Mysterious coolant leak.

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LilRobert1367

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I have what look like a coolant leak coming from around the 'A' pipe on the Pair System on my 1979 c20 250. I want to know what I might need to do to repair this. I've tried tightening it down but not loses at all. This is leaking right around the 2nd cylinder.
 

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Bextreme04

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I have what look like a coolant leak coming from around the 'A' pipe on the Pair System on my 1979 c20 250. I want to know what I might need to do to repair this. I've tried tightening it down but not loses at all. This is leaking right around the 2nd cylinder.
It looks to me like you have a core plug just to the right of the fitting that is wetter and appears to me to be the actual culprit. Hose down that whole area with some brake cleaner and scrub it to see what it actually looks like there. If the engine has been run with old or no antifreeze in it for any amount of time, you could have corroded core plugs starting to leak.

The solution would be to buy a replacement for a few bucks from a local parts store, knock the old one out with a screwdriver and hammer, then put a bit of No. 2 sealant around the rim of the new plug and pound it in with an appropriately sized socket with electrical tape around the rim to make it fit nice and snug.
 

LilRobert1367

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It looks to me like you have a core plug just to the right of the fitting that is wetter and appears to me to be the actual culprit. Hose down that whole area with some brake cleaner and scrub it to see what it actually looks like there. If the engine has been run with old or no antifreeze in it for any amount of time, you could have corroded core plugs starting to leak.

The solution would be to buy a replacement for a few bucks from a local parts store, knock the old one out with a screwdriver and hammer, then put a bit of No. 2 sealant around the rim of the new plug and pound it in with an appropriately sized socket with electrical tape around the rim to make it fit nice and snug.
There is a actually a bolt right next to it. I got a better picture of the area just now trying to see the plug that you are talking about.
 

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Bextreme04

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There is a actually a bolt right next to it. I got a better picture of the area just now trying to see the plug that you are talking about.
Wow... real hard to see what's going on around there. I would suggest step one is still to clean the area so you can see what the heck is going on. Honestly, with only the one zoomed in picture, I'm not even sure what part of the engine we are looking at there.
 

LilRobert1367

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So it basic if you fallow 'A' pipe its leaking right next to the carb or slightly in front of the carb. I cleaned the area good and saw that there was a Bolt right next to were I thought it was leaking and realized the bolt was where it was actually leaking. When I unscrewed it the bolt and there was coolant coming out of the hole when I would knock the top radiator hose. I cleaned up the bolt and put it back together. Doesn't seem like it's leaking anymore.
 

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PrairieDrifter

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I know the middle four intake bolts go into the crank case so they need sealer. I'm having a brain fart, I think the front and back four go into coolant passages, so they would too if they do.
 

LilRobert1367

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I know the middle four intake bolts go into the crank case so they need sealer. I'm having a brain fart, I think the front and back four go into coolant passages, so they would too if they do.
New sealer. Like high heat rtv and what? Where would I put the sealer?
 

Bextreme04

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New sealer. Like high heat rtv and what? Where would I put the sealer?
No, you generally use a thread sealer with PTFE like this: https://www.permatex.com/products/t...ants/permatex-thread-sealant-with-ptfe-16-oz/

It's basically liquid teflon tape... but better.

The sealer goes on the threads of the bolt before installation. You do this on BBC head bolts too because they are open bolt holes into the coolant passages of the block and if you don't put thread sealant on them they will leak coolant into the cylinders and from around the bolt heads. Same thing on SBC intake manifold bolts. If you don't put thread sealant on the middle bolts you will get oil pooling on top of the manifold below the throttle linkage.
 

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