Hounddogjake

All of a sudden my 2004 Vert starting over heating yesterday. New water pump installed last summer and no appearant leaks anyware,belt is good and fans working. First thought is thermostat sticking and or low fluid, any other ideas before I start on this thing today. Mileage 105,000. What size thermostat is recommended?

Grandpa1

Radiator sucked something on it and got itself blocked?

Hounddogjake

Possible,since it happened so quickly, didn’t have a chance to check anything last night. Thxks

JR-01

Definitely the very first thing to check.

Road Runner

I would also check the surge tank for pressure leaks. The tanks tend to have problems, loose pressure which will result in over heating.

knewblewkorvette

I agree with others, check the front side of your radiator. But I must ask, what do you consider overheating?
Caution, do not open surge tank went hot, it can instantly boil over. So I've been told

Vetteman Jack

Moved to C5 Tech.

Bill Curlee

What makes you believe that the car is overheating? Its a weird question but we have to ask. Anything up to 235, isn't out of the box! It should usually runs (with a stock stat) around 210. Just need to know some more about your indications. Higher in traffic and higher if its HOT out!

YES,,, Check the front of the car and look for obvious blockages. There's more to radiator air flow that just the front air inlet. There is also a space BETWEEN the AC Condenser & the radiator that can and will get clogged. If its clogged, air will not flow through the radiator. The space needs to be inspected and cleaned . Pull the air bridge and then the top plastic cover and look at that space. You should also use a garden hose to back flush the radiator to get any sand and dirt out of the radiator fins.

After air flow, you need to check the pressure holding capability of the system. Do the hoses get tight once the engine gets to full operating temp? There is a NEW UP-DATED 18 pound reservoir pressure cap. It replaces the old 15 lb cap. I highly recommend that you get that new cap even if it doesn't solve the issue.

BLEEDING THE SYSTEM: I would make sure that the engine block is completely FULL of coolant. There is a head steam vent crossover tube at the front of the head on the front of each cylinder head. Its secured in place with a single fastener. LOOSEN (do not remove) the fastener and see if you get any air venting out of the fitting. If you have a good dribble of coolant, you can be sure that the engine block is full of coolant.

THERMOSTAT: If all of the above check out, I would change the stat.. USE DEXCOOL and distilled water to get your proper freeze/boil over protection point dilution. I have a 180 degree stat but, the stock stat will work fine. If you have High HP mods, you may want to consider getting a 180 deg stat and having the cooling fans reprogrammed to come on sooner and run longer. If the car is stock, the standard stat should work fine.

FANS; Are your cooling fans working properly?? When the engine is at normal operating temp does the drivers side fan run, and IF, you turn on the AC, does the passengers fan turn on??

DO you have any DTCs??

Hounddogjake

Thanks for the detailed reply. By hot I mean the gauge pegs in the red and the check gauges light comes on. I did find the top 20% of the radiator had considerable debris packed under the plastic cover. After cleaning this out the car ran at 3/4 on the gauge but did not go into the red. I’m going to back flushing the radiator with water as I’m sure there is stuff I can reach or see. I was not aware of how the fans work so I’ll check that also,although they were running when the gauge was at 3/4. The car is in Florida but this happened during some pleasant 70 degree weather. I called the mechanic that installed the water pump last year and although he didn’t have the paperwork handy he said most time the water pump kits come with with a new thermostat,

knewblewkorvette

Ooo, red is bad. 3/4 up in 70 degree weather isn't good either. But, the DIC is your friend, it will tell you exactly what your temperature is. I wonder if it was burped proper after the water pump install?

73Corvette

It sounds worse than it really is...
TAKE THE RADIATOR OUT TO CLEAN IT!!!
You'll be amazed at what you'll find...

Hounddogjake

Hope to avoid that

Hounddogjake

Not sure about the water pump install, it was done by a very reliable shop last summer. This car get driven most every day with no problems. This over heating just started coming home one afternoon. The weather has been quite mild in the low 70’s

runner140*

Take 15 minutes and take the radiator out. While its out, clean the A/C.

Spaggs

Make sure you use distilled water, not tap water. The fewer unwanted minerals in the system, the better.
Spaggs

runner140*

The cheap and easiest first...change your pressure cap AND check to see if you got an air bubble in the system. Time to reburp the system.

mmartinez

Since your not sure if the thermostat got changed when your water pump was installed last summer, I would go ahead and replace it. Sudden overheating to me indicates that it's not just a clogged radiator which would have caused higher temps gradually over time. You did not mention under what driving conditions the car overheats, as that can help diagnose your overheating problem. If overheating is occurring at highway speeds then that rules out your fans as they are turned off at a certain speed.

JR-01

.....or always use the prediluted 50/50 mix. You don't have to guess what mixture you have.

Hounddogjake

I’ve been working on this problem as time permits and it’s better but still not quite right. I cleaned the debri from the top of the radiator between the air conditioner coil and the rad. The fans seem to working as described by another member on this link. Yesterday I replaced the thermostat. The old thermostat looked relatively new and I would say it was installed last summer when the new water pump was installed. The new I noticed the new stat had 3 holes in the bottom that the old one did not. I also did the 18lb cap.

Right now now the car will heat to the 3/4 mark on the gauge and then go back to the center(220). As you pick up speed the temp goes back to 3/4 and as you slow dow and even stop in traffic the needle goes back to around 220-230. I have run the car with and without the air conditioner and it doesn’t seem to make any difference.

When the engine is cold,how much antifreeze should be in the expansion tank and can some buddy give me a link to how to burp the system ?

any other suggestions would be greatly appreciated

69

If you are certain that you have no air in the cooling system, then I recommend the following approach;
You will need to determine if you truly have an overheating issue OR a Temp Gauge Indication Issue.
Your can purchase a Infrared Laser Thermometer very cheep at your local HF tool store (don't forget to get and use your 20% off coupon) and you can use this tool to determine actual temps on the various cooling system components.
Start the car, let it warm up and start to laser the water pump/hoses/surge tank to determine if in fact the Temp Gauge is operating correctly by comparing the laser temps to the temp gauge.
Upon gathering this info, you will have a better idea on the direction to solve the issue (Temp Bulb Sensor Drift?) that may be be giving the Temp Gauge bad readings?

Infrared Laser Thermometer
Cheers,
Goose