neil morse

Replacing Core Plug on '41 Super Without Pulling Engine?

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Posted (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.

 

bad_core_plug.jpg.00b3d320c2e4b1d1a9a2c0568c18a098.jpg

 

Here's what it looks like now.  It's probably leaking about a cup of coolant a month right now.

 

bad_core_plug2.thumb.jpg.21400edddce1f9dd9944d7ab0ef9769e.jpg

 

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 by neil morse (see edit history)

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Posted (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 by Matt Harwood (see edit history)
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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.

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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.)

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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.

 

rnb-568-011_ml.jpg

 

https://www.summitracing.com/parts/rnb-568-011/overview/

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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

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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

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The biggest problem is access to the plug...remove the manifolds as an assembly.

Then full access to the core plug.

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 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.

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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.

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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. 

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Posted (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:

 

PMPN_12070_600.jpg

 

 

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 by Matt Harwood (see edit history)
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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.  

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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.

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Posted (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 by 1937-44 (see edit history)
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It's almost zero access to get to the plugs and yes those manifolds must be dealt with care.

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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. 

 

 

IMG_1368.jpeg

IMG_1428.jpeg

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Thanks for the pointers, Charlie.  Wow, your engine looks really clean!

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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. 

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Thanks, Lawrence.  The hoist sounds like an excellent idea.

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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

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 Pulling the head might require a lift, but just pulling the manifolds can be done without one if you are reasonably fit.

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If working alone a lift is nice and keeps it steady when the final bolts are removed.  2nd on the Rem Flex gaskets.

IMG_1206.jpeg

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Thanks again to all for your helpful contributions!  I am mulling over my alternatives for now.

 

Neil

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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

 

 

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