Wacky temperature gage

Hi, I have a 1993 full size blazer. For a while now the temperature gauge will all of a sudden start moving towards the red and will go way beyond for a minute or two. When it gets really high the check engine light will come on. Then it will gradually come back down to normal for a few minutes and then repeat. I thought that perhaps I just had a loose wire or something but strangely enough I get more power and the engine seems to run better when the temperature gets elevated. Does anyone have a clue what this could be?

Thanks,
Ted

Hi, I have a 1993 full size blazer. For a while now the temperature gauge will all of a sudden start moving towards the red and will go way beyond for a minute or two. When it gets really high the check engine light will come on. Then it will gradually come back down to normal for a few minutes and then repeat. I thought that perhaps I just had a loose wire or something but strangely enough I get more power and the engine seems to run better when the temperature gets elevated. Does anyone have a clue what this could be?

Thanks,
Ted


When is the last time that the thermostat has been changed ?

The system flushed thoroughly ?

Tell us a bit more on:

Engine type, miles on engine, flush history, type of anti freeze, thermostat approx age....etc.

Could be as simple as a lagging thermostat that is slow to open, allowing temp to rise then lower once circulation resumes.

Could also be a cooling system that is low on fluid and takes an extended period of time to cool down once the thermostat DOES open since the level could be low etc...

So before speculation get out of hand...fill us in on more information and we'll see what we can do.......

When is the last time that the thermostat has been changed ?

The system flushed thoroughly ?

Tell us a bit more on:

Engine type, miles on engine, flush history, type of anti freeze, thermostat approx age....etc.

Could be as simple as a lagging thermostat that is slow to open, allowing temp to rise then lower once circulation resumes.

Could also be a cooling system that is low on fluid and takes an extended period of time to cool down once the thermostat DOES open since the level could be low etc...

So before speculation get out of hand...fill us in on more information and we'll see what we can do.......

Okay so it is a 350 V8 and has just over 130,000 miles on it. To be honest I don't know when the system was flushed last or the type of anti freeze. I'm guessing the thermosat is as old as the car ~12 years. On point I forgot to mention is that the temperature will start climbing right after turning on the car. Literally after driving less than a few miles the temp will get into the red. Seems hard to imagine the engine is literally that hot that quick but I guess if something wasn't working right perhaps it could so maybe the lagging thermostat could be the problem. Is there any easy way to check that?

I'll check the fluid level this weekend.

Thanks for your help!
Ted

That is the first thing you check.

And STOP DRIVING IT LIKE THIS.

When the engine is dead cold, remove the rad cap and see if the coolant is right up to the top.

If not, do the following.

1.) Check your oil and see if it is milky.

2.) Replace your rad cap with something that is NOT AC delco.

3.) Refill the rad if the coolant is not completely up to the neck of the rad. Use the proper coolant, if it is green, use green, if it is orange, use orange.

4.) Refill the overflow resevoir to the proper cold level.

And again, for the love of god, DON'T DRIVE IT LIKE THIS UNLESS YOU WANT TO REPLACE AND ENGINE.

You might have a coolant leak, griz, and if you get coolant circulation after startup, and an 'air pocket' gets to the temp sensor, the guage will spike. Then the coolant that you've still got will hit the temp sensor, while the air pocket moves on, and the temp guage will drop back to normal.
Check the fluid now, when it cools down!!!!!!!!!

Thanks all for the advice.

No more driving for the time being (it's my second car) and I'll check the fluids this weekend. Thanks for all the advice. I'll see how it looks and get back to you.

Ted

4.) Refill the overflow resevoir to the proper cold level.

And again, for the love of god, DON'T DRIVE IT LIKE THIS UNLESS YOU WANT TO REPLACE AND ENGINE.

So where is the overflow resevoir?

Okay, I found the overflow reservoir after looking for about 10 seconds. Not surprisingly your advice paid off and the temperature gauge isn't bouncing all over the place.

But this leaves me wondering if I have a coolant leak. Any suggestions on what to check for or how I might fix it?

Thanks for all the help!
Griz

replace the rad cap with something no AC delco.

Stant is a good brand.

Top the rad up to the top and fill the resevoir to the hot level in the overflow tank.

The system will purge itself of the air in the block which was probably causing the temp spikes.

Again, replace the rad cap ASAP.