: Bad batch of DELCO PLATINUM 41-950 SPARK PLUGS



Loose screw
05-14-06, 12:32 AM
May car was having some occasional misfiring that I could not trace down that started a few months after I install the new Delco 41-950 last year. It was gradually getting worse. I pulled the plugs and carefully inspected them. Three of the eight appeared to have vertical carboninzed hairline cracks inside the white insulators but very visable at the surface but still hard to see if you don't look under a bright light. I took them back and talked to the AutoZone manager who is also a good machanic and he was sceptical and was sure my problem was elsewhere. I installed three new plugs and the problem was gone. A couple days later I was back to the same store and mentioned it to the same manager - that the problem was fixed with the replacing of those three plugs and he said: " ya I had another guy come in, I think it was the next day, he was having the same problem with those plugs that he had installed in his Cadi. There must of been a bad batch of those 950s we don't sell that many of them and it was strange to have two customers come it with the same plugs having the same problem just within a couple days of each other. "

He was right I had installed mine last year! That was strange

So if you are now using the Delco 41-950s that first came out last year and you get some unexplaned misfiring and it is getting worse with time - pull the plugs and look for vertical carbon lines in the insulators (white tops). Appearently they start as micro cracks created in manufacturing and gradually the arching starts getting through them and builds up carbon trials which makes it worse and eventually they start actually shorting out to the metal on the plug nut that you start getting occational misfiring that can change with temp and operating condition but gets worse with time - inspect your plugs. My other 5 plugs were fine and are still in service.

Has anyone else had any Delco 41-950 plugs that have had simular defects?

dkozloski
05-14-06, 01:22 AM
Years ago I worked for the largest retail dealer of AC aircraft sparkplugs in the world. The rep that serviced our area. Snowy Coates, told us that if we ever saw lengthwise cracks in the insulators to call the distributor immediately as it indicated there was a serious problem in the manufacturing process. This confirms your story.

Loose screw
05-14-06, 02:52 AM
Thanks for the confirm.

These cracks did not appear to extend to the not nor to the top but were in the middle and one crack was over an inch long and the carbon trail could be felt on it's surface. They appeared to be stress fractures and the insulator may have even been less dense or even porious in this middle area. But it was hard to tell.

I suspect that the way you would have to test them is to remove the plug and then stick the thread end in a insulator (rubber hose) to hold it so it is not grounded ot near a ground and connect the top to a high voltage spark and then pass a grounded probe along the insulator and see if it will spark through there rather than jump from the nut or top but your likely to get shocked a few time before rule out that a spark can't get through the insulator at any point and you would have to cool and heat up the plug too. But I bet the factory has cool machine to do it all fast.

But even then once they are in use they go through many additional stresses and countless thermal cycles and cracks may not develp for some time. Sample extensive testing might be the only way to make sure bad flawed plugs don't get out the door but even then there are no real garrentee. There has to be a lot of engineering that goes into what looks like a simple part.

parts68
05-14-06, 11:30 AM
I pulled some new ones out of box and gave a visual,2 had the electrodes bent
off skew,I had to rebend them and checked gap. I think its supposed to be .050 but at least thats what the other new ones checked out to be.
Makes me wonder how many I installed that were a little off.

Loose screw
05-14-06, 01:13 PM
Any new plug right out of the box that has a electrode that is bent, is a plug I would take back to the store, as it may have been droped or some other bad thing happened to it that makes it not worth trusting. Sure you can strighten and reset the evidence (the electrod and gap) but the crime, abuse has been committed what ever it wasm or when or where it took place. It could have been done at the factory (if so there is no excuse for it getting out the door) or another person opened the box and screwed it up and took it back. Always ask for books that don't look like they have been opeed. What ever the reason :thehand: avoid possible problems down the road. Why use defective, damaged or even slightly suspect plug, why take the risk in such a critical and highly sensitve part that is also so cheap to just replace?

These were tiny and very tight cracks I doubt that they would be detectable without some carbon in them or something else to make them more visable.

There is what is called a penetrating dye test which tests for cracks. But even then the crack can't be compressed together. The way the test works is a thin wet blue dye is sprayed on the surface and allowed to soak into or be drawn into any cracks. Then it is washed off the surface with a solvent in a quick manor just to clean the dye only off the surface, what is left is a blue crack line as it is harder to get the dye out of the crack than off the surface. This test has to be done when the part has not been recently wetted so the crack is completely clean and most importanly totally dry. You can clean your plugs first with solvent and then warm them in the sun to deep dry them or warm them with a flame or in an oven for a few minutes and then cool before appling the penetrating dye.

You could try this with a new dark magic marker and just keep rubbing it on the same spot so it stays as wet as possible for a minute and then gradually move to anothe spot. After a few minutes wipe it off with a rag with a little solvent on it. If there is a crack and the dye can get into it, the dye will remain even after a second wipe in the oposite direction. And if made wet (put one drop on it) it may even bleed out from the crack. Not all crack have the same depth or have yet reached the surface that you able to examin or go fully into the interior. But this should help to spot something even on a new plug that you would never be able to see other wise and may only be detaectable or cause problems a few hundred miles down the road. :yup: Don't use any plug that is suspecious :hmm:

weister42
05-14-06, 01:20 PM
Last year when I replaced all 8 AC Delco spark plugs, one of them went totally dead in about 30 miles. No warranty either and they were from Napa, bastards.

I have faint misfiring when it's moist or raining out, warming up the engine solves the problem. My guess is the moisture are making electrical jams.

Loose screw
05-14-06, 02:28 PM
I have heard of that before the conductor and or resistor or their connection fracture in side once heated good.

At night in as darkest an area as you can find open your hood and look for sparks and with a water spray bottle mist all your spark plug wires and look for faint blue light glows, if you have old wires you may even see a real arching light show.

It is amazing how many problems can still be traced to wires and plugs after all these years.

parts68
05-14-06, 04:46 PM
one reason they went to COP
I couldnt return the 2 plugs,bought them off ebay.
I ll ask the guy if he can send more
box didnt look damaged,came in the master box of 8 and these were in middle.
My guess was it happened before it went into box.

eldorado1
05-14-06, 09:43 PM
It wouldn't surprise me if some worker dropped them off the shelf, and put them right back up.

If you ever drop a spark plug, it is DEAD. Do not try to reuse it. Handle them with care, always. Even if you drop it in the box onto a feather pillow.......well, maybe not the pillow, but you get the idea. ;)

Ranger
05-14-06, 10:36 PM
What you are discribing could also be carbon tracking, commonly mistaken for a hairline porcelin crack.

Loose screw
05-15-06, 01:26 AM
What you are discribing sould also be carbon tracking, commonly mistaken for a hairline porcelin crack.

Very true Ranger, but, of course if you examin enough plugs with carbon tracking carefully, you will find under a few (a rare few) a large or small spot or crack where the spark got through the insulator.

What ever the cause it is best just to replace the plug. Totally cleaning the tracks away takes a real serious effort which is not worth it.

One other thing that is seldom considered is if there is tracting on the plugs insulator surface you can bet there is a matching weaker carbon tracking now on the inside surface of the spark plug boot, which will continue the shorting or re-establish it and the tracking pattern on a new plug in time. Don't forget the boots - don't waste time looking for it in the boot you won't see the black on black. :bonkers:

El Dobro
05-15-06, 08:34 PM
While going through the BS of trying to remove the front valve cover on my SLS, I yanked the plugs and found the platinum piece on the ground electrodes of three of them were missing AGAIN.

Loose screw
05-15-06, 09:01 PM
WOW! what has happened to Delco's quality control. They better get their act together or they can kiss my hard earned parts money good by. There are plenty of other plug manufactures out there - and I don't give a manufacturs a third chances to sell me defective parts or parts that can't stand up to WOT. :rant2: Delco - can you here me now?

Maybe they are making them out of the country now? or replaced their experinced works or some stupid thing like that.

Hello, hello, Delco anyone there - is this thing on? Delco are you there? I don't think this thing is on! testing testing -
I think Delco has left the biulding... hmmmm

Murphyg
05-18-06, 08:18 PM
WOW! what has happened to Delco's quality control. They better get their act together or they can kiss my hard earned parts money good by. There are plenty of other plug manufactures out there - and I don't give a manufacturs a third chances to sell me defective parts or parts that can't stand up to WOT. :rant2: Delco - can you here me now?...............

But then whats the next best to use ?
Almost anyone will say the same thing....."Dont use anything but AC Delco plugs in your Lac. "
And thats been proven over and over. Ask anyone whos tried.

So where would you go and what would you use ?

STS 310
05-18-06, 09:12 PM
New dropped plugs are only good for one thing, windows.

Hey, I was a kid once!

heritageba
06-29-06, 04:12 PM
I had the same problem with my 96 Deville as mentioned above. Missing under acceleration and occassional backfire. I replaced the PCM control module, due to some bad codes, the secondary oxygen sensor, the fuel regulator, and the spark plugs (With the delco 41-950) All in all I spent about $950.00. The wires had been replaced last fall.

For a short time the problem seemed to be fixed. Then it was back. No backfire but missing under acceleration. The GM dealer could not figure it out. There were no codes this time and it was intermittent. I lived with it for another few months. I finally took it to my private mechanic a few days ago. He pulled the wires off and put them back on... and it improved the missing, but did not fix it.

Then I read this article. Today my mechanic pulled all of the plugs. Sure enough there is one out of the eight that has a one inch vertical carbon track (crack) up the porcelain.

He put in Autolites and my car is finally fixed.

Thanks for your help.

Brad

GreenMachine
06-29-06, 07:59 PM
if you can't trust AC Delco (who can you trust.....anyway) why not give Champion sparkplugs a try. They have been around forever, the seem respectable and offer good products. Heck their RJ19LM plugs for my lawnmower, snowblower, etc work great even when in the ugliest shape.

results for my 98 cadillac from thier website: http://www.championsparkplugs.com/results_app.asp?AAIA=1313773

Murphyg
06-29-06, 08:36 PM
if you can't trust AC Delco (who can you trust.....anyway) why not give Champion sparkplugs a try. They have been around forever, the seem respectable and offer good products. Heck their RJ19LM plugs for my lawnmower, snowblower, etc work great even when in the ugliest shape.

results for my 98 cadillac from thier website: http://www.championsparkplugs.com/results_app.asp?AAIA=1313773

There is a far cry difference between mowers/blowers and Cadillacs my friend.
Specially since most mowers, blowers, trimmers etc come with and recomend a champion plug.

Cadillac does not.

Cadillac comes with and recomends AC Delco

parts68
06-29-06, 08:51 PM
Bad news a second set of recently purchased"ebay" plugs
has a problem.
Ive put only about 1 K on another set and its already missing at idle.

Murphyg
06-29-06, 09:09 PM
Bad news a second set of recently purchased"ebay" plugs
has a problem.
Ive put only about 1 K on another set and its already missing at idle.

:violin:

heritageba
06-29-06, 10:57 PM
My mechanic put in Autolites AP605. Interestingly enough, he had another 96 Cadillac Deville in the shop this morning with the same engine missing problem. When he pulled the AC plugs on it, he found one that was cracked. What took us months to figure out on my Cady took him 30 minutes on that one.

GreenMachine
06-29-06, 11:53 PM
There is a far cry difference between mowers/blowers and Cadillacs my friend.
Specially since most mowers, blowers, trimmers etc come with and recomend a champion plug.

Cadillac does not.

Cadillac comes with and recomends AC Delco

I relize that, but what makes the AC Delco's such a great plug (this thread makes them not seem as nice) doing a quick search I couldn't find anyone who's tried Champion plugs and not liked them.

From my understanding GM uses AC Delco parts for one reason, they can supply the demand, for a great cost, and provide a quality product. Other than that there is nothing tying people to AC Delco. You could argue that Champions parent company does the same thing but they have been "the name" in sparkplugs for years.

Lets not forget they make everything from Oil Filters to Tail lights, who's to say a company dedicated strickly to Spark Plugs couldn't make a product for a Cadillac. Its not like I said to stick a cheap NGK in there.

The guy asked for an alternative and I gave him one :)

Loose screw
06-30-06, 11:24 AM
My mechanic put in Autolites AP605. Interestingly enough, he had another 96 Cadillac Deville in the shop this morning with the same engine missing problem. When he pulled the AC plugs on it, he found one that was cracked. What took us months to figure out on my Cady took him 30 minutes on that one.

I'm glade you found the problem But don't be surprized is it starts missfiring again in a few months - Why? because the inside of the spark plug boot likely has some faint carbon tracing on it. Right now most of the spark is going through the plug and your getting a ggod ignition spark at the end of the plug but some of the spark (a small part) is no doubt going from the top of the plug and down the inside surface of the boot. The spark will go were ever it can and most will go to ground through the easiest path. As this weak sparking continues it will gradually biuld up a carbon pathway and eventually not enough will go through the plug to cause a ignition spark. Repalce the boot or at least clean it with a strong solvent like Berryman B12 and with a small long wire brush in side with both and in and out motion and a twising motion. Your machanic mostly did not do this. You have to totally eliminate the carbon (which you can not see) completely or it will allow some arching which will cause some more carbon to build up and eventually misfiring. Take your time, let it soak and clean it several times. You will stay happy

parts68
06-30-06, 04:34 PM
never use a wire brush or anything rough on a spark plug boot.

Loose screw
07-01-06, 10:14 AM
never use a wire brush or anything rough on a spark plug boot.

Why? A rough or scratch surface may tend to hold oil or mositure more than a perfectly smooth surface which could lead to the possibility of shorting but the inside of the boot is not likely to be exposed to mositure so what is the problem with cleaning (scratching) the carbon out with a wire brush - please explain and do you have a better way to get carbon tracks off the inside of the boot than the combo of solvent and wire brush?

Ranger
07-01-06, 11:33 AM
While I would not swear to this, I seem to recall it being said before that you can never clean the carbon tracking completely and once tracked, the miss will always return. The only fix was said to be replacement.

parts68
07-01-06, 10:15 PM
I do alot of high voltage wiring.
We have industry standards to curtail "tracking".
If a scratch is put in a smooth dielectric surface it will
aid in high voltage tracking.
If the surface must be roughed up be sure its perpendicular to
path that current will try and flow(leak).
A good solvent cleaning with soft lint free rag followed by silicone grease
will help. Success with this depends on how long the wire was allowed to track.

ewill3rd
07-03-06, 07:25 AM
Yeah, those are not defective plugs, they are "carbon tracked".
That gives the appearance you see, but the real problem is when you found carbon tracked plugs you should have replaced the wires too.
The wire boots had the carbon growth just like the plugs did, and when you put the tracked wires back on you made it easier for the carbon tracks to grow on the new plugs, and then the next set and so on.
It's not a defect in the plugs, and it sounds like you already replaced the wires.
Over time it becomes easier for the spark to go down the side of the insulator than to go inside the combustion chamber and jump the gap, when the spark shoots down the side of the plug it builds up carbon on the insulator, every strike makes it easier for the spark to take that path and eventually you end up with a misfire on that cylinder. If you replace the plug and not the wire, you will see the problem again... and soon.