Temperature Gauage Falls.

[marsbar989]

Car is Avensis 1.8 Petrol. V 1999 reg.

7A-FE engine.

Forget that is cold outside now. But since I have purchased the car in August 2008, the engine appears to take forever to warm up.

If the car is started and left standing, the temperature will move slowing to the 9'o'clock angle and stay. Keeping the car on longer and the fan kicks in.

If the car is now driven the temperature falls. Sometimes to the 8'o clock position, usually to the 7 O'clock. (As its been cold now even to the "starting" position on the guage). While the car is being driven temperature will raise and fall. (to 7/8 o'clock position, never 9). It doesnt seem to make any difference if the car is doing 30mph or 70mph. I have driven the car for over 100 miles, (80 or so on a motorway at 50-70mph) and the temperate has never returned to the 9 0'clock position. The only time is does is if the car stops and after 5 mins or so its there.

There is very little heat from the blowers into the car also.

I have chekced the radiator (when cold) - its full. The expansion tank is also full (between the low and high marks). I have not topped up the radiator nor had the need too.

The effect of the temperature not being "right" is that the engine idles at 1600-1800 rpm even after my 100 miles journey. It cant be doing the engine any good with a rich mixture of petrol/air etc.

But what is wrong?

Many thanks

[Fitter]

Car is Avensis 1.8 Petrol. V 1999 reg.

7A-FE engine.

Forget that is cold outside now. But since I have purchased the car in August 2008, the engine appears to take forever to warm up.

If the car is started and left standing, the temperature will move slowing to the 9'o'clock angle and stay. Keeping the car on longer and the fan kicks in.

If the car is now driven the temperature falls. Sometimes to the 8'o clock position, usually to the 7 O'clock. (As its been cold now even to the "starting" position on the guage). While the car is being driven temperature will raise and fall. (to 7/8 o'clock position, never 9). It doesnt seem to make any difference if the car is doing 30mph or 70mph. I have driven the car for over 100 miles, (80 or so on a motorway at 50-70mph) and the temperate has never returned to the 9 0'clock position. The only time is does is if the car stops and after 5 mins or so its there.

There is very little heat from the blowers into the car also.

I have chekced the radiator (when cold) - its full. The expansion tank is also full (between the low and high marks). I have not topped up the radiator nor had the need too.

The effect of the temperature not being "right" is that the engine idles at 1600-1800 rpm even after my 100 miles journey. It cant be doing the engine any good with a rich mixture of petrol/air etc.

But what is wrong?

Many thanks

The problem may be a faulty thermostat. It is located in a housing attached to the engine block on either the return or flow hoses from the radiator depending on model. It can be removed to see if it is stuck open.

Fitter

[igormus]

Car is Avensis 1.8 Petrol. V 1999 reg.

7A-FE engine.

Forget that is cold outside now. But since I have purchased the car in August 2008, the engine appears to take forever to warm up.

If the car is started and left standing, the temperature will move slowing to the 9'o'clock angle and stay. Keeping the car on longer and the fan kicks in.

If the car is now driven the temperature falls. Sometimes to the 8'o clock position, usually to the 7 O'clock. (As its been cold now even to the "starting" position on the guage). While the car is being driven temperature will raise and fall. (to 7/8 o'clock position, never 9). It doesnt seem to make any difference if the car is doing 30mph or 70mph. I have driven the car for over 100 miles, (80 or so on a motorway at 50-70mph) and the temperate has never returned to the 9 0'clock position. The only time is does is if the car stops and after 5 mins or so its there.

There is very little heat from the blowers into the car also.

I have chekced the radiator (when cold) - its full. The expansion tank is also full (between the low and high marks). I have not topped up the radiator nor had the need too.

The effect of the temperature not being "right" is that the engine idles at 1600-1800 rpm even after my 100 miles journey. It cant be doing the engine any good with a rich mixture of petrol/air etc.

But what is wrong?

Many thanks

hi mate

-thermostat

the themp sensor gives a command to ECU to keep rpm as at cold starting = 1600-1800 rpm.

have it changed and all must be in order.

Cheers/Igor

[marsbar989]

Thanks, I previousily owned a corolla 1.8GXi (same 7afe engine) and have the Haynes book for the corolla. Would the thermostat be in the same place as the corolla (IE the haynes manual will be able to help me fit it?).

[BALIKBAYAN]

Most likely that your Haynes book about the Corolla will do very fine. There might be some differences if it is not the same generation of 7A-FE engine, but those differences would not affect the thermostat.

[Fitter]

Thanks, I previousily owned a corolla 1.8GXi (same 7afe engine) and have the Haynes book for the corolla. Would the thermostat be in the same place as the corolla (IE the haynes manual will be able to help me fit it?).

The thermostat housing is where the return hose from the radiator (bottom) joins the engine block. Remove the two nuts or bolts and detach the housing. The themostat will have its opening tempurature stamped on it ie 82 C. You can test it in a pan of water but it will be obvious if it is stuck open. Obviously you will lose come coolant when you remove the housing.

See

Fitter

[marsbar989]

Many thanks to all.

At the weekend I replaced the thermostat in my engine.

Drained the raditor, removed the 2 bolts, and saw the thermostat there.

Placed this in a pan of boling water and it clearly opened. Then placed this under a running cold water tap and it didnt shut completely. This I thought is the problem. (as the car takes years to warm up).

Fitted the new thermostat did the bolts up and filled the raditor.

Started the car and with the raditor cap off and filled as required. temperature on guage started to raise. Got "normal". Left car running til fan clicked on.

Checked for leaks - and left car to cool. about hour later - went and put about a pint of water in the raditor and filled up the expansion tank to full mark and went for a drive. (about 20 miles). - First thing I noticed was I had hot air from the vents - boy was it hot compared to what it was !

Upon coming home, and the car being cool - checked and again put about a pint of water in.

I will just check the raditor after each drive now - but problem is clearly solved -

So THANKS to everybody on here

[igormus]

Many thanks to all.

At the weekend I replaced the thermostat in my engine.

Drained the raditor, removed the 2 bolts, and saw the thermostat there.

Placed this in a pan of boling water and it clearly opened. Then placed this under a running cold water tap and it didnt shut completely. This I thought is the problem. (as the car takes years to warm up).

Fitted the new thermostat did the bolts up and filled the raditor.

Started the car and with the raditor cap off and filled as required. temperature on guage started to raise. Got "normal". Left car running til fan clicked on.

Checked for leaks - and left car to cool. about hour later - went and put about a pint of water in the raditor and filled up the expansion tank to full mark and went for a drive. (about 20 miles). - First thing I noticed was I had hot air from the vents - boy was it hot compared to what it was !

Upon coming home, and the car being cool - checked and again put about a pint of water in.

I will just check the raditor after each drive now - but problem is clearly solved -

So THANKS to everybody on here

ok cured, then

Have a godd drive

Igor

[marsbar989]

Ok, Sorry to bring this up again, but the temp gauge in the car does reach the midway point like it should and driving along the temp gauge falls to the 4 or 5 o'clock position again.

I've taken the old (less than 10 month) thermostat out and replaced it. The old one when put in cold water looks closed. Upon putting it in hot water it opens and then leaving it it looks clased again.

I guess it maybe faulty, and driving around this week I shall be able to tell.

[marsbar989]

Replaced the thermostat this afternoon. and the temp gauge works as expected. The old thermostat doesnt close fully I have noticed. Guess its faulty as I would have expected it to last longer than 9months. I fitted the other one on 17th Jan 2010.

[Thermal]

Was it an original part?

If so, show it to where you bought it and discuss the failure.

They'll probably put it down to an installation fault. (the "Jiggle valve", or "gasket not replaced")

Have your answer ready. ;)

Thermostats do fail sometimes, but very rarely twice during the life of a single car.

[marsbar989]

Was it an original part?

If so, show it to where you bought it and discuss the failure.

They'll probably put it down to an installation fault. (the "Jiggle valve", or "gasket not replaced")

Have your answer ready. ;)

Thermostats do fail sometimes, but very rarely twice during the life of a single car.

Thanks, The part was only 9 months old. No it was not the original part. A new Gasket is supplied and I replaced it last time and this time. It appears to be working fine, temp at right temp within about 5 minutes of driving, where as beforehand it took ages and then could fall during the journey to work. As I do the same journey to work its a very good measure of sucess.

Gonna take it back to Halfords on Saturday. It might only be a tenner, but a tenner is a tenner in this day and age.

[Thermal]

Hi,

The question now remains, is what caused the early failure.

The thermostat itself may have been inferior quality, but the real problem may be the cooling fluid.

The cooling system must be drained (radiator, engine block and interior heater) and replaced (the nice pink Toyota stuff) every 2 years.

A previous owner(s) may have skipped that, or even worse, mixed it with water. :!Removed!:

That may have started corrosion inside the system, and the repeatedly failing thermostat a sign of more to come...

If in doubt, I would replace the cooling fluid.

Cooling fluid is chemically inert, while water, no matter the level of purity, is not.

Never mix or top up the cooling system with water... not a single drop, because that triggers the corrosion process.

[Avensis 1999]

I had very similar problems with my 99 Avensis 1.8 7AFE, changed the thermostat, and thought I had cured it.

However took it out the next day for a long motorway drive, and the temp gauge stayed on cold ??? I reached my destination, left the car running for a few minutes, then the cooling fan cut in ??

So I figured it must be the temp gauge needle sticking, so I gave the dash a few taps, and the needle started moving.

Need to look into it some more thou.

HTH

[marsbar989]

ok, sorry to bring this up again, but the temp gauge doesnt show that the engine is ever getting up to the right temperature. Ie the needle is never halfway, it moves to the 4 or 5 o'clock position.

I cannot believe it is the thermostat again, as this one would have been in the engine for only 14 months. parts are from Half**ds.

I have purchased another thermostat from them today, a QTH210K. searching the net a QTH580k should be the correct part. Can anybody confirm this?

Car is an avensis 1999 7a-fe 1.8 engine.

Also as was said on here - would flushing the system help? I have added water and antifreeze in to a mixture of 50%.

whats wrong? A thermostat should last longer than 9 months of 14 months? shouldnt it?

When I replaced the radiator in my last toyota when the car was 9 years old its thermostat didnt go until the car was 14 years old.

many thanks