> Does it work as some sort of pop-off valve like the guy said? The holes are actually there for casting purposes. As an additional side benefit they make an excellent "weak point" and will pop out in the event that the coolant should freeze hopefully saving the block from cracking. Your engine has six lower freeze plugs. Three on each side. There are also a couple on the back of the engine and freeze plugs in the heads. Over the years they tend to corrode and fail. Unfortunately if one went the others may well be in poor shape. The proper fix would be to have atleast the six bottom freeze plugs replaced. Unless you are into self mutilation or have a desire to use more curse words in one day than you have in your entire life I would take it somewhere with a lift and let someone else do the job. As a temporary measure you can buy a rubber replacement plug at most any auto parts store that will work fine. You can install it yourself in about five minutes unless you lost the freeze plug behind the starter in which case the starter must be removed first. There seem to be very mixed opinions on the rubber plugs.. Some here on the list swear by them while others swear at them. I personally have been using six of them in a 413 for about a year without leaking a drop. Steve B.