Spark plug condition; possible head gasket leak?

[Kmvreter]

Background info:
This ’04 V6 4x4 is a DD that rarely sits for more than a day.
Took a short trip at the beginning of September so it sat at the airport for 8 days. Started right up and ran OK.
Went on vacation in early October so it sat for 12 days. Started with a slight short rough idle but then smoothed right out and ran OK. Didn’t think about it at the time because it was colder out.
Two weeks ago the truck sat for 2 full days while I drove something else. Started with a rough idle for a good 5 seconds but then smoothed out and ran OK. I thought “what the ???”
No codes present, no codes pending and no dash warning lights. Fuel consumption hasn't changed.
I do all the required scheduled maintenance myself. I “drain & fill” with 1 (sometimes 2) gallon(s) of OEM SLLC every spring plus I did a full coolant change when I had to change the bad rad almost 2 years ago.

Current info:
I just did the 288,000 Km (180,000 mile) service and found the following. Five of the 6 used spark plugs were dry, brown and “normal” (top plug in pics.) The #6 cylinder plug was wet and dark right back to the crush washer. The center electrode was ash coloured and grey instead of normal “white”. This is different than at the last service interval (240,000 Km.)
I also had to add ½ L (~ ½ quart) of coolant to get back up to the marked line. I’ve never had to add coolant between service intervals (except when the rad was going out; that’s why I’m anal about the indicator level.) The existing coolant still looks good and pink.
The used oil was also “normal” and not milky.

Need your opinions. Do I have a pending head gasket issue?
I’ve read almost all the HG threads on this and other forums. They mention a block test and hydrocarbon test. Are these the same thing? Can I buy a test kit for this (any links)? I also need to get a compression test.

 

[YotaDriver]

I'll preface this by saying that based on the information you provided here, it seems like it's probably your head gasket. I say that because in addition to the fouled plug, you've experienced the rough idle that's always described in conjunction with this issue as well as coolant loss. Your oil wasn't milky, but the other symptoms don't inspire much confidence.

With that being said, when I changed the plugs in my '06 V6 at the 90,000 mile mark, they looked similar. I also noticed when I changed them that they were half NGK, half Denso, so they were factory originals. Anyway, I'm posting the picture I took at the time (even though it's pretty much too dark to see details):

Again, I know that picture sucks, but the plug on the left came out of my #6 cylinder, and it was noticeably darker and looked like it was wet, even though it wasn't. Looking at the electrode, it looks like it could be a gray similar to yours, although that could just be the lousy lighting.

Mine's still running like a top at 122k, but you're well past that mileage.

 

[Kmvreter]

I'll preface this by saying that based on the information you provided here, it seems like it's probably your head gasket...
... when I changed the plugs in my '06 V6 at the 90,000 mile mark, they looked similar.

Thanks for the info.
So those plugs have 90K on them? (I might have to lengthen out from the recommended 30K interval.) I think you are right about the left most plug looking similar. I do have recent coolant use, however minor. I'm thinking it's early in the process so I'll monitor it. Maybe I'm just paranoid.

I forgot to ask in my opening post. For those that had a rough idle, how long did the truck sit and was that at every start, hot or cold? I normally don't have a rough start. Just the times it sat for more than a day. I'd like to test this out again (to try and repeat the rough idle) but I need to use the truck daily.

 

[Calimander]

Rough idle after sitting on a 04 v6 is a symptom of a bad head gasket. The coolant leaks into a cylinder(#6 most of the time) and the burning off at startup is where the rough idle is coming from. Hope this is not the case for you. Do you see coolant loss? Let it sit for a day or two and pull #6 plug and look for coolant.

 

[wrestler157]

Just had this fixed on my 05 I had all of the same exact symptoms. Its sneaky and I only popped a misfire code once. But turned out to be a headgasket. I would take it somewhere they can put a scope in it to check it out

 

[ToyoTech]

Like others have said. Sounds like HG is blown. You can do a leak down in the suspected cylinder but open your radiator cap and make sure it's topped off. Once you get air I'm the cylinder. I set it around 80-100psi. If it's the HG. Your will see the water start to rise. Done this test before and works really good.
Compression test won't show much.

 

[gm350reratliff]

You could also do an oil analysis. They should be able to tell if there is antifreeze in the oil.

 

[jow]

I tried to add some light to the plugs using Photoshop.

If you add psi on a leak down test, will you have to restrict the crank from turning while testing the cyl at TDC?

 

[Kmvreter]

Thanks for the replies.
I'll skip the compression test and get the leak down instead. Used oil looked good but I agree a UOA will help.
More testing and monitoring...

#V6sparkplugs

 

[mikebontoft]

Just had this fixed on my 05 I had all of the same exact symptoms. Its sneaky and I only popped a misfire code once. But turned out to be a headgasket. I would take it somewhere they can put a scope in it to check it out

highly agree with this. Finally diagnosed a bad head gasket on an Audi where it would misfire the first 7 seconds from a cold start. It had a misfire code once in awhile. Another shop replaced plugs and coils with no luck. I checked injectors and everything. Noticed the coolant was a little low so I checked for leaks.

Ended up pulling a plug and letting it sit overnight. took the borescope to find a small little stream of coolant coming from the head gasket.

 

[ToyoTech]

Sometimes the air pressure will push it down. I do it all the time and it usually only happens if you don't have it just right on tdc

A buddy of mine has a 05 taco and noticed a rough idle in the morning and goes away. Eventually he got a misfire code and ended up being a blown HG

Boreascope works to but not to many people have them.