1998 Avanti 454 engine issue - piston - REPAIRED AND WORKING!!-gctid818284

[Dadrock33]

Everytime I think I'm getting pretty savy on boat stuff, someone (thing) comes along and sets me back in my place for thinking such a stupid thing . . . . . recent issue: apparently lost a piston (so where did it go?) in my port 454 engine (380 HP) or so the rebuilder told the marina owner. He's thinking it's a detonation issue . . . . . ?? ok, I know I'm not the sharpest knife in the drawer but that just begs for MORE INFO, PLEASE!! So I'm thinking that has to do with the timing of the spark on the compression stroke, etc. . . . how far off am I? My limited research says it isn't "pre-ignition" (the ignition [not by spark] of the fuel/air mixture WAY too early) but is more (like I said) an issue of when the spark was triggered to when the piston was After TDC (top dead center). Issues of this sort have to go with the tune up and timing, right? Help me out here . . . . need some good advice . . .

[2850Bounty]

"Dadrock33" post=818284 wrote:
Everytime I think I'm getting pretty savy on boat stuff, someone (thing) comes along and sets me back in my place for thinking such a stupid thing . . . . . recent issue: apparently lost a piston (so where did it go?) in my port 454 engine (380 HP) or so the rebuilder told the marina owner. He's thinking it's a detonation issue . . . . . ?? ok, I know I'm not the sharpest knife in the drawer but that just begs for MORE INFO, PLEASE!! So I'm thinking that has to do with the timing of the spark on the compression stroke, etc. . . . how far off am I? My limited research says it isn't "pre-ignition" (the ignition [not by spark] of the fuel/air mixture WAY too early) but is more (like I said) an issue of when the spark was triggered to when the piston was After TDC (top dead center). Issues of this sort have to go with the tune up and timing, right? Help me out here . . . . need some good advice . . .

[color]blue wrote:
The BBC does not quite have the same issues as does the SBC with regard to combustion chamber design. In other words, the chamber does not give the flame front the hiding place as does the SBC with the dreaded Full Dished piston! :evil:

However, most any gasoline engine can undergo Detonation, and Marine Load Detonation can be among the worst!

And yes...... you are correct.... Pre-Ignition and Detonation are two entirely different phenomena.

Detonation may be caused by poor combustion chamber design, excessive cylinder pressures, low Octane Rated fuel, high cylinder temperatures, excessively lean Fuel/Air mixture, excessive spark lead (i.e, ignition advance) at the TA RPM range, over-loading at below the ideal cruising RPM, etc.

Be sure to perform your Forensic work prior to putting this engine back together. Find out what caused the Detonation.

You certainly don't want a repeat shortly afterwards!

.[/color]

[88fourwinns]

Unless someone has been tinkering with the timing the most likely causes for detonation related damage are lean fuel mix, low octane fuel, and running with too much prop pitch (so that the engine never reaches its specified max rpm). This is why it is a good idea to remove the spark plugs once a season and inspect them. If you have a lean fuel mix issue it will be clearly shown by the center electrode insulator. I also use premium fuel regardless what others may say because as an engine ages and accumulates carbon build up the octane requirement increases over time.

[Dadrock33]

"2850Bounty" post=818287 wrote:

"Dadrock33" post=818284 wrote:
Everytime I think I'm getting pretty savy on boat stuff, someone (thing) comes along and sets me back in my place for thinking such a stupid thing . . . . . recent issue: apparently lost a piston (so where did it go?) in my port 454 engine (380 HP) or so the rebuilder told the marina owner. He's thinking it's a detonation issue . . . . . ?? ok, I know I'm not the sharpest knife in the drawer but that just begs for MORE INFO, PLEASE!! So I'm thinking that has to do with the timing of the spark on the compression stroke, etc. . . . how far off am I? My limited research says it isn't "pre-ignition" (the ignition [not by spark] of the fuel/air mixture WAY too early) but is more (like I said) an issue of when the spark was triggered to when the piston was After TDC (top dead center). Issues of this sort have to go with the tune up and timing, right? Help me out here . . . . need some good advice . . .

[color]blue wrote:
The BBC does not quite have the same issues as does the SBC with regard to combustion chamber design. In other words, the chamber does not give the flame front the hiding place as does the SBC with the dreaded Full Dished piston! :evil:

However, most any gasoline engine can undergo Detonation, and Marine Load Detonation can be among the worst!

And yes...... you are correct.... Pre-Ignition and Detonation are two entirely different phenomena.

Detonation may be caused by poor combustion chamber design, excessive cylinder pressures, low Octane Rated fuel, high cylinder temperatures, excessively lean Fuel/Air mixture, excessive spark lead (i.e, ignition advance) at the TA RPM range, over-loading at below the ideal cruising RPM, etc.

Be sure to perform your Forensic work prior to putting this engine back together. Find out what caused the Detonation.

You certainly don't want a repeat shortly afterwards!

.[/color]

Thanks, Rick (2850Bounty). I was hoping that you would chime in . . . . before I do a "search" on the Internet of what to look for, how does one tell what caused the detonation? I don't believe that I was ever over 4,000rpm for any length of time (maybe 10 seconds at longest) on any one engine while adjusting for "sync" between the two (high rpm was recently given as a possible cause by the rebuilder) and then tuning them down to what I believe is a good cruising load (about 37-3800 is my thought - but not checked out yet). Also, and I am assuming that this is silly question to begin with, shouldn't all pistons be the same style (FD or Quench)?? I mean, you shouldn't use a quench style when overhauling if all the others are FD style, right? (Thinking of more questions to ask the rebuilder . . . want to be sure my bases are covered) :S

[mister_larry]

Bounty is right - try to find out what happened. One has to wonder how the other pistons look, and how the other engine looks. Did the previous owner "play" with this engine?

It is not uncommon for a DIY boat owner to rebuild an engine and not pay attention to how manifold ports match up with those of the head (s). When an engine gets working (and particularly a marine engine) and it can't breathe properly, there could have residual carbon left in the combustion chamber. As funny as it sounds, thousands of firings (or millions) can result in a carbon build up that is sufficient to change the combustion chamber size, increasing the compression ratio, increase temperature and the resulting heat = detonation.

Naturally, there are also fuel quality and timing questions, but these can be addressed when you get the boat back in the water and under your watchful eye.

Keep the faith.

[Dadrock33]

Well, hear she's in the water and waiting for us to climb back aboard . . . . thinking very hard about my recent boat experiences (my son took me on a lake tour from his house in Virginia Beach and yep, prop sheared off on some lurking tree trunk . . only 2 miles from the house and no paddle!) . . . . so may need to invest in additional safety equipment, pumps, liferafts, etc. . . :woohoo: :woohoo:

oh yeah, a fishing kayaker, whom the boy had befriended earlier that day, felt sorry when he saw the boy swimming us back (small john boat) that he TOWED us back with the kayak!! . . . . never ceases to amaze me . . . .

I'll post pictures when I get to see the piston . . . . should be interesting . .

[Dadrock33]

Ok, so no pictures yet . . . can't find the piston. Alright, not a big deal. Had her out last weekend and she held her end of the bargain up very well. Went through the rpms, climbing up the ladder (as they say) and she did very well. Took her upstream on the Delaware towards Trenton for about 90 min and then back . . . cruising along at about 3300 rpm (heading downstream, that was about 19-20 mph), using a lot of tab but cruising right along, very smooth.

Going to do the "Head for the Chesapeake" trip again this weekend. Would like to be down there for the Labor Day Weekend. Admiral is taking a day off from work to "watch my back" so we're leaving early on Friday morning and we'll see how far we get . . . . all the way?

New chartplotter looks great, AIS is operational and reading right and I have the "auto-guidance" programmed for our trip . . . should be about 100 miles, give or take a few . . . . we'll take our time though . . . . nothing wrong with a 10-12 mph pace. Going down as the tide is going out and should hit the C&D about the time the tide is coming back in . . . . we'll see how good that is!!

[Guest]

I read your posts about a dead cylinder but failed to understand what repair(s) were made. I have '99 Capri 2052 LSD that I tried to winterize 2 years ago. I open the large hose off of the water pump and dump the lake water out as much as possible (warm engine), then keep dumping antifreeze in and running the motor until I get about 2 gallons of AF into it. Problem is the starter would turn the engine over a few times, then bang to an abrupt stop. I had a much older Chaparral with the same GM 305 V8 and assumed the same starter. I was sure there must be flywheel must have a damaged tooth so procrastinated in removing the starter to see how bad it was. This newer engine has a gear reduction starter and I now also know the gear reduction section of the starter went bad and was jammed.

I apparently didn't get the engine as winterized as I thought because now I have a dead cylinder on the left bank. The engine starts and runs seemingly well but in the water it has no power and will not throttle up. No water is coming from the engine into the bilge so the frost plugs are intact. I am hoping you bought a "Genie In A Can" somewhere and it fixed your dead cylinder? Tell me it's so... Second best, does someone know what is the first thing go when a coolant freeze takes place? A head gasket would obviously be cheaper than an engine block replacement. My current engine has Vortec heads that I was also oblivious to before replacing the plugs, wires, cap and rotor in recent days. I am shortly going to take it to the shop and bite the bullet, hoping for the best.

Thanks,

Tim A.

[builderdude]

Smooth, you need to start a separate thread for your issue. If you've winterized successfully in the past your engine issues may not be freeze damage related.

Id start the engine and bring it up to operating temp then shut it off, remove the plugs and to a compression test on all cylinders followed with a leak down test of any cylinder that tested low.

[Dadrock33]

"KaptnSmooth" post=823522 wrote:
I read your posts about a dead cylinder but failed to understand what repair(s) were made. I have '99 Capri 2052 LSD that I tried to winterize 2 years ago. I open the large hose off of the water pump and dump the lake water out as much as possible (warm engine), then keep dumping antifreeze in and running the motor until I get about 2 gallons of AF into it. Problem is the starter would turn the engine over a few times, then bang to an abrupt stop. I had a much older Chaparral with the same GM 305 V8 and assumed the same starter. I was sure there must be flywheel must have a damaged tooth so procrastinated in removing the starter to see how bad it was. This newer engine has a gear reduction starter and I now also know the gear reduction section of the starter went bad and was jammed.

I apparently didn't get the engine as winterized as I thought because now I have a dead cylinder on the left bank. The engine starts and runs seemingly well but in the water it has no power and will not throttle up. No water is coming from the engine into the bilge so the frost plugs are intact. I am hoping you bought a "Genie In A Can" somewhere and it fixed your dead cylinder? Tell me it's so... Second best, does someone know what is the first thing go when a coolant freeze takes place? A head gasket would obviously be cheaper than an engine block replacement. My current engine has Vortec heads that I was also oblivious to before replacing the plugs, wires, cap and rotor in recent days. I am shortly going to take it to the shop and bite the bullet, hoping for the best.

Thanks,

Tim A.

Hey Tim . . . welcome to our version of the puddle!! My issue was detonation on one of the pistons which, apparently, ended up blowing a hole through one side of the piston (no pictures yet . . haven't been out there in a while) and that pressure went down into the oil pan and blew it all up through the breather . . . . yeah, it was a major mess!