No shroud? You identified the problem. Without it, the air just goes right back around and comes back in through the radiator after being heated the first time through. Also be sure there's no holes in the core support for air to bypass the radiator. Same with the rubber strip that clips under the front edge of the hood or on top of the core support. That blocks air so it has to go through the radiator.
It is also possible to cause an overheating problem by removing the thermostat. The hot coolant doesn't stay in the radiator long enough to give up its heat. If you have coolant that is too high in antifreeze and not enough water, overheating can result. Antifreeze doesn't hold as many BTUs of heat as does water so it's less effective at transferring heat to the radiator.
Any chance the pulleys are the wrong size and the water pump isn't spinning fast enough?
Sunday, October 16th, 2011 AT 12:13 AM