I looked through my service manual reference for your car for an hour last night to find a good diagram of the cooling system and read about how it works. It is a little bit of an unusual setup but it is different in that there is a pressure cap instead of a radiator cap. I tried to locate where the cap is, but no diagram that I found would show enough around the cap to be able to tell where it is mounted. Also, it works not only by a pressure hold using a spring and seal to keep pressure in until a certain pressure is reached that the spring is pushed to open the seal and release the pressure and then once it is relieved the cap closes again. The pressure cap you have adds another control. It uses vacuum to keep the hoses from collapsing during the point where pressure has dropped enough that the spring allows the seal to close which creates a vacuum in the sytem as gases are exiting at a quick rate and pull air with them and this collapses the hoses and keeps the sytem from cooling which starts the overheat and release pressure cycle all over again. The vacuum control is on the other side of the spring so the spring cannot close so quickly that it collapses the hoses. The vacuum makes the spring close very slowly allowing the pressure in the cooling system to equalize with atmospheric so the system coninues to work without the overheating cycle re occuring from the collapsed hoses.
Whew, did you cath that? It is a good idea, but if the spring is bad in the pressure cap the vacuum will always hold the cap open and the system will never build the pressure necassary to cool the engine. That is why I asked you to try and squeeze the hose to see if you could feel pressure in the system as it needs around 13-15 PSI to work properly.
The fact that your exhaust is smokey is a sign of a blown head gasket which keeps pressure from building up as it esapes into the cylinders. So, it will affect perfomance more and more as the problem persists. The fact that you do not have any heat in the system but the sensor says it is overheating makes me think that there is some overheating problem becasue of the lack of pressure which is either a leak, like the head gasket, in the system or the pressure cap is bad and needs replacement.
I am sorry I cannot tell you where the pressure cap is, but I can send you the diagrams I have and you could find it by orienting it with the few things around it you can see.
I think it is somewhere near the bottom hose as well as the temp sensor because the system is set up upside down from most to take advantage of the pressure cap that prevents overheat re-cycling by keeping the passages free for coolant flow.
So, check for pressure and let me know what you find. Also, let me know if you want the diagrams that I have so you can find the pressure cap.
Saturday, December 10th, 2011 AT 10:38 PM