Head Gasket

Yeah, I agree.

The worst part is, OP is only 16 years old.
And he's actually out there "trying" to fix his own truck.
I feel bad him. Really bad......
I hate seeing young guys in this shape, especially ones that are try to help themselves.......

OP, sorry bud.
To confirm your issue, you could stick an inspection camera down the spark plug hole and into the cylinder after it sits over night.
If you see coolant, well.......then you know.

 

It usually stops running rough after it gets to operating temps. Could that still be coolant?

 

I’ll take a look in the cylinder tomorrow and see if I can see any coolant in there. Thank you for all your help, i really appreciate it.

 

Its hard to be sure just translating advice over the internet

Looking for coolant in the cylinder with a boroscope like mentioned is the true test

Good luck

 

From what I've read, the head gasket doesn't fail on the 3.4L, the head cracks.

A fuel leak leaving a puddle should be visible with the engine running if you look around carefully. It could be a lot of things that you disassembled to get in there. Or would a leaky injector be dumping fuel so bad that it drips all the way through the engine?

 

The head gaskets can let go on the 5vz. Not super common, but plenty of members on here have experienced it.

 

Any engime setup with an aluminum cylinder head on a cast iron block is prone to gasket failure. Thats one of the reasons they started to go all aluminum

A fuel injector leaking enough to fill the cylinder with gas would probably hydro-lock the engine..

 

I think it might be the o ring on the injector or maybe i got send a faulty injector. I’ll have a look at it today and also check for coolant in the cylinder.

 

I had a similar problem with my 2001 2.7. I changed the plugs, I changed the coil packs that were out of spec (just 1 was slightly out of spec). It always helped but the problem always came back. Rough running at start but would smooth out and not be a problem. After it started having really sporadic hard starts I did the Combustion Leak Detector test and it was positive.

I would recommend doing the Combustion Leak Test first as it is the cheapest. Maybe under $50 including the blue chemical from Harbor Freight.

Prior to that, I took some of the coolant out (just enough so it wouldn't overflow) and let the truck idle for about 15 min. Even if it gets up to temp it may take a couple more minutes for the thermostat to fully open and water to flow. After the 15 min mark, i would slowly bring up the idle to around 2k for 20-30 seconds and once i could see the coolant flowing across the mouth of the radiator I could smell gasoline. Did the coolant test and it was negative, did it 3 more times and on the 4th time I got a positive. I had never done that test before but i for sure smelled gas in the coolant. I'll just chalk the first 3 negative results to user error.

The 2.7 head gasket was super straight forward, I believe you have the 3.4? Here's what I learned.... I've done a ton of head gaskets but never on a Toyota, it was my first one. If you decide to take on this job yourself (you can totally do it by the way) just know you may need to buy a couple of tools and give yourself plenty of time to learn about your motor and exactly what you'll be doing to it.
1. Tacoma World is a wealth of info, most of my google searches brought me back to this site.
2. watch a lot of YouTube and I mean a lot! There are very knowledgeable people doing these repairs every day, watch as many videos as you can on the subject and after a while you will spot mistakes and stuff that you don't want to do. There's always a couple of guys who make it look easy
3. if you can, I HIGHLY recommend taking your heads to a machine shop to be checked and surfaced. My head was basicallly a new one and so all i had to really do was surface it, ran me $40 here in Los Angeles. Also you will have to see how much material they take off so you can get the right head gasket thickness. Factory Toyta head gasket thickness is .040 If they mill any more than .010, i would recommend getting a .050 thickness gasket and so on.
4. You will need new studs. Under no circumstances should you use the original ones that came off, when they are torqued, they stretch and can't be reused.
(I think the last guy who did my truck before i bought it reused the studs and they seemed almost loose when i removed my cylinder head)
5. Get yourself a service manual, I just got a cheapy Haynes repair manual. Not the greatest but it saved me a lot of time and was actually very accurate so far.
6. This Part is gonna suck... you have to (more like you really should) check your valve clearances before you take the cams off. Almost my entire side of the Intake valve clearance was way out of spec. You'll need a good feeler gage (I used a Go-No Go style) and you'll need a good Micrometer. I bought a nice digital one for $50 from Harbor Freight to check the thickness of the valve shims. Worked perfectly.

For me, all in i probably spent around just under $500. I was lucky because It basically had new everything already, water pump, timing chain, oil pump, thermostat etc... For me it was just a head gasket kit, studs, machining and coolant.

 

Did the head gasket leak test and there is not a head gasket leak. Couldn’t figure out what was wrong with it. I was looking for junkyards near me with the same engine to see if I can buy a fuel injector from there and see if I got a bad fuel injector. Couldn’t find any near me. Took it to a reputable shop and they also checked for a head gasket leak and said no leak. They said that two of the injectors were bad. Makes sense because I moved an injector over and that cylinder started misfiring but again I couldn’t find known good fuel injectors. I got the injectors from yotashop.com which I have ordered other stuff from before and didn’t think the injectors wouldn’t work. This is great news for me though because a head gasket job would have been much more expensive.

 

I just recently went through this myself and if you moved the injector and the misfire followed you have found your problem. I bought one OEM injector and they are not cheap some of the rebuilt injectors are garbage.

 

Here is a link to my thread and what I went through.

The following members are awesome and a big thanks to these guys!!

@slater, @ControlCar, @b_r_o and @HondaGM

https://www.tacomaworld.com/threads/p0302-cylinder-2-misfire.860449/page-2

 

If you have to buy more injectors I hear these guys have really good ones.

https://motorwestperformance.com/?srsltid=AfmBOorTxOiwJ8-84aXAgNmJBIEuU3FUx6HvRS2kxMnmMe0zKv4Tr_g9

 

I can vouch for MotorWest. Go with them. Martin is a good guy to deal with

 

x3 for motorwest.

 

Great, those are a lot cheaper than straight from toyota. I will probably end up just replacing all 6 since it’s cheaper and comes with 6 anyways. Thanks for the suggestion!

 

Update:
Got it back from the shop today. Said to try changing the maf sensor because the readings were all over the place. Changed it do a denso one since i accidentally sprayed a little degreaser on my old one. Didn’t fix the problem. Also said to replace a few vacuum hoses since they were leaking. I ordered the hoses off toyota and will be changing that next. Over the phone he was saying that the injectors might be bad but he did a few more tests. He said that both sides were misfiring just not enough to cause a cel. He moved injectors 2,4,6 to 1,3,5 and now I got codes for them. I don’t know if he cleared the coded before or not. I cleared them at home and will see if they pop up on either 1,3, or 5. If they do, i will be ordering new injectors. Kinda bummed out because i was hoping they would figure it out and they charged me $364 and they didn’t really give me any new diagnosis. He said he thought it would be a simple diagnosis but he said he has 6 engine swaps to do so my truck was the last thing on his list and would be multiple weeks. I hope I can figure out the problem soon, i’ve dumped too much money into it trying to fix it.