jatoracing33

i think my jato might have an air leak, but im not sure and want to check it. ive heard of like a soap test or something but i have no clue what to do. can someone tell me????? thanks

daytimeninja

I had the same thing happen on my GT2. Check the manifold gasket.

twomanytoys

What you can do is take the motor out of the truck. Take the everything off of the front and rear crank. Make sure you have the plug in. Now take some soap and put some on the front bearing, rear and around carb base. Make sure piston is at bottom dead center. Plug exhaust hole with finger Now blow back through the carb and if leaks are bad enough you will hear them but you will also see bubbles from the soap.

What makes you think your motor has a leak? Does it run really hot really quick?

jatoracing33

that and it has an erratic idle and realy bogs down when i leat off the gas, but i didnt change the idle before so thats not the problem

twomanytoys

If it starts to bog down or die once you let off the gas from a high speed run your piston could be worn. Is it hard to start once warmed up?

If you have an air leak your idle will be really high and can be irratic. I know this is a stupid question because I know you dont use a temp gun but do you know what your temps are at? An air leak will make it run hot also. (another reason to have a temp gun)

jatoracing33

it starts like a dream all the time...i did check with my temp gun since smoke would be useless, and it went up a good 50 degrees er so in less than a tank...im guessin it was round 220 and it went to round 270-280. the glow plug wire gets in the way wen i do my temps,so i do it on the outside of the cooling head, and it was 250 halfway up the head. believe it or not, i lowered my idle and it got higher, so im wondering if that had anything to do with it.

digifox

this is what i do

1.plug exhaust port
2.take carb inlet(HSN)out and plug it
3.put the carb at WOT
4.start with piston BDS
5.Blow in to the carb while turning it over
6.find leak...if any

ehroof

in an engine that i think is sucking in air i will put some nitro fuel in a spray bottle and while the engine is at an idle, spray areas of the engine that may have an air leak, like the carb base, front bearing etc, one at a time, and not alot of fuel, just a spray. if the idle raises or changes that is where your leak it, its not easy to ignite glo fuel but be carefull anyways, i wouldnt suggest to do it on an extremly hot engine.

MiamizFinest

If you suspect a air leak its kinda pointless to "look for it" if i was you id just tear down the hole motor and seal EVERYTHING your self............problem solved!!!

jatoracing33

i did tear it done and it looked fine to me, but im still kinda new and not sure if somethings right or not... so doin a test is the best way to find out

MiamizFinest

when you tore it apart did you add sealer???? if you would have done that and put it back together it would have bein a type of test becuase if it was still acting weird then your problem wasnt a airleak.......

jatoracing33

i have no sealer unfortunatly...we have culking, will that stand the heat? what is a good sealant and where to buy?

ehroof

no, lol, dont use caulking, you need rtv silicone, something automotive.

jatoracing33

okie dokie

MiamizFinest

CUALKING!!!!!!!!!!!!! LOLOL oh man that was funny very creative.........have you read the back of it to see if it stands up to heat??? u never know if it claims it can hold up to atleast 400 degrees ull be fine with it..........if not ull need some RTV silicone they sell it at pepboys,discount auto parts, auto zone ect........and it cost's less than 5 bucks


i rember there was a thread on HOW TO seal a nitro motor on savage central dot com (there where sealing a STS motor) the thread was awsome so many pics and the guy really explained everything great.......maybe some one can provide you with the link??? i dont have it............

ehroof

it would have to be fuel proof too, caulk is neither but silicone is fuel proof when cured but i dont know if its heat resistent

jatoracing33

we have unlimited supply of cualking( dad works at glass co.) so thats why i thought of it first...its worth a try in my opinion. if i screw my engine up u can just get the better os 18 tz

ehroof

lol, if its silicone your probably ok, if its painters, paintable or siliconized it wont work.

jatoracing33

its silicone contruction cualking...but it doesnt say anything bout heat except not to let it dry at a temp less than 80F

droidswarm

I knew I'd seen a guide on this:

[link=http://www.savage-central.com/modules.php?name=Forums&file=viewtopic&t=54465]Checking for an air leak[/link]

Hope it helps

twomanytoys

Yah that says how to seal the motor not how to check for leaks.

RCtruckRacer

OK, the simple method: Start the car up. get it warm. Take some WD-40 and spray around the carb. If the engine dies, that is where your air leak is (about 75% of the time this is where it is in my experience). Also check the back plate and cooling head. To seal the engine get some of this from your LHS: