coolant questions

klseiverdSeptember 25, 2011

Fairly diligent about things like oil changes in my 04 Sante Fe. When done, fluids are checked and topped off. Other than that, only time I open hood is to add windshield washer solution and periodically check oil level... especially if I plan to be driving longer distance than normal.

Had a little "hic-cup" last week?? Was heading to teach night GED class on Thursday. Fairly warm and sticky/humid weather, so AC was on. Not a long drive... maybe 10-15 miles. Along the way, thought... AC isn't REAL cold?? Kinda went into Scarlett O'Hara mode... I'll think about that tomorrow. Then noticed temp guage was higher than usual. Has always just sat right at the half way point, but it went to about the 3/4 mark?? Didn't overheat and shortly after AC was COLD again and needle went back to normal position. This didn't happen on the ride home.

On Friday, bought a jug of coolant. Amount in reservoir under hood was... pretty much nothing, so I filled it up today before a drive of about 40 minutes. At about 30 minutes, needle rose but quickly went back to normal.

Should I just check & top off reservoir and dump rest in radiator... or should I be worried??

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jemdandy

Your vehicle is apparently low on coolant and you don't know how low. Since you saw very little in the bottom of the overflow bottle, probably much air has entered the coolant system. There are two ways to effect a fill: 1) add directly through the radiator fill cap and top off the bottle, or 2) add fluid only to the overflow bottle.

First, you should know how the closed system works. When the cooling system is completly full with no air, the fluid expands on heating until the pressure overcomes the spring loaded valve in the fill cap. Fluid runs out to the overflow bottle.

On cooling, the pressure lowers in the system until a small vaccuum develops and begins to draw fluid back from the bottle. (In addition to the pressure valve in the fill cap, there is a one way valve that allows easy flow of coolant back into the system. That is, if you have the proper cap.) When hot, there should be sufficient fluid in the bottle to refill the system when it cools. In this way, no new air is admitted and no new oxygen gets in. Oxidation is the main culprit for creating crud in the cooling system.

If the bottle runs low on fluid, new air gets drawn back into the sytem defeating the purpose of the design. Also, one can not know how low on fluid the system is; you can only see the residual in the bottle.

For your case, I recommend procedure #1:

Wait until the engine has completely cooled, like sat overnight. Open the fill cap and add coolant until full. Close the cap and top off the overflow bottle to a little above the "cold" line. Start the engine and allow to warm up. Watch the overflow bottle. As the engine comes up to temperature, if you see considerable amount of bubbles comming out, you know that there was still air in the system. After the engine comes up to temperature, check the overflow bottle and add fluid to fill at or slighty above the "hot" line. Stop the engine and allow it to cool. Fluid should be drawn from the bottle back into the cooling system. If not, there is a leak somewhere, probably between the bottle and the fill cap or the fill cap itself. If all goes well, watch the fluid level in the bottle and add fluid as necesary.
**************

Method 2:

With with the engine cold, add fluid to slightly above the "cold" mark on the bottle. Start the engine and allow to warm. When the engine comes up to temperature, fill the bottle to or slightly above the "hot" line. Stop the enigine and allow to cool. Fluid should be sucked out of the bottle. As the fluid recedes, add fluid (to the bottle) to prevent it from going below the "cold" line.

Perform the heating-cooling cycle until the fluid level in the bottle stabalizes and no more air burps out of the system on heating. It may take 2 to 3 cycles to completly burp the system depending on how low it was.
***********

Method #1 is recommended over method #2 in case the system is very low on fluid.

About that fluid you bought:

Antifreeze comes in two varieties and the containers look very much alike. In one case, the jug has 100% antifreeze and in the other case, it is diluted with water. The diluted one is intended for use as is. Its freezing poiunt should be on the container. The 100% stuff should be diluted before use. For most of the USA, the dilution is about 50-50 antifreeze to water. There should be information on the container that shows the freezing points at various dilutions.

Most antifreezes have silicates added. I recommend the non-silicate type - Its more expensive but is easier on water pump seals. I have not had a water pump seal failure since I've switched to the non-silicate type.

    Bookmark   October 1, 2011 at 6:59PM
Thank you for reporting this comment. Undo
jemdandy

Your vehicle is apparently low on coolant and you don't know how low. Since you saw very little in the bottom of the overflow bottle, probably much air has entered the coolant system. There are two ways to effect a fill: 1) add directly through the radiator fill cap and top off the bottle, or 2) add fluid only to the overflow bottle.

First, you should know how the closed system works. When the cooling system is completly full with no air, the fluid expands on heating until the pressure overcomes the spring loaded valve in the fill cap. Fluid runs out to the overflow bottle.

On cooling, the pressure lowers in the system until a small vaccuum develops and begins to draw fluid back from the bottle. (In addition to the pressure valve in the fill cap, there is a one way valve that allows easy flow of coolant back into the system. That is, if you have the proper cap.) When hot, there should be sufficient fluid in the bottle to refill the system when it cools. In this way, no new air is admitted and no new oxygen gets in. Oxidation is the main culprit for creating crud in the cooling system.

If the bottle runs low on fluid, new air gets drawn back into the sytem defeating the purpose of the design. Also, one can not know how low on fluid the system is; you can only see the residual in the bottle.

For your case, I recommend procedure #1:

Wait until the engine has completely cooled, like sat overnight. Open the fill cap and add coolant until full. Close the cap and top off the overflow bottle to a little above the "cold" line. Start the engine and allow to warm up. Watch the overflow bottle. As the engine comes up to temperature, if you see considerable amount of bubbles comming out, you know that there was still air in the system. After the engine comes up to temperature, check the overflow bottle and add fluid to fill at or slighty above the "hot" line. Stop the engine and allow it to cool. Fluid should be drawn from the bottle back into the cooling system. If not, there is a leak somewhere, probably between the bottle and the fill cap or the fill cap itself. If all goes well, watch the fluid level in the bottle and add fluid as necesary.
**************

Method 2:

With with the engine cold, add fluid to slightly above the "cold" mark on the bottle. Start the engine and allow to warm. When the engine comes up to temperature, fill the bottle to or slightly above the "hot" line. Stop the enigine and allow to cool. Fluid should be sucked out of the bottle. As the fluid recedes, add fluid (to the bottle) to prevent it from going below the "cold" line.

Perform the heating-cooling cycle until the fluid level in the bottle stabalizes and no more air burps out of the system on heating. It may take 2 to 3 cycles to completly burp the system depending on how low it was.
***********

Method #1 is recommended over method #2 in case the system is very low on fluid.

About that fluid you bought:

Antifreeze comes in two varieties and the containers look very much alike. In one case, the jug has 100% antifreeze and in the other case, it is diluted with water. The diluted one is intended for use as is. Its freezing poiunt should be on the container. The 100% stuff should be diluted before use. For most of the USA, the dilution is about 50-50 antifreeze to water. There should be information on the container that shows the freezing points at various dilutions.

Most antifreezes have silicates added. I recommend the non-silicate type - Its more expensive but is easier on water pump seals. I have not had a water pump seal failure since I've switched to the non-silicate type.

    Bookmark   October 1, 2011 at 7:00PM
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