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4Runner Head Gasket?

I’ve got a 2004 4Runner with 120K miles on it. It’s been to 3 shops (two of which were Toyota dealers) in the past 3 weeks a total of 6 times for the same problem/symptoms. I get different answers each time I go or return to them. Collectively they have replaced spark plugs, replaced #6 ignition coil (twice), replaced #2 bank of fuel injectors and each fix has failed. Yesterday a Toyota dealer introduced a new theory. They suspect a coolant leak and bad or leaking head gasket that is leaking into #6 cylinder. They say pressure tests indicate pressure issues in this cylinder though at this point the leak is not large enough to be visible to them or me and the coolant level is not yet low. They now believe the head gasket may be the culprit. After such a frustrating few weeks and not being much of a mechanic myself I’m really not sure what to believe, nor do I have confidence in any recommended fixes at this point considering what I’ve been through. Does this theory sound plausible with described symptoms and is a head gasket leak something that should occur on a 2004 4Runner with 120K miles? Also, dealer quoted me $3,400 just for labor on this. Was really hoping to get at least 200K miles before having major issues. Thoughts would be appreciated.


ooops, I know I typed the sypmtoms but they didn’t appear in orginal post…So…

Engine runs rough and shakes for about 40 seconds upon a cold start after sitting for hours during the day or overnight. After about 40 seconds the engine smooths out but check engine light remains on.

What are the trouble codes associated with the CEL? Are they indicating a misfire in cylinder #6 or something else?

It would also be helpful if you had the pressure readings from the compression test. It may be written on the invoice or you can try calling. There will be 6 numbers - one for each cylinder.

A compression test is not a good method for detecting a leaking head gasket. This is a dynamic condition where pressure is built up in the cylinders and then released very rapidly. Instead a leak-down test should be performed. This is a static test that applies a constant pressure to the cylinders to where if a head gasket is breached, this air under constant pressure finds it’s way into the cooling system and appears as bubbles in the coolant in the radiator.

And the leak-down test should be done with the engine both cold and hot to determine if a head gasket has been breached.


Thanks all for the thoughts. Definitely helpful in moving forward.