Ok I had a chance to mess with the car today. I just had a new water pump installed,and here is what it is doing. I will start cruising down the freeway water temp at 196, will work its way up to about 208-210. Then it will works its way back down to 196, and then back up again to 208-210, you get my picture. Is this normal? I dont remember it doing this before the new water pump. I thought it would run until the thermo opened and then sustain that temp. Thanks in advance........

 

17 looksies and know answers. Is this the way the rest of your vettes act or do they stay at a sustained temp after the thermostat opens....

 

Was a new thermostat installed too?

If so, it kinda sounds like it's actual open/close points are a little higher temp than the nominal rating. It's not a serious problem as you describe it, but it's not normal either.

Low coolant level could also create temp swings like that at cruise, but your description sounds more like the Tstat.

 

My first guess is that the coolant level is incorrect. Sounds like air in the system from your description.

Check the coolant overflow tank. The coolant level (obviously) needs to be above the COLD (Minimum) level with a cold engine (one that has sat overnight). If the level is low (which I suspect it is) fill with a 50/50 mix of coolant and distilled water. The coolant should be Dexron, an orange colored coolant. If the coolant is green ... whoever did the work put the wrong coolant in the engine.

 

Its a brand new GM water pump kit part # 89018034. I assume it comes with a new thermostat in it. Coolant level is at the bottom of filler neck cold. The pump has the themostat in it you can just replace the stat you dont have to replace the housing to.......

 

Or is it possible the pressure cap is shot.

 

Like I said above .... fill the coolant up ... you probably have air in the system ....

 

Its as full as it can be any more and it will over flow. If there was air in the system I would have bubbbles in my coolant, there are know bubbles........

 

Do a search on how to remove air from the cooling system. Looks are deceiving.

 

 

when I change the pump on YV's car the aftermarket stat would NOT fit in the new pump....







sounds like air in the system


I did the drain and fill procedure by the book and still had air in the system....I ended up loosening the pump and retightening everything and topped it off again to make it right...never ever had that happen before I have done a drain and fill numerous times never an issue until this last time.

 

Sounds normal to me, on expressway you get great air flow.

Around town does it get to higher temperatures? If not, your cap may be bad.

Here is the normal operation, fan set points are higher than most people think:

The low speed cooling fan is commanded on when the coolant temperature reaches 108°C (226°F). It is turned off if the coolant temperature lowers to 104°C (219°F). The high speed cooling fan is commanded on when the coolant temperature reaches 113°C (235°F). It is turned off if the coolant temperature lowers to 108°C (226°F). When the A/C is on and the coolant temperature reaches 85°C (185°F), the low speed cooling fan will be turned on at vehicle speeds less than 56 kPh (35 mph).

Here is proceedure for filling the radiator to ensure air is out. You multifill and rev engine to 3,000 rpm:

Document ID# 99062
1997 Chevrolet/Geo Corvette


--------------------------------------------------------------------------------

Draining and Filling Cooling System

Caution
With a pressurized cooling system, the coolant temperature in the radiator can be considerably higher than the boiling point of the solution at atmospheric pressure. Removal of the surge tank cap, while the cooling system is hot and under high pressure, causes the solution to boil instantaneously with explosive force. This will cause the solution to spew out over the engine, the fenders, and the person removing the cap. Serious bodily injury may result.



NOTICE
When adding coolant, it is important that you use GM Goodwrench DEX-COOL® or HAVOLINE® DEX-COOL® coolant. If Coolant other than DEX-COOL® or HAVOLINE® DEX-COOL® is added to the system the engine coolant will require change sooner; at 50 000 km (30,000 mi) or 24 months.



Notice
DO NOT use cooling system seal tabs, or similar compounds, unless otherwise instructed. The use of cooling system seal tabs, or similar compounds, may restrict coolant flow through the passages of the cooling system or the engine components. Restricted coolant flow may cause engine overheating and/or damage to the cooling system or the engine components/assembly.


Drain and Fill Procedure

Important
If the procedure below is not followed a low or high coolant level condition and/or vehicle damage could result.


Park the vehicle on a level surface.
Follow the steps below to remove the radiator surge tank fill cap:
Slowly rotate the cap counterclockwise1/4 turn and then stop. Do not press down..
Allow any residual pressure, indicated by a hissing sound, to be relieved.
After all hissing stops, continue turning counterclockwise to remove the cap.
To tighten the cap, use hand tight pressure only.
Open the radiator drain ****.
Allow the system to drain completely.
Inspect the engine coolant:
Discolored -- follow the flush procedure below.
Normal in appearance -- Continue with the next step.
Close the radiator drain ****.

Important
When filling the cooling system use a 50 to 60 percent concentration with DEX-COOL® coolant.


Fill the system through the surge tank opening.
Fill half the capacity of the system with 100 percent DEX-COOL® coolant.
Slowly add clean drinkable water to the system until the level reaches to the base of the neck.
Start the engine.
Idle engine for 1 minute.
Install surge tank cap.
Cycle the RPM, idle to 3000 in 30 second intervals until engine coolant reaches 99°C (210°F).
Shut off the engine.
Refer to step 3 above to remove the surge tank cap.
Start the engine.
Idle engine for 1 minute and fill surge tank to 1/2 inch above COLD FULL mark on the radiator surge tank.
Install the surge tank cap.
Cycle the RPM, idle to 3000 in 30 second intervals until engine coolant reaches 99°C (210°F).
Shut off the engine.
Top off coolant as necessary, 1/2 inch above FULL COLD mark on the radiator surge tank.
Rinse away any excess coolant from the engine and the compartment.
Inspect the concentration of the coolant.
Flush Procedure

Important
Do not use a chemical flush.


Block the drive wheels.
Place the transmission in Park or Neutral.
Engage the parking brake.
Run the engine until the thermostat opens.
Stop the engine.
Follow the drain and fill procedure using only clean drinkable water repeat if necessary until the fluid is nearly colorless. Refer to the drain and fill procedure.
Fill the cooling system. Refer to the drain and fill procedure.

 

A friend just installed a new water pump, and I think he had to buy a new thermostat separately from the pump because he was commenting on how they did not sell the thermostat without the housing.
You may want to verify that they did not reuse the old thermostat.

 

They couldnt reuse the old thermo, The dealer upgraded to the newer GM 2004 pump. Thermo is seperate from the housing........

 

Im going to try to remove all the air from the system today. I also bought a new cap. I was checking my old one out and the spring in the middle was pretty corroded,may not be enough pressure in system at 196 to keep thermo open........

 

OK guys, Heres what I did. Got all air out of system. put new cap on. Still pretty much does the same thing. During freeway driving temp will reach about 208 and drop back to 192 now insted of 196,and then back up again and back down. So Im gonna assume my old t-stat in my old pump was like a 187 and the t-stat in this punp is like a 197 therefore the 10 degree variance in temp reading. In town at lights it will get up to about 214 and then start to drop.........

 

OK, assuming you did get all the air out of the system ... we're down to only a few choices ....

1) Coolant temp sensor is flakey ... it is giving you invalid readings ...

2) Serpentine belt is slipping ... the water pump is not consistently moving water through the system

3) The new thermostat is flakey

4) The new water pump is flakey

I'd look at the belt first ... if it is showing any signs of cracking or glazing, I'd replace it. Relatively inexpensive, and about a 3 to 5 minute job to do.

Second thing I'd consider is the temp sensor ... since you replaced the pump and thermo ... it seems like the next likely suspect. You can replace it pretty easily, but if you have some way to measure the temperature of the head (one of those IR temp guns) see if the head temp is fluctuating as the gauge claims. Otherwise consider a new temp sensor.

Otherwise it comes down to the water pump or thermo being bad ... the coolant system is pretty simple, these would pretty much have to be the remaining causes.

Good luck, keep us posted .....

 

It has a new belt it was changed when the pump was. I dont think its the temp sensor because, Normally when those go bad they will peg and you will get the overheating bells. It cant be the pump because if it was it wouldnt be pumping water and it would over heat completely or leak allover the place like my old one did. So my guess is as previously stated its just a higher temp t-stat and therefore an increase in temps. It still hasnt gotton hot enough to even kick on the cooling fans.

 

Why not just buy a new thermostat, there under $15 for your car (the one thats not built into the housing) Swap it out its a 10 min change and see what it does then

 

Thermostats are not the most precise devices.

I stand by my original reply...it sounds like the new one is a little off it's nominal rating. Air in the system won't swing the temp in such a controlled fashion, and a bad temp sensor certainly won't either.