Auto Parts: 1988 toyota pickup 4x4 water pump, radiator cap, water streams

Question
i have a 1988 toyota pickup 4x4 that likes to overheat when on prolonged
road trips,  start and stop drives and coming up hills.  i live in hawaii and the
thermostat is completely removed.  i pop the radiator cap and it seems like
the water pump is working properly as water streams across the top,  i have
flushed the system on two separate occasions,  the radiator is in good
condition.  my only thought is that my diagnosis of the water pump could be
wrong.  how else could i test the water pump?  do i have to dismantle it?  i am
perfectly capable of doing the work but what does it entail?  thanks for your
response

Answer
Hi Jason,

Your problem is you took the thermostat out. That piece is not optional as you can clearly see by the problems you are experiencing.

Let me give you a brief explanation of why. Coolant is in three states in your cooling system. Hot, cold and holding. Holding is merely for storage of overflow coolant, reserve and expansion.

When all the coolant is in the cold stage, you have no issues but the coolant in the engine while it is running is being heated with the byproduct of the power your engine is making. Once this coolant reaches a pre-determined temperature, usually about 205 degrees, the thermostat opens and allows cold coolant into the engine and when the coolant is completely circulated passed the thermostat and it registers the cooler coolant, it closes to separate the cold from the hot giving the coolant in the radiator a chance to cool.

In your engine, the thermostat is missing. Therefore when you run your engine, all the coolant is collecting heat evenly, the problem is it's also releasing that heat evenly. In the climate you live in, I'm assuming the average air temperature is around 70-90 degrees, you don't have enough cold/cool air passing through the radiator to accomplish efficient cooling and the engine is making heat it can't disipate fast enough which is creating an overheating situation.

Buy the proper thermostat and install it. That will take care of your problems. Remember, a cooling system is not JUST designed to offer heat to the passengers, it's main task is to remove harmful heat from the engine. Running A/C also increases the likelihood, when you do not have a thermostat, of your engine overheating because the condenser is in front of your engines coolant radiator so all the heat the A/C system is removing from the passenger compartment, it is putting right back into the cooling system.

Thanks for the question, I hope this information was helpful to you.
Fred
www.knucklebusters.us
570-453-0910
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