3.0 mercruiser project

[skidoox11]

I just recently picked up a 1991 sea ray 170 with a 3.0 mercruiser. The guy I bought it from knew little about it, but says he got it hot. I bought the thing pretty cheap and the boat itself is in great shape. Interior, floors, and transom are very good. Today I got the motor to start but it is knocking pretty badly. The compression is at 140 125 140 140. Probably going to have to pull the motor and rebuild it. I was just wondering if any of you had any suggestions on where/what brand of parts to buy for the rebuild. I would love to swap it for a 4.3 but don’t want to sink the money into it.

 

[fishrdan]

Rod knock, or just noisy valve train? 3.0L engines are not the quietest engine in the world... Might be something else making noise, Ujoints, gimble bearing, engine mount, drive.

I'd check to make sure the engine and manifold are not cracked (freeze damage) before rebuilding. 3.0L engines are not cheap to rebuild, so finding a used engine may be the cheapest, if it's actually the engine making noise.

I bought a complete engine rebuild kit from Green Bay Parts World (something like that) for $5-600 and machining was another $3-400. Total cost was around $1,000, but I assembled the engine, tack on another $2-300 if you have the machine shop build the engine. This was 7-8 years ago, so probably more expensive now.

Upgrading to a 4.3 would require (fiberglassing) new engine mounts and replacing everything from the engine waterpump to prop, best to find an old rotted out hull with a running engine and drive, then swap everything over.

 

[southkogs]

Moved ya' to the Mercruiser forum. Welcome aboard.

 

[Scott Danforth]

3.0's cost as much as 5.7's to rebuild. however you can find running 3.0's in near free rotten boats and simply pay hull disposal fees, then sell the trailer to recoup those fees