nitro beginner needs help

[Racer 1966]

Your son's not much for words huh? I like the big sigh at the end.

I'm with Matt,you really need to pull the back plate and make sure of what is really happening.

 

[ohsnap]

Infinity's website isn't much help but I did find this pdf for an 18 engine.
http://www.team-infinityrc.com/download/RTR18S instruction manual -2.pdf
A search for an 18 cxp came up empty.

Seeing that your son had an external hex shaped owb in his hand in the video and that their site's .18 pdf shows that model, I don't think there's an internal owb that needs to be dealt with.

I'll go back to what I asked about from what I couldn't tell in the video.
I can see that when your son turned the flywheel, the piston went up and down.
It looks like when he turned the shaft on the pullstart end that the piston also went up and down - but I can't tell 100%.
Hex OWB not on the engine:
Turning the shaft on the pullstart side clockwise - does the piston go up and down?
Turning the shaft on the pullstart side counter-clockwise - does the piston go up and down?
If the answer to both questions is yes - I believe that the internals are fine and that the OWB needs to be cleaned or replaced - which is what I'll bet is the problem.
Soak it in denatured alcohol / dry it off / give it a light spray with wd-40 / put it back on and it should catch going one direction and spin going the other.
If not, replace.

If the answer to one or both of the questions is no - and if the PDF matches or is close to your engine - the only internal parts that I can think of being hosed to prevent the engine from turning over in one or both directions are:
AS46018 - One-way bearing shaft (the notch is gone)
AS46036 - The crankshaft - specifically the little nub on the end that slots into the notch on AS46018

One good thing - looks & sounds like you have compression.
I agree with Racer - his sigh is priceless.

 

[edfdave]

Hi, been away for a couple fo days. Ta fro all te replies.

When you turn the shaft on the pull start side the piston does NOT move. So I'm guessing that it's the bit with the notch or the other bit with the thing that fits in the notch is broken.

Thanks for all the heads helping here. I'm v impressed. No, my son has few words and is indeed V p*ssed about it all !

 

[speedingbulletbp]

The part with the notch in it that your talking about is called the one way bearing and is most likely the cause of why the piston isnt moving. There is also only one way to install that part otherwise the piston will not move

 

[edfdave]

hi this is edfdaves son.
@ TGF the owb just pulls off. it is fine as when i turn the owb (the hex thing?) the shaft its connected to turns so i think the owb is ok. when i turn the shaft coming out the back ( pullstart end) the piston does NOT move.

 

[speedingbulletbp]

that shaft is called the one way bearing, it may not be installed right. Theres a special way to connect it.

 

[Macguyver]

that shaft is called the one way bearing, it may not be installed right. Theres a special way to connect it.

the one way bearing is the black hex thing he had in his hand ..the shaft that comes out of the backplate is what it is ...a shaft ...it hooks up to crank inside the engine ...I've taken the exact same engine appart for a buddy ...i sealed it for him ...there is NO internal OWB......you need to take the backplate off and check inside to see if everything connects .....my best guess is that something is broken inside

good luck

 

[ohsnap]

Speedingbullet:
Look at the PDF for an Infinity engine.
The shaft in this case is simple a shaft and not one that is integrated with a owb.
The owb in this case is the external hex shaped owb and while it is possible for them to have put the owb on backwards, that would not account for why when he turns the shaft coming out the back (the pullstart end) that the piston "does NOT move".
It's very similar to how a Traxxas engine is constructed and not like a Picco (which has an internal owb).

Edfdave - you know what this means - you'll need to pull the backplate to see what broke.
1. Since you've already rounded off your allen wrenches - when that happens, I grind off the rounded off end with a Dremmel metal cut-off attachment - you may want to try this.

You can also...
2. Get a good set of metric allen wrenches and try again.

If you've enlarged the holes on the allen head, you've got a couple of options.
3. Get a good set of SAE allen wrenches - these sometimes fit the half size increment. I'm guessing that your allen head is 1.5mm and these guys are always a pain.
I've had success using 1/16 or 5/64 allen wrenches to fit heads where the hole has gotten too big for a 1.5mm allen wrench.

These last two options mean you've already decided that you're giving up on keeping / reusing the existing allen headed screws and are going to replace them. They're usually 2.5mm screws...and you can buy 2.5mm phillips head screws to replace them. Don’t have to limit yourself to allen headed screws.

4. Drill out the head. You need to be careful to not drill too far.
Pick a drill that is just larger than the threaded part of the screw. Drill down until you can pop the head of the screw off and then once you remove the backplate then use a set of pliers (or better yet vice grips) to grasp the nub of the screw to unscrew it.

There’s also a tool called a spiral tool extractor, but it never works for these little suckers.
By the time you drill the hole out to use the extractor, you’ve done #4 above.

 

[speedingbulletbp]

Sorry, I didnt really put into perspective what type of engine it was. It being like a Traxxas engine then yes you need to take off the backplate. I had to do it with my 2.5 4 years ago so I dont remember too much how a Traxxas engine is built anymore. I can still remember parts of what I did to fix it, and I do remember that it was a pain. Ill check it out again and see if I can remember what hes refering to. I apologize for the misunderstanding.

 

[edfdave]

Hi, I've had a look at the pdf at last and can confirm it is like the one I have and I agree with TGL.

AS46017 is definitely the owb (the "hex thing"). That leaves AS46018 One-way Bearing Shaft and AS46036 18 Crank Shaft for Pull Start as being the likely problem areas i.e. the notch &/or pin.

I've had a reply from the company and they say "it sounds like the small pin/spring has stuck in on the crank.this can be a common thing to happen when running in a new engine". Not sure if they also mean the same parts (I cannot see a spring tho') but it sounds like they might. They also seem to be saying that this would be fixable under the warranty so I guess I'll be sending it back. :\

 

[Foolproof]

Hope they get it fixed for ya man. I know I had a ton of headaches breaking my Revo in. It would seem that when you get a new or used nitro that you need to take a few things apart and put them back together better than the factory sends them out. I know for sure from now on that will be happening and if its used then that adds many more things to the list. Maybe you and your son will be able to enjoy it soon cause once you get them running right they are a blast for sure. g/l

 

[ohsnap]

Cool - let them deal with fixing or replacing it.

FYI - The pdf that I found was not specifically for your engine - it was kind of the next best thing that I could find under the circumstances.
So when I mentioned that one possible problem could be "The crankshaft - specifically the little nub on the end that slots into the notch on AS46018", their response to you when they said that "it sounds like the small pin/spring has stuck in on the crank" is equivalent to the nub that I spoke of.

On the end of the crankshaft is a round extension that the connecting rod slips over / connects to / rides on - which makes the piston go up and down.
Most pull start engines have a little nub sticking out beyond this round extension.
Some other engines like HPI's 3.5 hollow out the extension and put in a spring and hardened pin combo.
The pin is the equivalent to the nub that I mentioned.
The nub (or pin) is what fits into or catches the slot on the shaft that fits out the back of the engine - which is what the owb fits onto.

 

[edfdave]

Hi all, thanks for the help. I've learnt a lot but I think I'll be sending it back. I haven't mentioned a ton of other issues yet e.g.

1. Glow Plug Igniter does not take a charge so having to borrow a friend's.
2. Wheels do not really freewheel and it doesn't seem to be the disc brake. Not an issue yet as not even broken in yet.
3. Last but least ... one pair of shocks keep going rigid and then for no reason suddenly free up and work again ..!

Watch this space ...

 

[Metalhead Matt]

That's the nature of the beast with cheaper rc's. Check for loose grub screws on the driveshafts, make sure your gear mesh isn't too tight. I'd pop the shocks off and make sure they are the problem, and that the suspension isn't binding. Stick with it. You'll get 'er going.

 

[weezracen]

Yeah just stick with it the more u learn the easier it gets! Its a great hobby! I still have days where nothing seems to work right [ like today] and days where my rig can't be stopped. Good luck.

 

[winsta]

here's my another good way of getting rounded screws /bolts out if you can get into them, hacksaw a line across the head and turn it into a flathead screw saved me many many times

 

[hamz9561]

A Dremel tool works as well as the hacksaw and it's a bit faster.