neil morse Posted January 6, 2020 Share Posted January 6, 2020 (edited) One of the core plugs on my '41 has started leaking small amounts of coolant. I first noticed how bad it looked when I was investigating a coolant leak last April. Here's a pic of what it looked like then. It wasn't leaking at the time, but it's obvious that it had leaked in the past. Here's what it looks like now. It's probably leaking about a cup of coolant a month right now. It's located right under the place where the rear arm of the "Y" exhaust connector joins the exhaust manifold. So --- is it possible to fix this without pulling the engine? Has anyone done it? Related question: Are the "expanding" type replacement plugs that are made for a short-cut core plug repair any good? Pulling the engine on my car would obviously me a major headache, and I would very much like to avoid it if possible. However, I don't want to have a catastrophic failure of the plug either. Any advice would be most appreciated! Neil Edited January 6, 2020 by neil morse (see edit history) Link to comment Share on other sites More sharing options...
Matt Harwood Posted January 6, 2020 Share Posted January 6, 2020 (edited) Yikes, that stinks Neil. I've used the expanding core plugs and while I don't think they should be considered a permanent solution, I also don't think that an old car places much of a demand on them. Besides, if you know it's there, you'll keep an eye on things and deal with the problem later should it arise. They're not the best solution, but given that the alternative is to either disassemble the intake/exhaust system or remove the engine, I think it's worth a shot. Your best chance at success is to get the old one out and then clean the entire area as best as you can, making sure the walls of the opening where the expanding plug will be are as smooth and round as possible. If it's rough or irregular, it'll be tough to seal. The expanding plugs are also the kinds of things where too tight is too tight. Snug it up and then tighten it only enough to stop it from leaking. After a few heat cycles, check it again, and then keep an eye on it to see if it's coming undone. This is a solvable problem that shouldn't be catastrophic. Wait until you need to do it to tackle the really awful job. Keep us posted! Edited January 6, 2020 by Matt Harwood (see edit history) 2 2 Link to comment Share on other sites More sharing options...
kgreen Posted January 6, 2020 Share Posted January 6, 2020 Matt's recommendation is as sound as you can get. I've used rubber expanding plugs on a daily driver junker that I drove in college for years. No telling how long it will last, but guessing better than five years so keeping an eye on it is essential. Link to comment Share on other sites More sharing options...
neil morse Posted January 7, 2020 Author Share Posted January 7, 2020 Thanks for the quick responses, Matt and Ken. I really appreciate your advice and assistance. Assuming that I go with the expansion-type replacement plug, I see that there are two basic types: rubber (or neoprene) and copper. It's discussed in the blog post I've linked to below. The guy (who seems to know what he's talking about) says, "I have had bad luck with the rubber type: they blow back out quite often. I have had good results with the copper type (made by Dorman)." http://econofix.com/frezplug.html Do you guys have an opinion on this question? Also, I haven't tried to get a hand in there from underneath, but I don't think I can avoid having to at least disassemble the intake/exhaust system, even to stick an expansion-type plug in there. There is very little access to that spot (of course). I will do some more exploratory work and let you know. I haven't tried to do anything but photograph it because when I showed the pics I took last April to Don Micheletti, the first thing he said was, "Neil, whatever you do, don't try to clean up the area -- you'll just make it worse." Well, I didn't have to make it worse, it got there on its own. (Not that I'm surprised.) Link to comment Share on other sites More sharing options...
Matt Harwood Posted January 7, 2020 Share Posted January 7, 2020 I always use the copper ones. There's some debate over whether you should put any sealer around the perimeter. I like to install them dry but Dr. Francini liked to put a little black RTV around the edges to help seal up any pinholes. I suppose it can't hurt, right? Just not too much, only a skim coat on the edge. https://www.summitracing.com/parts/rnb-568-011/overview/ 1 Link to comment Share on other sites More sharing options...
neil morse Posted January 7, 2020 Author Share Posted January 7, 2020 Thanks, Matt. That's just what I needed to know. I will keep you posted. I'm just about to embark on a transmission job with Don's help, so this will be a good time to do the plug job as well. Neil Link to comment Share on other sites More sharing options...
michealbernal Posted January 7, 2020 Share Posted January 7, 2020 I put one of the expanding plugs in my 1962 International Scout engine. The 4 cyl 152 cu in engine has a plug directly under the exhaust manifold. Anyway it has been in place for about 15 years now and has not leaked even a drop. I put it in dry. I drove it across the Utah salt flats and thru the southern California deserts during summer with no problems 4 Link to comment Share on other sites More sharing options...
c49er Posted January 7, 2020 Share Posted January 7, 2020 The biggest problem is access to the plug...remove the manifolds as an assembly. Then full access to the core plug. 2 Link to comment Share on other sites More sharing options...
1937-44 Posted January 7, 2020 Share Posted January 7, 2020 On my 1937 Special I removed the manifolds, took out the old plugs and just put in new steel plugs instead of an expansion plug. Surprised me that it wasn't as hard as I expected. I figured if the original steel plugs lasted +/- 70 years the new ones should last my lifetime. 1 Link to comment Share on other sites More sharing options...
neil morse Posted January 7, 2020 Author Share Posted January 7, 2020 14 minutes ago, 1937-44 said: On my 1937 Special I removed the manifolds, took out the old plugs and just put in new steel plugs instead of an expansion plug. Surprised me that it wasn't as hard as I expected. I figured if the original steel plugs lasted +/- 70 years the new ones should last my lifetime. So you had room to swing a hammer between the engine and the fender well? That's what's concerning me. Link to comment Share on other sites More sharing options...
Jim Bourque Posted January 7, 2020 Share Posted January 7, 2020 Make a fulcrum that can be attached to the manifold studs/bolts and lever them in with a crow bar if you don’t have room to swing a hammer. 1 Link to comment Share on other sites More sharing options...
Matt Harwood Posted January 7, 2020 Share Posted January 7, 2020 (edited) I would recommend doing all you can to avoid removing the manifolds for this job. They can be removed as an assembly, but they'll still move around. Getting them sealed back on the block may be problematic and if they're even a little cracked, removing them can make it worse. It may be sufficient to remove the exhaust pipe from the manifolds to buy yourself some space and work from below. The expanding plugs don't need much room if you can get a pair of wrenches in there, or a wrench and an air socket. If that doesn't work, there are also air-powered close-quarters palm hammers that you might be able to use to drive in a new plug so you don't have to swing a big hammer. Check it out: If your manifolds don't leak, please do all you can to leave them alone. If they absolutely must come off, get an entirely new gasket set for the manifolds and reinstall carefully. I might even disassemble them at that point and even have them surfaced just to make sure the seal is good. Let us know how it goes. Good luck! Edited January 7, 2020 by Matt Harwood (see edit history) 1 Link to comment Share on other sites More sharing options...
Brian_Heil Posted January 7, 2020 Share Posted January 7, 2020 Two comments. All your core plugs are in a race to disappear and this one just happens to be in the lead. The others are still in the race and will follow. But we’ve all been where you are at some time or another. I once used a very large ‘C’ shaped valve spring compressor to install a plug in a difficult location on another type of engine where I could not swing a hammer. 4 Link to comment Share on other sites More sharing options...
neil morse Posted January 7, 2020 Author Share Posted January 7, 2020 Thanks, everybody, for the additional comments. Please keep them coming if you have any more thoughts. I will let everyone know how it works out. Link to comment Share on other sites More sharing options...
1937-44 Posted January 7, 2020 Share Posted January 7, 2020 (edited) 2 hours ago, neil morse said: So you had room to swing a hammer between the engine and the fender well? On a 37 Special there was enough room, but as I recall it was more tapping in then it was pounding in. The main reason I removed the manifolds was for the removal of the old plugs. I couldn't figure out a way to get the plug out I needed to replace with the manifold in place. Having one piece manifolds is one advantage of the smaller engine. Edited January 7, 2020 by 1937-44 (see edit history) 2 Link to comment Share on other sites More sharing options...
c49er Posted January 8, 2020 Share Posted January 8, 2020 It's almost zero access to get to the plugs and yes those manifolds must be dealt with care. 2 Link to comment Share on other sites More sharing options...
Kestrel Posted January 8, 2020 Share Posted January 8, 2020 Keep in mind that if one failed the others will follow sooner than later. I faced that with my '51 Super. Only one was bad but I knew they all should be replaced with regular steel plugs. Yes, the manifold is a pain to remove but there is no other way around it. It comes off easy but will probably need re-surfacing and planning as warping is common. Not a big deal for most machine shops. My engine is a 263 cu in. I removed it as one unit, intake and exhaust manifold bolted together. After removal, access was easy. There are many ways to remove the plugs but I had a friend use his welder to drop a few beads on the plugs then quench with water. The contraction then allowed the plug to basically drop out in one piece with minimal coaxing. The worst plug was so paper thin I just scraped it out. For installation you can use a socket large enough to cover the diameter of the plug then tap it in or there are specialty plug installing tools (maybe rent one). This is a GREAT time to clean out the water passages. I took out tons of rust particles with a long handle magnet. I reinstalled the trued up manifold using high quality composite gaskets. A fair amount of work but surely worth it. 5 Link to comment Share on other sites More sharing options...
neil morse Posted January 8, 2020 Author Share Posted January 8, 2020 Thanks for the pointers, Charlie. Wow, your engine looks really clean! Link to comment Share on other sites More sharing options...
Lawrence Helfand Posted January 9, 2020 Share Posted January 9, 2020 Removing the manifold is made quite easy with the use of a hoist. I positioned my manifold under an I beam rolling chain hoist in my garage but you can rent an engine puller hoist for this job as well. I put a couple of hold down straps under the manifolds which I did not separate and then unbolted the assembly. It was then easy to pull away the manifold and lift it . I left it hanging and cleaned up the surfaces and gave it a paint job. All the freeze plugs were exposed for easy access and reinstalling and positioning the very heavy manifold was a breeze not having to wrestle the heavy ungainly hunk around. An intimidating job was made easy and simple using a hoist. Why not take the opportunity to refresh your manifold gaskets paint your block as well and change all your block plugs the right way with plenty of room to work. 3 Link to comment Share on other sites More sharing options...
neil morse Posted January 9, 2020 Author Share Posted January 9, 2020 Thanks, Lawrence. The hoist sounds like an excellent idea. Link to comment Share on other sites More sharing options...
Ben Bruce aka First Born Posted January 10, 2020 Share Posted January 10, 2020 Neil, after hearing glowing reviews, I used Rem-Flex gaskets . Can't speak to longevity as they have only been on for six months or so. Buy them from Summit racing. About the same price as the copper clad from Best Gaskets that the vendors sell. Ben 1 Link to comment Share on other sites More sharing options...
1937-44 Posted January 10, 2020 Share Posted January 10, 2020 Pulling the head might require a lift, but just pulling the manifolds can be done without one if you are reasonably fit. Link to comment Share on other sites More sharing options...
Kestrel Posted January 10, 2020 Share Posted January 10, 2020 If working alone a lift is nice and keeps it steady when the final bolts are removed. 2nd on the Rem Flex gaskets. 1 Link to comment Share on other sites More sharing options...
neil morse Posted January 10, 2020 Author Share Posted January 10, 2020 Thanks again to all for your helpful contributions! I am mulling over my alternatives for now. Neil Link to comment Share on other sites More sharing options...
Daves1940Buick56S Posted January 10, 2020 Share Posted January 10, 2020 Neil: I went thru this as well as few years ago. I did manage to get the plug out without removing the manifolds (not at all a pleasant job), and used the expanding rubber replacement. It is still on there several years later. In the end I did have to take off the manifold and head for a valve and ring job, but that was almost a year later. Cheers, Dave 2 Link to comment Share on other sites More sharing options...
neil morse Posted January 24, 2022 Author Share Posted January 24, 2022 An update on my problem, and the news is not good! The original problem I posted about was the rear-most of the three core plugs on the left side of the engine. The two front plugs looked completely normal. Here's what it looked like in photos from March of 2019. Now the two front plugs look even worse than the rear one! I clearly can no longer put off doing something about this. Does anyone have any idea what could be causing the rapid deterioration of these plugs? I've driven the car about 3K miles in the period between the two sets of photos. Link to comment Share on other sites More sharing options...
kgreen Posted January 24, 2022 Share Posted January 24, 2022 Neil, I know from living in the salt belt that corrosion, like termites, can cause unseen damage in concealed areas that only shows when the extent of damage becomes visible as you witnessed in your photos. It is possible and to be purely speculative, the antifreeze that you use and which has anticorrosion properties has exceeded its' service life. If that was true, then corrosion could advance more rapidly. How old is your antifreeze? Here's where I put a target on my chest: you can pop those rusted plugs out and use the rubber expanding plugs to bide your time. Many say that these are purely temporary; they are, but in the era where I was struggling to properly maintain a car, I got that type of plug to last three years. 1 Link to comment Share on other sites More sharing options...
neil morse Posted January 24, 2022 Author Share Posted January 24, 2022 Thanks for the quick response, Ken. I'm using 50-50 coolant that was last changed out when I installed a new water pump about two-and-a-half years ago. But I have topped it up with plain water several times during that period. Anyway, that's all "water under the bridge" (pun intended) at this point as the time for the job has clearly come. Link to comment Share on other sites More sharing options...
Matt Harwood Posted January 24, 2022 Share Posted January 24, 2022 This stinks, I'm sorry Neil. But you know what to do and how to do it. I've learned recently on my other project that sometimes you know what needs to be done, you know how to do it, you just don't want to do it. Ultimately, it turns out to be not as big a deal as you expect. Hopefully that's the case here. It's also a chance to address other details before they have a chance to go south, like the manifold gaskets. I removed and installed mine several times during the header construction and it wasn't all that bad. I'd recommend the Remflex gaskets which may eliminate the need to do any machining to the mating surfaces. You might be able to remove it as an assembly and minimize the disruption to the whole system. You know what to do. Gird your loins and do it! 3 1 Link to comment Share on other sites More sharing options...
Daves1940Buick56S Posted January 25, 2022 Share Posted January 25, 2022 For a data point, I am still using the expandable plugs I installed in 2012 as detailed earlier in this thread. Almost 10 years later and they are still fine. 2 1 Link to comment Share on other sites More sharing options...
neil morse Posted January 25, 2022 Author Share Posted January 25, 2022 4 hours ago, Matt Harwood said: I've learned recently on my other project that sometimes you know what needs to be done, you know how to do it, you just don't want to do it. Ultimately, it turns out to be not as big a deal as you expect. Hopefully that's the case here. As you often do, I think you have hit the nail on the head here. Thank you for the encouragement. As a relative newbie, I have a tendency to think various projects are going to be more difficult than they are. So far, almost all of them have turned out to be much less trouble than I thought they would be. I hope this is the case here, as you say. I will keep everyone posted as I go forward. 1 Link to comment Share on other sites More sharing options...
neil morse Posted January 25, 2022 Author Share Posted January 25, 2022 4 hours ago, Daves1940Buick56S said: For a data point, I am still using the expandable plugs I installed in 2012 as detailed earlier in this thread. Almost 10 years later and they are still fine. Thank you for that information, Dave! Link to comment Share on other sites More sharing options...
Gary W Posted January 25, 2022 Share Posted January 25, 2022 Hi Neil! When you finish the plug change, may I recommend using a bottle of "NO ROSION" additive to your 50/50 antifreeze. I use it in every one of my vehicles to hopefully prevent future rust/corrosion...... Good luck with the project. You got this! Gary 1 Link to comment Share on other sites More sharing options...
neil morse Posted January 25, 2022 Author Share Posted January 25, 2022 Does anyone know what size plugs I will need for the 248? Link to comment Share on other sites More sharing options...
Gary W Posted January 26, 2022 Share Posted January 26, 2022 I used DORMAN 555-040 which are 1.953" Neil If you send me your address I can send you them. I have four or five here from the build. Gary 1 1 Link to comment Share on other sites More sharing options...
neil morse Posted January 26, 2022 Author Share Posted January 26, 2022 Thank you, Gary. I will send you a PM. You are very kind! Link to comment Share on other sites More sharing options...
neil morse Posted January 30, 2022 Author Share Posted January 30, 2022 (edited) Okay, after a lot of helpful consultation with knowledgeable folks, I have decided on a plan. We will leave the manifolds in place and pull the cylinder head. This will give access to all the core plugs, including the one in the rear of the head that's right up against the firewall, and also avoid the danger of cracking the manifolds and/or having to plane them. For people interested in "the rest of the story," I will post a detailed report in my thread on the "Me and My Buick" forum when I get everything I need assembled for the job. Edited January 30, 2022 by neil morse (see edit history) 2 Link to comment Share on other sites More sharing options...
Mark Shaw Posted January 30, 2022 Share Posted January 30, 2022 While you're at it, check between the firewall and the back of the engine for one more plug. When I replaced all the plugs in my 29 Buick Standard, I found a plug at the rear of the block that could not be reached from the engine side. I looked under the dash and found a flap in the firewall to access the plug. A previous owner/mechanic drilled a U pattern of holes & cuts between the holes to make the flap. Maybe you will be lucky too! Link to comment Share on other sites More sharing options...
neil morse Posted January 30, 2022 Author Share Posted January 30, 2022 Thanks, Mark, but I have been assured by a reliable source that the '41 248 has only four plugs -- the three on the left side and a fourth at the rear of the head. I've heard stories about people cutting a hole in the firewall to get at that fourth one, but I think we've come up with a better solution! 1 Link to comment Share on other sites More sharing options...
neil morse Posted February 23, 2022 Author Share Posted February 23, 2022 For anyone interested in "the rest of the story," I have continued discussion of this project on my thread in the "Me and My Buick" forum here (click on arrow in upper right hand corner to go the right post): Link to comment Share on other sites More sharing options...
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