water test method for air leaks???

[minmax89]

Hi guys.

In my search on how to seal a nitro engine I came across something that I thought was risky. A guy had a video on 'beatyourtruck.com' showing how to check for air leaks. He submerged the engine in just enough water to cover the engine and had a pipe connected to the carb air inlet and blew into it!

It highlighted where his engine had air leaks immediately. I thought it was a great idea but surely it's not good for the engine.

AND then I thought, well I could just strip the engine to dry it thoroughly but then any sealing that was done is undone.

Has anyone ever done this?

here's the link to the page but I'm locked out till I register.

Adam

 

[darkslayor24]

as long as you dry out the outside of the engine realy well after it dousnt seem like to bad of an idea....i would never try that tho

 

[alien13]

I think spraying wd-40 inside the engine first would be a good idea. Maybe even coat the outside, too. But otherwise it would work, as long as all water was removed before running it again.

 

[darkslayor24]

i didnt even think about WD-40

 

[MotoGod]

Use the soapy water test. Start the engine...lightly mist warm/hot soapy water on it. It will bubble where the leaks are ;-) A little safer than soaking a Nitro engine in water I would imagine.... I used to do this all the time on my Motocross tires to test for leaks as well.

 

[olds97_lss]

Well, you could do a mix of what he does and what motogod suggests. Engine out of the vehicle, wet the engine with soapy water as motogod suggests, plug all orifices, then blow air into the fuel line. The soapy water will make the bubbles where the leaks are.

I'm somewhat hesitant to spray a running engine with anything.

 

[MotoGod]

As long as you don't use cold water on a hot engine....you should be OK with it, but yeah the best of both worlds would be to yank it, plug it, spray it down with soapy water...and pressurize it and look for bubbles. I usually just do it with the engine running since it's quick and easy ;-) Just don't douse it like you're trying to put out a fire....a mist should do the trick

 

[cwest3355]

Spraying the engine while hot will just become steamy wouldnt it??

 

[SMaxxin]

Start the engine and shoot the carb, under the head, glow plug and backplate with wd-40 (use the straw), if you have a leak it will suck in the wd-40 and bogg the engine.

 

[minmax89]

Spraying the engine while hot will just become steamy wouldnt it??

I would think that too.

It seems olds97_lss has the best solution. But I suggest with warm, soapy water in the spray bottle. Might try it later.

All this is for my new .26 Red Dot.

Only had the thing a week and not got off the ground with it yet. No end of trouble. Some my own doing, some not. Seems to be leaking all over the place so can't even get it to idle proper. then EZ start wouldn't turn it over (think the battery is banjaxxed) so waiting on the delivery of a Ofna shaft start with new battery.

And then noticed the NEW front bearing is leaking like mad. Seems this is normal! Quotes everywhere saying, "...great engine, just change the front bearing..."
So I ordered a Boca one. As in this bad boy!

So once that is all here I can start again and might try this air-leak method we've been chatting about.

Adam

 

[MotoGod]

Well that's the thing....you don't need the engine to be hot to find a leak. Start it, spray it...check for bubbles ;-) Don't need to get it up to 200 degrees to check for leaks...and water boils at 212 degrees anyway.

Use whatever method you are comfortable with....tons of variations to find a leak.

 

[darkslayor24]

minmax89- maybe it is not your bearing that is leaking. you might need a new crankshaft. possibly theres a spot on the crankshaft that is not sealing with the bearing?

 

[moe7404]

iam new to rc but the above dialog, got me to thinking. what if you put a "T" in pressure line off the exhaust of one engine. ran it to the fuel input connector of an other engine, so that the pressure of one engine pressures the the crankcase of the other engine make sure the intake and exhaust are sealed. then use soapy water to check for leaks like you do on natural gas lines? just a wild idea.

 

[darkslayor24]

iam new to rc but the above dialog, got me to thinking. what if you put a "T" in pressure line off the exhaust of one engine. ran it to the fuel input connector of an other engine, so that the pressure of one engine pressures the the crankcase of the other engine make sure the intake and exhaust are sealed. then use soapy water to check for leaks like you do on natural gas lines? just a wild idea.

that post just got me confused lol, i put a fuel line on the fuel nipple, plug the intake and exxaust with my finger, and blow into the fuel tube.

 

[dub c]

i may be wrong, but is not the part of the engine under pressure the head gasket?
isnt the rest of everythin under vacuum? the the only bubbles youll get by sprayin it could be the head area.

tough motor to breakin though. i destroyed the pull start also. cheezy start didnt have the umph to start it. i found the traxxas pull start to be more reliable

 

[olds97_lss]

I've also heard of guys using canned air with the engine running. You blow it in the possible areas of a leak and it will force it to run lean if there is a leak. Less messy than WD-40 with a similar result.

Still, sprayed with soapy water and blowing into the fuel line is the simplest and easy to be thorough.

 

[moe7404]

maybe i didnt do a good job of saying what my idea was. my idea is to substitute the air out of your mouth with the presure from the exhaust of a diff engine running, gong into the fitting the fuel goes in, on the test engine.

 

[alien13]

maybe i didnt do a good job of saying what my idea was. my idea is to substitute the air out of your mouth with the presure from the exhaust of a diff engine running, gong into the fitting the fuel goes in, on the test engine.

Then you are taking pressure away from the tank that is supplying fuel to the running engine, and I doubt that would be enough pressure to test for leaks anyhow.

 

[moe7404]

to: alien13 thats true , but you are not looking to make lot of power, you just need to take a small amount of pressure, off the running engine. please note: i have not tryed this, its just an idea.

 

[SMaxxin]

maybe i didnt do a good job of saying what my idea was. my idea is to substitute the air out of your mouth with the presure from the exhaust of a diff engine running, gong into the fitting the fuel goes in, on the test engine.

It's possible that it would work but why would you go through all of that trouble? It's faster and easier to just blow in the tube with your mouth.