2003 coolant vs combustion issue advice

[dullbert]

Our 2003 recently overheated about 3 miles into a drive on local streets while idle at a stop light. Light changed, vehicle began shaking as making left turn, pulled over and shut it off. Maybe 40 seconds from the overheat indicator ding. Engine coolant thermostat housing had a hole blown in it below the cap. Replaced and bled per procedures found on this forum. Ran for 25 minutes with AC cranked in drive (while in place), no overheat. Fan turned on. Then turned on heat, fan turned off and heat worked. No overheat. My wife then drove it last night for about 3 miles, ran it through a drive through car was and shortly after, it began smoking. Towed it to dealer. They have not diagnosed but immediately jump to blown head or combustion issues. There is no apparent water in the oil checking dipstick and oil cap. Thoughts on likelihood this is really bad? Is an engine hard and expensive to source and replace in Los Angeles? My thought is to check all coolant system first. Water pump has already been checked and checked out fine (prior to this latest incident). The car has maybe 30k miles on it, purchased from first owner at 17k miles and it was pristine. I’ve not seen a used car with an engine so clean when we got it. OCD level upkeep with first owner.

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[Skeeter]

Our 2003 recently overheated about 3 miles into a drive on local streets while idle at a stop light. Light changed, vehicle began shaking as making left turn, pulled over and shut it off. Maybe 40 seconds from the overheat indicator ding. Engine coolant thermostat housing had a hole blown in it below the cap. Replaced and bled per procedures found on this forum. Ran for 25 minutes with AC cranked in drive (while in place), no overheat. Fan turned on. Then turned on heat, fan turned off and heat worked. No overheat. My wife then drove it last night for about 3 miles, ran it through a drive through car was and shortly after, it began smoking. Towed it to dealer. They have not diagnosed but immediately jump to blown head or combustion issues. There is no apparent water in the oil checking dipstick and oil cap. Thoughts on likelihood this is really bad? Is an engine hard and expensive to source and replace in Los Angeles? My thought is to check all coolant system first. Water pump has already been checked and checked out fine (prior to this latest incident). The car has maybe 30k miles on it, purchased from first owner at 17k miles and it was pristine. I’ve not seen a used car with an engine so clean when we got it. OCD level upkeep with first owner.

 

[Skeeter]

You may just have air pockets in your coolant system. I got a vacuum fill kit from home Depot and did my own, it was kind of fun and easy. And it worked great. if you have it vacuum filled, it will also show If there are leaks in your system. when you pull a vacuum on it , it will show if you have a head gasket leak etc. Hopefully that's all it is, good luck.

 

[jopizz]

The fact that the thermostat housing blew out could indicate exhaust gasses getting into the cooling system causing too high a pressure. You could have a bad head gasket and not get coolant into the engine. A coolant pressure tester will find that out pretty quickly.