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98 Z34 running hot!!

  #1  
Old 04-05-2011, 08:54 PM
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Default 98 Z34 running hot!!

Engine runs extremely hot and fans never turn on till I kick on the heater. After the fans kick on temp goes back to normal level. Did notice however that there is virtually no pressure in my coolant lines. In and out hoses can be squeezed fully when hot and cold. Also bottom hose doesnt really get hot at all.

Been suggested that the pump is bad, but the heat comes out really hot, even after only a short run time. So water is obviously making it to the heater core. Also unscrewed the little release valve by the thermostat while the engine was running and fluid did come out, just was under very little pressure, basically just flowed out slowly.

Also was suggested that the thermostat is bad. So I think I'm going to just replace it and see what happens. Good idea or not??

Also started wondering if maybe it could be just a bad radiator cap??

Any advice would be awesome! My engine running this hot is getting scary!!
 
  #2  
Old 04-05-2011, 09:08 PM
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Before replacing the thermostat, boil some water in a pot and drop the thermostat into it. If it opens, the thermostat is ok. If not, its bad and needs replaced.
 
  #3  
Old 04-05-2011, 11:03 PM
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Yeah I was already gonna do that in hopes that I could save a few bucks. I'm probably gonna replace the radiator cap too for good measure.

Someone else suggested the coolant temp sensor but that has already been replaced.

I'm just confused as to why the fans won't kick on?

Any more suggestions would be great!

Thanks!
 
  #4  
Old 04-06-2011, 08:07 AM
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If it's the original T-Stat, for how little they cost, I'd change it. While you are at it, if it's been a while since you flushed the coolant, take the time to do that (it may be sludging up and causing bad circulation).

When the car is running and the temp guage is going higher then it should, do you have good heat coming out of the blower inside the car or is it the ambient outside temp??
Also, when you open the bleeder do you get coolant flowing immediately or do you get air/steam coming out for a little bit?
 
  #5  
Old 04-06-2011, 12:37 PM
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Well I changed the thermostat and put a anew radiator cap on it. Let it idle for like 20 minutes and it is not getting as hot. Hopefully that fixes it.

Thanks all!
 
  #6  
Old 04-06-2011, 12:57 PM
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Changing the radiator cap was a good move, if your old one went bad and ruined the vacuum in the system it could change the boiling point of the coolant from around 260° to around 210° which is easy to achieve.

Keep an eye on your coolant levels if you haven't already.
 
  #7  
Old 04-06-2011, 02:50 PM
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Yeah so I changed all of that and it is still running a little hot. On the highway the gauge stays in between half and the red, but once I get through a few spotlight it goes right to the white line before the red!


Is this normal for these cars?
 
  #8  
Old 04-06-2011, 02:58 PM
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Did you bleed the system??? Car should be running around halfway on the gauge
 
  #9  
Old 04-06-2011, 04:51 PM
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Yeah I probably need to do that. Just open up the bleeder valve on top the thermostat right? Did that the other day before replacing the thermostat and fluid did run out. Didn't seem like there was a whole lot of pressure though. Maybe now that I have replaced the thermostat and cap it will build up more pressure.

I am starting to wonder if my guage is just off somehow. I've heard of it happening, just not to myself.

Any thoughts?
 
  #10  
Old 04-06-2011, 11:36 PM
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You'll have to bleed it for a little bit. If you only blead it once, then you may not have blead it enough.

Also, you shouldn't notice much pressure. The coolant system runs at 16psi. Very little pressure. But if that doesn't work, then let us know.
 

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