Temp Issues, ST162

[doobs]

Ey all,

Just after an opinion,

I've just got my sisters car back from getting a new motor installed (ST162, 3SGE), while it seems to run great, there’s an issue with its running temp... ever since she’s had this new motor, she’s said the heater is not as effective, and that the temp gauge is low, when compared to the old motor...

I changed the coolant and radiator cap today (came back from the mechanics with just water), let the car idle and heat up, the temp gauge reached just below half (its normal position) thermo fans came on and off, and it sat there idling away temp gauge happy. The heater was nice and hot as well.

I took it for a spin down the highway, the gauge dropped back to about a 1/4, and the heater seemed just warm, got into town and temp gauge rose slightly, and the heater got slightly warmer, got back to the highway and the gauge went back to a 1/4...

Seems to me, that its running as if it didn’t have a thermostat… I couldn’t check it because she needed the car.

What are your thoughts...

Cheers

[Jorrs]

or perhaps a blockage somewhere in the heater lines ?
who put the motor in ? u would think a new one would have been put in.. ? or the old one is buggered perhaps.

[Dale]

Thermostat stuck open, or part stuck open... put a new one in and it should be sweet

Most likely the reason it gets cool at highway speed is because the water pump is turning more water due to the revs so you're getting more cold from the radiator

Toyota are pretty cheap for thermostats, the rubber gasket to go around them is like $9 or something stupid though

[doobs]

Cheers fellas +rep

Motor was installed by Geelong Engine Replacments, as my sister somehow got it free, and well I was too lazy , soarers take up all the shed.

Both the installation work and the motor have 12months warrenty, but if its just a thermostat, I may as well do it...

[Jorrs]

yeh, well id say just change the thermo straight up, take it for drive and test it,
if its still playing up, ring them up and take it back and use that warranty, cos its then more likely something they have done wrong.

[celica_john]

would the top and bottom radiator hoses have different temps if it was working?? or is that just the case when it's stuck closed?

[Dale]

They'll have different temps no matter what

One is getting hot water out of the engine

The other is putting cooled water that's gone through the radiator back into the engine

[Jorrs]

though, heres a lil thought, if the thermo is fucked, and blocked, the water thats been cooled wont be able to move and will heat up ?

[Crazyracer]

Or they may have forgotten to put the thermostat in all together.

If you're getting a new one make sure its the right type. The 3SGE ones are a switching type, ie they switch the water flow from going through the radiator when hot, to re-circulating around the engine when cold. Your average thermo is just open or closed.

Also possible that he's mis-plumbed the heater, and connected it to the re-circulation circuit, so it gets no water once the engine heats up. But that shouldn't cause the gauge to drop.

Stuck or missing thermo seems the best bet.

[Dale]

though, heres a lil thought, if the thermo is fucked, and blocked, the water thats been cooled wont be able to move and will heat up ?

The car would overheat if the thermostat was fucked, so the water in the radiator would always be cold

Or they may have forgotten to put the thermostat in all together.

If you're getting a new one make sure its the right type. The 3SGE ones are a switching type, ie they switch the water flow from going through the radiator when hot, to re-circulating around the engine when cold. Your average thermo is just open or closed.

Also possible that he's mis-plumbed the heater, and connected it to the re-circulation circuit, so it gets no water once the engine heats up. But that shouldn't cause the gauge to drop.

Stuck or missing thermo seems the best bet.

The thermostat housing would leak if there was no thermostat, the gasket around the thermostat serves as the gasket for the housing too.

If the heater hoses are mis plumbed the temp gauge will show the car overheating due to air locks that can't get out and get trapped in the water junction

And yeah, make sure you get a thermostat from toyota, they'll be cheaper than repco etc anyway

[Crazyracer]

The car would overheat if the thermostat was fucked, so the water in the radiator would always be cold

Depends which way it gets stuck.

The thermostat housing would leak if there was no thermostat, the gasket around the thermostat serves as the gasket for the housing too.

Yeah but you know how much mechanics love silicon.

If the heater hoses are mis plumbed the temp gauge will show the car overheating due to air locks that can't get out and get trapped in the water junction

Depends how it gets mis-plumbed. There is a pipe that leads back from the thermostat and is supposed to plumb to the outlet at the flywheel end of the engine. If this goes through the heater first, water will only flow through the heater when its recirculating, ie cold.

[Dale]

There's only one way to mis-plumb them, I know what happens from experience the air never gets out of the heater

Had me stuffed what was wrong with it until I realised my mate had put them on the wrong way

[Andrew162]

The thermostat housing would leak if there was no thermostat, the gasket around the thermostat serves as the gasket for the housing too.

no, not necessarily. I had my 3S-GTE running with no thermostat (temporarily) when trying to diagnose an overheating problem, and there were NO leaks out the housing at all because we used the Toyota red gasket goo (yeah the expensive shit).

[Dale]

Well clearly it wouldn't leak if you'd bodged it up with enough gasket goo, my point was if you put it together the way it's meant to be done the thermostat serves at the gasket for the housing

[Andrew162]

nah, didn't need that much goo. come to think of it, it was the ST205 thermo housing, which didn't require the gasket for the thermo housing. different setup, I'm pretty sure.