1HZ Coolant Over Flow Tank Boiling

Joined
May 22, 2020
Messages
78
Location
Ventura, California
Website
ardnez.com
So I noticed that my coolant overflow tank was boiling after i went up an extremely steep hill, temp gauge was slightly below the red, do you think this can be due to a cracked head gasket, other causes or is this normal? Also pretty sure my radiator has a tiny leak since i noticed dried up coolant in between radiator and shroud and splashed onto timing belt cover, not sure if this can also be a cause. Thanks!
 
Joined
Jul 3, 2004
Messages
4,997
Location
Anchorage, AK
you don't ever want to see the temp needle anywhere near the red line. if you install a stand alone water temp gauge and you drove the same scenario you would be shocked at how hot your engine is. my engine wasn't an HZ but same concern. you can go to a local parts store and get a head gasket leak test, this tests the coolant for exhaust in the coolant which would indicate a cracked head or damaged head gasket, unless there is another way for exhaust to get into the coolant. I would run that test first.
 

FJBen

SILVER Star
Joined
Apr 1, 2004
Messages
6,318
Location
Northern Colorado
Sounds like your cooling system is in less than optimal shape. I would quit driving it ASAP.

You know it has a radiator leak and you have overflow boiling. Not a good sign. You "may" have already popped a headgasket, but maybe not. May have just got lucky an only started to overheat.

I'd pull the radiator and get it tested/repaired/replaced.
New water pump, flush system, new hoses

I'd probably even do a pressure check to make sure you don't have a headgasket blown.
 
Joined
May 22, 2020
Messages
78
Location
Ventura, California
Website
ardnez.com
The thing is that the coolant overflow tank only did this once ever since i’ve owned a 1HZ, and it was specifically over a 13% grade incline on a warm day for 7 miles, temp gauge slowly rose below the red mark and as i got to the very top i pulled over and opened the hood to check if anything was off and coolant was bubbling/boiling, this only happened once since 7 months of owning. Never again has the temp gauge rose over the half mark but radiator def needs to be replaced, small tiny crack, losing coolant at an extremely low rate but coolant overflow tank still stays above the low mark once the engine is warmed up.
 

FJBen

SILVER Star
Joined
Apr 1, 2004
Messages
6,318
Location
Northern Colorado
The thing is that the coolant overflow tank only did this once ever since i’ve owned a 1HZ, and it was specifically over a 13% grade incline on a warm day for 7 miles, temp gauge slowly rose below the red mark and as i got to the very top i pulled over and opened the hood to check if anything was off and coolant was bubbling/boiling, this only happened once since 7 months of owning. Never again has the temp gauge rose over the half mark but radiator def needs to be replaced, small tiny crack, losing coolant at an extremely low rate but coolant overflow tank still stays above the low mark once the engine is warmed up.

I'd imagine you are fine on your headgasket then. I would however replace/repair radiator, flush coolant, replace hoses and waterpump and then not have to worry about it.
 
Joined
May 22, 2020
Messages
78
Location
Ventura, California
Website
ardnez.com
Hoping its nothing more than just the radiator system, I will get onto it asap, do any of you know the exact OEM part number for the 1HZ radiator, I got 2 different ones on megazip.net so I’m not 100% sure.
 
Joined
May 22, 2020
Messages
78
Location
Ventura, California
Website
ardnez.com
16400-17080 is the OEM PN for M/T 7x series with 1HX engines.

Available in US market from your local Toyota dealer.

Very nice T.Rad unit.
I had this number written down but wasn’t 100% sure because I got these as well from megazip.net

49399A64-772A-439E-B3C2-FD1D06C31F7C.jpeg
 

OGBeno

Arakawa-san
Moderator
GOLD Star
Joined
Aug 28, 2004
Messages
31,368
Location
Patagonia, Arizona, USA
Yes it will do fine and it is the correct part number of you have a manual transmission. Correct and direct fit. You might need 16711-17011 though depending on the shroud you have in there now.

Shrouds are mated to radiators, design-wise.

Based on what’s happening, I’d highly recommend a cooling system overhaul at the same time— water pump, fan clutch, thermostat, all hoses. Don’t half-ass this.
 

OGBeno

Arakawa-san
Moderator
GOLD Star
Joined
Aug 28, 2004
Messages
31,368
Location
Patagonia, Arizona, USA
My 1HZ is an automatic trans is the thing /:

Bummer. Radiator not available in US.

So, do the following: get Toyota radiator, buy an aftermarket trans cooler and install for trans cooler lines to transmission.

Slush box radiator is almost $1K from overseas.

Or do what @Willis recommended.
 

Users who are viewing this thread

Top Bottom