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Changing a new Thermostat in 1972


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O2 Fans:

I searched through prior posts and it is a simple mechanical change out.

However, with my baby always like to ask before I attempt items.

IS there any particular " tweaks " one should do prior or after a Thermostat change out ?

In So Cal I tend to run a bit above mid gauge on 95 degree driving days and before I go to an improved radiator , wanted to try this route for any effect.

Thank you for the advice

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First off- check all the hoses. Do they need replacing?

I always drill the little air bleed hole in the diapragm when I install a new thermostat. There is a desription of it in the Mccartney book. 1mm, and it does not take a lot of pressure on the drill to go through- the diaphragm is very thin.

It may be a good time to do any other work on the heater since you have the cooling system drained. I'd also pull the radiator and clean all the dead bugs and junk that are clogging up the fins.

Do you have a Stant pressure tester? Kinda nice to pressure test the system after you have all the hoses back on, before you go on a long drive.

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Guest Anonymous

Big Thanks Kevin:

To clarify for my apparent ignorance :

* where is the diapragm you mention

* Mcartney book is new to me, have German dealer manuals and useless Chiltons

* no pressure tester, don't drive too far with baby, just 20 miles to surf coves, all new hoses been installed, so pressure should be fine after installing and testing with heater on etc

Again thank you for advice

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close the heater valve (turn the dash lever to cold) before you partially drain the system to swap 'stats. That way you won't get an air bubble in the heater core--which can be very difficult to get out.

And you won't need to completely drain the system--but once you've drained it partway down, have a big catch pan under the thermostat to catch the enevitable splashes. Antifreeze is attractive and lethal to pets; you don't want to spill any.

And if your radiator still has the bolt in the drain hole, use that big catch pan there--coolant will go all over the place when you remove the bolt. You can try wedging a plastic funnel between the sway bar and the nose panel just below the drain plug; that'll help direct most of the coolant into your catch pan...otherwise it runs all along the sway bar and goes everywhere.



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* where is the diapragm you mention?- It is inside the Thermostat housing. Look inside the straight end (not the one with the angle) and you will see a brass colored disc. Just drill a small 1/16" hole in the disc. Look on the opposite side to make sure you won't hit anything when it drills through. Remove all metal filings after you drill.

The hole just lets air pass, but not very much coolant. Air pockets in the cooling system can cause the thermostat to not open when it should, thus overheating. Sometimes you can squeeze the lower radiator hose to break the air bubble free. Other times you may not even get an air bubble. I just drill the hole on mine. Works for me.

* Mcartney book is new to me, have German dealer manuals and useless Chiltons

The Mcartney book is the 2002 Restoration Guide. A good reference. Points out common fail items and fixes. Was written with the help of several FAQ members.

* no pressure tester?

The Stant tester is a nice tool to have. Lets you test the radiator cap which is a common cause of overheating. Also lets you pressurize the cooling system so you can see if any of the hoses are leaking. Without the tool, just go back and verify all the hose clamps are secure. Even the ones you didn't loosen for this job.

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Thank you very much to all for the Thermo install tweaks and advice , greatly appreciated !

After I experiment with new Thermo and if it does not work , will probably go to one of those improved rads I seen and have read about , and really liked the feedback from the forum on how some brands are " true" replacement , drop in & bolt on and others are need of custom cutting and fabrication.

After many Fiats , street /race Alfa and even a fully restored Amazon 122s , the 02 has been an overall joy for the last 3 yrs.

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