So my car started overheating severely...hitting as high as 280 quickly before I was able to safely stop the engine. Then of course it went up a little higher. I took my '86 to a Chevy dealer and informed them of my problem. They found and fixed a leak and replaced the radiator. But they told me my cooling fan was not working. Well, they fixed the fan and it now works, and the car stayed between 180 and 240 for about a week. Well, it started overheating again, but now it just takes a little while longer to get to the higher temperatures. My overflow reservoir was pretty badly beaten up, so I replaced that thinking they're may have been a leak there. I filled the overflow reservoir to the "Cold" line. The next morning, the overflow reservoir was empty and the car was slowly overheating again.

Anything else I need to check? Maybe use some sort of leak fixer?

 

If you dont see a visible leak, I would not use any stop leak in it. The overflow may have been empty because there was air in the system. Top it off again and drive it more. If the over flow is empty, I would fill it up over the cold almost to the top and drive it. first eliminate the simple of having air in the system.

 

DO NOT put anything like that in your system.

As a matter of fact, I'd be suspect of what "Dealer" place in my radiator (not saying they are the cause of your original problem)

What is occurring is your water pump is slowly dying on you. I'll bet if you took a small mirror and held it under the pump you would see where the weep hole has been allowing small amounts of coolant to drip out.

Ask yourself if you seen a small puddle of fluid under your car that you really couldn't identify as anything other than "Water".....thinking to yourself it came from the A/C condensation

One day, you'll find a river of coolant and then you'll know for sure it is the WP dying on you.

As far as putting things in your radiator, if you have a new one, you are half way to curing your problem

Due to "scaling" or "fouling"........

http://en.wikipedia.org/wiki/Fouling

.......I suggest that you only use Deionized or Distilled water found at the grocery store. Tap water is full of minerals that will foul up that new radiator.

 

are they any small things I could do before I decide to get the water pump replaced?

 

For the age of the car and amount of money it costs, just replace the water pump without having to worry about it failing on you someplace in convenient.

Air in the system could be a culprit, the system may need to be burped so to speak. When I would refill a cooling system, I would fill up the radiator, start the car with the cap off, turn the heater on, rev the engine and watch the coolant level go down as a friend topped it off until the coolant level was almost at the top close to the neck, then let the engine idle and let the excess come to the top, spill and then replace the cap. I found the least amount of air problems that way.

 

^^That is standard procedure for filling any radiator.

You have to wait for the thermostat to first open on it's own....then when the cool water hits it, it closes again.....then you wait for the flow to begin again....only after two or three times as you keep filling it, will it be actually full.

Use Distilled water.

 

Yup, forgot the thermostat part. Distilled water does make the difference believe it or not.

I've seen so many service stations not refill a cooling system properly and it blows my mind. They just pour in anti-freeze and send the customer on their way.

 

Distilled water for two reasons.

1) Scaling (as the wiki link describes)
2) Electrolysis

http://en.wikipedia.org/wiki/Electrolysis

So, you have a DC power supply (your battery) running current through your coolant system (no way to avoid it as you use your block as a ground).

Tap water has tons of particulate in it which makes it a great conductor.....The more "Stuff" in the water the better it conducts....

Pure water is NOT conductive.....

So, if you use tap water, you are adding in super conductive water into your system then you add 12vdc and behold!! You've made yourself a electrolysis tank. Now whether your system deposits or erodes metal (i.e. head gasket material) has yet to be determined by me......but have fun on your own discovering what is being dissolved over the years. lol....

Or just use distilled water and avoid the Electrolysis as much as possible.

 

you think I should just inspect and maybe replace the thermostat first?

 

Thermostats usually work or they don't.....When they don't work, they usually stick.

If you'd like you can do it....but if you crack the thermo housing you might as well replace the old one.....they are too cheap to put back in the motor. You are having cooling issues, might as well replace disposables when they are in your hands

 

It's possible the cooling system was not "burped" after the new radiator/coolant replacement. There is a small screw on the thermostat housing for this exact purpose.

When the system is cool, remove the rubber acordion air intake unit, stuff some towels around the water pump and thermostat housings to prevent any moisture from getting to the optispark unit. Then carefully remove this brass screw. (it's on the highest point of the thermostat housing) If coolant doesn't show itself, gently squeeze the upper radiator hose. This should push fluid out the hole. If it does not, you have an air pocket in the sysyem.

Add coolant to the expansion tank and start the engine. As the engine warms up and the water pump circulates coolant, it should begin to push coolant out the thermostat housing hole. You can help the burping process by gently squeezing the uppoer radiator hose until coolant comes out the hole. When this happens, shut off the engine and replace the brass screw. Replace any coolant lost from the expansion tank, dry off everything in sight, and you should be good.

Sometimes, this whole process is helped by running the car up onto ramps (like when you're changing oil) This ensures that your vent hole (with the little brass screw) is now at the highest point of the car.

Hope this helps.

 

L98's (especially the ones with the alluminum heads) are very prone to head gasket failure. Take the car to a radiator shop for gas testing, and run a compression test. Hopefully it will just be air in the system, but if you are losing water, it has to be going somewhere. If you catch it before it gets worse, you'll save yourself a lot of money.

 

No sh*t, that dealer must be full of great mechanics.

 

The dealer shoulda done this as well if you said you were having overheating issues. As a diagnostic. Maybe before they replaced the radiator. I dunno, call me old fashion but........

 

If you burped it properly and coolant level is dropping and not into the resevoir then you have a leak.

If not try replacing the T-stat and radiator cap. My '88 IROC-Z had a split radiator tank and overheated, so I replaced radiator & T-stat but it still overheated when in traffic. Finally I found that the radiator cap would not hold any pressure; replaced the cap and all is now well.