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I just had a diagnostic done at a nationally known chain because the SES light came on my 99 Expedition 5.4L. I was told that the right head gasket is blown and that with parts and labor would be over $2000 to repair it. First, how would I know that it is a blown gasket? I have read posts about coolant in the oil as an indication. I have also replaced COP #4 twice in the past year if that is any indication. I don't know what code(s) came up this time, but previously have said excessive lean condition on Bank 1 Sensor 2 (O2 sensor). I really can't afford to have this repaired right now, which kind of stinks since my NYS inspection is due at the end of the month. The Expy will have to sit in the driveway uninspected. If it does turn out to be a blown gasket, am I better off having it repaired or spending extra and getting a rebuilt motor with a 100K warranty?
Keith
You should either have coolant in the oil or coolant in the exhaust. It will usually miss too. I would get it scanned at Autozone and post the code here. Is it losing any anti-freeze?
I have heard that before in the forums, about the heater hose. I guess that I will have the codes read at AZ and maybe bring it to another repair shop. Has anyone heard of O2 sensors going bad, because the manager at this repair shop said "O2 sensors never go bad unless something else is wrong in the engine."
Keith
O2 sensors can go bad, but they usually just fade away slowly.
Get the codes read, and post back here with all of them. Sounds like that shop was trying to pull a fast one, a blown head gasket is rarely something you can ignore - there would be clouds of smoke out the exhaust, it would miss, something!
A "bank lean" code can be the MAF requires cleaning. Or a big vacuum leak somewhere - check the PCV piping, especially any elbows - Ford's are known to crack and leak.
I went to AZ this morning to have the codes read. Just one code came up:
P0136 - Sensor Circuit Malfunction (Bank 1 Sensor 2).
After AZ, I dropped the Expy at another repair shop to get their own diagnosis. I'll keep you informed.
Keith
I just got a call from the repair shop. They did all their diagnostics including a 12 step flowchart, and said definitely the O2 sensor is bad. I hope they're right. After I get the Expy back, I need to do a drive cycle or two to get the sensors ready for state inspection.
Keith
Update: when I got to the repair shop, they showed me the old O2 sensor. There were 2 corroded pins in the connector. The mechanic cleaned out the corrosion from the Expy side of the connection before installing the new O2 sensor.
Keith