I have a 2007 Prius. I bought it knowing it had a bad head gasket (previous owner told me). It drove fine, no signs of blown head gasket. I figured I'd wait until it started showing some signs of a blown head gasket. We drove it for about a year. Then, I think it threw a rod and left my wife stranded in rural Idaho about three hours from our home. She had it towed to a small town that had a decent-sized repair shop. They replaced the engine with a used engine with about 120,000 miles on it. Since then, the car slowly loses coolant, very likely because air bubbles keep gurgling out of the radiator (maybe one large bubble every ten seconds). No obvious leaks. I tried bleeding and burping it for over an hour. Bubbles still came out of the radiator. I have taken it to two different mechanics to see if the head gasket in the newer engine is bad, but both said the head gasket is fine (compression tests, etc.). Anyone have any thoughts on why air bubbles might be coming out of the radiator (and creating pressure that then pushes coolant out through the overflow tank)? Thanks so much for any help you can provide
When the coolant was poured in, the car was not level, and some parts had air left in them. The coolant circulates, captures these bubbles and delivers them to the radiator. Have you checked the coolant level? There should be a drop in the level.
Your engine is a big air pump It's a big air compressor suck bang and blow. If there are leaks between the cylinder head and the pistons going up and down and all of that air combustion air can get pumped my newly or quite a bit into the water jacket this will help you see bubbles usually the bubbles are finer they're not one big bubble every couple seconds usually there are a lot of little tiny bubbles If you're getting a big gulp every so often almost bursting out of the radiator top and then down onto the floor in the plastics and the bottom of the underhood of the car then it seems like you have a good belching going on usually you can put your hand over the radiator if everything's not gotten too hot yet and you can feel the compression pumping up against your hand as the car engine turns over in a Prius this is hard to do because the engines always trying to shut off You can get the little bottle of green nonsense it connects to the top of the radiator and you just turn the car on and it turns blue or green or whatever color and indicates exhaust gas in the coolant end the discussion. There are other ways to do this with an air compressor too blowing air into the hole and all that stuff but generally no one needs to be doing all this they're not under those hillbilly type requirements. Head gaskets on generation twos are pretty rare but any engine can develop a head gasket leak from poor maintenance low coolant clogged EGR hotspots whatever depending upon what equipment the vehicle and engine has.
It could be a bad water pump. You might not be getting the right amount of coolant flow through the engine to cool it properly, and the coolant is boiling in the engine and forces coolant out into the overflow tank.
your mechanics don't do any sh*t on your car, do they know how to work on hybrids? did you try renting a pressure tester from the parts store? that will verify if you a coolant leak somewhere and after doing the pressure test check the oil, the leaking coolant will mix with oil if you have a head gasket problem.
The compression test is not enough and a leak down test should be performed to verify a blown head gasket or other leak. If the head gasket is confirmed to be good, I would suspect a cylinder head crack that opens up more when hot. Do you see a larger air bubble initially when the thermostat opens?
If I suspect that there's a head gasket problem, I use a pressure tester on the radiator (to 15psi) and leave it pressurized overnight. The next day I remove the spark plugs and look in the cylinders with a videoscope. Posted via the PriusChat mobile app.
Yeah I've got to buy me one of those cameras that can flip back up and look at the upper surface and all that Just haven't got around to it because it's so rare that I have to fool with this If I think that that's going on I just rip the head and the timing cover off and get it taken care of I've got an '09 right now that it looks like that's going to be the end-all be all I don't need the camera to look at nothing anything whatever It's right at 400,000 mi I would expect there ought to be a head gasket leak by now in any Toyota engine for the most part so actually finding a remanufactured head and stuff reasonable even for the one NZ is proving to be kind of silly so I may just take a low mileage takeout the one NZ is a solid engine so I don't expect problems like the ZZ or the ZFX or whatever the heck you guys want to call it those are just problematic you know or enough of them are that it makes me nervous and I don't want to fool with them. Like to get a scope too. But at this stage of the game maybe not I'd like to get a scope I could use on other things besides just automobileia.
