Change thermostat procedure - '65 Corvette

[Oliver S.]

Hello,

from what I've read in the shop manual the procedure of replacing the thermostat is straightforward. Since my radiator has a 2-wing drain cock down on the driver side this is helpful, too. But as ever in such cases I've got some questions ;-)
Can this drain cock normally be opened by hand?
Does it have to be removed completely in order to drain the coolant or is it possible to open it a bit and close it when a certain amount is drained?
Are there any other pitfalls that I might perhaps have overlooked?
Are there any pitfalls that I may encounter? In Germany we say: The devil is a squirrel. Thanks in advance.

Regards
Oliver

[Jack H.]

Re: Change thermostat procedure - '65 Corvette

In theory, the radiator petcock can be opened and the radiator partially drained. In practice, it's often the case on older car that the petcock is corroded due to disuse and when you go to open it, it refuses to budge. Use of the 'bigger hammer' approach can lead to twisting/deforming the petcock resulting in a rather messy replacement...

For this reason, you'll find mechanics who routinely work on these classic cars, simply ignore the petcock and remove (partially or fully) the lower radiator hose to avoid damage!

[Brian Monticello]

Re: Change thermostat procedure - '65 Corvette

I wouldn't play with the lower hose since you'll end up draining more antifreeze than necessary. The thermostat is pretty high up in the cooling sytem so the only fuild that will drain is the fluid that is in the upper radiator hose and maybe the very top of the radiator. If your petcock is not an option, I would just place a bunch of towels around the housing and pull it to initiatite a controlled drain.

Brian

[Chuck R.]

Re: Change thermostat procedure - '65 Corvette

I'd go for the petcock Oliver but first I would go to either your local radiator shop or parts store and pick up a new pet cock.

This way if the pet cock ends up being deformed or ends up a "leaker" you can replace it.

Place (usually) a 9/16" wrench on the pet cock hex body and place a closed up adjustible wrench over at least one wing and the stem.

Use the wrench to offset whatever strain you place on the valve stem.

I'd rest easier knowing that the petcock is in good working order in case I ever had a break down and needed to drain the cooling system.

If you replace the petcock and use teflon tape, make sure you hold the tape back one or two threads from the end to avoid loose strands getting into the cooling system. An automotive pipe dope/sealer is prefered though.

Prior to setting the new t-stat, bore a 1/8" hole in the housing of the stat so that it can assist in bleeding off trapped air. The hole will have no effect on the t-stats operation.

Also, if the t-stat housing hasn't been off in quite a while, make sure that you start the bolts with a box end wrench making sure you have a square bite on the bolt heads. Wratchets as far as I'm concerned (especially 1/2" drives) can place way too much torque on the bolt heads causing them to sometimes twist off.

Patience is key

Chuck

[Duke W.]

Re: Change thermostat procedure - '65 Corvette

The petcock should only be tightend "finger tight", but it may take a pair of pliers to break it loose depending on who last tightened it and how they did it.

Duke

[Phil P.]

Re: Change thermostat procedure - '65 Corvette

turkey bastor (spelling wrong) suck the radiator fluid out of the radiator through the rad. cap down as far as it will reach---most important part of this process is the removal and re-installation of the bastor in the kitchen before the wife knows---good luck 007

[Chuck R.]

Re: Ewwww! Phil!!!

Remind me not to come to your house for a turkey dinner any time soon!

Chuckster