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What Are The Symptoms Of A Blown Head Gasket?

16 posts in this topic

i have posted several threads trying to diagnose my car lol but to no avail i have yet to determine the cuase . i will do a pressure test but i am still curious about thius becuase i have never had a blown head gasket so i am not sure what to look for other then water in the oil or vica versa . my oil is fine but about a month beforew my car quit it was running funny sio i checked the oil and it had none so i am a little unsure . the engine sat for a year before i put it in my car .

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i also noticed alot of white smoke from the exhaust on start ups but not while driving ?????????

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There's a thread here about exhaust smoke colors & troubleshooting.

Blue smoke:

Burning oil. If blue smoke comes out only durning start up (maybe a few minutes after start) valve guides/seals are the most likely culprit. If blue smoke continues to appear, oil is making it's way into the combustion chamber. Could be valve guides/seals, spark plug tubes, anything where oil is on the other side.

Black smoke:

Unburnt fuel entering the exhaust system and being burned off. Also called running rich.

White smoke:

Water vapor. Common upon start up for most vehicles due to condensation burning off (think winter time, starting the car, you have water vapor). If you continue to have white smoke (steam/water vapor) then you're burning water (aka Coolant). You can smell it and it would have a sweet smell (don't sit there and suck fumes though, bad idea). Coolant is making it from the water jackets into the combustion chambers. High chance of this fault is from the head gasket, however cracked blocks/heads have been known to cause this issue as well.

Run a compression test on the motor. Ideal compression test is whenthe motor is at NOT. Once at normal operating temp, turn the motor offf. Remove EFI fuses and disconnect power to the fuel pump. Make SURE the car will not start. Remove #1 cylinder spark plug, install compression tester. Crank for 5 seconds, take reading. Remove tester, reinstall spark plug, repeat steps with #2 cylinder and so on. All cylinders should be within 10% of each other (I think).

Also you can buy a coolant test kit that tests the coolant for presence of exhaust fumes. Another good indicator that your HG is blown.

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You can, but you won't get the same readings. Pop the oil cap and look in there and on the inside of the cap. If it looks like chocolate milk, that's a bad sign. Pop the radiator cap and if there's oil in there, that's a bad sign. Both would indicate a blown HG.

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Look for oil in the coolant, coolant in the oil, burning oil in the combustion chamber, burning coolant in the combustion chamber. All indicate a leaking aka "blown" head gasket.

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well i have got some weird funky looking stuff in my anti freeze so i am thinking a cracked head or hg . the thing that gets me is the car will barely run i always thoiught they ran with a blown hg it wont rev about a 1000 rpms floored . unless i am losing alot of compression

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You can still do a cold compression test. It won't give you accurate numbers that a NOT test would, but if you get 120-120-50-120 you know you have an issue with your #3 cylinder. You can still pick up a exhaust gas tester kit for your coolant and that'll tell you quickly as well.

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would a blown head gasket do that ?? make to where my car will not rev past a certtain point like a 1000 rpm

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If your engine will not rev past a certain point it could be a totally plugged catalytic converter. A bad head gasket could have brought this on, I suppose it couldn't have helped to blow antifreeze through your cat. converter.

We had a car that had a cat failure. It was weird, couldn't get it to rev past 2500 rpm. It felt constipated. And that turned out to be the case.

Usually if you have a bad head gasket or cracked head the engine will overheat in short order. Another sign is if it fills the coolant overflow tank completely.

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i had taken the cat off and it didnt make a difference i dont know this is really starting to bug me i have never had this issue before so i really do not know what i am trying to look for .

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lmao i would scrap it first hahahaha its not worth the time and effort i have put into the car but hey thanks all for your input :biggrin:

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So why do you keep trying to bring it back?

Have you done a compression test or coolant test to check for exhaust gas? Those two would tell you right away if your problem is due to a head gasket.

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lol i love my mazda just at wits end lol . i will try both those shortly i dont have either thing for the the tests. but thats next on my list i thought mabye might have had the same problem . that could help me trouble shoot .

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  1. well here is a new development i took my maf sensor off and plugged in the original and it fired up and ran like a champ then it died again ??????? lol i was also low on gas so mabye its a issue with fuel /air ratio uggghh . i bought a new maf sensor and no change in perfomance and yes i reset the computer . i am wandering if its not electrical

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