henry you can get that head, already to go for about $350 good luck buddy

 

On the positive side, I'd say your lucky that the coil pack did'nt light up all that gas all over the engine compartment-very bad thing w/o full coverage. Like the other guy said, fix your head or replace it with a well checked out used one and you'll be rollin in no time
edit: I don't see how the plug port could be "completely stripped". Find out if the dealer did anything to aggravate the problem (bozo with tap?), and make sure it's not repairable before you buy another. You should locate a good machine shop. Good luck to ya.

 

Yea, I'm hoping they didnt do anything to mess it up more. I talked to a mechanic we've known for a while and he recomended a place that I'm going to bring it over to tomorrow morning. They have been doing helicoils and related stuff for a long time so I trust them alot more than I do the stealer. I should have talked to him earlier but he doesnt work on this kinda thing so I guess it just slipped my mind. Yet another stupid thing to add to the situation. Still praying that they can fix it without having to tear it apart and replace the heads.

 

I bought my engine with 13k miles, for about $1200 US and spend an evening of wrenching with two friends. Ironically this the quickest way to get the vehicle running, and you're not usually going to run into unexpected problems.

Lets hope helicoils will do the trick.

 

Henry, E-mail Bob at bob@norcalttora.com, he just went thought this on his 99 Tacoma. had the exact same problem and got it fixed. I believe he ended up pulling the head, but he got it fixed. Not sure how, but you may want to ask him what he had to do to get it fixed... Bob lives in San Francisco too BTW

Steve

 

Holy crap, I didn't think this would ever happen to anyone else. I had the -exact- same thing to me back in August. My 3.4l had around 108,000 miles on it at the time. The difference being I was miles from pavement 9,000' above sea level. Luckily I have a good friend with a trailer.

These pictures show a few portions of the motor coming apart:
http://bob.norcalttora.com/gallery/i...r=%2Fwrenching

Anyway. In my case the spark plug blew out, taking threads with it. The explosions continue happening in the cylinder because gas air and spark are all present. The explosions, instead of forcing the cylinder down, throw the spark plug up, smashing it into the coil pack. This is consistent with the burning smell you had, the explosions were melting the rubber on the coil pack (duh).

The process I went through was to pull the heads (why pull just one?) and take them to a machine shop. For $200 I had the heads machined and the one spark plug hole was cleaned up and a helicoil inserted.

After purchasing the fancy gasket engine rebuild kit from the dealer (I think this was almost $300 and includes head gaskets, valve stem seals, valve cover gaskets, the works) and a new coil pack ($70 I think) I put everything back together.

Truck has ~4k on it since the rebuild and has several starts in sub-freezing temperatures. Overall it runs quieter but that's about it.

All told the total top-end rebuild price was right around $1000. This includes $200 I gave to my buddy for gas, a few new head bolts, a fancy die grinder bit (whatever you do, don't strip a head bolt), coolant, some exhaust studs that decided to break rather than come out. It doesn't include the rent I should have been charged for tying up a spot in a friends garage, the help from friends, the pizza I bought for friends or the tools I borrowed.

If it happened again I would rebuild myself again. Especially after seeing your price quotes. The only other option that is easier would be to purchase a used motor.

Good luck.

 

I'm curious to know which cylinder went. Mine was cylinder #1 (passenger side, nearest the radiator)

 

Bob, you were a lucky duck because your friend had a lift to work on even!

Henry, I agree with Bob, you can certainly do the heads (repair the one plug with a helicoil and buy all the kits) and rebuild the motor that way but my suggestion to be the least amount of headache (but perhaps slightly more expensive) is to just get a used motor and sell the other one on ebay or the like. That way say you paid $1500 for the used motor....you sell the old one for $400....your used motor only cost you $1100 plus labor. Totally your call though. If you part the motor out you might even get more money than that, but selling the whole motor is the most painless way (also don't sell it until you get the new one in...in case you need donor parts).

 

Bob, thanks for the info and the pics. I was just about to email you when I saw Norcalvp's post, and I'm assuming he's the one who asked you over? If so, thanks for that Norcal. In mine, its cylinder #5 I believe. Passenger side, closest to the firewall. When looking at it, I was surprised it didnt do any damage to the hood and didnt make more noise seeing how it shot out of there. What you described doesnt sound too bad, especially when compared to what the dealer wanted to do and their quote. How long did it take you guys to finish everything? Just want to get a measure of how long it'll take.

Mtl, other than this, which was human stupidity, the engine has given me no problems and was running fine. It actually has a little less miles than my estimate and is actually around 72k miles. Hopefully it wont be too hard on the walllet and they'll be able to fix up my engine instead of getting another one with unknown history.

 

Alright, I'm reading and don't understand, so what caused the spark plug to be blown out?

 

I might look into pulling the heads first but if that is out of the budget then use enginbld trick. You can use a lot of grease on the tap to catch the shavings and clean and regrease the tap often, then clean the hole, then use a strong vacume with rubber tubing attached to it to put into the SP hole and vacume inside the cylinder. This way you can point the tubing around inside the cylinder at the points where most any shavings would end up. You might even go a step further. After you tap it, vacume it real good and with all the plugs out and the injectors done in a way so they wont spray fuel, turn the engine over for several seconds to blow any other chips out. Do this again after the helicoil goes in. that way, you are assured that most any flake will be out of the cylinder. Once it is done, run it a bit, change oil, run it a bit more, change again. Ive never done this myself mind you, its just a suggestion, but one that I would look into myself if I were in the same situation. Like I said, food for thought. You might even contact engnbldr and talk to him and see how you feel about trying a head on helicoil.

 

Who changed the plugs last?

What cyl # did this happen on?

CEL light before the mishap...hmmm.

 

It was actually a different buddy of mine that had the warehouse to park it in.

It took me from Aug->Dec to get it back on the road. For the most part I would only work 4-6 hours a day 2-3 days a month. We had a major hiccup that lasted about a month when I stripped one of the head bolts. We tried everything before finally finding a nice small carbide die grinder bit which ground the head right off.

We went from a block with pistons in it to a truck that started in 14 hours (one day). However an exhaust leak at the collector was giving us a huge headache. After breaking some studs we pulled the crossover pipe (without cutting it or removing the engine I might add, what a PITA) and cleaned up the exhaust. Put it back together and had no leaks. Fixing the exhaust probably cost us another 3 weeks.

For these time estimates keep in mind that this was the first engine work that myself or my friend had ever done. We were moving a little slow.

If you do go this route definitely just do your timing belt. You have to take everything off that you'd do for the timing belt except the water pump, which is just a few tools away.

I strongly recommend getting the SST for the timing belt tensioner (even if you don't change it) as it will save you the pain of removing the AC compressor. There's a picture of it on here somewhere. You can make one (we did) or buy it from snap-on or similar for close to $70.
http://www.toy4x4.net/timing_belt/index.htm

 

That's what I'd do. Don't forget what EB said about running a step cooler plug for that one cylinder because of the decreased heat transfer caused by the helicoil.

 

Thanks for the responses guys. Even though I'm not touching this stuff myself, its good to know some things about it so I can keep pace with the mechanics. The guy I took it to was recommended and sounds like he knows what hes talking about since he was basically repeating alot of the same info you guys have mentioned. A friend and I changed the plugs a few months ago, but I forgot who did the coil side. Probably me since I'm quite inclined to screw things up like this. It was #5 I think, closest to firewall on passenger side. No cel light came on, actually I havent had a cel ever since owning the thing. Dont know about Bob, but for me, it was most likely a loose plug that vibrated out and eventually just blew out the coil pack, taking the threads with it. Gonna find out more later when the guy calls me after inspecting it.

 

Sorry, I read your first post incorrectly. I thought you did have one.

I am really curious as to what caused this. I am sure theories will be thrown around, but I wish someone knew for sure. Maybe the mechanic that is working on it will discover the cause. Please let us know.

 

For a while I was thinking loose plug that got to the end and then just blew out the final 1-2 threads.

Once the head was off this wasn't the case. The threads were all screwed up on the bottom of the head (closest to the piston). Maybe I got a burst of some -really- good gas in there. Who knows.

Mine was cylinder #1. Despite having to drive ~5 miles with the number one cylinder completely hosed I never got a CEL.

 

At first I was thinking the same thing (ie just blew out the last 1-2 threads), but now I am not so sure.
I would bet the more likely culprit is overtighening if all the threads came out like that.

Do you have a pic of those threads by any chance?

 

I don't have a pic. If I remember right the threads on the spark plug looked perfectly fine. The threads for the spark plug hole weren't entirely gone, it was just one of the lower corners. Maybe 30-40 degrees worth and 5-6 threads starting at the bottom of the head if I remember right.

 

Does the 3.4L use a steel insert or are the threads aluminum on the head?
If they are steel then I would doubt overtightening as well..more likely thread on the plug would strip (but still possible).