View Full Version : Marine Power 454 trouble

07-07-2006, 07:33 PM
"I am novice at engine work, but am an engineer and have some basic knowlege. I've recently run into an issue with my Marine Power 454. Here's the skinny:

I have a 1997 Carrera 205 Custom Elite. Back in 2001 the previous onwer swapped the original 454 350HP for a performance 454 440HP. I bought the boat from him last year with 70 hours on that engine. It work great last summer...no problems. I did the service (2 oil filters, 3 fuel filters [1 water/fuel seperator, 2 inline], pumped and changed the oil, put in new plugs. When I turned it over, I noticed my starter sounding like crap and smacking the fly wheel, so I sent it out and had it rebuilt. When it came back, the engine fired and sounded great.

I took the boat down to the river this weekend. I ran one day great, no problems. The next day, I was cruising along arrprox. 5000 RPMs and the engine started to gag. I shut it down. When I refired, it was still gagging and I could never get out of the hole. I got Sea-Tow to pull me in, took it to a shop, and I pulled the plugs. They looked at it for a bit, said they ran a compression test and the compression was fine. 4 of the 8 plugs however were beaten to holy hell. The electrodes were bent all over and the ceramic inside the elctrode was cracked. At that point, I paked up and came home. I have an appointment at a local marine shop to take it in next week.

If I have something in there banging around, what acan be done? Will my engine have to be rebuilt if so? Depending on damage, can whatever it is be fixed and the same engine perform the same? If I do have to rebuild, what is the breaking point where I say forget it and I buy a new engine? If I buy a new crate motor, is it worth the extra cash to buy the 502? Any recommendation on where to go for crate motors? I'm at a loss here.

Can you guys give me some advice?"

John Davidson
07-13-2006, 02:25 AM
"First of all you have to be very specific with your diagnosis of your engine. For 1, were the plugs that were damaged all on the same bank? 2, you said you got towed to a shop, but you pulled the plugs, you didn't notice the damaged plugs? Or did the shop pull the plugs, and tell you that these particular plugs were damaged? My motto " Never trust anybody that makes profit from your loss". If all the plugs on one side of the bank were damaged, it seems like you might have to at the very least pull that head and inspect both sides of that head,(entire head,springs,guides valves,keepers etc...). If the plugs that were damaged are on both sides of engine, you can pretty moch expect to overhaul the whole top end.
I have no idea how your compression tests came within values, if you scored your cylendar linings with a foreign object. On the other hand, you can probably redo the entire top end for under 1000.00, depending on whether or not you damaged the camshaft,pistons or cylanders. Inquire with someone you can trust, that has some knowledge, and base your decision on where you go from that input."

07-14-2006, 02:33 PM
"Diagnose the problem before shopping for crate motors.

send pics of your plugs. Are we talking about damage from physical contact or detonation?

If this thing is high compression, it may have very little clearance around the plug and a plug with shorter "reach" may be in order. If you think there is physical contact to the plugs, try replacing with the same model plug and rolling the motor over by hand to see if you get contact against the plugs by the piston tops.

5k rpms is a lot of revs to sustain without breaking stuff... regardless of the motor."