Formula 26PC - Possibly seized starboard Merc 4.3L

[Scott Danforth]

dont confuse the external marine bolt-on parts with the internal GM parts.

the long-block came from GM. other than the cam, brass core plugs, stainless head gasket and the marine circulating pump, the motor itself is a truck motor as those found in an S-10 or a C1500

the accessories on the front of the motor, the carburetor, the ignition system and starter were bolted on by Mercruiser along with the marine exhaust manifolds.

Mercruisers at the time bought many of their manifolds (both intake and exhaust) from Barr, and they made their own ignition.

if you want to identify the exact year of your motor, read this https://forums.iboats.com/forum/eng...history-of-the-4-3-liter-with-casting-numbers

if you have 1989 motors, you have a non-balance shaft 4.3 with a roller cam

this is the part you are changing in addition to the exhaust manifolds. you should be able to keep all the rest of your accessory drive stuff and just move it over, especially if your replacement motor is a 1988-1991 vintage motor.

In 1992 they added a balance shaft, in 1996 was the vortec heads

 

[tpenfield]

Ok, so there are apparently at least two different drive shaft configurations out there for the Merc 4.3 and I'm not near my boat or sufficiently knowledgeable about it to say which one I have, but I assume it's the one you're talking about instead of the one shown in the service manual below:

Thanks!

The section (#8) of the Mercruiser manual that you referenced is for the extended drive shaft, where the engine is mounted several feet forward of the transom. This is not the case for your Formula . . . the engines are mounted at the transom and the drive shaft is part of the outdrive.

 

[PosessionSound26PC]

Thanks again - that matches everything I found based on the decals on the valve covers, I just wish the s/n's would match up on the chart. But good enough. You mention needing to replace the exhaust manifolds - I assumed this was the case IF they were corroded sufficiently, but I should replace them regardless because I'm pulling the engine?

 

[PosessionSound26PC]

Thanks Ted - that makes sense given the lack of room behind the engines!

 

[Rick Stephens]

Thanks again - that matches everything I found based on the decals on the valve covers, I just wish the s/n's would match up on the chart. But good enough. You mention needing to replace the exhaust manifolds - I assumed this was the case IF they were corroded sufficiently, but I should replace them regardless because I'm pulling the engine?

Absolutely not. Only replace them should they need replacing. If the motor is in saltwater, every 5-7 years. In fresh, clean, sweet, not briny water you can get away with indefinitely using the same ol' mani's for decades. I have 30 year old GLMs that still look nearly new.

 

[nola mike]

Also disconnect power steering lines. You can do everything prior to hooking it to the hoist. Don't use the hook on the thermostat housing to lift the motor.

 

[PosessionSound26PC]

Will definitely check the manifolds before deciding to replace. Previous two owners were strictly fresh water, not sure about original owner but guy I bought it from took off the big hoses and peeked inside - didn't see any corrosion worth noting. I have had in salt water for one season and flushed every time, assume they're still ok.

Haha - funny about the thermostat housing lift eye - I did notice that the manual points to the correct lift points

Are there any parts that I should just replace regardless if they still work? I know the port starter is dead so that will get replaced while the starboard is out. Should I replace fuel pumps or any other hard to reach items now rather than assume the old ones will continue working?

 

[alldodge]

If fuel pumps are original (doubt it) I would replace, otherwise you should be good