FWC with new gears, engines are on back order. Not many options out there for small blocks V8.
I'm wondering what you mechanics think given the circumstances....give it up and repower, sell the 454w/ gears and move on with fresh power...?