Broken Radiator Drain Petcock - Help Me !! - Classic Z Car Club Skip to content

Broken Radiator Drain Petcock

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I wanted to drain the coolant out of the engine and replace it with water + waterWetter, but when I looked for the drain petcock, it was missing. It has broken off.

So I call the friendly local radiator shop, and he says a new radiator takes two days to install! I asked why you can't just replace the plug, and he says "maybe they can drill it out."

Is there a good way to remove the broken part of the radiator drain petcock, and install a new one? I think the local AP has them (it has 10 x 1.25 threads.) I probably could just disconnect the lower hose, but I'd make a mess of the floor, probably, or can you inch it off and get a controlled leak?

I don't think it's loosing any coolant.

BTW, is it possible to protect the petcock so it doesn't get broken again? It probably broke when driving in some grass.

thxZ

Get a flat screwdriver hot and melt it into the petcock 1\16 of a inch. Then use the screwdriver to open and close.

You could heat up a screwdriver blade with a torch and melt it in to the plastic of the petcock stub. Might work. Drilling would be fairly easy also, except for the water dripping down on to the drill motor. You could also drill a small hole, or jam a red hot coat hanger through it to make a small hole, let it drain, then heat it up until it softens and pry or twist it out. Actually, if it was mine, I would probably do the last three things.

I replaced my plastic one with a metal bolt. It stuck down farther than I liked. Looked like upside down Mickey Mouse ears.

  • Author

Exactly. Those ears stick down so far the thing broke off. why can't they make the valve of a better plastic , or carbon, (teflon?) and have smaller lobes like an air cleaner wing nut?

Well, I did want to drain it anyway...

Dorman makes a replacement plastic drain plug, see link below. Any auto parts store should carry it. Like others said, you should be able to use a flat head screw driver to get it out. Once you, you may want to consider replacing it with a screw in brass drain ****. You would need to double check the threads to see if it is possible as there are several sizes out on the market. Keep us posted and good luck.

http://www.amazon.com/Dorman-Autograde-490-215-1-Screw-In-M10-1-25/dp/B0049DPLO4

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  • Author

I'll bet it's got imperial threads, instead of the correct metric.

One of the above or an easy out would probably work too. Or you could cut a slot for a flat headed screw driver with a tiny dremel cut-off wheel.

I probably could just disconnect the lower hose, but I'd make a mess of the floor, probably, or can you inch it off and get a controlled leak?

That's what I always do, not messy at all. Just put a large enough container under it. The drain plug on mine broke of to, I ordered a NOS one, put it in, and left it alone, I drain it by pulling the lower radiator hose.

  • Author

I would do that if I had a lift or a gravel floor. The cooling system is 10L, so that is a large container, unless you can put the hose back on when your small container is full.

I will see if it can be done.

  • Author

I bought one of those oil drain containers with the screw-on cover for the coolant, but the darn thing won't fit under the car! If I cut off the threaded neck, it would probably fit, but I'd still have to transfer the old oil to another jug.

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