Coolant leaking from cap at back of head

[Mike F]

I finally got around to starting the replacement job for my the weepy bleeder tee on my hot water valve (discussed in another thread). Since I was going to be draining the coolant, I figured I'd pressurize it cold and let it sit for a while before I started in order to see if there were any other leaks that I could fix at the same time. I didn't find any others the last time I did a pressure test, but I only let it sit for about 15 minutes. I figured I'd let it sit for a bit longer this time just to give any little pinhole leaks that may be there a bit more time to show themselves. I crawled under the car before I started, and found this:

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The first thing I thought was that the head gasket was seeping, but it looked like it was starting from above that. I dried it off, pressurized it, and eventually it started weeping out. Not a major leak, but a leak is a leak! It appears to be seeping out from around that cap, and judging by the crud there it has been for a while. I have never noticed that in all the times I have been underneath the car.

Can this thing be replaced? It looks to be pressed in. Has anyone ever had a leak from there?

[Delorean Industries]

freeze plug failure. This happens on engines that went a long time without a coolant change. The plug can be changed in car creatively. If you have a problem with that one the other ones are not far behind.

[Michael]

Freeze plugs have caused far many more problems than they have solved.

[Mike F]

Well, crud. That's no fun. Wasn't sure how common it would have been. Guess a freeze plug on this car isn't any different that any other, so why not, right? Chalk one up to the PO I suppose. I have replaced the coolant for a couple of projects since I got the car a year or so ago, but I can't say how long the car had old coolant in it before that. Typically you'd knock one of these sideways and pop it out, then tap (bang) the new one in with a socket just smaller than the plug (or tool of your choice); any cautions to that method on this engine? Definitely not much room to work here, though. Josh, you mentioned some "creativity" to doing in the car; any tips?