I did a lot of work on my cougar and now my monte is acting like it is over heated multiple times first when on the highway. It snaped the belt replaced the water pump and belt over heated again after flushing out and making sure there was no air in it. third after replacing the thermostat and the radiator hoses did the same thing. it already had the head gaskets replaced. after I did the hosses and thermostat I had a shop do a leak down test nothing. had every thing checked still nothing and over heats like a scalded dog. I am at a loss other than looking into getting another car all together. love the ride and a lot of memories in it I do not want to get rid of it. it is sad. radiator has been flushed repeditly and still didn't help. love the car. hate the engine. wondering if the ls ss engine slides right in that is what I am wondering about could a ss Malibu engine cradle would slide in from a 09 make and what I need from it

 

Have you verified the cooling fans are working?

Are you loosing any coolant?


Are the fins on the AC condenser in good condition and clean? Air has to blow through the condenser before it gets to the radiator.


Are the radiator fins clean?


Is the belt tensioner pulley spinning easily? The belt must be getting stressed for them to break like that.

 

So you took it to a shop and they have no idea what's wrong? Did you take it to a reputable shop? Did you take it to another shop for their opinion?

Overheating really shouldn't be that hard to diagnose for a professional mechanic shop. Are you sure the deck is flat? Perhaps the heads warped when it was overheated the first time?

I wouldn't bother swapping the engine until you positively identify the problem. You'd hate to ruin another engine if it turns out to be something else (radiator issue, fan issue, etc).