[MariahMX20]

my dad just had his new boat shipped in, its a 1999 rinker 232. i know its not a mariah but we have issues(he searched for a mariah to fit his needs, he loves them). anyways we get the boat to the hose and visually inspect her, besides being really dirty the boat looked awesome. we hooted the muffs up and started her up, started great and ran good, then we noticed water dunmping out of the motor. we figured out there was a frost plug poped out, so we replace it. then we noticed the exhaust manifold had a crack in it, we ordered a new one but it wont be here till monday so we pulled the old one and welded it which worked great. start her up again, still water, wtf!?!?! another plug on the opposite side, so i pound a new one in and start her up, runs great, no water leaks. then we decide after 5 minutes that we should check the oil again, this time we have a creamy mess! so now we have to figure out if we have a cracked block, cracked heads or bad head gaskets or maybe all 3. the boat has less then 100 hours and came from the south so we are thinking that it did not get winterized and it froze which cracked the block??? i wish i knew if this guy overheated it or froze it because that will make a huge difference in what might be bad. i am thinking the block froze and if we are lucky we can salvage the heads and either buy a short block or find a new block and swap the internals. can anybody tell me what would cause the plugs to pop out, freezing or over heating? also the motor is not a mag, my dad said he would like to go for the mag if possible since he is swaping it, would that screw up the computer or can someone tell me the difference between a normal 454 and a 454 mag? thanks for an help!

[WetWilly]

Hi MariahMX20,

Well in all the years I've worked on motors, I have never seen multiple freeze plugs pop due to overheating... I have seen a few that leaked because they weren't installed correctly. There is a reason they're called "Freeze Plugs" and from what you've described, I'll make an educated guess, your motor was frozen. In either case, I wouldn't trust anything from the original motor, instead, go with another motor, rebuilt or new for piece of mind especially if you're going with a MAG.

I'd say it could be more like the computer messing with the MAG, if the MAG requires different fuel and ignition mapping verses the stock 454. I recommend contacting Mercruiser, if anyone is going to know, it should be them.

Good luck and let me know what you find out,
WetWilly

[Z275]

Sorry to hear about your mess. As WetWilly stated, the engine definately froze. Since it was run with water in the oil I would not trust much of the internals either. It needs completely torn down and rebuilt or replaced.

As for your 454MAG questions:
The 454MAG has high flow cylinder heads with larger intake ports. It also uses hardened valve inserts, forged steel crankshaft, connecting rods, and alloy pistons. A different cam is also used. I believe all the MAG engines also have a water cooled fuel pump and run a single serpentine belt to pick up a few more horses. The ECU is DEFINATELY different for the MAG engines so you would need to replace that as well. The fuel curves and max RPM would be different.

[MariahMX20]

i dont think it ran long enough with water in it to do any internal damage..... i have seen worse rebuilt with no issues. we still will most likely replace the short block entirely, i cant seem to find a bare block for any cheaper then a short block. we are waiting on whats going to happen with the seller but its going to the shop today so we can document the issue. if we decide to do it ourselves i am going to pull the intake and heads and have the heads checked out and visually inspect the intake for cracks and decide what to do after that.

[Kuli]

I hate to be the bearer of bad news but most likely the engie froze and opened up a water jacket (usually near the exhaust or heads) or the inside of the manifold cracked and let water into your engine.

Search the WWW for "454 water reversion" and revel in why I am looking for a new 454 for my '99 Z252. Your exhaust valves overlap your intake valves, this was done moreso on big block to let the exhaust pressure pull the intake mixture into the cylinder. The problem is that water can get from the water jacketed manifold into your engine through this same phenomenon.

If you don't let it sit too long (mine sat over winter before I discovered it) then you can usually change the oil 3 or 4 times and get the water out, the rest should evaporate. Otherwise you're looking at the engine coming out.

Assuming you had popped freeze plugs and a cracked manifold you can join me on my quest for a new engine

www.Michiganmotorz.com and www.1800runsnew.com are the best places I have found but haven't had the $5k plus labor to do it in 2 years.