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  1. #1
    RC poster
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    Jul 2011
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    Exclamation 1 month and 3/4 of a gallon and I'll have to replace the engine...

    Hi, I bought my Slayer Pro 4x4 about a month ago. This is my first RC and first Nitro engine.

    I broke in the engine according to the manual and it was great! My temps ranged between 220 F and 280 F. Soon as it hit 280 F I would richen the mixture. I was worried when my temps reached 300 F. It still had nice smoke so the engine is still being lubricated. It was beating some 1/8th models with big blocks! It had torque and it's speed was awesome! I also liked how it almost sounded like an F1 roaring down my street!
    It all went to crap when I heard a bad noise coming from the engine...
    It sounded like some kinda clattering/grinding noise.

    Here's some issues I had with the truck.

    - throttle servo was glitching during break in (replaced it)
    - carb is sticky (when I pulled on the throttle the carb would stick near the beginning of the slide.)
    - 2 weeks after and 1/2 a gallon the engine was making a weird grinding noise.*

    Someone at the local track told me that it's the one-way bearing that supports the shaft connected to the EZ start assembly. Apparently it's a common problem for these bearings to go out. I was told that the EZ start is part of the problem and that it puts unnecessary load on the shaft. Hence the reason why the bearing went out.

    I was told that I should order the bump start engine next and that it should fix my problem and that it will give me 20% more power and a better weight ratio as a bonus. I was given this advice from someone who owns 3 models with the same TRX 3.3. He said he kept having the same problem and that he went through a couple engines because of that bearing...
    He runs his models hard and he's serious about racing. He posts great times on the clock with his slayer too but when I heard that he had gone through 14 engines, I was skeptical. I am a diesel mechanic so I understand the whole concept of compression engines. When it came to tuning it I found out that they are a totally different animal than the diesel engines used in the transport industry.

    The engine was great until it started to make the sound. Soon after I knew that it was definitely the bearing because I started to see shrapnel in the fuel that was exiting the exhaust and I could feel the vibrations traveling through the engine on the head and through the easy start.

    Should I really blame the EZ start and that shaft it needs to spin the engine?*

    The EZ start is convenient and I was even thinking about installing a remote starter but if the one-way bearing keeps breaking then I may have to consider some options.

    A bump start isn't a bad idea if I want more performance but the remote starter is convenient.*

    Should I go with the bump start to avoid this apparently "common" issue?

  2. #2
    RC Qualifier
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    May 2011
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    new york near a few big lakes
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    You could try a different brand of bearing by a aftermarket company like avid rc I now sells hole kits for the entire engine and even ceramic bearings as well. I have not thrown these in yet but imo when mine does give out I'm going to give this a try. I'm at a gallon and a half cleaned the one way bearing at a gallon and have had no issues yet. But I have different problems with mine right now. And I'm sure someone on here has thrown in something different then a oem one and could give there input.

  3. #3
    RC Turnbuckle Jr. Snook Man's Avatar
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    Jan 2008
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    The OWB or starter shaft most likely had nothing to do with the crank bearing going bad.

    Long extended WOT runs down the street sounding like a F1 will kill a bearing or con rod often.

    Taking advice from someone who admittedly has gone through 14 engines would not be a good idea in my opinion.
    No slipper/tall gearing/power = broken parts.

  4. #4
    RC Champion
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    14 engines? man he must tune worse than I do LOL.





    God answers prayer,pray,believe,NEVER GIVE UP!!!

  5. #5
    RC Champion
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    OWB and EZ-Start nothing have to do with a failing rear engine ball bearing but long WOT runs yes. In my opinion Traxxas engine bearings are not the best in the market (sorry Traxxas), even though good engine bearings sometimes last less than 4 gallons depending on the way you drive. Go for aftermarket bearings like Avid or Boca and give them a try.
    There are no stupid questions, just stupid people.

  6. #6
    RC poster
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    Jul 2011
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    This is my first RC so I'm still learning how these nitro engines behave and how I should treat them. I haven't gone longer than 5 or 6 sec with WOT. When I do finish a pass or drag race, I give short blips to cool the engine.
    Please correct me if that is wrong because I don't want to be going through 14 engines, haha!
    Hence the reason why I turned to this forum for some advice.
    Although, I have passed the controls to friends and I haven't counted how long they hold the throttle...*
    That may have been my down fall.

    Thanks for the info! I'll order my new engine and get things rolling again. Any suggestions for the break-in? I broke-in the first engine without any real guidance except for the manual. I'm just wondering if there is anything I should be aware of. I know plenty of smoke is good because it means the engine is being lubricated. Is there anything else?

  7. #7
    RC Champion
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    Do the break in as said in the Traxxas Manual, just be careful not to exceed 220F the first few tanks. After that you can start tuning for performance and try not to go beyond 270F-280F. Never tune for temps but always watch temps.
    There are no stupid questions, just stupid people.

  8. #8
    RC Champion
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    Definitely the crank bearings, not anything to do with the starter. A bump start is great for racing. If your engine was fully broken in and tuned correctly you should've been able to hold it wide open for most of your radio range....as long as it's getting into 2nd gear and everything is spinning freely.
    Friends don't let inexperienced friends drive their rc cars....it rarely ever goes well.
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