Spark plugs "stuck"
 

I was attempting to change my plugs today. I started with the driver front and it will not budge. I was afraid of stripping it out. I know these cars have aluminum heads. Should I try again and use extreme force, or should I let the shop do it? They said they would change them for $20. (labor). Plugs cost me $20, so I would have $40 in this task if I get them to change.

I think the plugs are original. It is ludicrus. :rolleyes:

For $20, let them get dirty!!!:wacko:

LOL. Yeah, but the negative is that he cannot do it until Friday and knowing them, they will have it until Monday. They have done me like that in the past. I will take something in on Friday morning, then they get to working on other cars, then mine sets there all weekend, as does everyone elses. Since this is a "quick" repair, I guess they may get it done fast.

I feel like a fool, because they are ridiculously easy to get to, yet I still cannot change them myself. I do not know why there are in there so tightly. I may try again tomorrow and hope I do not damage the heads. :rolleyes:

Try to remove them with the engine hot.

I prefer changing plugs with the engine cold. If room temperature plugs are installed and torqued to spec on a hot engine the aluminum head will shrink as the engine cools and the plug heats up and expands, which will combine to increase the head's grip on the plug, especially with taper seat plugs.

If you can get them out, let the engine cool to near room temperature. Then install the new plugs and torque them to the minimum spec using a torquewrench and the published spec range. It may be in your owner's manual. The spec is in my owner's manual - 10-20 NM (7-15 lb-ft) for the M103 taper seat plugs. Look in the index under "spark plugs".

For stuck plugs it's best to use a T-handle and apply equal force to each side, so you don't place a bending moment on the plug, which can break off the insulator. If you use a conventional breaker bar, support the pivot point with your free hand to mininmize the bending load that you place on the plug.

Also, use a large 1/2" drive T-handle or breaker bar and put a shock load on it - like an impact wrench. A shock load is more likely to break the plug loose than a steadily increasing pull.

Duke

Thanks. Well, the engine was rather warm, but not "hot" when I tried to remove it. I did not even attempt the others after the first one failed to turn. I used a 1/4 inch ratchet, so perhaps I should use a larger 1/2 inch ratchet? Unfortunately, I do not have a "breaker bar" nor a torque wrench. I have changed plugs in a lot of cars and I have always just got the plugs finger tight, then used the socket/wrench to snug them in- never had any problems doing that.

Thanks for that tip. I am off again tomorrow, so I may give it a whirl again if the weather co-operates. It was 66* today, but 41* forecasted tomorrow, so it may have to wait. Back in the 50s and 60s after tomorrow, then I am not off again until Tuesday. Go figure. :rolleyes:

I learned a long time ago that buying the right tools saved way more than their value in damage I created by using the wrong tool, especially when dealing with aluminum engine components. I would never attempt to change spark plugs with 1/4" drive socket components, and I always torque spark plugs to the proper specification. Taper seat plugs, in particular, need to be properly torqued. Many overtorque them which is why they are sometimes tough to remove or take the aluminum head threads with them.

Look up Harbor Freight on the Web and buy some tools including torque wrenches. A lot of their goods are made in China and pros may look down on them from their Snap-On tool boxes, but for the amateur/occasional mechanic you can't beat their value.

Duke

Remember to use some Never Sieze on the threads when installing the new spark plugs. That should eliminate the removal problems next time. I'd try a 1/2" breaker bar to remove the stuck plugs with the engine warm. A 1/4" ratchet is undersized for the job.

Breaker Bar leverage
 

I had the same problem with two ML's, but simply put a short piece of pipe (12" or so") on the end of the breaker bar, which supplied sufficient additional torque to break loose the plugs... they were not all tight, just a few of the 12 on that car. As suggested in previous replies, put some anti-seize lube on the new plugs when installing them. If you can't loosen them with the pipe extension, then I would take it to the shop. The other thing you can do is spray the plugs with a high level solvent; I forget the really good new one that is better the old types ... and let it sit overnight. That could also help a lot.

Ben Carter

The following product has worked well for me on rusted,corroded,or gunked-up threads:

WURTH-"ROST OFF" spray,300ml(10.1 fl.oz.)
Art.-Nr. 08902-U

:) :) :)

Removing spark plug help
 

I fully agree that 1/4 inch wrenches are too light for spark plugs. I use both 3/8 and 1/2 inch wrenches depending on the space I have to work. A T-handle is also a very good idea if room permits.

I use a little never-seize on threads when installing plugs.

A very good product for loosening stuck threads is PBlaster. :)

I agree with NOT using anti-seize compound on spark plug threads. There is always some leakage of heavy fuel components up the threads and if you combine this with anti-seize, it can make a real mess. AT MOST I might put a very thin film of anti-seize on the seats of taper seat plugs.

I've never had a taper seat plug come loose from an aluminum head when torqued to a little above the minimum spec, and I've also never had one come out tough or strip the head threads.

I use conventional copper core plugs, and pull them for inspection at 15K miles and usually reuse them for another 15K.

I would be reluctant to use a "100K mile" type spark plug for fear that they would not come back out without difficultly or stripping the thread.

Changing plugs on my M103 and Cosworth Vega (both have aluminum heads and use the same geometry plug, but the CV uses a resistor type and my current plug of choice is the NGK TR5) is so simple that I will continue to use conventional plugs, pull them at 15K mile intervals, and replace them at no more than 30K intervals, and torque to little more than the minimum spec of the range. At the rate I am accumulating miles on both cars it will take years to add 15K miles, but even if I was driving 15K miles a year, I would follow the same procedure.

Duke

I have always used anti-seize on spark plug threads, I have never had a problem. Be it GM, Ford, Jag, Toyota, Volvo, Mercruiser, or MB.

I wouldn't go nuts and dip the entire plug in but a light coating works like a charm.

The problem is the heads are aluminum and the plug threads are steel so they corrode in place. Be carefull or the threads will come out with the plug!

Get a 3/8 drive or if you have the room 1/2 is even better. Also spray the plugs with a good oil like PB Blaster, that usually helps stuck ones along.

FYI thats why their is a time and mileage intervial for changing plugs. Most of the new platnium plugs are 100k miles or 4 years. The reason they say 4 years is so you can get them out of the heads without stripping the threads.

Thanks. Well if the old oil was any indication of other things, these things probably have a lot of miles on them. It does not miss or anything, but it does have a slight splutter at idle and I want to change them.

I may give it a whirl with the 1/2 inch drive and see if that works. Like you said, I do not want to strip the head. :rolleyes:

86560SEL, your best bet at this point would be to have an experienced tech remove the plugs. In your attempt to save a few bucks you're liable to create more and expensive problems. As mentioned previously an experienced tech with an impact wrench can likely remove the plugs without stripping the threads in the block. In the future you can change the plugs on a routine schedule.

I don't recal ever seeing an experienced tech using an impact wrench on spark plugs. :rolleyes:

Moneypit, I figured the experienced tech might use an impact wrench to break the plugs loose and then remove them with a ratchet. Whatever, the tech will likely have seen this situation before and know how to proceed to prevent stripping the threads in the block.

This ENTIRE post should be repeated, and repeated often. This is not an iron-head engine from the 60's, where you could not go wrong. Here is the equation:

Inexpensive torque wrench from Harbor Freight: $15
Other related tools: $20
Anti-seize: $4

OR

Easy-out to remove broken spark plug barrel from engine: 10-20
OR
Loaner car: $$$
Head removal and EDM work to remove thread, etc: $$$$

It's really simple. I had a POS Pontiac where I was in a hurry and actually paid a mechanic at a tune-up shop to overtorque the plugs and I broke the plug removing it when I tuned it up the next time, leaving the threaded part in the head. I dodged a major bullet with an EZ-OUT. Never again!

When I removed mine I am sure they were in there for 50,000 miles. I removed them dry and didn't know if I was unscrewing the plug or taking out the threads. They all came out okay but they were very stuck. I would now use PB Blaster for pennetration and let it sit overnight. Spray them again, wait a little and blow out the remainder of the fluid with an air hose. Use the T bar or however you will keep from breaking the plug. Good luck.

I had a mechanic tell me that some of his co-workers would remove and install plug with an air hammer. They didn't care if they cross threaded them because by the time they need to come out they won't be the one working on it. It is beyond belief. This is another reason to diy. I used anti-seize and next time they came out by hand (after breaking the torque).

When you get your plugs out it would not hurt to chase the head threads with a tap. Put some grease on the tap and run it in and out. Be sure that the piston is down far enough so as not to contact the tap.

I like this idea, but how do you remove all the dirt from the threads that's fallen into the cylinders before reassembly? Also to make sure you don't hit the pistons, would you have to turn the engine by hand for each thread you want to clean? At least one of the pistons is going to be at the top, surely.

I've always wanted to do my own plugs, but I've been terrified of breaking one of them and having to pull the head to get it out. Keeping the threads clean, using anti-sieze and torquing correctly would make me feel better about doing it.

stuck spark plug removal.
 

Hello:
I had a simular problem with my 1992 300-E The spark plugs expand with head and cool and will tighten especially if the dealer cranks them down. first always change spark plugs on a cold engine. I used a little Wurth Penitrating oil spray to help loosed the seat the plugs are in. Make sure you you have the right socket for your plugs and use a firm slow preasure keeping the socket and rachet and socket stright not cocked.

I put a little anti seize on the plugs and a dap of dielectric silcone in side the plug boot so they will come off much easy next time.

Take you time :

Happy New Year
Bob Geco

take another week and start soaking with PB Blaster [available at most auto parts stores] Apply 3 or 4 times daily, hot and cold. Will come out easily.

Regarding anti seize, I use a little at the lower threads and wipe most off. Porsche recommends not using it because it inhibits electrical conductivity but I think it's a risk worth taking, if you don't coat the whole thread and crush washer. It does gunk up after a number of applications. I am considering buying a tool to clean the threads the next plug change.

Regarding cleaning the threads, you don't want to drop anything into the cylinder. Always blow out the plug area with compressed air before removing the plugs. You can clean that area prior to air as well. There is a tool that is filled with grease then compressed to slip into the plug hole. When released it engages the threads and can be backed out, catching any crud in the grease. It's like using a tap with grease, only better.

If you:
rhgtara@localne "take another week and start soaking with PB Blaster [available at most auto parts stores] Apply 3 or 4 times daily, hot and cold. Will come out easily. "
Then blow out with air and using a flex coupling of some kind and a T-handle or properly support it, if the threads come out a mechanic would most likely do no better. Most stuck fasteners come out better with shock, like an air hammer or sharp blow, but I would not personally use one on a head or aluminum part. Good Luck! MHO

smharr4,

Read my post where it says, "put a little grease on the tap". One you are not cutting new threads where there will be a lot of swarf, and two, what little sward and dirt that you will produce will be caught in the grease on the tap.

Tap sets consist of 3 taps, a starting tap, a middle tap, and a bottom tap. Each has varying amounts of taper on the starting end. The starting tap has the first 1/2 to 3/4 inch of its threads ground down so that it will guide itself into the untapped hole and prevent misalignment. The second tap is designed for existing holes and could be used to chase your spark plug hole threads. The bottom tap is designed to get threads as close to the bottom of a blind (dead end) hole as possible. It is used only after the frist two taps have done their job.

To tap out existing spark plug holes you can probably get the proper tap at a parts shop and not have to bother with the full set. Mostly you will never use the starting and bottom taps.

Here's some info on the "Back-Tap" tool:

By Dan Barnes
Photography: Dan Barnes

Not long ago, one of my shop mates salvaged a junkyard engine. The only problem found was that one spark plug hole was cross-threaded. The labor cost to pull the head and repair it with a hardened thread insert was more than the value of the car; a moment's carelessness by a mechanic or the owner was the end of the road.

Fortunately, my buddy was assisted by a highly skilled pro, and they were able to do the job properly, with the only cost being their time. But if the insert ever sticks to a spark plug instead of the head, it will be a big problem. I've seen someone doing the same job on an outboard motor. He was scared, because marine parts always cost two or three times what an equivalent automotive part does. Both situations would have been reduced to a minor inconvenience by the Starr Products Back-Tap, which was invented by a technician who had similarly "oopsed" a spark plug hole on a Jaguar XK120.

I have cross-threaded other holes, or been around when someone else did, and had the joy of correcting the situation with a conventional tap, trying to distinguish the true threads from the cross threads. With a lot of care, a little skill and some luck, I've always gotten it right, but I've almost never been sure I would at the beginning.

The Back-Tap begins chasing good threads at the bottom of a hole rather than damaged threads at the top. Machined from heat-treated 4130 steel, it compresses smaller than the thread's inside diameter to be inserted into the hole. A mandrel is drawn into the tool with a knurled nut at the top, expanding the threaded portion. Then the expanded Back-Tap is threaded out through the hole. Filings are brought up and out of the hole along with the tool; greasing it before starting ensures that even the smallest shaving is retained, as well as making it easier to turn. Go in steps, leaving the Back-Tap slightly compressed at first, subsequently expanding it until the damaged portion is clear to the same diameter as the rest of the hole. Tolerances on spark plug holes vary, and some may be too tight if the Back-Tap is fully expanded.

The Back-Tap is sold through tool trucks and NAPA stores, in 10mm, 12mm, 14mm (the most common spark plug size) and 18mm. The latter is extra short, for use on O2 sensor ports. Hopefully, your need for the Back-Tap is rare enough that it may not be worth having in your toolbox all the time. But if you ever need it, you now know it exists and where to buy one.


The Starr Products Back-Tap is a simple tool that will safely clean damaged threads in a cylinder head or exhaust manifold. It can save pulling a head, and maybe even save a whole car.

The Back-Tap cleans threads from the inside out by compressing smaller than the threads, as shown here. The mandrel is then drawn into the Back-Tap with the knurled nut at the top, expanding the threaded portion as in the main photo. By backing the expanded tool out from the bottom of the hole, the damaged threads at the top are restored.
Sources
Starr Products, Inc.
(360) 961-2671
www.starrproducts.com

FYI found this at Snap-on Tools

http://buy1.snapon.com/catalog/tools.asp?Group_ID=16723

A year ago I was able to buy a 14mm "Back-Tap" from a local NAPA store. The tool package had a KD part number of 3545. Now, neither KD or Snap-On lists a 14mm "Back-Tap", the most common thread size for Mercedes and other vehicles, in their catalogs. Wonder why ???.

:confused: :confused: :confused:

Spark plugs Stuck
 

Is there a size available for the Glow plugs as well???? Willie(Poor Soul)

As far as contaminants falling in the chamber, what's worng with blowing it out? With some air nozzles you can easily make an extension out of a length of copper tube. Just insert the extension deep into the chamber and blow. The turbulence should eject the particles out the hole.

OK. Thanks for all of the replies. Well, I decided to tackle this task myself and we got the plugs changed today. My father helped me. He did one side and I did the other. Seems as if that first plug on the left front was the tighest, but I did get it loose with the larger 1/2 inch drive wratchet. Luckily the others were not as tight, because I really do not think that would have fit in there. They all were very tight to say the least, but I managed to get the rest out with the 1/4 inch wratchet. Dad suggested spraying a little WD-40 or something on them, before we removed, but I was hesitant, because I did not want a smelly engine. The old plugs were old and was in need of replacements.

Thanks again for all of the tips/advice!

wow!
 

1/4" rachet?

even very loose plugs would be a problem to get out with that little pea shooter.

bet you meant 3/8"

anyway, glad they came out.

tom w

I did mean 3/8 Tom. Its been one of those weeks.... :D