All cylinder heads were removed and sent to machine shop for inspection and overhaul. All four heads had cracks. So, no overhaul-they need replacement. The starboard (worst side) valves were found "tuliped" in 2 of the 3 zero compression cylinders. The other valve had a hole through it. They found large pieces of water impeller in the exhaust manifold water jacket. (And I replace them every 2 years!). I was surprised to see how small the water jacket passages on the manifold are - the size of a drinking straw. Clearly, this was a major factor in excessive heat. The heat was so bad, it caused a melting of the top of the cylinder block between the two adjacent cylinders which resulted in a "valley" between two cylinders at the surface where the cylinder head gasket is placed. The gasket in that area was burned away and black on the edges. Because of this valley, it was recommended to replace the starboard engine. The repair option would have required the engine being removed, sent to machine shop, and overhauled completely. The overhaul is a policy of the machine shop so if the engine shows other signs of failure, the owner can't blame the shop if something else should happen when returned to the boat. For maybe $500+ more, I would get a new VP Longblock engine (remanufactured) which comes with new cylinder heads and oil pan. Also, an overhaul takes a few months to complete (due to being too busy), whereas a new engine takes 3-5 days.
The pieces of the impeller were found past the water temperature thermocouple, so the reason why I never had a high temperature alarm.
I saw the water passages of all exhaust manifolds and risers. I could not believe how blocked they were from corrosion! They were about 75% blocked on both engines. The pieces of impeller put the starboard engine over the edge in no heat removed.
The port engine is being looked at for a second opinion. The mechanic did not see anything wrong with the port engine block. But, I asked for a second opinion and the machine shop will take measurements to look for warping of surfaces and cylinder out of round. If the port block looks OK, then all that engine needs is new cylinder heads, exhaust manifolds, and risers. I also felt inside the thermostat housing and it felt like the Grand Canyon inside, so they are being replaced in addition to new thermostats - which looked awful, but intact. I think they are made from bronze.
Lessons Learned: Sh__ happens! I do a freshwater reverse flush after every run. Winterized with the purple stuff (not red). New impeller every 2 yrs. O/D maintenance every haul out. New distributor,rotor, and spark plugs every two. The boat is in the Sassafras River (brackish water) and this is the boat's 12 season (first season was in full saltwater) and about 470 hours. So, eventually, something was going to happen. The guesstimate on cause is the port engine was now taking on more load to compensate for the low power on starboard engine. With much smaller cooling water passages and higher load, is the probable reason the port heads were cracked too. At this point not sure how much more cracked than starboard. Don't buy a 8-9+year old FW in salt/brackish water without records of riser/manifold being inspected or replaced.
I should have probably inspected the risers and replaced them at year 8 maybe? Someone told me that Mercruiser even recommends replacement every 5 years. But for a 298, the engine compartment is tight to remove the risers. And after all that effort, knowing what I now know, I would replace rather than inspect. However, you need to consider replacing the exhaust manifolds too. The corrosion was just as bad there.
The cost estimate is still being calculated as we don't know yet if the port engine will need replacement too. But, when it was just replacing both engine's cylinder heads, exhaust manifold, and risers (12 pieces of heavy iron), the estimate was $6,800.
Home Equity Loan - here I come!
On the good news side - she should sell quickly with a new engine and new exhaust components.
Login
FAQ
Search
