attn motorheads: need your advice please

*Hey CD, I need help with an auto repair question.

Can anybody tell me how to remove the drain plug from the radiator of a 1998 Chevy Lumina?

I need a definitive answer so I don’t strip or break this thing.

See attached pix.



If you trust another random internet forum:

“The radiator drain petcock in those years was a push-in twist lock kind. Twist it about a quarter turn counterclockwise and pull to remove”

The problem is, how to tell if it has already been twisted a quarter turn clockwise and just needs to be pulled out.

Is there a telltale clue?

I don’t want to twist the plastic grip off the top trying to turn it, if it has already been turned.

Does it turn in either direction? :confused:
Is it stuck?

The tell tale is visible in your second picture. See the bump on the plug is seated in the notch in the tank? That is the retaining feature to keep it fully seated which means it is currently closed. You’ll know when you’ve turned it far enough both visually and you should be able to feel the hard stop when it is time to stop turning and start pulling. Sometimes you need to wiggle as you pull.

Also note sometimes these plugs have a retaining feature to keep them from falling into the drain. If it pulls out 1/2" - 1" and then you feel resistance don’t pull any further.

If it’s closed, why is there a very visible gap between the green flange and the black seat? (see the first pic attached)

The flange is the retaining feature, not the sealing feature. The sealing feature is an o-ring on the end of the plug. Find a picture of the plug here: GM used this type of drain plug across almost all of their models for a decade. So there is one on the shelf or a hook in every auto parts store in US and Canada, unless the person before you just bought the last one.

The flange itself doesn’t actually “retain” anything.

The flange does restrict how far you can push the plug in I suppose.

Can someone with first-hand experience confirm that it is normal to have such a visible gap?

I can’t turn the plug by hand. I’m proceeding cautiously before reaching for the vice grips.

I should have said the flange is part of the retaining feature.

I also should have said that I know that they fit millions of GM vehicles because I’ve operated them dozens if not hundreds of times on everything from a Cavalier to a P-30.

My go to tool is my 5" pair of arc joint (channel lock) pliers. A small adjustable wrench closed down tight on the wings is another good choice. Once you force the retaining feature up out of its notch and break the o-ring free it should be much easier to turn.

*Why would the plug start to leak when it hasn’t been touched for 3 years?

Should I expect to have to clean baked-on o-ring debris out of the bore when I remove the plug? If so, what’s the suggested way to do that?

THe o-ring is just hard and compressed, that is why every parts store in the US has one in stock. I’ve never had the need to clean out the bore, just put a new one in and you are good to go.

Thanks for your helpful posts.

If it’s not raining tomorrow I’ll give it a go.

I forgot to ask: if that happens, how do I get the plug out so I can replace it?

If you are afraid of breaking the plug, pull the lower hose. More mess but it may be your only alternative.
My brother says that if the tab (on the plug) is in the groove, the plug hasn’t been turned.

Hi Wayne. Thanks for posting, but…

… I need to pull the plug and replace it.


But do you have any suggestions concerning this?

Just pull.

I can vouch for the above being accurate.
It WILL be stiff and balk at being removed, but it will come out.
Advice: Unless you wish to replace your coolant, have the replacement in hand first.

As Mr V said, an adjustable wrench is probably the best way to go. I wouldn’t use vise grips or Channelocks on plastic. Their teeth are a lot sharper than they look.

I would, of course, fold a piece of hardy cardboard over the drain plug wing before (lightly) clamping the vice grip on there.

The vice grip’s mouth is well over 1/2" wide (see img 5987), and I would clamp it over the drain plug wing head-on (not perpendicular), to reduce bending load. Then I’d grab the head of the tool and twist it.


All right, that looks reasonable. The plastic should be fine if you do it that way.