Mazda 1.8L Special Plug Socket??

jerry_njApril 7, 2007

I am thinking about replacing the spark plugs in my 1999 Mazda 1.8L, it has about 40K miles on it.

But, looking I find that the four plugs are mounted vertically and reside about 3-4 inches below the head/valve (??) cover. The HV Wires go to cover and have a stiff rubber extension, again about 3-4 inches long that "reached" down below to cover to connect to the spark plugs. It would appear that it takes a special socket to remove/install plugs. The socket would have to be long enough, much longer than the depth needed to go over the head of a spark plug, and have a sponge (or something) lining to hold the plug to pull (place) it up (down) in the "hole".

Any advice/experience out there? Appreciate any tips/tricks.

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This is a common arrangement when the plugs are placed over the center of the combustion chamber. I had a 1955 Dodge "hemi" engine with the same arrangement.

This does require a spark plug socket. Get one for your size of plug and that fits your socket drive; 3/8 inch and 1/2 inch drives are popular. These sockets are available at automotive parts stores and Craftsman at Sears. I have found that two sizes has covered all the engines that I've owned over the past 20 years.

Sparkplug sockets are extra long to clear the length of the plug and have inserts of sponge rubber that lightly grip the plug insulator to keep it from falling out - Very handy. Replace the insert or socket when the insert fails to hold a plug. However, good inserts will last for years for the casual user. Frequent contact with very hot plugs such as in a service bay will shorten the life of the insert.

There is one precaution. The upper end of the socket extension rod must be supported when loosening or tightening the plugs, e.g., the socket should be kept aligned with the plug. It is all too easy to lean the socket sideways and break the insulator.

    Bookmark   April 7, 2007 at 5:21PM
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Thanks "jemdandy", I feel prepared with your expert advice/information and how-to. I am familiar with the sponge insert, but have never used one. My real fear here was it didn't "Compute" that the plug would be top-dead-center, but looking in the "hole" with a flash light I could see the top of a spark plug, and there's not mistaking the high-voltage ignition wire. Still, I appreciate you giving the facts, as I think about the engine may be my first overhead cam, maybe a dual overhead camshaft. Funny I'm sure I knew when I purchased the car, but sitting here at my computer I can't remember...but the center spark plug arrangement would be a nice "geometry" in my mind/eye - does that have anything to do with the spark plug placement?

    Bookmark   April 7, 2007 at 5:56PM
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" but the center spark plug arrangement would be a nice "geometry" in my mind/eye - does that have anything to do with the spark plug placement? "

Oh yes indeedy! When Chrysler designed its hemispherical head, they put the spark plug in the top center of the combustion chamber. The downside was that you had to go through the valve cover to get to the plugs. This necessitated adding a plug tube and sealing it at both ends, in other words, extra parts and places to seep oil, and extra cost. During the '50s through 80s, this design was avoided in many engines, and plugs sprouted from the sides of the heads. At one time, I had a 400 CID V8 with the plugs under the exhaust manifold. I had to crawl under the car to change number 7 and 8 plugs. I got a frost bite burn one winter doing this.

It became painfully obvious in the '70s that the kluge fixes to meet cleaner exhausts was not a permanent solution. Engine output fell during this period and in many cases, efficiency fell too. To track what the Japanese engine makers were doing, look at their motocycle engines. Many things were tried on these engines and the sucessful stuff got incroporated into their automotive engines about 2 years after a success in a motocycle engine. Multiple valves was sold in cycle engines before these appeared in cars. Yahama was up to 5 valves per cylinder, 3 intakes and 2 exhausts, before settling to 4 valves per cylinder. Today, many car engines can be found with 4 valves per cylinder as a means to boost the breathing of small displacement engiines.

Next came a pair of counter rotating weights spinning at twice engine speed to take a lot of the "buzzies" out of the 4 cylined engine. These first appeared in cycle engines, then car engines.

There is one precaution one should take with spark plugs down a tube, or for that matter, any sparkplug, and that is to prevent debris from entering the cylinder when the plug is removed. If you have an air supply, its a good idea to blow out any loose stuff before removing the plug. When the plug is in a hole, shine a light down there and look for any liquid that might be lurking there. If you see any, sop it out before plug removal, because that liquid will drain into the cylinder when the plug is removed and can cause problems on startup if too much is in the cylinder. If there is any junk in the fluid that can poison the catalytic converter, it will, although the likelehood of this is small.

    Bookmark   April 8, 2007 at 3:04AM
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Thanks for the history and tips.

Looking at the valve cover I do see DOHC and 16 Valves, i.e., 4 each. The plug tubes have a built-in cover, another factor that made me wonder, at first, where the plugs were. I first look on the sides (front and back) and finally concluded the high-voltage wires going to a rectangular "rubber" cover, four of them, had to lead to the spark plugs. On pulling, out came the long "rubber" rigid tube going down to the spark plugs. I do see some loose debris around the top of the valve cover and around the tube cover. I do have air to clean before opening and will look for anything in the "hole" before removing the plugs.

I'm thinking of using Autolite AP3924 as replacement for the NGK BKR5E-11 (per the owner's manual). Any view on the Autolite sustitution?

What I read it this little engine does have top design features. It has performed well, but is geared rather low (differential) making it more peppy, turning about 3200 rpm at 65,and getting good mileage anyway, 28 or better in rural driving. My Chevy Colorado on the other side turns about 2200 rpm at 65. The Chevy (small pickup, larger than the Mazda) has a much larger 2.8L 4-banger, but is much slower off the mark and isn't as economical (mpg), getting around 22 mpg in my rural driving. While this Chevy, which is my first return to American made vehicles in 25 years, has performed well, I haven't had any trips back to the dealer save one recall on a break light switch, it seems to be behind the curve on engine design. I don't understand how GM can have so much invested in engine technology and still not be able to build good performance/economy into an engine/drive train. I'll keep the truck, but am a little disappointed that the large 4 cylinder engine doesn't have more "punch". My previous was a Dodge Ram50, and Mitsubishi truck, with a 2.5L 4 cylinder. It was an old design 1988, but seemed to have more power/economy than the much newer Chevy. The Dodge did develop serious carb problems at about 100K miles and I traded (gave it away) it in on the Chevy during the GM employee price sale in 2005, I did get the small truck for a very low price.

In retrospect I do frequently see Consumer Reports reporting American made engines as rough and unrefined, i.e., my experience with the Colorado. Well, I do not have any drag-racing plans ;>

    Bookmark   April 8, 2007 at 9:54AM
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