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JOHN aka Eauto
JOHN aka Eauto, The Car Guy
Category: Chevy
Satisfied Customers: 15841
Experience:  ase tech
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99 blazer overheating, i have replaced the thermostat, water

Customer Question

99 blazer overheating, i have replaced the thermostat, water pump radiator, and heating core. it runs about 200 degrees and overheats with hard driving and ac use its about 90 degrees here during the day. i noiticed water leaking passenger side right behind front wheel
Submitted: 1 year ago.
Category: Chevy
Expert:  JOHN aka Eauto replied 1 year ago.

is the fan clutch working?

Customer: replied 1 year ago.
Fan is working.yes
Expert:  JOHN aka Eauto replied 1 year ago.

this has a 305 or 350?

Customer: replied 1 year ago.
4.3l v6
Expert:  JOHN aka Eauto replied 1 year ago.

so s a s 10 blazer?

Customer: replied 1 year ago.
99 chevy blazer 4wd 4 door. i thought i put in this information when i filled out the form ....
Expert:  JOHN aka Eauto replied 1 year ago.

you said full size.. s10 is not full size.. that's why I'm asking

Customer: replied 1 year ago.
I thought it was asking if it was a short (2door) or (long 4door). sorry for the confusion
Expert:  JOHN aka Eauto replied 1 year ago.

the fan clutch is locking in and spinning fast?

Customer: replied 1 year ago.
it starts when it is cranked and spins fast
Expert:  JOHN aka Eauto replied 1 year ago.

any coolant leaks?

Customer: replied 1 year ago.
well i haven't found any yet. I have checked the upper and lower radiator hoses. checked the heater core hoses, pulled the radiator reservoir checked it for leaks. when i got home last night it was boiling hot about 240 degrees and i saw leaking behind the passenger wheel. it was a pretty good drip. I couldn't see anything under the hood it was too dark. checked it today in the light and couldn't find any leaks. drove it and got it hot and nothing. but it overheats like every few day or so.
Expert:  JOHN aka Eauto replied 1 year ago.

have you checked the intake gaskets?

Customer: replied 1 year ago.
I have looked at it for leaks but haven't found any and nothing looks wet on the intake. I have saw a few drops of water from tail pipe lately
Expert:  JOHN aka Eauto replied 1 year ago.

does the exhaust smell sweet like coolant?

Customer: replied 1 year ago.
I looked at it, felt of it, and smelt it and it looks like just water. ive only noticed it a couple times and it was when the engine was cold
Expert:  JOHN aka Eauto replied 1 year ago.

some condensation can be normal...it is possible that the head gasket is failing...is it pushing coolant into the overflow?

Customer: replied 1 year ago.
im not sure what you mean....the reservoir tank?
Expert:  JOHN aka Eauto replied 1 year ago.

the coolant resevoir

Customer: replied 1 year ago.
well it always seems over the "full hot line", but i cant say that its pushing. i dont really know what that is
Expert:  JOHN aka Eauto replied 1 year ago.

when its overheating is there big bubbles in that tank

Customer: replied 1 year ago.
haven't noticed any bubbles but when it has over heated and i take the cap off the resesvior tank it has blew out some. not sure if thats normal
Expert:  JOHN aka Eauto replied 1 year ago.

sounds like head gasket failure...I would have a combustion leak test performed to verify

Customer: replied 1 year ago.
one note to add i have been running pure water since the spring time weather is here after i replaced the radiator.. i was trying to get all leaks fixed before i put in antifreeze. will running just water make it over heat?
Expert:  JOHN aka Eauto replied 1 year ago.

ahh water out of the tail pipe and no coolant in the system points to head gasket...water is not the cause

Customer: replied 1 year ago.
well no coolant in the system is by choice i didnt add any when i replaced radiator
Expert:  JOHN aka Eauto replied 1 year ago.

gottcha... the water wont cause the overheat or the failure...but the symptoms point t head gasket

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