Originally Posted by cruzinquick
The flow isn't the problem, it's when the pump stops working that's the problem. Your car will still cross state lines. It's not like it's going to shut off and die. You will have warning signs. Any pump you change to will not run the car any better. If you increase the pump too much you will actually run the flow too fast and have an adverse affect. If you had the larger ic than the increased flow of a johnson would bring you back to normal. Otherwise the stock flow is fine, just the pump motor is what is the problem. That clear it up? Will the johnson pump last longer? No one knows. Has anyone left one sitting in the sun for 2 years then installed it to see how long it works? Montana is inferring the johnson is a better product, it may be. No one has had one on long enough to prove otherwise. It's up to you, if you are leaving your car stock and don't want to splice any wires or hoses, brackets, clamps then just replace with a stock one or see how long it lasts.
cruzinquick, you have made a statement that I have thought of all along on the "Johnson Pump". The OEM pump flows 4.X GPM and the Johnson Pump flows 7.X GPM, thats almost double. There is a point that the coolant can flow to fast through the heat exchanger that it will not get the full cooling effect. I may be wrong, but when the German engineers designed the I/C cooling system on these cars you would think the 4.X GPM was what was required to cool the system at it's best. I just went through a similar deal with my old 64.5 Mustang, I had installed 3:55 gears in the rear end and started having trouble with the car over heating at highway speeds. At first I thought it was sucking (collapsing) a radiator hose shut, but after trying different thermostats, better hose's and radiator caps. I came to the conclusion that it was pumping the coolant through the radiator so fast it was not cooling the coolant. I changed the rear end to a 3:25 gear and no more over heating at highway speeds. I myself for now will stick with the OEM pump till she goes out, then make the choice of what I'll do.