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chrisexv6

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  1. Bashing
OK, this is a culmination of a bunch of things that I've been asking about for the last two weeks, I'm totally stumped, as are two LHS guys that I know.

During the off-season I tore my 'Maxx completely apart. Upgraded the tranny to a FOC, new chassis, bulks, and bumpers. Did the spring mod to the rear diff and packed the rear diff cup with auto wheel bearing grease. Put everything back together, it all seems fine. Truck pushes freely forward, binds a little when going backwards (I assumed this to be the FOC working). Each diff by itself spins freely.

Didnt touch the TRX that I ran last season. Also noticed that it had rust on the inner main bearing. No problem, replaced the internal main bearing with a Boca version. Started her up, it runs like mad. Almost *too* mad. The RPMs seem to wind out way too quickly. Idle always seems high, but I kick it down a little, and it seems fine for a little while. Even if I give it a light touch of the throttle it seems like the engine wants to rev to redline and beyond. Naturally, I get thru half a tank and the engine overheats.

Flash forward a little..........I assumed the issue was with my TRX, and since I wanted a Fantom already anyway, I ordered and installed it. Went to break it in, started having issues from the beginning. Bogged in midrange throttle, figured it was too lean. Richened it, ran it half a tank of break-in, stalled and wouldnt restart. Brought it to an LHS, we got it to start, albeit running very rich. Brought it back to my break-in location, ran for another 1/4 tank or so, stalled and wouldnt restart. Took the temp after each stall........the highest it had gotten was 294, which is well within what Fantom says is OK.

My question is if anything I did in the off-season could be causing my issues. The FOC seems installed correctly. The diffs are in correctly, and spin freely. I dont feel any binding. The clutch pads and bearings are brand new. Fuel tank and lines are brand new, only thing not swapped out with them was the fuel filter, but it has been cleaned 3 times.

Did I go from a bad TRX engine to a
defective Fantom (how many of THOSE are out there?)? Or is something on my truck causing me to hurt engines right away.

Fantom is fixing the engine for me though. I pulled the glow plug and noticed black shavings on the plug itself, and the sleeve was scored.

My goal is to find out if I just had bad luck with engines, or if the truck is the issue.....preferably BEFORE I get the replacement Fantom, so I wont break that one as well if the truck really is the problem.

Any ideas?

Thanks!!!
-Chris
 
My TRX is the biggest piece I have. It sounds to me like you should have leaned the Fhantom, not richen.

Also, traxxas' means of breaking in a motor suck.

Start with idleing a few tanks slowly leaning out and adjusting idle speed keeping temps down. Then lean some more to reach opperating temp at idle. Keep heat cycling allowing motor to cool between tanks. Once idle is smooth and temp is good you can start putting around. I'm sure someone else has a differant oppinion, or at least something to add

I ruined my first 2.5 by following traxxas' break in proceedures. Lucky for me they rebuilt it free. Still don't like how finaky it is. Hope to have .21 conversion soon. Or maybe that picco 21 they say is dirrect replacement.

Good Luck
 
Well, I'm pretty confident I needed to richen the Fantom when she started cutting out at midrange, but I will talk to Fantom before I even get the replacement engine to make sure.

As far as Traxxas' break-in procedure, once I saw Fantom's, I have to say that anything is possible!!! Although, I'm surprised Traxxas and Fantom dont have the SAME procedure. The engines run in the same temp range (as much as Traxxas wants to say their engines never get over 270, its just not true), same build, etc.

I did notice, however, that the Fantom piston and sleeve are noticeable thicker than Traxxas. I'm sure that helps the longevity and heat-tolerance a little.

I neglected to mention that I also added a Sirio pipe during all these mods. Is it possible to have a bad tuned pipe that would cause overheating?

-Chris
 
Is it possible your fuel filter (if it's the screw apart kind) is sucking air? mie was, took a long time to narrow it down.
 
Its actually a one piece design, the Sullivan CT-1.

I had the Du-Bro two piece, but got rid of it because I could never really tell if it was leaking air or not.

-Chris
 
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