eric_ok

Hi every one,

today i just register in this forum because i got several problem with a redcat o.18 engine

to make a short story about;

the engine crank but no start (have a roto start,no pull start)

the glow plugs is good

carbs look ok

cylinder sleeve//piston look good and have no scratch or anything...

the rear bell housing is seal an front engine bearing have 0.0005' of travel in both sense

a strange thing i see on the engine is i have no vacumm from the intake and low exhaust but i have compression on the engine and never see a air leak...


did someone can help for plz???


thx to every one can helping me!

Swamp3r

A few things was the engine running before? Did you test the glow plug with your ignitor to see if it glows? Have you checked for leaks around the carb? Have you primed the carb? Do you have a 1 mm gap(to start) inside the carb take off the air filter to see, have you checked your lsn and hsn to make sure they are factory for now? I hope this gives a start from here we can help you more if this isn't one of the problems. What truck is it btw?Edit...Make sure your radio and truck are on when you look at the gap in the carb. Another thing make sure your exaust pipe is sealed and the header is tight.

eric_ok

thx for the faster answer!

the engine run before, but something like 2-3 minutes with a low power, when the engine begin to make hard start, when he start he try to make overspeed with a complete close carbs.

i know for now the only method i see to start the engine is with a electrical (3600rpm drill) and when he start is run like full throttle for 25 second with a close carbs.

the glowplug ignitor is reaaly good and glow plugs too, i dont see any leakoff from carbs or header and the muffler is good (i reseal the exhaust manifold with cinetic liquid high temp gasket maker from permatex (a kind of really heavy lock tite)

what is the lsn and hsn exactly?? ( i dont know exact term they used in r/c world)

what can happens if the radio or truck battery is off ?? they dont supposed to work?? someone tell to me to check the battery but all servo work normaly....

eric_ok

oh.... btw, is a redcat tornado boggey.... with factory .18 engine on

Swamp3r

Ok lsn means low side needle hsn means high side needle then you have your idle screw. Make sure the radio and the truck is on when you check for the 1 mm gap inside the carb. And to answer your question if the radio and receiver is off the servo will be set where it was last shut off. Meaning if it died at 1/4 throttle it will be at 1/4 throttle when you try to start it thats why I said to have the truck and radio on. You can keep asking questions we are here to help each other out.Edit I had to fix typos lol

eric_ok

for both needle is factory reset....

i'm a truck mecanic, and for me is look if they have a intake valve broke on the engine... just the engine alone without carbs or muffler, is look has the engine breath is not a flow of air.... but i see i have a good compression on... that the real thing i never understand...

Swamp3r

Cool your a mechanic then you know these trucks use the exaust as a fuel pump. Check for leaks there.Edit did you test your glow plug like I said take it out and plug it into the ignitor it should glow almost instantly

eric_ok

i put air in the fuel tank to be sure they was pressurise... but the only thing they happens is the fuel run all over of the truck and the carbs dont try to take air... the reason why i remove the carb to see if the engine try to got air from the intake.... but they just breathe...

Swamp3r

K I need you to test the glow plug in your ignitor to see if it glows first then we can go from there. Edit I'll be up for a few more hours so ask away.

eric_ok

lol, all five minutes i remove the glowplug and make a check to be sure they have a good red colors.... so i know the glow plug on the engine and the ignitor is really good

Swamp3r

Ok prime the engine through the carb 2 drops at the most and make sure the carb opening is around 1 mm I'd have the truck up on blocks so the tires aren't touching. No diff than priming a normal car

eric_ok

this test is already do.........

Swamp3r

So your saying you have primed it and it doesn't even fire? If it doesn't I'd go with a hotter plug. Does it even fire up? if it does then we have other issuse's If it does fire up and dies you may be waaaaaaay tooo lean.Thats the big question does it try to start when you prime it?

ugly duck

It sounds to me like a MASSIVE air leak in the bottom end. If you've got good compression your piston/sleeve is probably still good, but you've probably got a really bad leak in the bottom end. I'm saying this because when it does run it runs very fast with a closed carb, and it won't stay running.

Remove the engine from the car, attach a piece of fuel tube about 10" long to the fuel inlet on the carb, and blow. Air should come out the carb. Plug the carb with your finger and blow again. You should hear an air leak from somewhere: front bearing, the base of the carb, or the back plate. Seal them up with RTV sealer, but make sure the RTV sealer you're using is resistant to Nitro fuel. Obviously you're not going to use RTV on the front bearing, so at that point you've got to decide if you want a new engine for $90 or repair your old one for $??? and the time investment. If you've got the VX-18 (purple cooling head) it's not worth rebuilding. Get the SH-18 from the link in my signature or look around for an engine at your local hobby shop.

If the engine doesn't leak air from the carb, front bearing, or back plate, try plugging the carb inlet and the outlet of the pipe/muffler, and blow again. (Whenever I remove my engine I tend to leave the header & pipe connected to it, so I'm imagining you doing it the same way) If you've got a bad exhaust leak, it's probably between the header and the head. If this gasket is leaking, you can get a package of gaskets for cheap or build your own out of automotive stuff - I've done both. Don't just use RTV here because it won't last. If you've got a leak in your exhaust, you might not be able to pump fuel into the carb and the engine will run lean or not run at all.

Then turning around, look at your fuel tank. There will be one hose from the pipe to the tank lid, and one hose from the tank body to the carb. Plug the one to the carb and blow into the one from the pipe, and you shouldn't get any leaks here either. If you do, you'll probably want to replace the tank or the hoses or both. It's important that you don't have any fuel or air leaks.

littlegirl

passes above the redcat with a truck! it should be walk :P

Swamp3r

Huh?

ugly duck

Dang, you Frenchies are strange...

eric_ok

so, i dont got the time to make the test for the massive air leak....

but is possible to have a internal leak? like a kind of one way valve or something?


""passes above the redcat with a truck! it should be walk :P ""

what the hell means that thing??? i dont understand that...

real big thx to all for the technical support!

ugly duck

It doesn't really take that much time: 4 philips screws, 1 grub screw, and a couple pieces of fuel tube. If the whole test took you an hour from start to finish (including checking clutch bell gear mesh), I'd be amazed. It will take much longer to fix than to find, and you DO want it fixed, right?

The only other thing that might help you to find it is to put a little nitro in a spray bottle, get the engine running, and squirt some fuel towards the three major players: front bearing, carb base, & backplate. Don't hose the engine down and try to keep the spray away from the exhaust, obviously, and do it at your own risk.

I think the "passes above the redcat with a truck" was suggesting that the Redcat is piece of garbage, and she's jumping over it with her working RC. Whatever - she probably drives a Traxxas and it'll be broken in a minute.