Overheating issue causing code p0327 ?

Hello everyone. I have an ebony 2001 that I bought used with only 9,000 miles on it (back in 2005). It now has 107k miles. Last week it overheated on my wife, lost coolant, so towed home. I had been putting off the timing belt service, but now with leak in radiator I decided to tackle the job, since I would be replacing radiator, and hoses anyway.

I was able to successfully replace the timing belt, water pump, tensioner and pulleys (Gates kit TCK 303 ). Filled new radiator with distilled water, with the intent to keep flushing to remove all the old coolant. (Drive short trip, drain, add distilled water, drive, drain, etc) I did this 5 times, then drove across town, about 15 miles on highway in 95 degree heat. Did not overheat UNTIL on the trip back home across town. It got hot, blew the lower hose from the radiator, and steam cleaned the engine with the distilled water ;o) Towed home again. Re-attached lower hose, and filled with 50/50 mix coolant. I thought maybe I hadn't "burped" all the air out of the system. I was able to get 8 quarts coolant into it, ran it till warm, then added almost 2 quarts more coolant.

Next day I drove it several times on 20-30 mile trips in 90 degree weather, ac running. No leaks, did not get hot, temp gauge just below mid-point, felt like hoses full of water..... Then today I drove it about 5 miles and it overheated on me again. Can a thermostat be "intermittent" ? Work sometimes and then stick closed?

Also, the check engine light came on, and I read code p0327, knock sensor low. Could the sound of boiling water in the engine make this code? It looks like I will be replacing the thermostat, and was wondering if I should replace the knock sensor while I have the intake off, or will the code go away when the overheating problem is solved?

I'm not a professional mechanic and I need some wisdom. Anyone have any thoughts on this ? The engine runs great, no noticeable knocks or valve ticking. However, I've never adjusted the valve lash or changed spark plugs. Never felt like it needed it.

Can the thermostat be changed without removing the intake?

P0327 is typically caused by electronic problem....usually bad connection or sensor. It's unlikely boiling water would trigger this code. More likely the blown lower hose jarred wiring loose, baked it, or caused a connection problem.

I haven't changed the stat on my VX but would be shocked if the intake needed to be pulled to swap it out....and yes, failing stats can be intermittent -- making it a good next step. Hopefully, it's not a head gasket....which can also be intermittent in the early stages.

I am in the process of changing my thermostat at the moment, and have the intake fully off. I could not see any other way of doing it. With the overheating problems you have had, I would be replacing all the small coolant hoses, plus the water pipe o-rings, that are under there at the same time. They will also be cooked, and it is a lot easier to do it all once, rather than having to pull the intake manifold off several times.

PK

With the knock sensor throwing a code, a simple test from a mechanic can tell you if it’s your head gasket. You can also get a combustion leak tester for around $40 from an auto parts store. Some do not come with the testing fluid, so make sure you check the package. It’s a simple test, if the fluid changes from blue to yellow then you have a bad or failing head gasket.