Ok, I have read the odd post on here that talks about this, but I don't not know what they are refering to.

Is this the small hole that gets drilled?

Also, on that topic - does anyone have a picture of the hole and how big do you make it?

thanks,
Tim

that is commonly refered to as a piddler valve

the small hole is there for 2 reasons...
1) to avoid an air pocket under the thermostat
2) to allow a small amount of hot coolant to warm up the plumbing
to avoid going from dead cold outside the engine to very hot too fast

i usually drill 2 1/8 holes across from each in the flat porton of the body
if the engine is on an angle i index one of the holes to the high side

sometimes the manufacturer's put a small loose rivet in there.

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[This message has been edited by vortecfiero (edited 11-18-2006).]

I always drill 1 number 1/16 hole works fine
Don

What is the hole for? What does it do?

The hole relieves pressure on the thermostat during cold start up and keeps from bending the tang on the thermostat for one thing. Another thing it will do is to increase the heat flow at a steady rate and not at a one time and off open of the thermostat. Have you ever noticed that your heat gauge may go up the ladder a bit and then back down? This is because the thermostat opens and then the cold water hits it and it closes again. The hole will stabilize this flow.
Don

Does anyone have a pic of where to drill the holes?

that's gonna be hard to show. I can describe it.
The problem is the fiero tstat has that outter channell for the o ring. on most standard disk types, you drill the hole in the outer disk, but that is not really possible due to the o ring.
So that leaves the center disk. anywhere in the outer flat area of the disk is fine. I prefer 2 smaller holes, like 1/16" inch, but a couple of 1/8" holes will work fine too.

here's a quick cad thing, view from top, the bar is the part the mechanis pushes on in the middle, the darker gold is the raised area of the mechaism, the lighter is the outer disk.

this is a drilled 3800 thermostat

Thanks a million guys--*all you* allready have A+ from me... Wish I could give more...

...yes thanks to all that helped... :cheers:

Let me add one more note.
Stant has a new thermostat for our Fiero's and is called a super stat. It is heavy duty and much better. I think the part number is #45819.
Don


I just rechecked on the part number and this is the correct number
Don

[This message has been edited by ka4nkf (edited 11-19-2006).]

The reason to drill the stat is, when racing the engine will heat up much faster than the stat will open, so there is always some flow of coolent.
Side effects are, that it lets any air bubbles out and hopefully wont kill the engine when the stat fails. I use 2-3 1/8th holes myself.

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I really think that with two holes coolant flows too much. I drilled one 2 mm hole (0.079") and radiator was really REALLY warm before thermostat opened and engine took much more time to warm up. This test was done in 35 def F, and for under 0 deg F one 1.0-1.5 mm hole could maybe be just fine.

Thanks for the info here. I just replaced my thermostat and drilled one hole into it. I had order the Hypertech from The Fiero Store, but because I live in NY and the winters can get kinda cold up here, I decided to stay with the 195.