So I bought a used nitro from a kid.

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Alan81

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Long story short he said it was only 1 year old, runs and drives fine, but just needed a glow plug, and it was missing the body because he broke it and never got a new one. Guess that should have been my first clue, but I figured if someone is telling you something, you take them on their word. So I gave him 120 bucks for it, which isn't an outrageous price, but I probably would have offered less had I known what I know now.
(Supposedly it's a traxxas rustler, but i'm working with traxxas to get a positive ID on it.) It has a TRX 2.5 engine on it.

Anyway, i'm going around and around with this engine trying to get it dialed in.
Here's what i've done :

Cleaned the fuel tank, lines and carburetor
Added new fuel
New glow plug
New glow igniter (the one he gave me was broken)
Zero'ed out the throttle servo and linkage (it was running wide open the first time i started it)
Fixed the brake linkage
Reversed the shock tower (it was installed backwards) so that the upper chassis deck was actually attached to it.
Tore apart shocks and added motor oil to them (don't flame me for this I just wanted to make sure they didn't need new seals, I'm going to get shock oil on my next trip to LHS 2 hrs away)

Pull start is currently broken and on order. It should be here tuesday or wednesday. So I used a drill to start the engine. In order to have access to the OWB, I had to rotate the exhaust pipe up. What I found was that it was running so rich that it was filling the exhaust pipe up with fuel, and the engine was dying. Is there any reason other than the settings on the carb that would cause it to run so rich like this? It was spitting fuel all over the place out the side of the exhaust. I did turn the needles back to what the manual for the engine says they should be at. LSN flush with the front of the throttle arm and HSN 4 full turns out from closed position. Problem is with the exhaust in the position it was in, I couldn't run it long enough to make any adjustments.


Pictures :
http://imageshack.us/a/img812/302/8ec1.jpg
http://imageshack.us/a/img713/8321/kiru.jpg
http://imageshack.us/a/img818/5374/iup9.jpg
http://imageshack.us/a/img194/9443/2bz4.jpg
http://imageshack.us/a/img268/5705/t9hx.jpg
http://imageshack.us/a/img547/7600/uxdm.jpg
http://imageshack.us/a/img23/8185/x9uf.jpg
http://imageshack.us/a/img823/7463/4h3o.jpg

I'm very mechanical, so this kind of stuff comes pretty easy to me at least the basic understanding of how things are supposed to work. Disassembly and reassembly is simple to me. If anyone can give me any tips on getting this engine working that would be sweet.

Thanks in advance

-Alan
 
First off, welcome to the site and the crazy hobby that is RC. I'll confirm for you that that is a Nitro Rustler. I'm also 99% sure that it's older than a year, I think the newer Rustys have gray upper chassis plates. How's the compression of the engine? If it's worn, it'll let excess fuel past the piston.

Sent from my GT-I9300 using Tapatalk 2
 
that is deff an older version black shock bodies and am radio are a dead give away
I would go and seal up that engine while you are waiting on parts but if there is little to no compression I would put a new 2.5 on your shopping list
 
First off, welcome to the site and the crazy hobby that is RC. I'll confirm for you that that is a Nitro Rustler. I'm also 99% sure that it's older than a year, I think the newer Rustys have gray upper chassis plates. How's the compression of the engine? If it's worn, it'll let excess fuel past the piston.

Sent from my GT-I9300 using Tapatalk 2

I don't really know how to check the compression.

When I rotate the OWB, I can feel the piston building pressure against my finger over the exhaust port with the exhaust pipe removed. I'm sure that's not as accurate a reading as I need, but it's the best I can do for now.

that is deff an older version black shock bodies and am radio are a dead give away
I would go and seal up that engine while you are waiting on parts but if there is little to no compression I would put a new 2.5 on your shopping list

What do you mean by "Seal up that engine" ?
 
There's a sticky on how to seal up your engine. When you take off your exhaust header look into the exhaust port while turning over the engine with your finger, if you see any lil bit of brass on the piston as it strokes then its time to rebuild it with a new piston/sleeve/con-rod combo. You probably only need the piston and the sleeve, but your there you might as well change the con-rod too.
 
There's a sticky on how to seal up your engine. When you take off your exhaust header look into the exhaust port while turning over the engine with your finger, if you see any lil bit of brass on the piston as it strokes then its time to rebuild it with a new piston/sleeve/con-rod combo. You probably only need the piston and the sleeve, but your there you might as well change the con-rod too.

Is the brass color worn from the sleeve onto the piston, or just the surface of the piston worn away? Just curious for my own future reference. :) I'll go check it out.

Just for info added to this thread, when turning the OWB, I do have a spot where it "sticks" and becomes difficult to turn with my finger. Not impossible, just noticeably uncomfortable on the fingertips.

---------- Post added at 9:43 PM ---------- Previous post was at 9:32 PM ----------

This is what you mean?


http://imageshack.us/photo/my-images/580/1aq8.jpg/


:\

And this would cause the fuel spraying out of the exhaust?
 
The brass is what's under the silver finish, I believe it's like that on both the piston and sleeve

---------- Post added at 9:54 PM ---------- Previous post was at 9:44 PM ----------

Yup that what i meant. Yes it can cause excess fuel to pass around the piston and out the exhaust port, but to some extent that has to happen anyway. The tuned pipe in your rusty is suppose to force that fuel/air mixture back towards/into the combustion chamber to get ignited by the glow plug. R/C nitro engines don't have intake or exhaust valves to open and close the combustion chamber so the engine relies on the back pressure of the tuned pipe connected to the header to not let too much fuel escape.
 
So even if the engine was running super rich, it would just run crappily, not spray fuel everywhere, is that correct? I'm pretty sure I have the needles set to factory settings.

If it were your 120 dollar hunk of junk would you just rebuild it, or put a whole new engine on it? :)
 
I'm very mechanical inclined. It bothers me to see a perfectly good engine block go to waist. Once you wreak the crankshaft or put holes in the block itself then I would consider getting a new engine, but that's just me. If you want more power then definitely look into an aftermarket engine.

When you tear the engine down check the inside of the block and crankcase for scratches if its got scratches then yup get a new engine.

---------- Post added at 10:18 PM ---------- Previous post was at 10:16 PM ----------

I'm sure that engine will act fine for about 6-7mins before it heats up causing expansion in the engine components then it will start to give you problems, like the one you posted.
 
I'm very mechanical inclined. It bothers me to see a perfectly good engine block go to waist. Once you wreak the crankshaft or put holes in the block itself then I would consider getting a new engine, but that's just me. If you want more power then definitely look into an aftermarket engine.

When you tear the engine down check the inside of the block and crankcase for scratches if its got scratches then yup get a new engine.

---------- Post added at 10:18 PM ---------- Previous post was at 10:16 PM ----------

I'm sure that engine will act fine for about 6-7mins before it heats up causing expansion in the engine components then it will start to give you problems, like the one you posted.

Got it. I guess i'll take it apart and see what I find.... :(
 
So even if the engine was running super rich, it would just run crappily, not spray fuel everywhere, is that correct? I'm pretty sure I have the needles set to factory settings.

If it were your 120 dollar hunk of junk would you just rebuild it, or put a whole new engine on it? :)

It'll be cheaper to buy a new one vs doing a "correct" rebuild.

Sent from my GT-I9300 using Tapatalk 2
 
Have any of you tried using the power up/exchange program directly through traxxas?
 
Have any of you tried using the power up/exchange program directly through traxxas?

I did it through my LHS, I've never done it directly through Traxxas though. I would recommend just putting another 2.5 on there, the 3.3 is overkill on a Rusty and doesn't let the front end touch the ground. :D

Sent from my GT-I9300 using Tapatalk 2
 
It sounds like it still has compression, I would tear it down put a bit of after run oil on the bearings, seal it once its cured fire it up and see what it does
I just did the exact same thing to a 2.5 that I thought would be toast as in it was totally seized but with a bit of elbow grease I fired it up and it runs great
 
If I were to post a video of the piston moving would that give any extra insight to the condition of it? If so I could do that tonight.
 
A video of the piston moving will not help much to determine if the engine is still in good condition.
Unless you have a lot of experience in the “feel” of the compression the best way to determine if the engine is salvageable is to remove the piston and sleeve. Once removed if you can slide the top of the piston (with minimal force) even with, or past the top of the sleeve it’s most likely worn out.
You also want to look for scratches/scarring on the inside of the sleeve/outside of the piston, and on the crankshaft.

FWIW, Traxxas doesn’t make an engine that’s worth a rebuild. You will be better off buying a new mill if needed.
 
A video of the piston moving will not help much to determine if the engine is still in good condition.
Unless you have a lot of experience in the “feel” of the compression the best way to determine if the engine is salvageable is to remove the piston and sleeve. Once removed if you can slide the top of the piston (with minimal force) even with, or past the top of the sleeve it’s most likely worn out.
You also want to look for scratches/scarring on the inside of the sleeve/outside of the piston, and on the crankshaft.

FWIW, Traxxas doesn’t make an engine that’s worth a rebuild. You will be better off buying a new mill if needed.

I ran in to the same thing with my 2.5
After looking on rebuilding it it just wasn't worth it.
Got a 3.3 power up for $110 and swapped it. No more fuss.
Snook is very right trx engines are not worth rebuilding. Not even worth spending time to trouble shoot when they look like that IMO.
 
This has all been very great help. Thanks to all.

Now does anyone have advice on how to break this to my wife? :hehe::hehe:


Since i've already ordered a pull start, i should be able to get a 2.5R without pull start, amirite?
 
Instead of getting a traxxas engine, have you considered a picco, or a novarossi. Snook Man I think has experience with novarossi engines, I've got 3piccos, but I have lil to no run time on them. Well I ran one for a tank of fuel.
 
The one i got came with a pullstart but dont worrie you never have enough pullstarts lol.
As to the wife....... well 2 options
#1 lay down the law!
#2 get her one or the kids if you have any.

I went with #2 as i want my coffee and dinner made :)
She runs a 1/10 scale buggy
And my 9 yr old runs a jato 3.3 now. The other three have helis that i picked up today.

---------- Post added at 10:22 PM ---------- Previous post was at 10:19 PM ----------

Funny how you come home with toys for the kids and nothing was said but let me come home with a new emaxx and boy she was mad as hell for like 20 min.

---------- Post added at 10:28 PM ---------- Previous post was at 10:22 PM ----------

EMAXX was well worth it tho. Oh and a big big tip. Never ever let them see how much you sent lol.
I spent almost a grand on emaxx bl with charger and telemetry
 
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