Coolant Leak - Soft Plug Location

1999 Ford Taurus, 180k miles, 3.0 V6, Automatic Transmission.

I was driving home tonight, the temp gauge rose quickly and I pulled over. Steam was coming out, so I let it cool and added coolant. Once I started the engine, coolant started coming out. Location is down a ways beneath the spark plug coil pack (general location) at the driver’s side front corner.

Had the car towed and the driver said he thinks maybe the soft plug went. No slow leaking of coolant, no other signs before today of coolant loss.

Where is the soft plug located? Don’t see it in the Chilton manual.

Any other ideas?


Frost plug, not soft plug. They are round and some are in the head, some are in the block. I call them freeze plugs.

My old high school shop teacher refered to them as “w(h)elsh” plugs,whatever they are called their purpose is to provide a way to remove casting sand.

Never saw one pop out as “freeze protection” have seen many rust through and leak. I always wondered if they were freeze protection how did the engineer know it was going to freeze at just the right place to pop the “freeze plug” out and why not in some other place.

Really the only thing I ever saw freeze crack was a dead battery, the theory of weak coolant freezing and expanding sounds real good I just wonder why I never saw it even once.

Thanks for the clarification. Where do I find the freeze plug? Just follow the leak? Is there much to be broken down before I reach it? Does the diagnosis sound reasonable?


I too grew up hearing them referred to as “freeze-out” plugs. I’ve seen several engine blocks split down the middle when insufficient coolant caused the cooling system to freeze solid. The freeze-out plugs never helped at all.

As oldschool noted, they are not freeze-out plugs. The only purpose in life for those holes is to remove the casting sand when the engine block is being manufactured.

These plugs are located on the front and rear of the block, you probably have 4,5,or 6of them.You can replace the leaking one or all of them but you probably can’t get at all of them. They are perfectly round, shallow steel cups on a round hole in the casting. You can buy them at the dealer or any parts store. To replace them you can pound a large screwdriver through the center and pry the old one out. Take a sawed off section of wooden broom handle and drive the new one in by placing the broom handle in the center and hit it with a hammer to drive the plug in and flatten the centert to expand it tight.

Installing a replacement freeze plug as oldtimer 11 suggested may be impossible with the engine in the car. (no clearance to drive a new freeze plug in with a dowel and hammer). Luckily Ford makes a replacement freeze plug that work similar to a toggle bolt that can be installed with minimum of clearance. The only problem is some freeze plugs are between the engine, and transmission. Hope its not one of those that is leaking.

Final post with results. Let’s call this one dumb luck. I hooked a hose to the flush tee and ran water to trace the leak. The leak was right on the back of the engine. I pulled the battery out and there it was - a hole in the plug about the size of a nail. Got it out, got a replacement, put it all back together. One hour time, including the drive and wait at the auto parts store.
Thanks for the help!

When one goes, more will follow…They make rubber expanding ones that are easy to put in…

Its hard not to think of the worst case being the cause of the leak belive me I do understand how you can get caught up in imagining that the fix is going to be something either hard to do or expensive.

It would have been “optimal” if the mechanic that looked at your car explained that “it could be the freeze plug but before I cause you grief from worry let me look harder as there are a few more likely causes of a coolant leak” It ends up knowing how to talk to your customers. You don’t want to appear ignorant that these plugs can leak but also you don’t want to send your customer over the edge needlessly.

I got the rubber expanding plug. Your statement, “when one goes, more will follow” makes sense. Should I have my mechanic change them out?

I should have read slower, your leak was at a freeze plug. A good case could be made for premptive plug replacement but most people must consider cost and then how long do you plan on keeping the car?

Get a bid on plug replacement,this may lead you to an answer.