HBergh Posted May 27, 2016 Share Posted May 27, 2016 When I filled the radiator of my 1923 4-cylinder Touring today, water started running out of a new place, other that the drain plugs. I found the water was coming from a hole of about 7/8" diameter just below the the rear-most exhaust port. It appears to be a rusted out freeze/expansion plug, in the most difficult place, of course. First of all, where can I purchase such a replacement plug? Secondly, has anyone replaced this plug to tell me the best way to do it? It looks like the exhaust manifold will have to come off, if that is even possible. Thanks! Link to comment Share on other sites More sharing options...
nearchoclatetown Posted May 27, 2016 Share Posted May 27, 2016 Howard, I have not replaced this one, but I have others on a four cylinder. I use a big screwdriver, drive it in the center of the plug and pry CAREFULLY in different directions to get it loose. The plugs are available at any GOOD parts store. But they come in boxes of 10, and being an order item even my buddy made me buy the box full. They are only about $1 a piece. SO, the good part was I replaced one about 15 years ago and bought a box. SO I needed another last year and, you guessed it, couldn't find the box from before. SO I bought another box, used one and decided to put the rest in my tool box. In doing that there was room right beside the other box. Get yours out and take an accurate measurement of the hole. I'm sure the ones I have are 7/8. Let me know and I'll send you one. Have fun, take your time, maybe take off the manifold to make more room to work? Link to comment Share on other sites More sharing options...
Spinneyhill Posted May 27, 2016 Share Posted May 27, 2016 Just a note. They have nothing to do with freeze or expansion. Water doesn't expand on freezing in discreet locations, it expands everywhere. They are core plugs, filling holes in the casting from which the sand for the cooling jacket mould was removed. 1 Link to comment Share on other sites More sharing options...
JACK M Posted May 27, 2016 Share Posted May 27, 2016 7 hours ago, Spinneyhill said: Just a note. They have nothing to do with freeze or expansion. Water doesn't expand on freezing in discreet locations, it expands everywhere. They are core plugs, filling holes in the casting from which the sand for the cooling jacket mould was removed. There is no such thing as a freeze plug. Somebody must have made that up when they got lucky once. Link to comment Share on other sites More sharing options...
JACK M Posted May 27, 2016 Share Posted May 27, 2016 I usually drive them in with a socket that is the right size. Use some sealer. Link to comment Share on other sites More sharing options...
TonyAus Posted May 28, 2016 Share Posted May 28, 2016 Ok, some specific answers to your problem. Yes, the exhaust manifold will have to come off. If you don't wish to disturb the flange (or can't get the nut undone) undo the muffler brackets and pull the whole assembly toward to - after removing the three nuts from the locating studs. The offending plug is (from memory) of the bucket type and about 1/2". Before rushing out to buy a replacement from your friendly corner parts store, check the plug seating in the block for corrosion. In my case the seating was so badly corroded that a bucket plug would not seal - yours may also be bad if a leak has occurred. To get over the problem I used a lens (dish) type plug in the recess machined around the hole. You may or may not be able to buy a standard lens type plug to fit. I couldn't get the right size so I turned one down - holding the plug against a convex piece of steel in the lathe chuck with another drilled for the tailstock centre. A bit of folded emery cloth helps the convex bit drive the plug. The new plug is fitted by applying an appropriate sealer and expanding it into the recess by hitting the convex side in the middle with a flat punch or piece of round steel, preferably nearly as big as the plug. Hope this helps. Link to comment Share on other sites More sharing options...
JACK M Posted May 28, 2016 Share Posted May 28, 2016 I'm not much of a fan of the convex plugs. I recently built a 392 Hemi that had those. The first time I got on it one came out, I replaced it with a rubber expanding plug and when I got on it again it blew one on the other side. I jacked up the engine and pulled the motor mounts and starter and replaced all of them with the rubber ones. I may have been a bit timid when I drove them in and the Hemi before this one still has them but This time it was a real PITA. I now have about forty miles on the car and the plugs are OK so far. Hopefully your engine doesn't have the step in the casting and you can put the cup style in there. If not and corrosion is scary they make those rubber plugs in several sizes but I don't know about 7/8" But if it were me I would replace them all regardless. Link to comment Share on other sites More sharing options...
HBergh Posted May 28, 2016 Author Share Posted May 28, 2016 Thank you everyone with all your helpful suggestions as well as a little history, which was very interesting! Since I don't believe the exhaust header has been off since it was built, I've begun the manifold removal process by dousing the port connections with penetrating oil. It all looks a little rusty! If I find anything interesting to see, I'll post a picture of two. Thanks again, Howard. Link to comment Share on other sites More sharing options...
TonyAus Posted May 28, 2016 Share Posted May 28, 2016 The port connections are not your problem - only the three nuts on the locating studs and the flange nut. And when replacing the manifold you will need a set of four copper crush rings which seat it to the block. Link to comment Share on other sites More sharing options...
nearchoclatetown Posted May 28, 2016 Share Posted May 28, 2016 Howard, I too would not separate the manifold and pipe. That nut is a pain to get started straight after being off, easy to cross thread. I think all the blocks I've looked at have the step. No biggie. I wash with thinner to get rid of all traces of antifreeze and use real sealer NOT RTV. Let it sit a day or two to set up. Have never had an issue with leakage. Link to comment Share on other sites More sharing options...
HBergh Posted August 8, 2016 Author Share Posted August 8, 2016 I disconnected the exhaust header by removing three bolts and as suggested, I disconnected the tail pipe hold-downs to allow better mobility of the header and better access to this hidden expansion plug hole. I cleaned out all the loose rust from inside this hole. (see picture) I was unable to locate a cup expansion plug of the exact size (31/32") for my 1923 engine. I was shown a piece of copper water pipe coupler which had an OD that just fit into my hole. I then found a 3/4" copper water pipe cap whose OD also fit nicely into my expansion hole. I ground down the cap to about 3/8" from 3/4" length. I applied a layer of contact adhesive-sealant around the surfaces of the cap and expansion hole. After a couple of minutes of drying, I tapped the cap into the hole such that it was flush with the engine body so that it looks just like the original. Even though there appears to be a slight gap at the top of the finished job, there are no leaks! I'm ready to roll again! Now, on to repacking my water pump..... Link to comment Share on other sites More sharing options...
JACK M Posted August 8, 2016 Share Posted August 8, 2016 Looking good !! Link to comment Share on other sites More sharing options...
jan arnett (2) Posted August 9, 2016 Share Posted August 9, 2016 nice job Link to comment Share on other sites More sharing options...
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