Best way to check for head gasket failure?

Hmmm, interesting. Haven't done a spray test, but when I was pulling the spark plug from #4 I did notice the top connection of the crankcase breather hose from PCV valve is cracked at the connection, but only about a quarter inch and the nipple it connects to is about an inch long so I thought it would still be sealing properly. I do plan on replacing the hose, but I didn't think that would actually be the issue, because misfire only occurs intermittently at start up. Starter fluid my best bet? No hissing hoses though

 

Idle and spray all over the engine bay. Might very well find a vacuum leak.

 

Sometimes if you're getting coolant leaking into the combustion chamber, the spark plug will be shiny and clean instead of the typical grayish brown sooty appearance.

 

That's a gape, not a gap.

 

I was getting random missing a few months back and after further inspection noticed that my pcv crankcase hose was cracking at the ends as well. Figured it was an easy replacement albeit a long shot fix but knock on wood, I haven't had the issue since.

 

That gap tho! That looks like a .125 Gap from the picture!

 

Cool, perhaps a glimmer of hope for me? Was your random missing at start up only or noticeable while driving as well?

 

cool, figured out how to multi-quote. It's a mighty big gape, right?! Hehe. My loop gauge fit through the gap with a tiny bit of extra room at .060, .080 did not fit. That was a picture of my #4 plug which has now been replaced and I'm still getting the code. I do have the rest of the plug set ready to go in when I do the compression test tomorrow or this weekend. At this point, I'm thinking I will clean mass air sensor, throttle body, and pcv valve, replace the two vacuum hoses, switch injectors, and do a compression test. Not sure what else to do. Will post results. Oh, and I did do the spray test and was unable to locate any vacuum leaks, i sprayed all over the place like a cat in heat.

 

Not at start up it only happens randomly while driving. And it happened over a span of a few months. I don't daily my truck anymore but this week we had snow so I drove it 5 straight days and had zero problems. Like the old saying goes, start simple and cheap.

 

See post #7 in this thread:

https://www.tacomaworld.com/threads/coolant-reservoir-bubbling-and-filling-up.437255/#post-12676768

 

Great thread, thanks for pointing me in its direction, didn't find that one when searching previously. I've gotten a lot of great input, thanks to everyone on here. I've got some work ahead of me this weekend, I will be posting back with my findings..

 

Ok, I'm going after it today. I pulled the spark plugs with some interesting results, see picture attached. #4 plug looks cleaner and brownish when compared to the other five which all have black burn marks and are more grayish in color. As far as gapes go, #1,#3, and #5 were all 0.059. Driver's side however... #2 is at 0.055, #4 at 0.061, and #6 at 0.060.

To me, this all but confirms my initial dread that it's my HG. I'm about to try Lester Lugnut's suggestion above and compression test to confirm before I start taking things apart. Any tips or strategies for head removal that come to mind would be appreciated!

 

If you have an air compressor hook it up to the compression tester and put about 70 psi through it. Look inside your radiator and you will see bubbles if you have a bad head gasket. I had the same code and cleaner spark plug like you. In the end it was a bad hg and the head was cracked in several places. Replaced them and it runs like a top

 

correct. Thanks for catching that. Sometimes I take things for granted like tdc.

 

I followed directions in the link and my radiator burped, then slowly rose again to the top with the engine cranking. Not sure if it's from coolant or fuel since I only stuck a plug in #4, but after removing the plug again after the test I peered inside with a flashlight and saw moisture in #4 and the others were dry. I don't see a point in even compression testing anymore.

 

i'm moving on to HG replacement, will be posting with pics, questions, results ect to this thread:
https://www.tacomaworld.com/threads/p0304-cylinder-4-misfire-headgasket-replacement.468942/page-2

 

Have you tried moving the coil pack to a different cylinder to see if the misfire follows it?

 

Get a manual and follow the instructions on how to remove head. There is a sequence to follow. If you don't you will warp the heads.

 

Replaced it with a new one. No go

Got a manual, I pretty much bought one immediately when I bought the truck. I'm not Mr. Mechanic, but I have successfully completely rebuilt my Corolla engine, and I've already had to do some fairly major repairs to my truck since I got it 3 years ago including removing the tranny to fix that damn throwout bearing squeal. So while I won't be getting things done at lightning speed, I am careful and I somewhat have an idea of what I'm doing. Lot's to learn and figure out, lots of research, and some bloody knuckles and swear words are likely just ahead of me..