I'm not sure it's time to take Old Yeller to the shed just yet, lets see what others have to say.
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Haha! Fair enough. I try to assume the worst, hope for the best on this thing. I'm coming from a 1st gen Tacoma that was mechanically sound, and meticulously maintained. I knew coming into this that it would need some tlc, I'm just not super stoked on replacing the head.I'm not sure it's time to take Old Yeller to the shed just yet, lets see what others have to say.
It's only failing emissions at idle. The HC's were like 420. In Salt Lake we're only allowed 200. I don't think the thermostat is the culprit behind the failed emissions. They're either unrelated, or connected by a failing head gasketI used to be a smog tech guy in CA and I have never seen or heard of a bad thermostat do what you describe.
Is it only failing at idle?
Did you check for a manifold leak,like the gasket or EGR sticking open or a bad brake booster?
When coolant leaks into a cylinder when the engine is running, it steam cleans the top of the piston to look shiny brand new. Normally the top of the piston is coated with a thin film of black carbon/soot.
You can take a close look at the spark plugs but if a ($75) bore scope was inserted into the spark plug socket and aimed down at the piston, you could verify with absolute certainty if coolant was getting in the cylinder. The top of the piston would be clean shiny aluminum.
Digital Inspection Camera
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Well, there have been some recent developments. Maybe they're unrelated, or they're the direct cause. We took it up to Idaho today to see the fam, and it ran great. It's about a 100 miles up there. Engine temp was normal and everything seemed good. We were there for like 3 hours, and then headed back. 20 minutes into the drive back, engine temp went up over half for a sec, then came right back down. It did this 3 or 4 times. None of them while I was climbing hills or accelerating, and the last time it went up and touched the red. I backed off the throttle, and it went right back down. Checked the overflow when we got home, and it was empty. Three weeks ago when we changed the oil, we filled it. Do I have a leak in my head gasket, which is causing the idle issues, and the high HC's?? It runs great at cruising speeds, and is not blowing smoke. It does at idle when the engine is cold, but I thought that was due to the lower Temps outside, and the unburnt fuel. Help?
I agree w @Trapper50cal. The 62 temperature sender (unlike the 60 sender) is mounted horizontally and low the thermostat housing up front. It is immune from bubble entrapment or steam influence.
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