jay863fl

Ok so today after 9 tanks of gas thru my Miss Vegas I was all excited to see her finally run without being too rich.................unfotunately the rod wasnt rdy to go to work Basically, I started to lean it out a little bit after about 10 full tanks of a rich mixture thru all of last week(lots of smoke and frequent die offs in the middle of the pond, 2.5 turns out on the HSN).
I started it up, was running kinda nice, so I leaned it out a little bit and poof, the rod broke. The piston is stuck to the cylinder lining, and theres small metal bits running around the crank. According to my infrared temp gauge it was running approx 150 degrees. The case is shot, I think. Also inside the case is this mixture of what appears to be oil and water, but its almost fused to the engine. I had a local guy come out last week and help me tune it, etc. but in all honesty, I dont have a lot of experience with Nitro engines. And as far as the receipt goes.....in a move of great utter stupidity I left that in the bag of assorted stuff I got with the boat (glow plugs, etc) and its is now in the local dump, so an exchange under warranty is out of the question. So do you guys have any advice for my next go round? Is the OS engine really worth the extra price? Has anyone ever converted this hull to electric? Not sure what Im gonna do just yet, just looking for ideas. Thanks for reading my vent, I am going to go bang my head on the wall for a few hours.........[sm=cry_smile.gif] Pics coming soon.

piper_chuck

My Feedback: (12)

If you bought it from a hobby shop or online source, they may be able to print a new receipt for you. I know Tower maintains receipts online for quite a while.

jay863fl

Well, I took the engine apart, got the piston released from the liner, and so far it looks ok. I cleaned the case out really good, dried it and lubed it. So far I think its just the rod thats busted. I didnt realize I could just order the rod alone , but just found and ordered it on the tower website. So if I am lucky its just gonna cost me the $11.00. Man I was bummed out till I found the rod. The piston looks good, no scarring and the liner look really good. I dont know, defective rod maybe? I am pretty sure that I was doing things nie and slowly, but heck, could have been my fault also. At any rate, thanks for reading and trying to help me out, thats what the hobby is all about, thats what attracted me to it at any rate. So hopefully I will be back on the water by next weekend. Should I go thru and try to "rebreak" the engine in do you think? I hope all works out good, because compared to some of my other ventures this has provided the best bang for the buck.

Dan S

I know carb settings vary with Location etc. etc. but 2.5 turns should be it, no less.

Again, you guys may have to go a bit less but no more.

Dan.

jay863fl

When you say no more, do you mean dont lean it past 2.5 turns, or not to go any richer? I would assume you mean no less than 2.5 turns, meaning that 2.5 turns would be the leanest I could go, IE 2 turns would be too lean.

Dan S

Correct,

over here depending on Temp, pressure etc.etc. my Vegas as been running from 2.5 to 3 turns out. Now where you live could be different but I believe so far everyone is at 2.5 maybe a few at 2 1/4 but that would be it.

I don't think thats what caused the rod to break, in your first post you say that you found some water, if you did than that could very well be the culprit, since water doesn't compress something else will.

if at anytime you think the engine may have ingested water, flush it with after run or WD-40, flip boat upside down and fully drain the engine.

Dan.

avenge

thats to bad. Same thing happend to me with my vegas. Con rod let go, I had more damage though I lost rod, piston, and liner, cause the piece that broke of the rod wedged itself inbetween the piston and liner[X(] very nasty sound when this happens. I cant remember where I read somewhere that the aqua 18 was prone to break at the con rod, so dont feel to bad its happend to others I included.

jay863fl

Avenge, whew, well, now I dont feel so bad. I compared the rod from that engine to another make of engine and it did appear either the Aqu rod was a little thin or the other rod was well overengineered.

Dan, I didnt actually find any water in the engine, the rod let go on the boat stand within seconds of starting it after it was dry docked at my home for 4 days so I am almost positive there was no water on there. I meant there was a mixture of what appeared to be water and some oil based substance. I have seen this "look" before when racing motorcycles that are 2 cycle and water gets in the crank, so thats the most similar thing I had ever seen so thats what I likened it to. Im sorry for the confusion, should have elaborated a little more. And yes, I have seen what happens to 250cc motocross engines that ingest water while running, I could only imagine that to a .18 it would surely cause much devastation.

I really appreciate all the help , etc guys, makes this forum definately a nice place for new guys to learn.

Square Nozzle

My Feedback: (1)

With the needle set at 2 1/2 to 3 turns out you should not be to lean. How many of you guys have been setting the needle on the beach and running the engine up to high RPM to see if it's set right. If you do, you deserve what you get. A broken rod.

f16man

Also the crank bearings most likely have damage or at least metal shavings in them, new crank bearings are not expensive and since the engine is apart now is the time to change em out, good luck and happy rooster tails!!!!!!

jay863fl

John, I am confused by your statement, does 10,000 rpm in the water affect the engine differently than 10,000 rpm on the shore , assuming the temperature and high speed needle settings are the same? I would think that without the resistance of water on the prop the shore would actually be easier on the engine.

piper_chuck

My Feedback: (12)

Running the engine at high RPMs on the shore will lead to broken rods. Ask anyone who has been around nitro boat engines for a while, nearly all will confirm it. The problem is that on the shore there's no load on the engine. I've never studied exactly why they break, but my guess is that when the piston reaches the bottom of its stroke, the unloaded crankshaft exerts more force on it than normal, leading to the bottom end of the rod being pulled off. It could be something else, but to me, it doesn't matter, the end result is one broken rod.

Note that nitro boat engines are much less likely than gas engines to be damaged by a sudden dunk in the water. This isn't saying that you shouldn't IMMEDIATELY kill the engine if the boat is about to flip, but the odds of breaking the engine are low.

For example, I've had many a nitro boat end up topside down. The only time this has lead to rod failure is when I launched my Sprintcat off bouy 4. It went airborne for an amazind distance. I got it back to shore, cleared out the water, and the rod failed when I started it. Since I shut the engine down before it hit water, I'm reasonably certain that the rod failed not due to the water, but due to the engine running free in the split second it took for me to react to it's attempt to go into orbit.

Contrast this to my fist gas engine. I bent the rod and messed up the cylinder after jumping a bouy. The boat didn't even land upside down, and it wasn't airborne very far, but it got enough water inside that it got in the carb and killed the engine.

To add one more example, I'll take you back to the first inboard engine I ever owned, an OPS .45. The engine ran pretty well. One day I made the mistake of allowing a "more experienced" boater tweak the tuning. While he was revving it up on the stand I was worried he was going to break the engine. It did survive the onshore part of the tuning, but the damage was done. It only made 3/4 of a lap before the rod gave out.

So, back to the original point, don't run the engine up to high RPMs on the shore.

jay863fl

Ahh so the water acts sort of as a harmonic balancer possibly, absorbing some of the energy. Like I said, I am more than willing to claim responsibility, as I am still learning. It just didnt make sense is all. And to be told " you deserve what you got" well..........[sm=thumbs_down.gif]

piper_chuck

My Feedback: (12)

A governor might be a better analogy, but I'm not sure that's right either.
Perhaps we need to send John back to charm school?

jay863fl

Oh well, I appreciate the input. I was shown thats how to tune. But in all fairness to the guy, he was an airplane guy, not a boater, so he wouldnt have known better either. Also, as he was tuning airplane engines, they would have been under load with a prop while he tuned, so....... at any rate, a lesson learned. And Chuck youre EXACTLY right, the bottom of the rod let go. Oh well, shes all cleaned out good, waiting on the ups man to show up with my new rod and header coil. Also, I ordered some new fuel, O'Donnells 30% boat as the LHS sold me O'Donnell 30% car. Is there that much difference? And if so.......um, what?

Dan S

Same rules apply's to the full size marine engine, you can have your engine running in your driveway kooked up to your garden hose in neutral only.

with no load on on the prop the rod is free floating, kinda driving around with your car but with no exhaust system only the header, not good for the valves (no pressure, no restriction to prevent valve from floating).

Dan.

Dan S

Oil Content.

piper_chuck

My Feedback: (12)

This is right, an airplane engine is under load. Tuning plane engines and boat engines requires similar concepts, but entirely different experience.
Check the oil content in the car fuel, it may not be high enough. The typical recommendation for boat fuel is 18% or higher oil.

jay863fl

Ok, couldnt find anything on the fuel, or the website, so I will just give this to a friend and run boat only from now on. Man , what a learning curve =P. Thanks Dan and Chuck for the help, guys like you make it a lot easier.

avenge

If it's worth anything you could you heli fuel. I have used the heli before because where I am from I can not get boat fuel. Only problem was that it was just synthetic. No cator, but 20% synthetic

Square Nozzle

My Feedback: (1)

[Perhaps we need to send John back to charm school?
[/quote]

Charm school!!, they failed me and sent me home. My point was, it's been said over and over on this forum that you do not run a marine engine at high RPM on the beach. Sorry it cost you an engine and it's a tough way to learn. Be sure you have thoroughly cleaned the interior including the bearings. Debris in the bearings no matter how small can cause the balls to skid or spall and result in a bearing failure. If you start chasing the needle valve and never seem to get a good setting, check the bearings. Don't ask why because I'm not real sure but the rough bearing sets up vibration that affects the fuel mixture. We see it a lot with the small 2 strokes.

jay863fl

John, forgive me for not knowing. I read at least 12 pages of engine break in and never once saw not to run it on the stand to tune it. At any rate, I dont have anything to say to you, and would prefer you keep it likewise.

f16man

Well so there.

Square Nozzle

My Feedback: (1)

Sorry to have offended you and got under your thin skin sonny. The next new car you get, break in the engine by sitting in your driveway with the car in neutral and push the pedal to the metal for an hour or so. That should be equivilant to about 1000 miles.

Someone once said "Common Sense Isn't so Common"

But as I tried to tell you, make sure you cleaned those bearing well or you'll be back on the bench with that engine.

piper_chuck

My Feedback: (12)

Charm school attendance seems to be on the decline...