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leaking coolant


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I am pretty sure that coolant is leaking out of the front of my motor where it sits on the cylinders, becasue dirt is sticking right there. My spark plug has a yellow tint on the part that is supposed to be white, below the electrode. I discovered this after a plug chop. I have heard that the cubs have been having a leaky head problem. How do i fix it and how much damage has it already done?

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I am pretty sure that coolant is leaking out of the front of my motor where it sits on the cylinders, becasue dirt is sticking right there. My spark plug has a yellow tint on the part that is supposed to be white, below the electrode. I discovered this after a plug chop. I have heard that the cubs have been having a leaky head problem. How do i fix it and how much damage has it already done?

If the deck surface or the cool head is not flat, you can have issues. There's really no way to know how much damage it's done until you pop te head. Where are you located?

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CD...there's been a few threads lately about the top of the Cub Surface being uneven...

 

You can do it yourself...but, of course you have to take 'em off.

 

PUll the studs, find a nice, flat bench or large piece of metal stock. Take some medium grit sandpaper, lay it flat.

 

Move the cylinders (top side down) back and forth across the sandpaper in a figure 8 motion.

 

Do this for about 10 or 20 seconds...see if you have any high or low spots...

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You are going to have to remove your head.... check the surface for abrasions and replace the gasket.... if need be, resurfacing is very simple just be sure not to remove too much metal....

 

it is also possible that the coolant is traveling up the cylinder on the piston... there is a regularly leaky seal on the bottom of your cylinders.... if you take off the jug and look at the bottom towards the front there is a rubber plug that tends to leak.... screw a screw partialy in to it and grab it with a pair of pliers....DO NOT PRY..... they are cheap and just pop right back in....if you take the jugs off you should consider replaceing the base gaskets as well....

 

hope that helps

 

Colin

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if you take off the jug and look at the bottom towards the front there is a rubber plug that tends to leak....

 

He's got a Cub motor...

There are 4 holes in the bottom that are not used, and there are 4 threaded inserts that should've came with your motor, along with 2 stud extenders....

The rubber plugs on the stock cylinder...:)

 

That shouldn't be the problem... It's gotta be the head, the deck surface or an Oring.

 

I put a thin, thin coat of Orange RTV on all Orings when I put mine back together, partially to help seal, partially to help hold them in place...

 

And...if you take them off...hell yes replace the base gasket. Make sure you get the big bore cub gasket...or you'll end up cutting a bit of a standard one...

Edited by dajogejr
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Once you rule out that you don't have a leaky o-ring or gasket, you'll need to have your head checked to make sure it's nice and flat on the surface. After that, you should be able to re-install it and all should be well.

How you you rule out an o-ring? I have had a problem with mine leaking coolant also, but when I take it apart the o-ring looks fine. Is there some other signs to look for?

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Top and bottom of the cylinders needed to be decked a little to make them flat.

Now I have to run a slightly thicker base gasket to accomodate this for port timing, compression and squish angle....

 

I think my guy put a .035 gasket on there...normally you run a .015 or .020...I think....

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