Cooling system on 1999 Isuzu Rodeo

My son's Rodeo occasionally ran hot so he replaced the thermostat. Now it runs hot every time he starts it and drives a mile or two. Will a pressure test show what the problem is? Could it be the water pump?

Asked by for the 1999 Isuzu Rodeo
A pressure test will help you find a leak, that's it. If the engine is overheating there can be several reasons. It may have an air bubble in the cooling system from when your son replaced the thermostat, the radiator fan may be broken, the water pump could be bad or several other things.
Best to not drive this if it is overheating, you will damage the engine. Have it towed to a shop and get it looked at by a professional, don't let him learn the hard way when it comes to a potentially expensive repair like this.

My Isuzu Rodeo is in the shop all torn apart waiting on a part. My mechanic is having a hard time dealing with the Isuzu manufactor getting a silly rubber fitting that seals a pipe going into the back side of the thermostat. The fitting is kind of the shape of a o-ring but fatter & flatter. Do you know of a site where we might find this rubber fitting?

All sad Gibson
1 more answer
I have a Rodeo with the same problem. Your water pump is probably not the problem unless it is leaking. Because and is likely to be working fine since it is powered by the timing belt. (Timing Belt is fine since the car is Starting). I would suggest running the car till it looks like it is overheating then loosen the radiator cap (1/2 turn to the left) so that it is still on but relieves dthe pressure. Then check your temp gage and see if it continues to overheat. If it stops overheating then it is the radiator cap. But I warn you it is very difficult to find the right cap to releave the proper amount of pressure I refuse to pay isuzu $30 for a Cap