Luke Ashlocke

Guys, I keep buying Thermostats from Auto Zone and im now on my 4th one in 1 month. It all started when I replaced my water pump because I thought it was bad due to whining sound. Went ahead and replaced my thermostat too. Well, after 2 water pumps from AutoZone and the final one from RockAuto (actually works) now im having the same issues with my freaking thermostat. This time, my temp gauge is waaaaay low and ive got the steam rising from under hood. What can I do?

Thanks in advance, gentlemen

gat

What year is your Cherokee? Do you have an open cooling system with a cap on your radiator and a reservoir tank or do you have a close system with no cap on the radiator and a pressure bottle?

I don't know how a thermostat would cause steam to come off the engine. Prior to this have you ever worked with the cooling system and bled the air of out the system?

As far as the steam goes did you scrape the old gasket material well and use a new pre-manufactured gasket or a liquid gasket material? Did you use Teflon tape or liquid Teflon for the bolts that went into the water pump? If the bolts into the water pump are not a liquid tight seal, then it would make sense that the escaping liquid would be steam.

Did you ever knock anything into your radiator during your multiple repairs? A hole in the radiator would produce steam.

The temperature sending unit is on the rear driver's side of the head. The thermostat opens based on temperature where it is located. They could be different if there are air pockets or of the water pump isn't pushing the coolant thru the system. How long does it take to idle to produce the steam? Can you find the origin of the steam? A temperature gun would help.

Idunno

Lack of water across the temp sending unit will give an erroneous reading (usually low). Purging air from the system will take quite a few minutes running time with the radiator cap off.

The best way to accomplish this after a pump R&R is to remove the thermostat and replace the thermostat housing onto its boss with a good gasket, bolts tight, and then service the radiator with fluid until it's full. Then, start the engine. The water in the radiator will immediately be circulated by the pump through the engine, moving the air to the radiator, allowing more fluid to be added to the radiator. Because there's no thermostat that needs to be opened by proper operating temperature purging the air from the system air is a snap and takes very little time. Once the system has purged the air from itself, which is indicated by the radiator fluid level stable and visible in the filler neck (cap off), turn the engine off. Then, leaving the radiator hose attached to it, remove the thermostat housing and lift it high to prevent excess fluid loss (hold the housing down firmly onto the boss until the bolts are removed during this step). Drop the thermostat in and quickly relocate the housing onto the boss and secure the bolts. Very little fluid will be lost and easily purged by a second purging run. Top off the radiator, leave the cap off, and run the engine. Wait for operating temp to be reached at which time the visual indication shows the water level at the radiator filler neck getting nervous, bubbling up and then drawing down again. That's the typical reaction when final servicing the coolant system when a thermostat is functioning. Top off the radiator until the level remains visible. Then replace the cap. Service the over-flow bottle.

Note: Thermostats can be installed upside down rendering their function from poor to useless.