I had one of the freeze plugs give way due to age on a 1990 C2500. Has anyone changed the plugs themselves or is it a job left to a garage?

Depends on where it's located and difficulty accessing it. Given that it's a truck, it may be somewhat easier than a car. Is it leaking to the point you're looking at having it towed to the garage if that's the route you choose? If so, you might say you have little to loose trying except maybe your patience. It takes multiple pretty good strikes with a hammer to seat one of those. Have you done it before?

One of the rear freeze plugs gave way and I had it towed home. Crawling around under a vehicle may be too much verses working under a lift.

Replacing the freeze plugs themselves is trivial, they are cheap, and it isn’t rocket science. (Says the guy who replaced all the freeze plugs on a 327 that he rebuilt. Of course, said guy replaced them on then the naked block was on an engine stand and easy to rotate to get a comfortable angle.)

As mjlennon points out, access may be challenging. If you have to remove the engine to get the access you need, you may want to let someone else handle it.

I know many years ago there were freeze plugs made that were brass with an expandable rubber ring. I used one and it worked well. Allowed you to remove the old one and insert this one and turn a pre-threaded bolt and nut to expand the rubber gasket into the opening. Could be a short time fix if they are still available for sale and use like the one in the link below.

https://www.autozone.com/exter...KvD_BwE&gclsrc=aw.ds

Depends on if it is hiding behind the motor mount.

Core plugs were one of my most dreaded jobs, and I had a lift to put the cars on. I think the center one is behind the engine mount, too, so you have to jack up and support the engine while you're working. They are easy to pop out, but driving them back in is another matter. There are core plug driver tools available so you don't mangle the plug, but you still have to have room to swing the hammer.

The temptation will be great to use a rubber plug.



These are slipped into the hole and have a bolt running through the center to compress the rubber on the back side of the block wall. The SBC's block walls may be thin enough that the rubber will expand and seal, but there is great risk of them popping out. An inch-and-a-half hole in the block will instantly spew all the coolant out. Use steel or brass ones.

I'd recommend the garage, if you've got a trustworthy one.

There isn't much room to knock them back in on the rear drivers side. Thanks

quote:

Originally posted by egregore:
... but there is great risk of them popping out. An inch-and-a-half hole in the block will instantly spew all the coolant out. Use steel or brass ones.

This man speaks a great truth.

BTW, freezing protection (i.e., the plugs getting pushed out by the expanding ice and preventing the block from cracking) is not these plugs' function. Ice expands unpredictably, and they won't necessarily be pushed out. The only way to get the sand out of the interior of the casting is through these holes. The plugs simply close the holes up.

I would be concerned about the rest of the freeze plugs on a motor that age.

There’s a couple of freeze plugs in the bell housing area only accessible after the transmission is moved back and the flywheel has been removed, could be those that failed.

It is always smart to pay off debt