275BBoss

Hello Everyone,

Out on the water this past weekend my Merc 496 mag blew. Was coming in at about 55mph, all gauges were normal and the engine just stopped. On inspection the oil is full of coolant which I know is pretty much a sign of death. First off I have no clue how this happened, especially since the engine only had 200 hours on it.

Secondly, I am not sure what my options are in terms of replace or repair. Is there somewhere that I can send my engine to in it's current state and be sent back a rebuilt motor? Based on the price of these engines new it's almost the price of a new boat!

Any help is very much appreciated!

dereknkathy

you need year, serial number and state you are in.

Keith Atlanta

You can buy a 496 short block and bolt on all the new stuff.

Or, buy a used engine with low hours.

thisistank

Buddies going though this right now with a 496. Engines 14 years old but only had 130 original hours. I guess the 496 isn't rebuildable and a short block cost more than it used to cost to completely rebuild a motor 10 years ago!!

BUP

iTrader: (9)

Before buying anything for the 496 - if not knowing why ones engine went down - I would look at the whys and costs to fix the root of the cause first whether it was one thing or many that contribute to the failure. It is possible one is better off going back in with a 502 or even with a 454 depending on the issues with the 496.- 8.1 L

BUP

iTrader: (9)

Totally an Opinion on my end -- 14 year old engine with 130 hours only --- prob fuel issues caused the failure and would say possible fuel issues that was from gas tank contaminants, poor performing fuel pumps, possible internal fuel rail contaminants and the fuel injectors needed to be flow tested and cleaned for anything that sat around that long with very low time on the clock. Boats do a lot better running more than sitting around all the time.

thisistank

good call, I agree. gotta run em.

But it had water in two of the cylinders (no milky oil though). Either some type of reversion or a leak somewhere.

AJ Barrett (Barrett custom marine) is on it and has a motor to put in so it's all good.

dereknkathy

as BUP said. these fuel systems die as a matter of time, not hours under pressure. I don't think running them helps that much, but you got more use before the thing died. the pistons are cast. GM found forged pistons worked real good in the 502 which never saw the inside of a NEW GM engine compartment. but they built the 8.l1 for trucks. therefore it was a LOT of pistons. therefore the price of euctectic cast was (in their little minds) justified. so as soon as these get a little lean, pieces of pistons start going out the exhaust...in some ways it is an improvement on the 50 year old big block. they straightened out the ports. they got 6 head bolts around each cyl, instead of doing without 2 cuz the ports were in the way. the cast crank stands up well enough. you find a rebuilder that'll do forged pistons, and get the fuel system right you will have a decent piece. you can find a whole truck with this motor for 2k or under running rusty bad trans if you wanna start with a new block. but your bores are a LOT less worn than this truck block, unless a piston broke a chunk outtta a bore, in which case yours needs a sleeve. 2-300 or consider 2 cents a lb. at the scrap place. although 30 will usually clean em up. this is the same with 1500 ebay truck 8.1's. you got no idea how tired till it shows up at your door. local scrap yard better. there is 1 guy around Detroit on ebay selling this motor rebuilt around 6k, but that is all cast parts. might as well throw a used piston in your engine. speaking of which, do an autopsy on yours. take it apart. see what died. see what it destroyed in the process. see if you can figure out what made it die. and then, when you have an idea what, if anything is still good, talk to Raylar, and BUP. they will both steer you the right direction, although slightly different directions, both are correct directions.


bup.

dereknkathy

year, serial number, and location and we can point the shortest drive to the bestest guy. good luck. where you are matters. shipping heavy parts, and never standing there looking the man in the face are a bad idea. drive to a guy. meet, make friends, of a sort. don't send your block to Podunk.

BBYSTWY

could buy my 525 sc I have for sale lol

stewart