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fuel leak under cooling head!!

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jpgregorc08

jpgregorc08

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chardon ohio
RC Driving Style
  1. Racing
hello,

I just recently noticed that my savage is spitting some fuel out from underneath the cooling head. i called my local hobby store and they said that it could be that the head is loose or that the gasket is bad but the cooling head is tight and the gasket looks ok there are three thin brass looking gaskets in there is there supposed to be more? Is there anything that anybody can think that would solve this problem? it's bubbling a little in the little space between the cooling head and the block and everthing in the back of the truck is getting covered in fuel/oil. Any answers are appreciated...thanks
 
I wouldn't take them out as they are what sets your compression ratio. Taking them out could cause a detonation issue (fuel explodes before it should in the cycle) which is bad.

I'd take the head off, clean everything really well with DA that makes contact with the shims, including the shims, then put the head back on. Just make sure to tighten all the head bolts very gently, then tighten them one turn at a time in a star pattern to get the head to seat properly. If you don't, the head will more than likely seat crooked causing the problem you have now.

Or, the leak is coming from somewhere else, like the glow plug (stripped threads, missing copper washer) or the header (torn/bad/missing seal).
 
olds97_lss said:
I wouldn't take them out as they are what sets your compression ratio. Taking them out could cause a detonation issue (fuel explodes before it should in the cycle) which is bad.

I'd take the head off, clean everything really well with DA that makes contact with the shims, including the shims, then put the head back on. Just make sure to tighten all the head bolts very gently, then tighten them one turn at a time in a star pattern to get the head to seat properly. If you don't, the head will more than likely seat crooked causing the problem you have now.

Or, the leak is coming from somewhere else, like the glow plug (stripped threads, missing copper washer) or the header (torn/bad/missing seal).
Click to expand...

So what your saying olds is that a buildup of grease / oil on the washers will make it leak?? and do you know how many washers are supposed to be there from stock?
 
I'm saying if there is a large enough gap to leak oil, then there is a large enough gap for dirt to get in there and make a bad seal. Which means just tightening it down evenly may not help. So, whenever I take a head off, I clean everything really well to remove any speck of dirt/sand that may be there before putting it back together.

You can take a look at the parts explosion or manual for the engine you have to see what is on it in stock form. Most engines are shimmed to run 15%-25% nitro. Going any lower/higher may cause the need for less/more shims. Higher nitro requires more, less nitro requires less shims.

All I meant is that if it's a "stock" engine, the shims that are on it are probably the right amount for what your doing.

I just had another thought, it could also be the seal between the sleeve and the crank case. In which case, I'd pull the sleeve, clean it with DA really well and clean where it sits on the crank case really well, then put it back together.
 
I'm with olds, do not pull more than one small head shim unless you can check the clearance and understand the effects it has on compression.
If the engine was overheated it may be warped or it could be a factory casting defect.
Do what olds said and clean it all up spotless. Put it back together and make sure you do not have the LSN set too rich.
 
Scrogg said:
I'm with olds, do not pull more than one small head shim unless you can check the clearance and understand the effects it has on compression.
If the engine was overheated it may be warped or it could be a factory casting defect.
Do what olds said and clean it all up spotless. Put it back together and make sure you do not have the LSN set too rich.
Click to expand...

What does the lsn being rich have to do with anything? just curious
 
If an engine's LSN is set overly rich the excess fuel cannot be burned. It finds the easiest place escape the pressure. I have seen several engines running too rich that leak in places until they are tuned correctly.
 
is it true that you can't or you shouldnt adjust the hsn or the lsn while the engine isnt running? I've heard someone tell me this but I'm not sure
 
You can adjust with it running or not running. It's just a good idea to set them to factory if they are way out of whack before starting to avoid running too lean.
 
I prefer to make most of my needle settings with the engine running. I usually start it up and let it get to temp by making a few runs back and forth. Make small adjustments and then give it a little run to see if it's changed anything. Always pay attention to the amount of smoke and if you have a temp gun monitor temps while you're making adjustments.
 
Okay so I cleaned everything out good with da and put it all back together. Started it up and got the engine tuned pretty close to perfect with a temp of about 240-245 the leak under the cooling head seems to have gone away so maybe it was a lean issue and was just escaping idk. But before all of this happened in order for me to get it started I had to hold the throttle or else it wouldn't start which I think means the engine was too lean. Now I am able to start it without the throttle. So its deffinetly better. One question though, how mch smoke should there be when you take off slow and when you punch it from a dead stop. I noticed that when I had it idling for a few minutes and then hit the gas it would have alot of smoke and then clear up is that normal or am I a little rich? Thanks for any replys
 
Fairly normal. Depends on how long it's sitting and idling. Does it take off cleanly (no engine bogg/gurgle) after it sits and idles for a bit? If so, then you should be fine. If it hesitates, smokes and gurgles some, then you may be a bit rich on the LSN.
 
as long as your temps are good you should be fine. bogging on throttle means your bottom end is rich. if you need to open up your carb in order to start, this is an indication that you COULD not always, but COULD be rich on the lsn. you are trying to get a good tune to start the engine by allowing more air into it. do not base your tune solely on temperature. i have an associated .15 and it barely runs at 200 degrees, but I'm afraid to lean it up more because there already is not that big of a smoke trail, and it runs great
 

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