: Freeze Plug?



Bro-Ham
11-12-09, 10:20 PM
Just had my car serviced at the Cadillac dealership and a note written on the multi-point vehicle inspection form stated: "one freeze plug starting to leak." The service manager said it is not serious but that we should watch it. What, if anything, needs to be done to correct this? What causes the leak? What is a freeze plug? :) Thanks! Dave

jayoldschool
11-12-09, 11:02 PM
Everyone still calls them freeze plugs, but they are really just plugs that are press fit in the block to fill holes leftover from the casting process. To fix, the coolant gets drained, the plug is knocked/pulled out, and a new plug is pressed/hammered in place with a socket that is the same size as the ID of the plug.

The "freeze plugs" are the round shiny plugs in the side of the block here. This isn't a Cadillac, but it is the right colour ;)
http://z.about.com/d/autorepair/1/0/Z/s/00000105.gif

csbuckn
11-13-09, 12:10 AM
is that the infamous 4.0? Do you have to take the head off to get the lifters out of a straight motor?

dirt_cheap_fleetwood
11-13-09, 02:50 AM
Freeze plugs are just to fill the holes left from casting, as stated above. They do have a little bit of purpose though. If your coolant starts to freeze and expand, there is a slight chance they will pop out and you will not crack the block. However, it doesn't always work that way.

77CDV
11-14-09, 02:50 PM
If they're starting to leak, replace them ASAP. When I had my '77 SDV, I left it parked while I went away for a week. I came back to find the garage floor flooded with coolant. One of the freeze plugs had failed. Not something you want to happen on the road.

Bro-Ham
11-14-09, 04:07 PM
If they're starting to leak, replace them ASAP. When I had my '77 SDV, I left it parked while I went away for a week. I came back to find the garage floor flooded with coolant. One of the freeze plugs had failed. Not something you want to happen on the road.

Thanks for the advice - - should I have all of them replaced or only the one that has the dampness? I rely on this car every day and I don't want problems, especially if they can be corrected in advance. :) Thanks for the advice!!

77CDV
11-14-09, 06:55 PM
May as well do them all in one go. If one is heading out, the others are just as old and can't be far behind.

Bro-Ham
11-15-09, 07:06 PM
Thanks for guiding me. I will get this done ASAP. Any tricks to know to do this right? :) Dave

jayoldschool
11-15-09, 08:52 PM
To fix, the coolant gets drained, the plug is knocked/pulled out, and a new plug is pressed/hammered in place with a socket that is the same size as the ID of the plug.

That's about it. You usually get the old ones out by using a chisel, a big screwdriver, or a pry bar. You can thread a sheet metal screw into it and yank the mess out.

Bro-Ham
11-17-09, 11:36 AM
That's about it. You usually get the old ones out by using a chisel, a big screwdriver, or a pry bar. You can thread a sheet metal screw into it and yank the mess out.

I hate to ask this - - does the engine need to come out?? :)

Caddy75
11-17-09, 02:53 PM
If its the plug behind the starter motor you'd only have to remove the starter motor (as well as drain all the coolant of course).This plug seems to be more exposed it was this one that corroded on mine and this one also on a friend's '78 limo.
Just make sure you use a brass one for the replacement so it won't corrode.
If you replace just the one, you may actually be ok, if other plugs are leaking you should see a slow reduction in the coolant level over time.