Originally Posted by Kmvreter

@mgson What product did you use and is it compatible with the Super Long Life Coolant? Keep us posted if things change.

Originally Posted by Kmvreter

@mgson

Bar's Leaks has several products. Can you be more specific on which product?

Thanks.

Originally Posted by happy camper

Great to hear this worked. Still no negative results? I'm about to give this a try.

275,000 miles on this otherwise bulletproof 4R. Love this truck, but I'm getting the classic symptoms and lights. I did replace radiator 3 months ago as I was really consuming coolant. After that no discernible coolant loss.

Originally Posted by _Zort_

This particular thread has proved to be the most current and on-point for my situation. Thanks to you guys for sharing your knowledge and experiences!

My 4.0 V6 is in an '05 Taco, and it has the classic symptoms of the head gasket issue, including coolant in cylinder 4. Local shop (Kelly Clark) says at 170K it's asking for trouble to replace the HG. The bottom end would likely develop problems soon after, they say. Thoughts on this?

My girlfriend has an '08 4Runner, so I'm wondering if we'll end up in this situation again with her truck.

I am original owner of the Taco, have all the regular maintenance done, don't abuse it, and I was really hoping to get 250k out of this Toyota. Is it really a bad decision to replace the HG now at 170k? I won't be doing the work myself, so it wouldn't be cheap. Other options would be to buy a used low-mileage motor from a yard and have someone install it. Also not cheap Looks like a used motor is about $2500 or so), but this might be a better long-term solution? Finally, I suppose there's always the cheap HG Fix attempt.

Again many thanks for your previous posts and any additional thoughts or knowledge you might share.

Zort

Originally Posted by 4unnerftw

My 2006 had the head gasket replaced by previous owner, but it was actually built in 05 (maybe before they changed the design).

When I start it, it does have a few very quick small vibrations here and there which now have me worried. I'll take a look at the coolant and make sure it isn't losing coolant. This is really freaking me out now.

Maybe i should try that sealer.

Originally Posted by kcdehart

Don't use the sealer unless you're sure the HG is bad and you don't have the money to properly fix it. I was talking to a mechanic friend when I thought mine was bad and asked about the sealer. He said to absolutely not do it, as it will clog other parts of the cooling system and can seep into the head and cause issues, apparently. It's the last resort when you know your engine will be toast otherwise

Originally Posted by 4unnerftw

ok, thanks for the advice. Sounds like monitoring coolant and then a compression test would be the way to go.

Originally Posted by blackmax

sorry for kinda long.....

So, P0306.....it seems to be something of a "known issue" for the 4.0 liter engine. with higher miles. However, it's also true that reading a forum can make things look more prevalent than they really are. If 8 people all come on and say "Yea, me too"...it sounds epidemic. But maybe it's just 8 out of 300,000. Or maybe it really is a problem and needs to be considered.

Anyway,it seems that quite a few people have complained that they got the dreaded P0306 code (misfire in #6). Many then took it to the dealership who promptly nailed them for a "tune up" including plugs and a coil....only to eventually get to the real problem- "your head gasket failed at #6; and it's leaking coolant into the cylinder. You're F'd." It seems as if ALL of these people were at 120,000 - 160,000, with the majority seeming to be right at 150,000 miles.

Symptoms beside the code would be rough (as if missing a cylinder) at startup, especially after sitting for while.

I'm wondering if most or perhaps ALL V6s over 100k miles have this leak, but it's so small that it simply isn't noticed (yet); plus, it seals back up very quickly after startup, due to the intense combustion temps? After reading all the post on this subject, I'm convinced that mine has had this small leak for 100k miles now. It must just be soooooo small, that it hasn't become (and perhaps never will) a major issue. Why do I think I have a small leak, and have for long time? Here's what I've experienced-

1- maybe 10 times since I bought my truck (10 years ago) it shuddered for 5 seconds after startup....but later smooth out.
2- a couple times in summer, while climbing a hill, I could see white smoke in my rear-view mirror. Why it's only happened 3 times (that I know of)....I can't say. But I know it did happen.
3- And this is the big one for me: I pulled all the plugs. They ALL look exactly the same......except #6! It had significantly more deposits on it (not black).

Now, like I said, I'm wondering if perhaps most 4.0 engines have some leakage at #6 (seems it's an admitted design flaw, and Toyota has changed the HG design, as I understand it), but since the leak is so small, the owner is just unaware. So the real question is- how many drivers have over 175,000 miles on their 4.0 and have not seen the CEL come on, and find out it's P0306?

Sorry for the length....but this could be a serious issue for people wanting to get high-miles out of their 4Runner, like me. I wonder if:

1- everyone with over 100k miles on their truck pulled the #6 plug plus any other plug....if they'd see an obvious difference with lots more deposits on #6? or,
2- not that many would, and the real truth is that though HGs will fail on our engine, just like any engine, it's just that when it does n ours, it happens at #6.



Again, sorry for the length.