Spark plug blew out - helicoil?

[Adamdmc]

Current progress. These are the donors. Once the heads and covers are cleaned I will start disassembly of my engine. Then I plan to rebuild this one as a spare. So far, I've got about $500 &24 hours labor invested. That includes donor vehicle and parts ordered to date (gaskets, head bolts & washers, cleaning solvents, etc).

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[RonJR]

It's not that hard to destroy the threads in an aluminum head, even if the plug was not over torqued. The spark plug is steel, so it's going to win any fight with the aluminum. Usually what happens is that, if the plug has been in for a while, especially if anti-seize has not been used, the aluminum threads start to gall (roll up, basically) due to the friction with the spark plug. If you then keep applying torque, the aluminum threads will stick to the plug, and come out with it, leaving a hole with little or no thread left.

The secret is to be patient. Usually the plug will break free readily, and then get hard to turn a half-turn or so later. When that happens, the instant you feel the removal resistance increase, immediately reverse your ratchet and turn the plug back in a small amount. Then try backing it out again. You'll probably get a couple of degrees further, and then will have to repeat the process. Sometimes it may take 20-30 cycles of this to remove the plug, but it usually eventually works. If you just try the brute force method on a tight plug, you almost certainly will destroy the threads.

 

[gamefreakgc]

Alright folks, started the teardown of the donor engine today. Finally got the head off, however I ran across something a little baffling though. The head was full of burt oil that closely resembles ash. Any ideas on what problems that this engine could have that would cause this?

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That would be engine sludge, old stuff by the looks of it. Looks like they never changed the oil or the PCV valve was completely gunked up.

It's a delicate operation to remove it but you could try soaking in solvents and see if that loosens it up enough to wipe it off. You definitely don't want it in your new engine though.

I highly recommend switching to synthetic oil if you do indeed end up using that engine. It helps breaks down sludge slowly over time so it doesn't clog the oil pickup screen.

 

[Adamdmc]

Alright "Yota Masters" was tearing down my engine tonight and found something extremely odd, at least to me. Bear in mind the engine ran great until the spark plug blew. When I set the timing mark a "0", both cam shafts are a full tooth past the timing mark. In order to get the cam timing Mark's to line up, the crankshaft is set at "15". When I reassemble, do I set it back the way that it is, or do I set it correctly?

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[brillo_76]

Alright "Yota Masters" was tearing down my engine tonight and found something extremely odd, at least to me. Bear in mind the engine ran great until the spark plug blew. When I set the timing mark a "0", both cam shafts are a full tooth past the timing mark. In order to get the cam timing Mark's to line up, the crankshaft is set at "15". When I reassemble, do I set it back the way that it is, or do I set it correctly?

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Someone advanced the timing at some point. I run factory spec timing. So this would be up to you. :]

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[MaineRunna]

Take the crank pulley and the lower timing cover off and use the mark on the crankshaft sprocket instead.
As far as stripped out spark plug threads, I find that usually it is caused by under tightened plugs unscrewing to the point that they blow out, not over tightening or lack of anti-seize lube. This can be easily fixed on the vehicle in minutes with a spark plug thread repair kit. Comes with a tap that reams out the hole to an over sized thread, 2 or 3 different length thread inserts and a tool to set the insert so it won't come out.

 

[Adamdmc]

Well, I finally got it all back together. Since I knew that everything was good to go with the exception of the spark plug threads, I decided to just get the insert put in and roll out. Now I have a new problem, a break cant be had. It has a bit of a slip. Not as regular as a cylinder missing every time, but more intermittent. It seems to smooth out while driving, so it's not a dealbreaker, just want to get it right. Any suggestions?

By the way, I decided to heed everyone's advice and set the timing to "0" @ TDC.

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[gamefreakgc]

Check for a vacuum leak. Will notice it most at idle and low throttle.

 

[Adamdmc]

Check for a vacuum leak. Will notice it most at idle and low throttle.

What is the normal idle speed? I'm idling between 675 and 725.

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[Adamdmc]

Now I'm getting a cylinder 4 misfire code. I can clear it and it will take 3-5 min for it to return so figured I'd try some stuff. I've tried swapping the #1/4 coilpack with the #3/6 coilpack and it persists. Undid that and just slaved in a plug wire from my donor engine, and it persists.

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[Adamdmc]

Sorry that I'm posting so many times, but this should be it for a while, at least. I have found the problem. Apparently some bonehead (me) didn't pay close enough attention when installing the spark plugs and one of the grounding tangs got buggered. Now that I've got that sorted out, she's purring like a kitten.

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[mesooohoppy]

how is that even possible? did you drop it? did it come from the factory that way?

 

[gamefreakgc]

Sorry that I'm posting so many times, but this should be it for a while, at least. I have found the problem. Apparently some bonehead (me) didn't pay close enough attention when installing the spark plugs and one of the grounding tangs got buggered. Now that I've got that sorted out, she's purring like a kitten.

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Yeah that would do it! Basically you had no spark and running on 5 cylinders, I bet it did run rough! Glad you figure it out and it was just a $3 fix.

 

[Adamdmc]

how is that even possible? did you drop it? did it come from the factory that way?

I'm assuming that maybe I dropped it I to the hole or something, but I do know that it didn't come out of the box that way. I verified the gap on all 6 plugs. I didn't even have to replace it, I just bent it back out and reset the gap to the 0.043" that the book calls for.

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[Adamdmc]

Hopefully this is the last update on the spark plug that blew out. After getting everything reassembled and ironed out it has been running Fantastically. I would dare say that it runs as smoothly as when it was new. And about the previous questions on timing, I'm so glad that I followed everyone's advice and set it to zero and not the 15 degree advance that it was. Seems to have better throttle response than before. Now on to refreshing the suspension and steering.

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[4x4runnerMT]

I’ve heard from a few folks that time certs are the way to go.

 

[Adamdmc]

Quick update:

Here we are a little over a year and 50k miles later. The spark plugs (and their threads) are holding fast. Having other smaller issues here and there, but going strong. Total Milage on odometer reads 321,216 miles. Thread inserts rock.

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[ATX4runner01]

Spark plug blow out - Coil broke

Hey all. Thanks for the thread on this. Looks like I'm not the only one.

I bought this 4runner in July. I had 7,000 miles on it since i bought it. Coming back from Chicago to Texas (Tulsa OK) I had this spark plug blow out on me. 45 miles from Tulsa, 55 from Springfield. NOT a good situation. I rented a van and continued to Texas. Left the 4runner there for a week then went and picked it up and brought it back down to Texas. Where it sat for 3 months....

Come to find out... Spark plug blew out of the head and destroyed my coil. the old man that i bought this off of said he put new spark plugs and wires on it. He must have somehow smashed these threads on this spark plug. Lasted 7k miles before it shot out... I guess that's the way it goes.

Looks like it is fixable so that is good.. I'm on the fence about a helicoil or the Time Sert method.

I have a new coil, wires and spark plugs coming Wednesday. So looking to spear head the tap soon.

Adding a few pics for kicks.

 

[jgue467]

A proper helicoil job will work, most likely for the remainder of the engine's life.

This is somewhat common and I double anyone messed the threads up going in , it is poor metallurgy from the factory - that is why the thread is so long.

Which one? Its usually the right middle that blows out and destroys the coil along the way.

 

[ATX4runner01]

A proper helicoil job will work, most likely for the remainder of the engine's life.

This is somewhat common and I double anyone messed the threads up going in , it is poor metallurgy from the factory - that is why the thread is so long.

Which one? Its usually the right middle that blows out and destroys the coil along the way.

Thanks for your input! I see your in ATX too. Rock on! This 4runner spent most of its life in Oak Hill.

I'll do the Helicoil tonight.

Yes middle cylinder on passenger side.