| III Stock Limitations & Solutions |
| Now lets focus on the marginal or at-risk areas that most often contribute to failure. |
| a) Coolant Tanks |
| The main coolant tank has a few issues worth addressing. The initial design locates the temperature sensor in the coolant tank. It should be in the block. Invalid readings can be reported if the coolant level drops below the sensor. It is easy to switch, and most owners have already. Next, the coolant tank(s) are built to Italian specifications. The height of the neck lip (the surface that the cap seals against) is too deep for a U.S. spec cap to dependably reach. This causes the calibrated spring in the cap that is designed to release at a specific pressure, to release at a much lower pressure. Additionally, the sealing surface of the original tank neck is rough and many caps cannot reliably seal against such a surface. To make matters worse, the cascade of water from a releasing cap runs down the right rear inner fender panel and directly into a conveniently located cutout in the right frame rail. Of course, there is no drain, so the water sits there quietly rusting your frame from the inside out. To amplify a bad situation, if the secondary tank overflows, the drain hose dumps out right in front of the rear tire. Coolant is very slippery, and this can cause an over-steer spin leading to complete loss of control of the car. |
| One solution is to have a U.S. spec neck soldered to the stock tank, another is to replace the bottle(s) with aftermarket ones, or to use (rather expensive) Euro-spec radiator caps. Insure that the cap and hoses are tightly sealed, otherwise during cool down, instead of coolant being drawn from the overflow tank back into the coolant tank, air is re-introduced into the system. The next time, the water level will be low and the engine heats up even more, pushing more water out thru the defective tank neck and a cooling failure occurs. It is suggested to keep the coolant level in the secondary tank no more than � full to avoid dumping coolant in front of the tire, and it is a good idea (and required by racing rules) to run the overflow hose to the back of the car. |
| The Pantera coolant tank differs from most other designs, in that the tank is right after the water pump. This necessitates a higher cap pressure rating than nominal. For example take a typical system design that uses a 12-pound cap. As RPM increases, the pump output pressure increases. If a system is hot, and near the cap pressure limit, just high RPMs could cause the pressure to rise in the area of the cap, and result in the cap pressure valve opening. If the coolant tank were positioned on the upstream side of the water pump, this would not occur. |
| b) Air in System |
| Air in the system can cause hot pockets therefore successfully purging the system of all the air is critical. The shape and location of the components makes this non-trivial. To bleed the system I have found the following procedure to be successful. |
| Some versions of the stock radiator, and many aftermarket radiators have a bleed screw on the upper corner(s) radiator. To bleed out the air with this feature, raise the front of the car, and with the engine off but warm so there is pressure in the system, open the bleed screw and release any air that may be trapped. For systems that do not have this feature, I strongly suggest having the bleed screw added. Next, raise the back of the car, as high as possible. Run the engine until warm, ensuring the thermostat opens. Shut the engine off and let cool. Top off the coolant as necessary. Lower the car. This procedure of bleeding the rear may need to be done several times over a period of days. Driving the car will help move the bubbles to the coolant tank. You may hear gurgling at the water pump as the engine returns to idle. Any gurgling means there is still air in the system. |
| There are a couple of locations in the heads that are high enough to trap air. Some owners have tried eliminating this pocket by tapping the heads at the water passage and venting any air at that point. |
| On later (1973-1974) cars, there is a bleed tube that is connected to one of the pipes close to where it attaches to the radiator. This small tube goes down and then to the back of the car and up to the coolant tank. The idea was that water flow would force any air to vent into the small tube, and then be pushed back to the header tank. I find it hard to believe this works very well. Air trapped at the top of the radiator is not likely go down, then to the back and up to the coolant tank. After you�ve gotten all the air out of the system it has been suggested that radiators, fans, and heat load are 90% of the problem/solution. |