Rising Temp Gauge in 2000 Chevy S-10 4.3L

[SWMuskeye]

Hey Guys,

Lately, my truck's temp gauge will escalate very high and the check gauges light will come on out of nowhere.

It comes and goes, and it isn't due to increased acceleration, rpms, etc.

Anyone have any idea why it will do this? Usually it sits at high and the check gauges comes on, then it will typically go down right away to about the half-way level.

I am stumped!!

Thanks for the help everyone.

[lawdog]

Low fluid level?

[Eric Wettschreck]

Low coolant level or t-stat not opening?

[Macgyver55]

Have you checked the coolant level? If not, thats the first thing to do. Don't just check it at the reservoir though, you have to check it at the radiator itself. (Make sure it is cool when you do it to avoid a nice hot water volcano) If its low, of course refill it to the proper level first, then, since the water had to have gone somewhere, you need to either pressure test it or at least visually check it for leaks. If it is/was low and you see no visual leaks you may be looking at a leaking intake manifold gasket. Its a fairly common problem on these. In my experience external leaks are most common, but they can also leak internally and the coolant will contaminate your oil. If this is the case you need to deal with it quickly to avoid further damage.

If the coolant IS at the proper level and its still doing it I would suspect a sticky thermostat.

[Bobby Bass]

thermostat gets my vote.

[Shack]

+ Sending unit or T-stat is a good guess. Could be cooling fan assembly or relays.

Check to see if fans are on during this time.

It could be one of a hundred different things. If you can, test the cooling system for hydro-carbons. This will tell you if there is a small internal leak starting. Short of that, further testing of the vehicle will need to be done.

It could be restricted radiator, water pump impeller blades worn of or loose from shaft. The list goes on.

[Jeremy airjer W]

Low coolant caused by a leaking intake gasket gets my vote as well. Typically they will leak right behind/under the a/c compressor. Very common repair.

[ec30_06]

I have had to put head gaskets in several 4.3l chevys.

[Macgyver55]

I could be wrong, but I don't recall the 2000 having electric fans so that should eliminate those and the relays.

[Shack]

Very well could be a regular belt and pully fan and yes this would rule out any fan or relay issue. Have not popped a hood on one of these for awhile and it being a rear wheel drive, this most likey is the case. Just got in cooling system run.

[Hookmaster]

I had a 1995 S10 Blazer that went much higher in temp than normal, then dropped when the thermostat opened. This happened while hunting in North Dakota. The next morning the thermostat stuck and the dash lit up like a Christmas tree with all the warning lights. I opened the radiator and couldn’t see fluid. It turned out to be a slow leak in the water pump. I was able to get back home without a catastrophic failure. The leak was so slow that it would not drip on the driveway. It collected in a cowling and either evaporated or drained out while driving.

[Shack]

You where lucky. All it takes it a little air bubble stuck in T-stat housing to prevent opening and the over heating starts and stays untill bubble passes into rad...

Some model's, even a small patch of air can hatch and eng.