Hey guys, I just built a flat 6 for a 47 Plymouth, the machine shop installed the freeze plugs, and while I was heat cycling it, one of the freeze plugs popped out. So my question is, should I drive it in nice and tight, or nice and tight then dent the center to expand it in the bore ? They are dish type plugs.. And what do you use to seal it in ? Green loctite ? Thanks.
Yep. Lay the peen end of a small hammer on the center of the dome of the plug and hit with another hammer to dent it in. I'd use Permatex #2 (non-hardening) Make sure the bore & the plug are CLEAN before assembly..... if space allows, a small wire brush in a Dremel works good to get in the bore. Wipe with lacquer thinner to make sure everything is clean.
I have also used Ultra Black as well. If your in question on reliablitiy since it popped out, you can always go to a Boat store, they sell a rubber type temp one with a turn wing nut to expand. Its not permanent, but if it ever fell out on the road, instead of being dead in the water, you could limp it home
I would make the machine shop do the refit. If you don't and it pops out again and you cook your motor technically you have voided any potential claim you have against them.
I think if your plug popped out it was installed incorrectly, or the wrong size, and the shop ought to be on notice and acknowledge it in writing. After a new plug is installed I would want to pressurize the cooling system to the max in an effort to make the other incorrectly installed plugs leak or pop out under controlled situation. I think 2 different types of "freeze plugs" are being discussed. Both could be described as "dished." One type is a ~ flat disc with a shallow dished curvature. http://imageserver.grainger.com/is/image/Grainger/6AJU1_AS01?$productdetail$ It should install fairly easily up against a shoulder, and with the cup outward. Finally the curvature has to be flattened some by striking to make the diameter enlarge and seal. The other type has 3/16 to 3/8 inch long cylindrical sides (which are actually flared outward a little bit). http://www.vertexauto.com/UserData/Images/Large/94.jpg They are usually installed like this - http://usauto.vo.llnwd.net/o37/prod/73/ea/73ea7e0a54e8fa2a84b3b3a12a4403f1f195a32812572239078002.jpg Maybe either type would seal perfectly in a freshly machined bore, but I use a little sealer. Even carefully installed plugs are a little risky. Witness extra efforts made to retain them in racing and HP applications over the decades. http://image.off-roadweb.com/f/30936897/0912or_13_+408_windsor_engine+freeze_plug_drilled.jpg http://www.clubcobra.com/photopost/data/500/9528MVC-012S.JPG http://www.industrialinjection.com/...cture-cr-freeze-plug-1561_jpg_250x250_q85.jpg http://www.circletrack.com/enginetech/ctrp_0811_freeze_plugs/viewall.html
FlatHEAD 6, flatHEAD 6. They used the convex disc type plug, not the cup type. You put the plug in with the dome side out then give it a couple of raps with a hammer and drift to expand it. A little Permatex or your favorite sealer, is good insurance against leaks. If one popped out it was not installed properly. You need to flatten it a bit for it to seal tight. Hidden areas like behind the flywheel should get 2 plugs for extra security. There are brass plugs available for marine and corrosive environments. If you use antifreeze the steel ones will last indefinitely, if you don't they can rust through in 20 to 50 years.
thanks for the replies guys. the plug is behind the oil filter canister, so I removed it and put a new one in with green loctite, dented in the center like advised, to tighten it up. did that last night. I'm fixing to go out to the shop, get the engine back up to operating temp, and see what happens, I don't have any way to pressurize the system, but I will be telling the machine shop what happened.
Had one of the dished (shallow plugs) in my MGB and it popped out while I was racing at 112 MPH and backed down to fast. Fortunately it was near the distributor and when it popped, the antifreeze drowned the disty. No harm done, just embarrassing. Put a new one in with a little perm2 and was good to go.
Definately record it with the machine shop. I'd be concerned with any other machine work, etc. they may have done on the engine if they couldn't properly seat a freeze plug. Have you used the shop before?
yea, iv been using them for proubly 7 or 8 years, i build 5 or 6 engines a year, mostly flathead stuff, and iv never had a problem till now. i guess shit happens, ill tell them, this is the forst freeze plug iv ever seen poop out.
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