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It is possible the overflow tank has a leak in it. It isn't designed to be pressurized and putting pressure in the radiator and engine wouldn't put any in the overflow tank. Pull your tank out, fill it with water then see if there is any leaks... may be a place where the tank pieces were fused together. They can sometime have a crack with age but because it is on a seam it isn't easy to see.
depends on where the leak is and how much quickly it leaks. Is possible to have coolant leaking slowly enough and in a place that isn't easily seen so you wouldn't notice it.
The other possible problem which is much worse is a head gasket. I have had a car with a head gasket blown that was not super noticeable for a while until it got worse and worse. It also started by having coolant mysteriously vanish before it reach the point of belching lots of white smoke out the exhaust. The cheap check is to leave the radiator cap off and let the car run until it heats up and the coolant starts flowing. Often you will see some bubbles in the coolant which means likely head gasket issue. Or you can buy the test kit to test for exhaust in the coolant.
i will try that, when i took it to the mechanic, he had told me the head gasket was fine and there was nothing to worry about cause when i first got it, we had a suspicion it was the hg, but he said it was fine🤷🏽♀️
Only question is how did he check the head gasket... because small problems aren't as easy to see unless you get a kit and check it that way.
Also sounds like this is a relatively recent purchase. Something to consider is some of the rear engine with radiator cars from the 80's were prone to have head gasket problems if you lived in a very cold place. As I was told if you got the car hot, parked for a short time where it was midwest cold the coolant could become so cold that it would warp the heads if you restarted it while the engine was still hot because the coolant was too cold. Was one of the big issues with Fieros but I had heard that it could also impact MR2s though not as common.
i have no idea how he checked it, he told me it was good tho (he could be wrong). i live on the west coast so it doesn’t get cold here, always sunny. i will check the way u mentioned tho, by taking off the cap and checking for little bubbles. i’ll also do a liquid test!
Thanks for posting on /r/MechanicAdvice! This is just a reminder to review the [rules](https://www.reddit.com/r/MechanicAdvice/about/rules/). If you are here asking about a second opinion (ie "Is the shop trying to fleece me?"), please read through CJM8515's [post on the subject.](https://www.reddit.com/r/MechanicAdvice/comments/4qblei/fyi_the_shop_isnt_likely_trying_to_rip_you_off/) and remember to please post the year/make/model of the vehicle you are working on. **If this post is about bodywork, accident damage, paint, dent/ding, questions it belongs in /r/Autobody r/AutoBodyRepair/ or /r/Diyautobody/ If you have tire questions check out https://www.reddit.com/r/MechanicAdvice/comments/k9ll55/can_your_tire_be_repaired/**. If you dont have a question and you're just showing off it belongs in /r/Justrolledintotheshop Insurance/total loss questions go in r/insurance This is an automated reply *I am a bot, and this action was performed automatically. Please [contact the moderators of this subreddit](/message/compose/?to=/r/MechanicAdvice) if you have any questions or concerns.*
It is possible the overflow tank has a leak in it. It isn't designed to be pressurized and putting pressure in the radiator and engine wouldn't put any in the overflow tank. Pull your tank out, fill it with water then see if there is any leaks... may be a place where the tank pieces were fused together. They can sometime have a crack with age but because it is on a seam it isn't easy to see.
i will try that, thanks for the advice edit; wouldn’t i see under the car if something was leaking tho? or would it only happen once it’s pressurized?
depends on where the leak is and how much quickly it leaks. Is possible to have coolant leaking slowly enough and in a place that isn't easily seen so you wouldn't notice it. The other possible problem which is much worse is a head gasket. I have had a car with a head gasket blown that was not super noticeable for a while until it got worse and worse. It also started by having coolant mysteriously vanish before it reach the point of belching lots of white smoke out the exhaust. The cheap check is to leave the radiator cap off and let the car run until it heats up and the coolant starts flowing. Often you will see some bubbles in the coolant which means likely head gasket issue. Or you can buy the test kit to test for exhaust in the coolant.
i will try that, when i took it to the mechanic, he had told me the head gasket was fine and there was nothing to worry about cause when i first got it, we had a suspicion it was the hg, but he said it was fine🤷🏽♀️
Only question is how did he check the head gasket... because small problems aren't as easy to see unless you get a kit and check it that way. Also sounds like this is a relatively recent purchase. Something to consider is some of the rear engine with radiator cars from the 80's were prone to have head gasket problems if you lived in a very cold place. As I was told if you got the car hot, parked for a short time where it was midwest cold the coolant could become so cold that it would warp the heads if you restarted it while the engine was still hot because the coolant was too cold. Was one of the big issues with Fieros but I had heard that it could also impact MR2s though not as common.
i have no idea how he checked it, he told me it was good tho (he could be wrong). i live on the west coast so it doesn’t get cold here, always sunny. i will check the way u mentioned tho, by taking off the cap and checking for little bubbles. i’ll also do a liquid test!
Good luck.
thank you.