I have a 1998 Camaro Z28 with 172000 miles on her. Recently out of no where my temp started to rise to about 230. I think its the thermostat. Also the main hose running from the radiator to the block does not build up pressure and is so soft you can easily squeeze it. If it is the thermostat where is it located and can i do it in the garage with a couple of tools.
yeah believe you have to remove the belt to get to it. But just follow that upper radiator hose to the block, and where it connects is the thermostat. Just make sure when you buy one it is the housing and all. When you put it all back together fill the radiator up, and idle the car in the drive way. Once in a while kill it and fill the radiator... DO NOT instantly take the car out unless you are no more than a block away from the house and constantly watch the temp. I failed to do this and had a lot of air bubbles in the system, 2 miles out the car overheated badly.
But yeah, sounds like a thermostat issue. Could be a clogged radiator also but not likely.
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When you replace the thermostat don't be surprised if at first the temps get up higher than normal, as long as it stays out of the red zone. The new thermostat sometimes needs a break-in period, it'll sit closed longer than normal then suddenly pop open and the temps will come down pretty quick. Then they'll rise again when it shuts, then plummet when it pops open. It may do this several times but after a little bit it normalizes.
Mine did that when I replaced it (not this car, my old one) and I was disappointed at first because it was still running warm then suddenly the temp dropped and it began that cycle. It only took 30min of driving or so to get it broken in though.
Like camaroguy26 said, check coolant levels as well, the system will burp out air bubbles and you'll need to top off a few times.
Thermostats are usually pretty good and do not fail, but I would not bet on it.
I would check the radiator cap and replace that first.
For a 1998 and 172k miles, has the coolant system ever been serviced? If not, you are certainly over the 5yr/100k mile mark.
if you squeeze the upper radiator hose, when car is hot and without burning your hand, and rev the motor up to 2000-3000 rpm you should be able to feel a surge in coolant, that's the water pump pumping. If you don't it may mean the water pump is on it's way out... provided the thermostat is working properly also and is fully open. Would be a good idea to check this before you pull anything apart.
the best way to fill the cooling system is disconnect the small coolant hose on the throttle body, this is roughly the highest point on the engine and makes a good air bleed- keep filling the radiator till coolant comes out the line then reconnect it to the throttle body, fill the radiator to the top and put on the cap. Make sure you're overflow bottle is filled about halfway between the cold and hot mark. Then just run the engine normally, with radiator cap on so it builds pressure, and what little air that's in the system will work it's way out and the system will refill itself from the little extra coolant that's in the overflow bottle. If you fill the radiator slowly and allow the air to come out the throttle body hose, it's small so it takes time, it's a one-step procedure and pretty easy and when you take off the radiator cap the following day to check the level you will find you won't have to add anything.