Droped cylinders

[fishlady]

this has got the best fooled, i have a 25ft. 97 proline with a 350 5.7 merc i/o bravo 2 and only 400 hours on it,mostly fishing hours. last year while running in from fishing the boats rpm's started dieing off and sounds started happening. after nursing it back to dock. i had a marine mechanic look at it and he said i droped two cylinders.last winter they took it in the shop and tour it down,sent it to a shop and had the heads done and put it back together.ran it and said it was fixed. authorized merc dealer/mechanic i must add. took it out in spring and it ran like crap.told them and they ran it,then they said it needed a distributor adjustment module. now for the books i have $2500 of my money into it. took it out and it ran like a raped ape. but only for about 40 hrs same thing happens now ,only with 3 cylinders gone. as i under stand the adjustment module advances the distributor so bad this is taking out the cylinders. does anyone know if i have a case with merc seeing the worantee is off, and a contact name? does anyone have a clue to what is happening to do this? is the motor still good for another repair in the shop or what. HELP sleepless nights!

 

[Stanp]

Re: Droped cylinders

Fishlady,<br /><br />What exactly is a dropped cylinder? Loss of pressure during a compression check? Unless there is a recall from merc, they will probably not honor the repair out of warranty. Time to call a lawyer and spend time and money fighting your case. I'd probably sell the boat or find a new or reman'd block. Sorry I can't be more help.

 

[fishlady]

Re: Droped cylinders

no compression at three plugs, possible head gasket?

 

[Knoxes]

Re: Droped cylinders

I'm no expert by any stretch, but no compression at all? I guess you could have dropped valves into the cylinders and punched holes in the pistons. This can happen if a timing belt breaks. I guess also if the timing is off, the valves are open at the top of the stroke. That could mean the belt wasn't re-installed properly when they put the heads back on. But then, I think you wouldn't get any pressure in ANY cylinders. And you would notice this right away. Maybe the valves simply were not seated properly after the head job. Another thing you should notice right away. I'm pretty sure the module just advances the firing as rpms increase, which isn't mechanical, it's electrical and would result in repeated misfires, but not a loss of compression. Loss of compression is mechanical,i.e pistons (rings) or valves. The piston will compress whether or not the plug fires. Repeated misfires could cause some damage over time, I guess. Do you know which cylinders have gone bad? Again, I'm no expert, just trying to provide some ideas. Regardless, I think after having dumped $2500 into it, sounds like the shop didn't fix the problem, and they should make it right.

 

[Stanp]

Re: Droped cylinders

I'm not sure what knoxes means by timing belt, most 5.7 350ci merc's are basic chevy blocks with timing chains and don't get affected at all when you remove the heads. However, knoxes is right about compression dropping is typically a mechanical problem. Fact is Merc uses crap gaskets for heads to begin with. If a mechanic pulls the heads to put new gaskets on, the heads should automatically go to a machine shop to be re-decked. If not, the heads won't seat right even with good quality Felpro gaskets. It sounds like one bad event following another. Now, to get the heads pulled, redecked, and new gaskets installed, it cost me $450.00 for my 350 crusader(454ci). Maybe the shop that performed the work before would pay for someone more reputable to do the work, but I certainly wouldn't let them touch this engine again.

 

[Trevor]

Re: Droped cylinders

three droped cyl.<br />are they on the same side?<br />head gasket may be gone<br />The only way that modual would cause this thing to blow is if you initial timing was set way too high like 30 degrease this will cause hard starting and run on when shutting of the engine.<br />good luck Trevor <br />I would make sure the dealer that fixed this rebuilt this pay for the rebuild I know up here most of the shops would warrent this if they had done it Just for PO.<br />Trevor

 

[Knoxes]

Re: Droped cylinders

Like I said, I'm no expert. Thought it might be a chain, but wasn't sure. Just trying to help.

 

[Bondo]

Re: Droped cylinders

I can see where the ignition module could be the problem from the start... the initial timing maybe at 7/8obtc(so it starts easy)...but if the advance Jumps to full advance to soon,( it sure would "run like a raped ape) you could smoke the pistons,+ never even here it, in a boat... If the loss of compresson is from the hole in the top of the piston that detonation causes...look at the plugs..?? are the center eletrodes burnt ??? <br /><br /> the motor maybe salvageable, But it's going to the machineshop first....<br /><br />the thunderbolt ignition is a top notch system... But i'd be looking it over Very closely....<br /><br />you can fight with Merc. about it, but i don't think you'll end up a happy camper....

 

[fishlady]

Re: Droped cylinders

thanks guys for all the replys,will let you all know how i make out,this is truly a great site.

 

[DJ]

Re: Droped cylinders

fishlady,<br /><br />Some of the GM engines had "issues" with "crossfiring" between cylinders. <br /><br />An ignition module can cause this as well as a distributor cap. The crossfiring introduces spark into the cylinders at the wrong time (read early) and causes detonation problems. The detonation usually attacks pistons, however, the excess heat, at the wrong time, can also effect valves.