Thermostat Modifcations

[Conn47D24]

Has anyone seen this or tried it ?

 

Is this recommended for positive results ?

 

As copied from the Vintage Power Wagon site.

 

"In some cases you may want to drill a 1/32” hole in the top plunger (the piece
that opens) of the thermostat towards the outer lip. This allows for circulation
before the thermostat opens, reducing deposits in your cooling system
and reducing the possibility of pressure build-up. This also helps bleed air
from the system, reducing the chance of air pockets which can create hot
spots in the engine. Don’t forget to replace the thermostat housing gasket. "

[rekbender]

I've done this on both thermostats used on a '41Mercury flathead, as well as the thermostat I just replaced in a  Dodge 318. It makes filling block much quicker without having to burp the cooling system repeatedly. You will also see this hole on some thermostats like this Nissan I found in my junk stash. This one even has a little valve to block the hole when coolant is flowing. Some foreign engines ( Renault Alliance) were a real problem to get the the trapped air out of the system. I don't think bypassing this small amount of coolant hurts a thing, although I've never tried it on a MOPAR flathead.

[Adam H P15 D30]

Once the air is bled out of the system, you should not be getting any air pockets unless there is something wrong.  When filling, I hold the valve open with a couple of aspirin while filling and burping.  Aspirin dissolves and system works as designed.

 

Adam

[rallyace]

41 minutes ago, Adam H P15 D30 said:

Once the air is bled out of the system, you should not be getting any air pockets unless there is something wrong.  When filling, I hold the valve open with a couple of aspirin while filling and burping.  Aspirin dissolves and system works as designed.

 

Adam

And your car will never tell you "not tonight I have a headache".

 

[sser2]

This thing, called "juggle valve", is optional - some thermostats have it, others don't. It helps in burping the cooling system during fill-up, but doesn't provide any other benefit.

[Adam H P15 D30]

I cannot see how a tiny 1/32 hole would do anything to minimize build up.  I think the author is full of it.

Edited August 9, 2018 by Adam H P15 D30

[dodgeguy]

I have been doing this for 30 years on small block Chevys', 1/8 inch hole works well, I do it only to eliminate air,  and steam pockets. Then one day I walked in parts store and bought a Stant brand it was already pre drilled. I knew I should have got a patent on it 30 years ago!!!!   LOL  btw older Hondas had best set up , a bleeder screw at highest point of cooling system, some where on T stat housing some were on intake even saw one on a hose coupling, just open till you get steady stream of coolant.