The Stovebolt Site Forums The Shop Area Engine Shop Replacing expansion plugs

anyone online that can tell me how to place a new expansion plug in the back of the engine. It is the upper one on a 235. It is the cupped one not the plug one. I am trying to get the engine installed now.

I just find a socket that fits the cup and tap it in - make sure the edge of the hole is quite clean - some folks use sealer on them, but careful to not push any inside to foul the water jacket - also don't just replace one, if one needs it, do them all

Bill

Thanks, This is the dome type, like on the king pins where you tap the center to spread it. Any wisdom on that.

I've always called them "freeze plugs" and the ones I have seen the "dome" actually goes to the inside. When you can get to them you just pop one edge of it with a punch or something to flip it sideways and then hook a screwdriver in it and pop it out.

Like red58 says, Replace them all and don't knock it inside the block and leave it. I have seen this done on hard to reach plugs and its a no no. I replace one long ago and stuck my finger down inside the block and pulled out 2 more that were rusted so you can imagine what they do the water cirulation! Some will be rusted out right in the middle and some leak on the edge. Clean the rim where the plug goes and use just a "tat" of sealer and your good to go.

The plug should dome outwards. After the old one is removed and the hole is cleaned out, put some sealant around the lip and place it in the hole. There is a ridge inside which stops it from going in further. Now place a hammer against the plug and smack the hammer with another one. This will deform the center a bit and expand the outside diameter which will cause it to be secured in the bore. Here are some photos from when I replaced mine. I did it when I had the toe board cut out.
http://rides.webshots.com/photo/1316417356041873203xTDshC

yes, NOT like a kingpin [which are grease cups], the dome goes in, and you don't want to pound on the center of the new one or the cup will deform and leak, if the old ones were in so the dome was out, they were done wrong, more reason to change them all!

like on this small block, drive in like so and they're installed ... and if you haven't bought a set yet, get brass ones

Bill

I think the soft plug that is being asked about is NOT the cupped type you linked Bill...it is the domed type that truckernix shows, which is installed dome out, then popped with a hammer or flat bar to pooch it out and "lock" it in place...just as he explains and shows in his pix! Isn't this right?

Stuart

never seen a freeze plug other than the type I linked, and if you look at the 'full size' of Fred's linked pic, it's the usual cup you'd find at any auto parts store, just rotten and leaking expansion plug

I can't imagine being able to get the 'cup' side started in the hole, unless the hole is hogged or rusted out, and I've never seen one with a lip to stop it from going all the way in on a 235 [what's being asked about], maybe the 228/248 is different, but I've never seen one installed the way Fred's second pic shows

Bill

I have to agree with TRUCKERNIX. The plugs on the each END of the block should be installed with the dome out. The plugs on the SIDE of the block are installed with the domes in.

why the difference? maybe talkin about the oil gallery or camshaft plugs? I'll accept being over ruled .... and carry on doing it the way I learned

Bill

I don't consider myself an authority but in all my years I have never seen a plug installed with the dome out. I worked at the dealership many years ago, brother built engines for years in his shop and I visit and see engines in nearby garages all the time. This isn't to say something got by me all these years.....or that this 235 isn't different..BUT.....!!!

Maybe its worth noting that these plugs are really freeze plugs. They are to pop out before an engine freezes and cracks the block. Back in my younger days I seen this happen many times. The water in the engine freezes and expands thus pushing out the plug and keeping the engine from cracking.

Early fifties my grandaddy couldn't afford antifreeze so he would pour a bottle of rubbing alcohol in the radiator, run it a few minutes to cirulate and then throw an old quilt over the front of his pickup to help keep the wind out.

I know what you mean about never seeing them,but originally on the block ends only, that was the case. If you noticed there is much less block to cylinder wall clearance on the ends then the sides of the block. Maybe factory installers installed them dome out because of the minimal clearance.I don't really know,but having done 2 235's and recently a 216, the end plugs were dome out.Of course my 235's were 1955 vintage,so maybe the newer 235's have the end plug dome in.It probably doesn't really matter anyway as long as they are installed carefully and with no or minimal sealer.

I looked for a Dorman products online catalog, but alas, no soap. The style used on the back end of the block is called a domed expansion plug. It isn't the same as the cup plugs being talked about above. The back of the 216/235 block has always had this plug...very common.

Truckernix's pictures are accurate and tell it like it is.

Stuart

Alvin,
The idea that those plugs are for freeze protection is urban legend. They are actually core plugs. That's where the pour the sand out of the casting moulds when the engine is being formed. They then have to plug these holes because it was the water jackets that the sand formed. They will pop out if water does freeze because they are a weak spot, but won't protect the block from cracking. I have an old 305 that froze with a 10" crack down each side of the block to attest this,
Scott

Stuart - I think most listings call them expansion plugs, like the one I linked from RockAuto .... the question is which of Fred's pictures are "accurate"? the one showing the old [possibly factory] plug dome in, or the one showing the way he put the new plug in, dome out?

and Drew, I'd find it hard to believe all the engines you've worked on had factory original freeze plugs where none of the ones I've seen did

Bill

Red58,
I don't know which "two" pictures you are talking about. The photo that I linked to shows the block with the plug removed. You can clearly see the ridge that holds the plug from going in. The plug on the lower right is for the rear of the camshaft. Both the front and the rear have this type of plug. The expansion plugs on the side of the engine have the other type with the shoulders.

dang! gonna hafta start using the glasses more that one looked too much like rotten plugs I've seen ... sure don't recall a casting like that on the 235 blocks I've dealt with, including the 57 I replaced the plugs on a few years ago .... but thinkin about that one, maybe because it was Canadian made? I'll hafta investigate

I guess mbt knows what to look for now!

Bill

Bill, Im guessing its cause your up in canada. Theyre a strange bunch up that way...

Man, thats why I love this place. Infomation highway. Even old farts like me still learn. Right on Scott about the sand deal. I was taught that but didn't remember! (CRS!) Thanks to all and I will now be able to "authoritatively" speak upon the subject. If not I'll refer folks to truckermix,Red58,DrewP, and my old buddy Scott!! ya'll the best and thanks for helping keep at least me straight!