Blew Out Spark Plug

[NV Zeno]

'83 EA 81 wagon:

 

This has happened probably twice before, each incident a year or two apart. Until yesterday. Three times in about half an hour while running around town (groceries, mail, etc).

 

I did a search, and found some interesting reading on the subject. There were lots of suggestions about how to correct the problem, I've yet to try anything.

 

As was posted (and I've noticed), my Craftsman spark plug socket didn't fit all the way down. GD suggested using the "emergency socket" that came with the Subaru toolkit, I'm sure it's just as pristine today as it was in 1983. I guess I'll try that first.

 

I read some about "Timesert", but couldn't find any pix or details about that.

 

Some of my motorhead buddies are familiar with helicoil, and mentioned that, and discussed on the USMB also.

 

What I'm most curious about is the "chaser", specific to spark plug holes. I found a few on the NAPA website (I searched "chaser"), I managed to get them all to display on the same page: http://www.napaonline.com/Search/Compare.aspx?R=BK_730_0100567522+BK_2123_0100567522+BK_3379_0100567522+

 

Any recommendations or comments on the products listed?

What size is the EA81 hole?

Should I be working on this while the engine is stone cold, or warm/hot?

Some of the USMB guys mentioned using Anti-sieze, whaddya all think?

 

Am I asking the right questions?

 

More specific info upon request.

 

Thanks.

Edited November 1, 2010 by NV Zeno

[idosubaru]

yes, use the special spark plug chaser tool. they make one that you insert down through the hole that does not engage the threads. then once it's through you "expand" the chaser threads at the bottom so they engage the good threads at the bottom of the hole and then chase out.

 

someone just used this tool on subaruxt.com and said it worked.

 

heli-coil and timeserts are thread repair device and are the same type product, just different brand names. you drill out the bad threads and then tap the hole with an included proprietary tap. then it comes with a special tool that allows you to thread in a special insert (looks like a spring) that has outer threads that match the ones you just drilled and tapped - and inner threads that match the original threads of the spark plug. a nifty little device. being a stronger material than the original aluminum the repaired threads end up being stronger than the originals. you just need to manage the debris from drilling and tapping to keep it from getting into the cylinders. fill them with shaving cream or maybe there's other tricks for that.

[987687]

I have used the insert things twice on my Legacy now. They worked awesome! Still running fine about 20k later. I filled the spaces on the tap with some heavy wheel bearing grease to catch the shavings. When I took it back out the grease was full of shavings. Not sure if any got in the cylinder.. It's just aluminum, it will burn off or get blown out anyway I guess... But I haven't had any issues with it. Performance or otherwise.

 

It's going to be a hell of a lot easier on an ea81 than an ej22!!!

[silverhelme]

The one I use is the NAPA Balkamp threader and inserts. It requires no drilling and if you use wheel bearing grease clean it often as you thread it to keep chips out of the cylinder. The ones I have done have held up 40k plus.

[NV Zeno]

Thanks guys, very good info.

 

I went into NAPA today, and saw the Balkamp threader mentioned just above. They were out of the size I need, but it'll be at the store tomorrow. Just as I was leaving, I remembered the Autozone nearby rents tools. I found a few that looked like they were the right one, but there were many different sizes/pitches. Which is the correct one for my application?

 

While at NAPA, I saw and asked about the thread chaser tool, and was told that it wasn't the right tool for stripped threads, which I have. I stuck my finger in the hole, and while not completely smooth, the threads are not good. So I guess I agree with the guy about that.

 

I've got some time before it starts snowing, but my 2wd Acura will be useless when it does..I can still get to work while the wagon is down (for now).

[WoodsWagon]

The thread chasers are for if you crossthreaded a sparkplug and cranked it in partway bunging the threads up. What happened for you was the plug wasn't tight enough, it rattled back and forth in the threads until it pounded them straight out of the head. So there's a hole there but no threads.

 

Helicoils work. They're the spring things that take the place of the threads. I personally don't like them for bolt holes where the bolt is going to be removed and installed a bunch of times, like spark plugs. They tend to partially unthread if things get sticky.

 

Timeserts are better, they are a sleeve that's threaded on the inside and bigger threads on the outside to bite back into the block. Then you use a specialized punch to spread the locking nurled area at the top into the head.

 

Use grease on the tap to catch the chips. Aluminum chips aren't so bad on an engine as steel chips, but still not good. Hooking a compressed air line to the vacuum brake booster hose and rotating the engine so it blows out the removed spark plug hole can be a good way of keeping the chips from falling into the cylinder. Wear eye protection, the chips can come out fast.

[GeneralDisorder]

Yep - Heli-coil time. Just do you best to avoid getting chips and such into the hole. Don't be surprised if you miss a few - don't worry about it. Aluminium will just burn away in short order or be blown out the exhaust valve.

 

You'll do fine.

 

GD

[NV Zeno]

OK just so I'm sure here, do I still need to prepare the hole somehow like with the tapping tool I mentioned earlier, before inserting the helicoil?

 

I also saw "inserts" that came with the tap (and also sold separately), they're sort of a ring that's threaded on both the inside and outside surfaces (this sounds like the Timesert mentioned above). I know those are different than a helicoil, but seem like a more permanent fix. I really have no preference, I'm just trying to understand this clearly.

 

Another question..I noticed several depths available, what's the correct size?

Edited November 3, 2010 by NV Zeno

[987687]

I prefer the insert type to a heli-coil for spark plugs.

You need to tap the new threads before inserting the thread insert.

 

To get the correct length insert I just made sure I got one that was about the same length as the threads on my spark plug, but no longer.

Just bring the plug to the store with you.

[GeneralDisorder]

Yes you will need to tap it - just make sure you tap it straight and true.

 

Length should be the same as the threads on the plug.

 

GD

[NV Zeno]

OK, thanks..it's crystal clear now.

 

I managed to borrow the proper tapping tool, and will get started in the next couple of days (thanks Rick at Harrah's Tahoe Casino).

 

I stopped by NAPA on the way home and picked up a pack of inserts. I didn't have a sparkplug with me and guessed it was the middle or "normal" size: 1/2 inch. I threaded it onto the plug, a little short..not much, about 1/8 inch. Whaddya think, will it work, or do I need to exchange for the longer size?

 

Thanks again for all the help so far.

[987687]

It would work. Yes. But it would be worth it to get the correct size. It's going to be there for a while, may as well do it right.

[NV Zeno]

OK, an update.

 

I've been working on this project occaisionally and in short bursts, these old bones can't stand more than a few minutes each day of leaning and reaching into the work area.

 

I managed to tap out about 1/4 to 3/8 inch of the plug hole, the spark plug with the insert attached threads in and holds when the engine starts. I'd like to complete at least another 1/4 inch, just so I'm a little more confident about having enough threads for the plug to seat firmly..I'd hate to have it blow out in a blizzard at night. It's bad enough my Hitachi carburetor isn't working all that great right now either.

 

Hopefully I'll have the spark plug job completed tomorow..then I can see what I can do with the carb/intake system.

[NV Zeno]

Got another 1/4 inch or so tapped out, insert is in, and new spark plugs all around. Took it for about a 100 mile shakedown run (up/down Spooner and Brockway a couple of times, also some freeway), no blowouts. I feel confident that part of the job is successful, it's time to return the borrowed tool to Rick at Harrah's.

 

I then went to see what I could do about a rough/non-idle and stalling situation with my carb. I sprayed the inside of the carb with Gumout, as there was some "stuff" built up inside, but nothing unusual or anything I haven't seen before. I took the aircleaner box off and started spraying the outside of the carb, lots of gunk built up on the exterior and linkages and such. While the aircleaner was off, I noticed a broken electrical wire. Turned out that wire was connected to the "idle solenoid" on the front of the carb. I repaired the wire, and voila!, the engine idles just as smooth as can be (considering it's a Hitachi), the only real issue that's left with the carb is the accelerator pump isn't so great..a real riot to drive in stop-and-go traffic, especially around South Shore. for right now I'm satisfied, and until I can be without my wagon for awhile, the accelerator pump will have to wait..probably til summertime, when I don't need my 4WD, and have another car to drive.

 

Thanks to all for your responses tips and advice, I consider this repair finished and a success.

 

.

Edited November 11, 2010 by NV Zeno
Spelling, punctuation

[987687]

Awesome! Good job.