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Engine won't come up to temperature

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Anonymous Poster

Apr 8, 2009, 8:14 PM

Post #1 of 2 (1608 views)
Engine won't come up to temperature Sign In

95 GMC, 1/2 ton, 4wd, 5.7L, 160K miles. The temp gage has been reading ~170 def F for some time, going on over a year. I don't recall it suddenly going down, but approx a year ago I replaced the thermostat with no change, and then changed the gage temp sending unit with no change. At that point I thought I had a bad gage and just lived with it. With summer approaching I decided to get an aftermarket gage that I propped up on my dashboard. I was surprised to see that it matches the dash gage. So if I have a good 195deg thermostat, how can the engine not be getting to 195? No codes have been thrown.

Tom Greenleaf
Ultimate Carjunky / Moderator
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Apr 9, 2009, 7:07 AM

Post #2 of 2 (1601 views)
Re: Engine won't come up to temperature Sign In

If the 170F is the true and steady operating temp it really can only be blamed on the thermostat. That's about what I'd expect to see if a 160F thermostat was installed - almost no vehicles should be using those but they are sold everywhere. Might even be a mistake in manufacture.

Once at operating temp the reading should stay very steady. If it's fluctuating now and not overheating it may be leaking past the thermostat somehow. Upper hose should remain cold from a cold start and stay cold for several minutes. If there's any temp increase noticed early at the radiator end the thermostat isn't working properly.

If you can take a temp reading right at the housing of a thermostat is should read pretty close to it's rating once warmed up,

Long retired now

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