Engine overheating and heater not working

[DP75]

98 runner with 100,000 on it.....just recently my tempature began to go up I looked in the resivour and there was no coolant I put some in at first it kept getting hot but it eventually stopped. Acouple
Days later it started again and now the heater is pumping cold air...I have not replaced the thermostat so I'm
Hoping that's the issue no belts are broken and
There is no visible leak after looking around any help before I take it to the shop would help thanks.

 

[kball]

Is the reservoir empty again?

 

[4runner9808]

u may want to check ur heater core

 

[pauls4runner]

Even though you may not see any leaks, you definitely have a leak. when you are low on coolant, your heater core wont have any operating temp coolant inside of it which is why the heater doesnt work, and the engine temp is higher because of lack of coolant to keep the temps down. when you first start your 4runner, after it has idled or run for about 10-15minutes (providing its not too hot at this point) check your exhaust for smoke, also check your oil dipstick, see if their is evidence of coolant mixing with the oil.

 

[Jon]

Stat FTW!

I highly doubt it's a head gasket with only 100k. Really hope not! A stuck thermostat can cause this. No flow, no heater and high eng temps. A blown head gasket wont drink the coolant up fast enough to cause a no heater condition. There'd be coolant pi$$in out of the exhaust or milky oil shooting out of the dip stick. This sounds more like a blockage- stuck thermostat. At least it's a 5spd so it's not gonna be pink milkshake! Good luck

 

[Hawaii5Oh]

updates?

i know this post couple years old, but was wondering if you ever found the leak? or what was cause.
my wife's 96 is doing same thing.
i already flushed the coolant,and replaced the thermostat.
and issue creep-ed back after 2-3 days.
so my questions where is my leak, as i know i have one.

thanks for help

 

[BlackCat914]

i know this post couple years old, but was wondering if you ever found the leak? or what was cause.
my wife's 96 is doing same thing.
i already flushed the coolant,and replaced the thermostat.
and issue creep-ed back after 2-3 days.
so my questions where is my leak, as i know i have one.

thanks for help

You might just have a big air pocket.

 

[Ck6599]

i know this post couple years old, but was wondering if you ever found the leak? or what was cause.
my wife's 96 is doing same thing.
i already flushed the coolant,and replaced the thermostat.
and issue creep-ed back after 2-3 days.
so my questions where is my leak, as i know i have one.

thanks for help

Same issue here

 

[devbo]

Leaky freeze plugs? I'm dealing with this on my 1998 with only 131K

 

[19963.4lsr5]

When I see titles like this I first think low on coolant which contributes to overheating.

Then it’s where is it going?


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