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re instahl freeze plugs

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ddirksen

New member
Hi guys, new to the forum. I did a little searching but didn't find my answer.

I have a PCM Ford 351 in my 91 Nautique which I bought new. I have babied her all her life and she's pretty much been flawless still pulls strong with about 650 hours. My issue is I drain the water every year and the holes the brass plugs screw into just keep getting rustier, and now the plugs don't go in far enough to seal good.

Is there a recomended way to clean these up, or to re tap them? Thanks
 
There are rubber expanding type plugs that you can use instead of the drive fit ones. These have a bolt in the center you tighten up and the rubber expands to fit the hole. I don't have a source but they're pretty easy to come by.
 
Thanks for the quick replies guys. I was hoping to continue to use the brass plugs if possible just because thats the way it originally was. I have wire brushed the heck out of them but the crud is just too stubborn and hard to reach. I've used several types of wire brush and no luck. And I've used teflon tape on the threads for a little more holding power. Its more like I need to re tap the threads. I would do that but I think its like a special pipe fine thread. It's definately not a course thread.
 
Welcome aboard. You should be able to find a tap of the right size. Take one of the plugs with you to the harware store. Before you buy a tap though, ensure that you won't bottom out on anything internally, there are special taps for this that don't require a clearance beyond the material thickness such as you'd need in a manifold. I have had much luck over the years using a regular threaded steel pipe nipple (about 3-4 inches long from plumbing section) of the correct size, I always keep a few common sizes in my tool box for this. Unlike the brass plug, the steel threads won't get wrecked while threading on. I also like that this method isn't as agressive as a tap that may cause further problems is not done right due to working blind or bad angle. Just go slow and easy. Curious, do you take your plugs out for off season and leave them off? If so, I find that is the fastest way to ruin the threads. Always put them back in and the threads will last longer.
 
Thanks.

Yes, I did always take them out and store them in the glove box. What you say makes perfect sense, lots of water/humidity, lots of air, lots of rust. I just never thought of it.

I did find the tap and new brass plugs at Oriely's auto parts. It is a pipe thread, so I will check the depth and should be good to go. Thanks again.
 
99.9% sure they're 3/4 NPT. I bought a tap from Mcmaster Carr just for cleaning up the holes on exhaust manis. Teflon thread tape is pretty useless stuff. Better to use a pipe dope compound. If you are going to go to all the trouble of cleaning up the threads, go one step more and install a bronze ball valve on a brass nipple so you don't ever have to unthread anything in the future.
 
Just to report back the steel pipe idea worked great. I bought a short piece of pipe and a "T" piece of pipe which gave me some grip to twist and got them cleaned up. Put new brass plugs in (the block) and it looks/works good. Thanks again.
 
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