Leak from cooling head junction

[echelon6]

After taking the cooling head off a few times to inspec the insides, I notice bubbling at the junction of the cooling head and the engine block when I move the piston to TDC. Also I notice the pinch is almost nonexistent

I've screwed the cooling head down as hard as I can with the supplied allen keys and my bare hands, wondering if the problem is because I'm not screwing it down hard enough? Should I proceed to the next level and twist the hell out of it with huge pliers holding the allen key? Is this what you all do when reinstalling your cooling heads?

Or is this a good time to try to apply some high temp rtv over the gaskets/shims?

 

[NCNitro]

NO sealer, and NO locktite on the head. Sounds like your shims may be bad from removing the head several times. Pick up a new shim kit and try that first.

I would also recommend picking up a good set of hex drivers.

 

[GrudgE]

NO sealer, and NO locktite on the head. Sounds like your shims may be bad from removing the head several times. Pick up a new shim kit and try that first.

I would also recommend picking up a good set of hex drivers.

+1 agreed your loss of pinch is because of the leaking head.

 

[echelon6]

Thansk for the suggestions.

How can shims break? I just can't imagine how copper disks (or w/e they're made from, someone enlighten me?) can stop doing their job, which is to exist and be softer than the surrounding steel which forms a seal under pressure

Might I fix this simply by screwing down the head ultra tightly? or just tight-ER?

 

[NCNitro]

It's not that they break, but by constantly pulling them on and off they can get deformed, bent, and just not seal properly. You can try tightenening the screws more. Are you tightening them in a criss cross pattern? If not you should be.

Why are you constantly taking the head off your engine anyway? You ever heard if it ain't broke don't fix it? There is no need to constantly be pulling a head off. Whenever I pull one of mine apart, which is not that frequently, I replace the head shims. They are cheap enough and I don't want to cause premature engine wear by having an air leak, causing a lean condition because of a used shim not sealing properly.

 

[beason]

I'm with nc. make sure you tightend it down properly it could be setting a little crooked and causeing the leak. I've done it before.

 

[GrudgE]

Agreed the copper shim does compress and form a seal but its only gonna work once once it compresses its not gonna compress again. Also keep in mind your crankcase is only aluminum you tighten the head bolts to much and your gonna pull the threads right out.

 

[NCNitro]

keep in mind your crankcase is only aluminum you tighten the head bolts to much and your gonna pull the threads right out.

Very good point! DO NOT wrench them down too tight or you will indeed damage the threads in the block, and your head leak will become a moot point as you will now need a new block as well.

 

[Webbage]

Now I know nothing about Nitro engines but I do work in the motor parts industry. Would I be right in thinking the copper shim fits between the block and the head, and is equivalent to a cylinder head gasket?

If it is the case and it's copper, it's a throw away, you should fit a new one every time you remove the head. Copper gaskets, as GrudgE said, are designed to compress and fill the gap under pressure, but they'll only work once. Any further refinements will lead to a poor or failing seal, which is what you are seeing.

 

[GrudgE]

Roger I might be new to Rc but I have been a grease monkey since I was big enough to hand my old man wrench.

 

[CharliesTheMan]

I'm with you grudge. You are going to strip the threads in the engine if you keep trying to tighten it, and that pliars and cheap wrench is a disaster waiting to happen. You need to get a decent set of wrenches first, and you should never be reusing that head gasket. They are designed to be compressed once to form a seal.

It's kinda like asking why you need to use clean toilet paper everytime. It's not like the paper magically dissappears after you wipe, so why wouldn't you consistently use it again and again over and over. I mean its still paper isn't it...

You shouldn't need to put any more torque on those bolts than what you can do by hand. I would hope that you've been torquing the bolts to spec in a criss cross pattern. If you put any more torque that when it feels snug by hand, you're just going to strip the threads. These things are designed from lightweight material that's quite soft.

 

[echelon6]

Thansk for all the suggestions, ok seems like good advice I'll replace the shims

But I called up the LHS today and asked for shims and they said to go to the HPI website and find the part number, but I wen't to HPI's evo3+ page and it doesn't actually give me the part number for the shims every other part is seemingly listed except this

 

[beason]

take your shim up there. they should be able to match it.

 

[GrudgE]

Just Call HPI