I did a lot of three-cylinder driving yesterday. I was running errands in town and heard the telltale chuf-chuff-chuff of a leaking spark plug. I pulled off in the shade to check the plugs and found that #3 was the culprit. Its base was still solidly in the head, but the collar was loose. Taking the plug out and opening it up, I found that the insulator was badly broken. Not having a spare with me, I called my cousin for a ride home, got a box of plugs, and went back to town and installed an Autolite 3095. I drove home and put the car away. This morning I rechecked the plugs and found that #4 was loose.
This is #4. Like #3, it has a broken insulator. The other one was worse, broken in several pieces. #3 had the original washers, and #4 had one of the copper crush gaskets I've been trying out. Apparently these plugs break with either type. I think I've now had five or six broken plugs in the last couple of years. Anybody else have this problem? Any explanation?
Why not just put 'em on the shelf and get newer more reliable ones? You've spent enough time on the side of the road.
Will either JB weld or Marvel Mystery oil fix this?
I don't know a lot about these old plugs, but I have a theory. Could it be that the collar was tightened a little excessively, then over time engine heat caused expansion of the insulator thus causing it to break? Further, once the insulator is fractured wouldn't the collar tend to loosen?
Nothing at all strange with X breaking; especially if they're used originals not NOS originals.
Now you know why Champion offered more expensive "Heavy Stone" plugs. Almost all other plug makers at the time also offered a heavy duty line often called the "Giant" or "Senior" series.
Steve, have you tried the NOS cores you purchased at Hershey yet?
No, I haven't yet. I'm going to try a set and see how they do.
I haven't tried this, but I wonder if a skim coat of hi temp RTV on the gaskets would help seal things and provide a cushion to help save the insulator. Give the RTV plenty of time (like a week) to fully set up before using the plug.
The advise in this old issue of FordOwner cautions on too tight a bushing on the porcelain. Bushing should be tight enough to hold compression, but not too tight to allow some expansion from heat.
Either too tight or old, worn porcelain, with missing glaze on the surface with cracks
I have noticed that the Champion X take a part plugs can sometimes have hairline cracks in the insulator that are very fine and hard to see.
In my experience with them about 1 in about 3 have been that way. My guess is some were cracked when the were originally put together and when taken apart to clean up and reuse they tend to be prone to finally crack out after being used a while. Of course you have to be careful tightening and retightening them.
To me its like reusing an original working mag ring and re varnishing the original insulation and hoping it will be OK. It might be last but you never know for sure.
BUT the plugs are easier to change than the Mag ring! That's the good part!
Could part of the problem be only having crush rings on the bottom. I would think having a slip ring on top between the porcelain and nut might help prevent this. A slip ring would let the jam nut ride on it insted of directly on the porcelain. Did these plugs have the slip ring? I have seen the take-apart plugs that used them.
I see the one you posted the photo didn't. I typed and posted while that photo was loading.
Those Champion's porcelains aren't supposed to break.
But....now that you have a collected a few busted ones...here's a new sport.
Here are a few hints in 1920 issue of Motor Age about spark plug cleaning and care. Further states to carefully tighten just so.
In Dan's first post above is a Champion ad. In part, it says,
".... porcelains are double cushioned against breakage. At both shoulders of the porcelain there is an asbestos cushioned copper gasket to ease the force of the explosions and absolutely hold the compression in the cylinders."
In his second post, the Motor Age article says,
"If the porcelain is broken, a new one with new gaskets should be used."
Crush washers are still used with aircraft spark plugs and, I believe, in some car applications as well. In the aircraft that I'm familiar with, the mechanic is admonished to always use a new washer when installing or reinstalling plugs. Once used, the gasket is crushed and can't do its job properly a second time.
So maybe the broken porcelains are the result of reusing an old crush washer.
Some of the broken insulators have had reused original washers, and some have had these new copper crush washers under them. Unfortunately, these won't fit over the top of the brass cap plugs.
There are three basic types of X plugs, with other variations among them. Earliest are completely take-apart with a straight insulator. A transitional type is completely take-apart with ridges. Both these types have a 5-40 thread. Last, most common, has the non-removable center electrode embedded in a brass cap that's crimped onto the insulator. This is the type still available.
Here's one of the transitional plugs disassembled. It has the copper/asbestos washers above and below the insulator. At the bottom is a current X plug. It has only one thin copper ring under the porcelain. I bought one of the new ones just to see what they're like. I haven't used it in a car.
There's a bit more on X plugs here: http://dauntlessgeezer.com/DG95.html.
I had this happen years ago,switched to champ. A25's, had miss under load problems with them.Switched to Motocraft F11's,that ended my plug problems. I put a lot of miles on and never clean or adjust them. I have original take apart's in my 24 I am just finishing up and it runs good but before I start driving it for real it will have F11's. As a bonus I think it's the least expensive plug you can buy.
Which is the plug with glued-in terminals that fall out?
I still think you are on the right track with the crush ring style that you show. They do come in lots of different diameters.
Just a thought and someone please correct me if I am wrong...'crush' is the wrong word? Wouldn't you want to pull it up just enough to 'deform' a seal against both sides and still have a little bit of 'cushion' in the ring??
I say that because on manifolds with crush rings, My experience has been that I do only use them but once, and do only pull them down just enough when I mount them in the first place...I do not squish them flat and it seems to work on manifolds and keep them from leaking
Just my experience; I've been running A-25 plugs in my speedster for three years with no problems. My dad ran them in the car for many years in the 60s and 70s also with no problems.
For those still thinking...
About 5 years ago, Champion had a whole batch (or 2, or 3) of A-25 where the top nuts would seat OK the first time, but...trying to UNSCREW caused the whole top electrode to turn out of the plug and once the 'glue seal' broke, lot-sa-luck getting them to ever fire right again was the general experience.
Here is one that never got the chance to even get sooty!
George those A-25's that the tops would unscrew go back more then 5 years. I had some more then 15 years ago that if you got the nut too tight the top would unscrew.