Mercruiser 4.3 MPI/EFI - 2004 -- R&R Risers / Manifolds?

[pdmathisjr]

I have a 2004 SeaRay 200 Sundeck with a 4.3 MPI/EFI 220hp - 2004 Mercruiser, 151 hours on the engine. Boat has been operated in saltwater since new. After each trip, flushed 10-15 minutes, including using Salt Away at the end of the flush. Boat operating temp is 160 degrees during normal operation. Boat is trailered and garaged when not in use... yes, we baby it. I'm looking for guidance and understanding on a few questions:

1. When should the Risers and Manifolds be R&R'd? Are there any early indicators to watch for (temperature increase during normal operation?)

2. I've had to replace one IAC valve on the engine. Is this a normal high failure rate part --- should I have a spare on hand?

3. I have had three instances of what appears to be vapor lock but seems quite unusal on an EFI engine. I'm told the warm waters of Florida PLUS high temperatures during the summer can lead to a more frequent vapor lock problem normally not seen in upper states / cooler climates. Also, the ethanol / gas challenges many boaters are being faced with may be a contributor, so I've started adding STARTRON to fuel and increase fuel grade from 87 octane to 89 octane. And finally, it's being suggested to add octane boost to my gas to help mitigate my "possible" vapor lock problem. Thoughts? Any experiences with facts and good corrective actions.

4. Last question.... expected engine life on the Mercruiser 4.3? Oil change every 50 hrs, 100 hr maintenance done at MarineMax dealership (big expense), Alpha 1 drive maintenaced per schedules. Any feedback is helpful and appreciated.

Thx so much.

Pdmathisjr

 

[havasuboatman]

Re: Mercruiser 4.3 MPI/EFI - 2004 -- R&R Risers / Manifolds?

1, If you start having water flow/temp increase issues NOT related to impeller or impeller housing, then an inspection of your risers may be in order. Trust me, your service tech will alert you to that eventuallity.
2, You shouldn't need worry about the iac valve, they are not prone to failier.
3, Instead of octane booster, which can foul sensors, put out the extra 10 cents a gallon for 91 octane gas. It's how we deal with 120 degree air and 90 degree water in Lake Havasu.
4, From what you say about how you treat your boat, I would count on many years of reliable use. I mean, 151 hours in 5 years is hardly any use at all. Just be sure to get those services done at the begining of each season. Remember, the 100 hour service is "yearly, or every 100 hours".

 

[pdmathisjr]

Re: Mercruiser 4.3 MPI/EFI - 2004 -- R&R Risers / Manifolds?

Thx Havasuboatman... I appreciate the information.

I just fininshed speaking to a Merc Machanic now semi retired and he's providing very similar information. Risers definitely need to be regasketed at this point and a full inspection of risers / manifolds should be done now. Engine should last for a long while as long as basic preventive maintenance is done at regular intervals, just as you said. He provided some great information on the importance of looking into the distributor and plug wires at this time. Looks like a good opportunity to change out and upgrade to a "better than" product. Wires with less resistance and a distributor with improved venting to mitigate condensation build up and corrosion.

Any insight on the outdrive you can share? I have an Alpha I Gen II OD. Well maintained also, annual lube changes, impeller changed every other year, ZERO issues so far. But I understand there could be a corrosion issue I could encounter on the top of the unit due to a rubber cap being used and degrading over time in the salt water. Any thoughts, feedback?

Thx.

Pdmathisjr.