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Hi All. Assistance YET AGAIN please.
Decided to change thermostat, got the correct one, second time around with (Triumph foot at 88 deg) fitted now overheating, No water in thermostat housing. My thermostat housing has no filler plug fitted as Haynes manual illustrated. Am I seeing things or is the thermostat housing higher than the metal expansion tank, If this is so I can't get water in there, Or can I?
Regards
Gareth

G.P.Albrighton

Gareth, our cooling systems are quite simple, I suspect something minor has occurred. As for the thermostat housing, it is the highest point on the engine. I always remove it for the initial fill just as was done back when the other housing had the filler plug. This method insures there is coolant in the engine. Next, the overflow tank is filled which reloads the radiator. I then start the engine to get the juices flowing about. Once the thermostat housing reaches 180 degrees, the thermostat should open and the upper radiator hose warms as the hot coolant is pumped into the radiator for the cooling cycle to start over.

Is this the procedure you are following?

Mildred Hargis

Hi Mildrid
Thanks very much for the quick response.
First off I snapped one of the bolts in the thermostat housing. I carefully drilled it out and fitted new bolt new gasket and new thermostat. I did fill housing up with water, then filled expansion tank and let engine run till gauge went up to half way,I squeezed the hoses but there didn't seem to be any water in them.
Only the bottom part of radiator is getting hot and the expansion tank isn't getting hot at all. All was fine till I changed the thermostat.
Thank you
Gareth

G.P.Albrighton

What about the top hose? Is it hot? If the top hose is not hot, no coolant is getting there.

And, be sure you are using a 50/50 blending of antifreeze and distilled water. I would avoid those premixed blends. Mixing our own means we know exactly what's going thru our coolant passages, and it costs less.

Mildred Hargis

P.S.

I hope you did not install the thermostat upside down.

M.S.

No I put the thermostat the right way up Mildrid.
The top hose doesn't seem to be getting very warm either, could it be air locks as I don't think there is enough water in the system yet the expansion tank is full and cold. For some reason water isn't circulating.
Regards
Gareth.

G.P.Albrighton

Do you have an expansion bottle or a header tank?
(or what model year is your car)

<center>
<font color="blue"><i>1976 TR7 FHC (needs some TLC ...)
1980 TR7 DHC (my first car, a.k.a. Kermette)
1981 TR7 FHC (Sprint engined a.k.a. 't Kreng
</font id="blue"><b>[url="http://www.tr7beans.blogspot.com/"]<u><b><font size="3"><font color="red">My full Weblog</font id="red"></font id="size3"></b></u>[/url]</b></i></center>

Hi Beans
1980 2.0L FHC
It is the metal expansion tank on left side of engine bay.
Thank you.
Gareth

G.P.Albrighton

Gareth, please try this. Remove the thermostat and run the engine a short while. This will get the coolant circulating and flush out any air pockets. Do this with the radiator cap removed as well. When the upper hose gets hot and you hear coolant moving thru it, shut things down and reinstall the thermostat and radiator cap.

Also, occasionally squeeze the upper hose to burp the system.

Mildred Hargis

Wait just a minute here! Is it possible the thermostat is sticking closed? Have you manually depressed the valve to ensure it CAN open? Do you think it necessary to boil the thermostat on the kitchen stove to make sure it will open at the stated temperature?

Do you have a temperature gun to verify the temperature of the housing as the engine warms up? If not, this is a good example of why you and everyone else needs one.

Mildred Hargis

Why did you decide to change the thermostat? Was there a previous problem ? Perhaps the stat is faulty - try it in a pan of hot water - and bring it to the boil to check it's working. What indication is there that the engine is overheating - is the gauge going to HOT?
Hah! We crossed 'Mildred' !!

Thanks All
I changed the thermostat because I was putting antifreeze into the coolant so thought a new stat wouldn't do any harm. That's a joke HO HO. [V]
I will purchase an infared digital thermometer in the morning and follow the methods all have put forward, Will check stat first cooker in saucepan and read operating temperature.
Will also unbolt the metal header and and raise it higher than stat housing.
Will update asap. But work tomorrow so will be Wednesday. Many thanks.
Best regards.
Gareth

G.P.Albrighton

Sorry Yes the Gauge is going to 3/4 on scale. I stop engine prior to any further travel.
Gareth

G.P.Albrighton

Let's see, you're about six hours ahead of me so that would put you in bed asleep at midnight as my clock reads about 10 minutes after 6 o'clock in the afternoon. That means it's too late to suggest you trot out to the car and install the old thermostat for comparison purposes.

Yes, go ahead and get the temperature gun, but first swap the old one back into the engine.

Mildred Hargis

There are many methods of overcoming air locks in our cooling systems.

Perhaps the easiest is, when you don't have a filler plug in the thermostat housing, simply take the top hose off the thermostat housing, & fill it through the hose. Remove the header tank/radiator cap, & keep pouring coolant into the hose until that overflows.

I went to the effort of fitting an overflow recovery system to my 7, while having problems with the faulty new water pump, but once the system settles with the coolant 30mm below the top of the header tank, the system doesn't seem to use it, & the top hose remains full.

Hasbeen

With the later type coolant system(with a header tank) it shouldn't be much of a problem to fill up the system without locking air in.
But there are a few things to bear in mind;
First of all the thermostat should have a small air valve to expel air into the header tank;
While filling the system allow air to escape by giving it time to do so, and by squeezing the lower coolant hose;
I always fill to the neck of the header tank (make sure the overflow hose is fitted properly), leave the car for a few hours, go for a drive making sure the thermostat opens and check when everything's cooled down.
Level should then be about an inch below the neck of the header tank.


<center>
<font color="blue"><i>1976 TR7 FHC (needs some TLC ...)
1980 TR7 DHC (my first car, a.k.a. Kermette)
1981 TR7 FHC (Sprint engined a.k.a. 't Kreng
</font id="blue"><b>[url="http://www.tr7beans.blogspot.com/"]<u><b><font size="3"><font color="red">My full Weblog</font id="red"></font id="size3"></b></u>[/url]</b></i></center>