Sticking Thermostat 1991 Coupe

[R5T]

Evening all,

Iv'e given the lubrication a good flush through on my 1991 2.3 coupe and wanted to flush the cooling system through properly.

I had the bottom hose off the radiator and drained all that was there. Obviously there is still old water in the engine so wanted to flush it out.

Had the car up to temperature, fans kicked in, but once id filled the water tank it didnt dissapear ? The engine was running for around 15 - 20 minutes but still the water didnt dissapear. Is the thermostat stuck closed ?

Im not a mechanic but try my best, is there any other way of telling wether the thermostat is stuck closed without taking it apart ? If not then how difficult will it be to take the thermostat off ? and where about is it positioned on the engine ?

I'm a bit of a newbie so apoligies for my ignorance.

The car is a 1991 Coupe 2.3e 10v NG non quattro

All helpful remarks appreciated.

Thanks

Sam

[shaun5]

Originally Posted by R5T

Evening all,

Iv'e given the lubrication a good flush through on my 1991 2.3 coupe and wanted to flush the cooling system through properly.

I had the bottom hose off the radiator and drained all that was there. Obviously there is still old water in the engine so wanted to flush it out.

Had the car up to temperature, fans kicked in, but once id filled the water tank it didnt dissapear ? The engine was running for around 15 - 20 minutes but still the water didnt dissapear. Is the thermostat stuck closed ?

Im not a mechanic but try my best, is there any other way of telling wether the thermostat is stuck closed without taking it apart ? If not then how difficult will it be to take the thermostat off ? and where about is it positioned on the engine ?

I'm a bit of a newbie so apoligies for my ignorance.

The car is a 1991 Coupe 2.3e 10v NG non quattro

All helpful remarks appreciated.

Thanks

Sam

You need to have the blower motor flat out on hot setting, on the bulkhead you will see 2 pipes, 1 with a bleed screw on it. To be honest dont try to undo it as it will more than likely sheer off. Easiest thing is to undo the jubilee clip and crack the pipe of to allow the air to escape.
You will also see on the radiator a 13mm spanner bolt head, undo that with the engine running until coolant comes out, be carefull when refitting it, dont do it up to tight as it will crack the radiator (if its still the original plastic one)

[shaun5]

The thermostat on a 2.3 is pretty easy to access, its below the power steering pump. held on with 2 bolts. To flush the whole system remove the pipes to the heater matrix and connect a hose pipe to it. You might be asking for trouble with that tho as if the heater matrix is dodgy it could cause a leask after.

[msh]

I don't get it - what had to disappear - level in expansion tank? 5 pot cooling system is very straightforward in filling - in order to fill up entirely dry system, one has to top up the expansion tank, somehow spend some 3-5 minutes while the system is slowly filling up and afterwards there will be only air bubble in heater matrix which will flow out when the engine will be started.

[shaun5]

Originally Posted by msh

I don't get it - what had to disappear - level in expansion tank? 5 pot cooling system is very straightforward in filling - in order to fill up entirely dry system, one has to top up the expansion tank, somehow spend some 3-5 minutes while the system is slowly filling up and afterwards there will be only air bubble in heater matrix which will flow out when the engine will be started.

Any system is straight forward in filling its the bleeding that can be difficult, ive done quite a few and never had one you can just pour water in the header tank and its been done. Especially if all the pipes have been removed. You defenatly need to remove the bleed screw on the radiator.

[mikes2]

Best method is to undo the 3 screws for the expansion bottle and lift it as high as it will go.

That makes bleeding it much easier as the expansion bottle then becomes the highest part of the system

[msh]

Originally Posted by shaun5

Any system is straight forward in filling its the bleeding that can be difficult, ive done quite a few and never had one you can just pour water in the header tank and its been done. Especially if all the pipes have been removed. You defenatly need to remove the bleed screw on the radiator.

That's the point - as I mentioned, the only thing you can call "bleeding" on engine like mine is starting it in order to get the bubble out of heater matrix, as the other system fills up nicely. Of course, if one has little patience, he can quicken it up a bit [or simply spend time] by squeezing the upper radiator hose. With B3 4 pot engine it's a bit harder, as it doesn't fills up that nicely as 5 pots, but still straightforward.

And about these bleed screws - please, don't mention them. Fortunately B3 didn't had them, at least earlier ones - unfortunately mine has one, as when I got my A90q, one hose was damaged and the only one I can find in junkyard was from B4. The screw, as always with them, has been overtightened, so in order to make it not leaking, I had to use some sealant. And since there's no need to have them anyway, because there's absolutely no problem to bleed the matrix without them, these screws are simply ugly, useless and unneeded.

[R5T]

To clarify any un-certainty,

I was trying to flush the system due to the cruddy water in the expansion tank. Obviously there is going to be cruddy water in the block and head as well ... I dropped all the water from the radiator and expansion tank, put all hoses back on and filled the tank up again.

I started the car and once the engine had reached temperature I was expecting the "thermostat" to open and let the water from the tank/radiator flow through the whole system ... It didn't.

This is why I asked in my first post "Is there any other way of telling whether the thermostat is working correctly ?" ... i know how to bled the system with the heater matrix pipes etc. My queery was only with the thermostat.

Thanks to all that made an input, the thermostat is now out of the engine and I have succesfully flushed the whole sytem of the cruddy water.

Thanks again

Sam

[mikes2]

To test the thermostat, stick it in a pan full of water and boil it.

Just before the water starts to boil, the thermostat should start to open

[R5T]

New thermostat is now fitted all is working beautifully.

Thanks

Sam