Water temp fluctuates.

[Hybrid4g64Spyde]

Last night, I was driving my car around town, I noticed when I would accelerate my temp gauge would drop and when I would let off it would go back up to normal. Is my thermostat going out? Also, one other thing, when my car sputters under acceleration my tachometer jumps around erratically. Is this a problem with my trans.....coil pack.....or my o2 sensor being fuzzed up?

 

[GTM]

Last night, I was driving my car around town, I noticed when I would accelerate my temp gauge would drop and when I would let off it would go back up to normal. Is my thermostat going out? Also, one other thing, when my car sputters under acceleration my tachometer jumps around erratically. Is this a problem with my trans.....coil pack.....or my o2 sensor being fuzzed up?

Check and _properly_ fill your cooling system.

Cheers,
GTM

 

[Hybrid4g64Spyde]

What is "properly" filling my cooling system? Is there a right and a wrong way to do it?

 

[Mindslayer]

YOur th**stat is going bad and your sensor for your tack is missing up.

 

[GTM]

What is "properly" filling my cooling system? Is there a right and a wrong way to do it?

Yes, you should check when the engine is cool enough to safely remove the radiator cap with the car at least level and preferlably on an incline facing up hill. Fill the system, turn the heater to max temp and defrost and start the engine and keep adding coolant until it is circulating when the thremostat opens while also checking the defroster outlet is hot. You may have to race the engine and release to force the bubble out of the heater core several times. Once this is done replace the cap and fill the overflow bottle to proper level. If you have any doubts about the radiator cap functioning correctly then replace. When the engine gets hot it will force excess coolant into the overflow, but when it cools off the check valve in the cap will allow it to return to the engine. If the level in the bottle is too low it can't syphon back to the engine so this can be a source for problems.
.........

The reason for this bleeding process is the heater core is the highest point of the cooling system so naturally air will get trapped there. When you think you have it filled in fact you have a large bubble if you will, which when a little hot water gets forced into the heater core expands and forces water back into circulation throught the radiator and the engine cools off. What you are seeing is from accelerating the water gets sloshed from the radiator back into the pump which then puts it into circulation but when constant speed is attained it is evenly distributed with the air trapped and low coolant level.

If you get it full and properly operating but the problem returns some days later this could be the sign of a leaking head gasket and more investigation needed. All this is based that you don't have any leaks.

Cheers,
GTM

 

[GTM]

YOur th**stat is going bad and your sensor for your tack is missing up.

One thing at a time before we start blindly condemming parts. There was no mention of it overheating for it would run "normal" and then drop to cool, not normal and get hot. Since I don't know what a '99 has for sensors it could have a low water level which is throwing a code and causing the tach to missbehave while it's trying to figure out what's going on.

I'm sure you have heard the expression: :if it ain't broke don't fix it!" So take care of the obvious first and then see how things act before blanket discarding other parts.

Cheers,
GTM

 

[Hybrid4g64Spyde]

Thank you, sir! Will do that tonight.

 

[GTM]

Thank you, sir! Will do that tonight.

You are welcome, let us know how it turns out so we don't have to guess if you got the best of the car or the car got the best of you.

Put some water in it before you leave for home.

Cheers,
GTM

 

[Hybrid4g64Spyde]

I had a tech here at the dealership I work for "burp" my car with his little funnel doohickie. T-stat needs a replacing.