I'm having problems with a Celica GT-R 4WS. Radiator cracked and engine overheated for a very short while, so some sort of plug about 10mm in diameter has popped out of the engine block. In the manual they refer to 'freezer plugs' at a Toyota dealer they seem to think I mean a core plug, so they have sent me a core plug which is about 25mm in diameter. Somehow I just don't think it will fit in the hole.... Hole is below and to the right of the water pump. Anybody know what should be in this hole?

how much bigger is it?

hmmmm don't think thats gonna fit no matter what size of hammer you hit it with, sounds like they've sent you the wrong bit. if all else fails could you tap a thread in the hole and get a bolt in instead?

I think Alistair is right. They've sent you the wrong bit. When the engine overheats the core plugs (or freezer plugs as they are sometimes called because you have to freeze them with liquid nitrogen to get them in) disappear (they're an interference fit but when the block overheats and expands to much they pop out). they act as a tell tale. if you get the right size plug you might be able to freeze it enough with a freeze spray (easier to acquire than liquid nitrogen - should be able to get some from RS or Screwfix). I only know this because one of the oil platforms I work on overheated one of the diesel generator sets and I got talking to the Turners Diesel engineer who came out to fix it. i'd get this theory checked out with a garage though, as there are some right jokers in my industry. sounds feasable though.

Oh my God PMPL at some of the answers on here for the core plug! freezer plug never oh never have I heard it called that before, and yes before you ask I have sold 100's of these, freezing it indeed DOH! The plug you described was it like a discus shape or totally flat? The core plug you need is probably like a cup shape they are shamfered at the bottom so you can line them up and hammer them in, and yeah I have 10 mm ones at work, with about another 50 different sizes, never had any of my mechanics come in and say "got a tub of nitrogen so I can get this bastard in" more like they just use a bigger hammer. The core plug in engines is usually just there because they deep drilled an engine part for oil flow or coolant flow and behind the plug is usually nothing, they usually sit flush with the block or part they are missing from or sit in just a fraction 1 mm. Core plugs are prone to rotting away over the years I wouldent think it just popped out. If you know the exact size I can send you one in the post, but beware they go up in .5 mm increments. Dave.