Losing coolant

1998 HONDA CIVIC
151,000 MILES • 4 CYL • 4WD • AUTOMATIC
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PMP
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Hi I brang my car to the shop and they pressure tested it and found no leaks under 15lbs of pressure and ran a leak down test and said everything is good. Today I drove about 25 miles and before I left my house the radiator was full on cold engine and after the 25instrument miles the Guage went up a little then went down and I opened the radiator and sure enough it was low again. It doesn't overheat and there no coolant in my oil and no oil in coolant and no white smoke. Where could my coolant be going? Im bringing it back to the shop again tomorrow. Ty
Dec 12, 2011 at 12:46 AM
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RIVERMIKERAT
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Are the floorboards wet? It HAS to be leaking somewhere. Tell them they need to test is to 17PSI with the engine at operating temperature.
Jan 28, 2021 at 9:34 AM
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PMP
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The floorboard is dry ill check it again tonight
Jan 28, 2021 at 9:34 AM
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RIVERMIKERAT
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Ok. Let us know what you find out.
Jan 28, 2021 at 9:34 AM
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PMP
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ok, the floorboard is totally dry. i even used a flashlight and checked everywhere underneth the dash for any drips and saw nothing. i waited till the car was warm and filled the radiator up again right to the top and stood there and watched it get lower and lower. earlier in the day when i did the 25 mile drive some coolant spilled out of the radiator because i had the car running and letting air bubbles out of the cooling system. i drove 25 miles home when i checked this. There was what looked like a leak on the bottom cornor of the radiator with a little coolant on the ground. Now im starting to wonder if its the radiator?
Jan 28, 2021 at 9:34 AM
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RIVERMIKERAT
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That's what it sounds like. The pressure test will tell for sure.
Jan 28, 2021 at 9:34 AM
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PMP
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k the shop called me today its gonna be 270 and hes getting all the parts from honda.

Upper radiator hose.
some piece on the black that connects to the upper radiator hose. What is this piece called?
heater control valve
heater control valve hose
Jan 28, 2021 at 9:34 AM
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RIVERMIKERAT
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Upper radiator hose to block is most likely the thermostat housing. All of these items are things you can do yourself, and save a significant amount of money. The hoses and control valve are 2 clamps each; the valve is secured to the bulkhead by 2 bolts. The thermostat housing is secured to the engine by 2 bolts also. Remove those 2 bolts and pull the housing off the engine. Clean both sides with a wire brush or scraper, use gasket sealant on both sides, replace the thermostat, and reinstall the bolts. Make sure you pay attention to thermostat orientation. A $20 investment in a Haynes or Chiltons manual (from a store like Pep Boys, Advanced, or Autozone) will give you detailed instructions with pictures.
Jan 28, 2021 at 9:34 AM
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PMP
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i got the car back today and everything is good except for one more problem now. The coolant is leaking from under the cap. i replaced the cap about 2 months ago from one from auto zone. When i put my ear next to the cap i hear a sizzling and air sound. How can the cap just start leaking? what do i do now
Jan 28, 2021 at 9:34 AM
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RIVERMIKERAT
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Let it cool. Remove it. And see if there is any grit or foreign objects on the radiator filler neck, or on or under the gasket on the cap. If these are all clean, check to see if the cap or filler neck is dented.
Jan 28, 2021 at 9:34 AM
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PMP
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well it cant be dented its a plastic radiator. The cap looks the same as it did before. I drove it to advance auto earlier and opened the hood 5-10 mins later and i opened the cap and it had no pressure in it.
Jan 28, 2021 at 9:34 AM
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RIVERMIKERAT
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How long of a drive was it to Advanced?
Jan 28, 2021 at 9:34 AM
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PMP
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I drove for about 10-15 minutes
Jan 28, 2021 at 9:34 AM
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RIVERMIKERAT
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That isn't long enough to build up much pressure. Advanced ought to be able to pressure test the cap for you. The radiator filler neck may not be able to be dented, but plastic can be chipped or gouged.
Jan 28, 2021 at 9:34 AM
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PMP
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The radiator looked good to me but is it possible they damaged the filler neck just by pressure testing?
Jan 28, 2021 at 9:34 AM
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PMP
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Will they be able to fix this
Jan 28, 2021 at 9:34 AM
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RIVERMIKERAT
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Not if they knew what they were doing. If the mating surface is damaged, you should be able to use a very fine sandpaper to smooth it out. If the neck is cracked, a good waterproof epoxy will patch it.
Jan 28, 2021 at 9:34 AM
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PMP
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well i went back on the highway today and drove 25 miles and i got off and it did the same thing again. and i checked the radiator and it was really low this time. it was good all week. im bringing it back to the shop tomorrow. im sick of this ****box already im ready to dump it. every week its in the shop. what do i do now
Jan 28, 2021 at 9:34 AM
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RIVERMIKERAT
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If you have the time, stand by your car as they are looking at it and working on it. Check the gasket on the cap. Make sure there are no rips or tears in it. Again. Is it a pressure vent release safety cap or no? Also, make sure it's the right size. Not oversize.
Jan 28, 2021 at 9:34 AM
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PMP
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Its a brand new cap and the right cap and there is no safety thing.on.it
Jan 28, 2021 at 9:34 AM
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RIVERMIKERAT
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Hmmm. Have you had it pressure tested yet? The cap? And the cap is where you believe the leak is coming from, right? Might it be the filler neck?
Jan 28, 2021 at 9:34 AM
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PMP
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I see no coolant anywhere on the radiator and the cap isn't leaking now I replaced it
Jan 28, 2021 at 9:34 AM
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RIVERMIKERAT
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Ok. So everything is resolved?
Jan 28, 2021 at 9:34 AM
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PMP
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No im having the same problem it was hood all week around town I drive prolly 200can't miles then I went on the highway and got off and the Guage went up a little and really.didn't come down and then I pulled over and filled it up and it was good the radiator was really low
Jan 28, 2021 at 9:34 AM
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RIVERMIKERAT
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I'm stumped. I'm going to ask one of my colleagues to peek in and see what he things.
Jan 28, 2021 at 9:34 AM
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SATURNTECH9
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So if you pressure test it there is no visual leaks correct?If there isnt then i want you to go to auto zone rent whats called a chemical head gasket tester.The rental is free with a returnable deposit you just have to purchase the chemical for it.It comes with basic instructions to operate it let me know what you find there.If its negative then i want you to go buy some coolant leak dye to add to the system then add it.Get a dye light when the coolant goes low and track your leak down with the dye light.Let me know what you find.
Jan 28, 2021 at 9:34 AM
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RIVERMIKERAT
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Why didn't I think of those?
Jan 28, 2021 at 9:34 AM
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SATURNTECH9
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You were probably just thinking way too hard about the problem.
Jan 28, 2021 at 9:34 AM
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RIVERMIKERAT
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Probably.
Jan 28, 2021 at 9:34 AM
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PMP
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Ok they said the car held.20 lbs for 30the mind and the only thing he found no was the radiator cap is not sitting right because the top of the radiator and not in good shape so the radiator isn't transferring coolant to the resivor and back he said its only 250 labor and part. He said that's the only thing it could be
Jan 28, 2021 at 9:34 AM
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SATURNTECH9
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So what part is he saying to actually replace?Also what is your zip code so i can make sure thats a good price.
Jan 28, 2021 at 9:34 AM
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PMP
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The radiator and cap. He said the filler neck os basically worn and the cap is not sitting right and leaking
Jan 28, 2021 at 9:34 AM
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SATURNTECH9
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So is that 250 just for labor?Or is that with the part?
Jan 28, 2021 at 9:34 AM
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PMP
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Both
Jan 28, 2021 at 9:34 AM
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RIVERMIKERAT
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Radiator, cap, coolant and labor. That doesn't sound too terrible to me.
Near me, the radiator averages about $80. The cap between $5 and $10. Antifreeze/coolant averages about $15. Labor should be about an hour, so call it $100. Then add tax.
Jan 28, 2021 at 9:34 AM
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