Firestone said they only did a "Block Test". They've also been somewhat dodgy. I initially asked them how they knew it was a blown/cracked head gasket and they said "easy, you pull the spark plug and there is coolant on it." I went back to my mechanic and pulled all the spark plugs: no coolant, no discoloration. They were also evasive when my mechanic called them.
Mark: Is it possible that there is some residual CO present from when the head gasket blew last time? For example, in the hoses? I've read that these tests are very sensitive. 1st mechanic thinks this is possible.
Cylinder head was sent to machine shop, checked for cracks, machined, and had two valves replaced.
Country Boy: I'll look into a cooling system pressure test. Maybe my mechanic can do that.
Engine is not overheating. Since getting the gasket fixed I've actually been driving the car for about a month. No problems, reliable, no misfiring -- nothing but rough idle when you first start it up.
A stamped steel head-gasket never cracks between the cylinder head and block. An inexpensive *cooling system pressure test will find any external or internal cooling system leaks. IF an internal leak is found a cylinder leak-down test will show exactly where the internal leak is found. The only way an aluminum block with steel sleeves crack is the middle of the Winter when the cooling system doesn't have enough antifreeze in it.
You're the only person who knows if the engine ever has overheated. The cylinder head is the hottest part of all internal combustion engines. When they overheat the valve seats can fall out the cylinder head will warp then the head-gasket leaks.
Not really, blue chemical reacts to carbon monoxide in cooling system, yellower it gets, more CO present. Possible hairline crack in head, but should have been caught w/ head gasket job. Was head re-surfaced/pressure tested? 1st mechanic sounds reasonably competent, but we all make mistakes.
From your posting, I would trust the Firestone mechanic. Doesn't sound like the 1st mechanic has the tools to properly diagnose the problem. False positive - probably not. Firestone may have pressurized each cylinder and fond that one of the cylinders was causing the pressure in the cooling system to rise from 0 psi to 15 psi which indicates a head gasket leak or a cracked block / head between that cylinder and cooling system water jacket. There's probably an easier way to check for that leak.
I recently had a blown head gasket repaired in my 2001 Honda Accord LX (4 cyl). New radiator also.
The only problem afterwards was that the car idled rough -- sometimes stall when stopping.
Took it back to the mechanic (he told me it was idling rough before he gave it back to me) and he replaced the idle control (idle regulator?). This made it better, but did not solve the problem completely. The car then would idle a little rough, but smooth out. If you UNPLUG the CT sensor, the car idles rough when cold, but then runs smoothly when warmed up. If you PLUG IN the CT sensor, it starts smoothly, but rough when in Drive. Check engine code = Idle Error Metering
My mechanic couldn't figure this out. He replaced the CT sensor, and some other parts in the electrical system, and it didn't help. He told me I needed to find someone with more knowledge about the electrical/computer system. (He didn't charge me for any of this electrical work.)
I took it to someone else (Firestone mechanic) and they did a diagnostic and tole me I have a blown or cracked head gasket!
He apparently did a Block Test, and it came back positive (for emissions in the coolant). I took it back to the original mechanic and he has done a compression check (all cylinders are at the maximum PSI of 125), checked the spark plugs (clean with no discoloration), and checked for overheating.
Is there any way the Block Test could be giving a false positive? Could emissions be present from before?
