legbuh

Thanks, Dr. Nitro. Great explanation. I am familiar with Magnuson Moss (the MC/ATV folks I chat with have to be reminded of it often, especially the polaris riders who think they only can use polaris oil/filters). I almost brought it up when talking with Traxxas, but thought I'd wait. I am going to use Top Fuel for the new engine though just to see. The gallon of Trinity I have will make great starter fluid for bonfires..

What bewilders me is I never saw it coming. But when I really think about it, it did seem to slow down after time. Barely noticable.

Then one day ripping around it made a weird noise and instead of a nice high pitched idle it turned into this low pitched slower idle. I would give it gas and it wouldn't rev up much at all, and not even move the truck.

I immediatly checked the tranny. That was fine. Cleaned everything up and tried again. Same low pitched "weird" sounding idle, hard to start, etc. Then... clunk. No more. Remove the backplate and the rod fell out as pictured.

Seized top pin on the rod that slowly went over time? That's my guess. Then the top broke, the rod smacked up into the piston and cracked.

Traxxas didn't honor warrenty because of "obvious signs of running way too lean" such as carbon on the piston and exhaust port. It may have been there, but running lean can't be the only cause for that (what about burn off for ARO or WD? What about a good running engine... with all that oil there would be no deposits? I can't believe that... what about running rich? Would it be like a 2 stroke and cause piston wash?)

I always had good smoke, 220-240 temps. I did a lot of high speed runs with it, but never for more than a few seconds. I know it was rich just by the sound. And if "factory" is set rich for breakin, LSN was actually richer than that, and HSN was right about there as well.

That's where it ran best. I noticed when I started leaning it it wouldn't get any better like in the "video" they send you. So I went the other way and it DID get more responsive. Especially on the LSN. At factory it wouldn't wheelie at all, but a couple small turns richer on the LSN and it really woke up!

Part of the issue I think is that they're still using the 2.5 tuning on a bigger engine. Same carb, same settings, same instructions. To me that just doesn't pan out. Bigger engine needs more fuel. At least in my years of tuning 2 and 4 strokers, that's how it's been. But according to the Traxxas dude "nitro engines and 2 or 4 stroke engines are completley different..." Oh.. ok.. lol

Dr Nitro

You have to realize that 2/3 of the jokers at all these big rc companies that actually work on repairing or replacing stuff are highly trained morons that are doing nothing but going by the "company policy" If for one moment, they could just realize that castor varnish is a GOOD thing and brown/ black piston tops is 100% normal.
One must also realize that these morons have been trained by other higher ranking morons, so it seems that nobody has ever been properly schooled in little two stroke engines, so they are just applying what limited (or incorrect) knowledge they have. Its kind of like a poluted gene pool from incestual in-breeding; you just can not get rid of the bad genes once a new life is born.

It was rather easy to tell from the picture that lean running was not the sole problem, a little bit of "silent ping" is not going to do that kind of damage on a rod with no internal defects.

I had a very long chat with Fuelman this morning regarding your post, and we are in total agreement. He said that he's seen this happen on a couple engines, very similar failure both caused by hydrolic lock in OS 70 heli engines, same as the one I saw. he also said that there was no way possible that it was a fuel/ lube related issue.

Don't get me going about Polaris, I love their sleds, I hate their company.

rawkfist2

We have 2 Polaris 500 olimpic sleads that are ok. But i love the Polaris 500 Mossy Oak 4 wheeler that we just got. I cant get it stuck and the power response is amazing. I would call Traxxas back and tell a different assosiate of your problem. I bet someone else would swap an engine for you or just at least the rod. Then sell it.

legbuh

Just got the new 3.3 today. Registered it online and was sure to leave a note about most of the CS I received was great, but this engine replacement was not and I was upset.

I understand "the moron theory" all too well. Having knowlege of engines, I backed him into a corner and he started to give. Should have just pushed a little harder or mubled "OS is on the way"...

If this next one lasts, great. If not, well, it will be fun for me at least.

wjvail

My Feedback: (3)

Since I mix a little fuel in the local area I keep track of how folks are doing with their engines. We have a strong following of folks running our fuel and a great reputation with the car folks. I was a little alarmed when the 3.3's came out and the first 5 sold in the local area broke rods or piston skirts! The cause will not likely be positively, exactly, and without-a-doubt explained but the engines stopped failing when folks started building more heat more quickly in the engine when it was being broken in.

The rod for the 3.3 is the same part number as the 2.5 and the 3.3's I've played with were shipped pretty tight. It also has a much larger heat sink head than the 2.5. With a bigger piston, tight piston/sleeve, slightly under sized rod(?), better cooling and a cold break-in I think the engines were damaged on the first tank. Often when an engine is damaged and replaced, a less than experienced hobbier might be tempted to break-in the next engine "more carefully" I.E. Richer and colder and thereby ensuring the next engine will fail sooner.

legbah... Can I ask how you broke your engine in? Do you have a temp gun and did you use it? I'm not pointing fingers or looking for blame. Just looking for a common cause.

Bill Vail

nitrorcjunkie

IMO after run oils and WD40 have no place being used inside an engine. If you run your vehicle with any regularity(once a week or more) you do not need to use anything in the engine. With the synthetic oils being used in just about all fuels available today for r/c car use( all the brands of fuel on the market are produced in 3 or 4 plants, no matter whose label is on the bottle) there's enough residual lubricant in the engine to protect the internal parts. as for the color of the top of the piston, My 2.5R (on my 7th gallon of Byron's 30%-yes, I log every run) piston is black, my Mach .427 is brown, so color is not a very good indicator of a lean condition. I'd have to agree that the rod damage is the result of metal fatigue, but what caused it? Traxxas is an excellent company all around, and since the 3.3 is new on the market they should have been interested in getting your blown mill back to do some diagnostic work to determine if it was indeed a mfg. defect or an inferior batch of billet or whatever. My friend and basher buddy (victim) got the first 3.3 in Georgia (thru HobbyTown) and has had no trouble out if it at all. If there is indeed a mfg. problem with the 3.3, Traxxas knows about it and will more than likely remedy this situation.

legbuh

This particular one that blew the rod I broke in per the book, ie Traxxas style. Never again will I do that.

My 2nd motor I broke in using Heat Cycling, following posts made by Fuelman. This motor is still fairly strong and I've run 2 gallons through it so far. I was running it too lean again, but one day I played around using 1/2 gallon of fuel and found some neat things to figure out jetting a little better.

These 3.3s will get better the leaner you go. Even if you're too lean they don't cough, complain or anything. And still put out decent smoke and stay around the upper 200s in temps. But, at that leanness I found the wheelie factor goes away fairly quickly.. like in a gallon (from engine wear). Luckily this time I saved it before it was too late.

Anyhow, one interesting thing I found when tuning is that when doing the pinch test, if the HSN (yes, HSN) was too lean, even though I'd get 3-4 seconds to die, if the RPMs went up more the leaner the HSN was. Even with the time remaining constant (ie adjusting the LSN only affected time, not RPM rise, HSN seemed to affect RPM rise during pinch test)

So instead of running around 3.25 turns out on the HSN and the LSN 2+ turns out past flush (where I finally stopped leaning because it just didn't feel right, but ran great) I am now a little less than 4 turns on the HSN and maybe 1/2 out past flush on the LSN.

I went through 1/2 gallon of fuel just playing with settings thinking this motor was gonna be toast soon anyhow. If not, this winter it will be for sure. Then I'll give the 3.3 another chance and know not to follow any of Traxxas' recommendations for break in or tuning.

smaxx3.3

i have heard alot about 3.3's breaking rods. i have 4 gallons and the piston is still the same color as it was when it was new.

wjvail

My Feedback: (3)

I'm finding this is a common thread in the 3.3 failure story. I don't, and never have, recommended the Traxxas break-in. Their procedure is a nice controlled procedure for those with no other modeling experience or help. It prevents folks from "firen' 'er up and blazing around the yard WFO, full on lean." Unfortunatly I believe the Traxxas book break-in is too cold.

One day I was in the hobby shop when the local hobby dealer sold a new 3.3 to a fella and recommend a long break in per the Traxxas manual (why wouldn't he) and not over 200deg. After the person left, I mentioned that I believe that cold break-ins were the source of failures. I recommended getting the motor up to 240(ish) quickly and running around the parking lot. Failures stopped shortly after that conversation.

Bill Vail

rawkfist2

Yea the LHS guys are retarded. Some dude who needs money and just wants to sell you things.

wjvail

My Feedback: (3)

Careful now... The folks at my LHS are very good friends of mine and ether I've misread your post or you're out of line here... In the case of my LHS, nothing in your post is correct.

Bill Vail

beelzebubishere

My Feedback: (1)

Not surprising Bill.....read some of his past posts....
Sometimes you just need to frequent the smaller to avoid that sorta thing.... http://nitroobsession.proboards79.com/index.cgi

BlackLabel4682

That is crazy .. I have never seen any type of engine damage like that before in my entire life.

Mr. Mugen

here's one