Thermostat higher than top of radiator?

BBShark

BBShark

Garage Monkey
Staff member
Joined
Mar 5, 2008
Messages
5,064
Location
Right here
Just noticed that my thermostat sits up higher than the radiator cap. Looks like it is the highest point in the system and would trap air.

This must be common and I guess there is water pumped into the thermostat housing and out the hose but, the air pocket must end up right back in the same place, correct?

What part does the overflow tank play in this?
 
Interesting question. Wouldn't the water flow force most of the air into the radiator and then out through the surge tank as the water heats up and increases pressure in the system??
 
Noticed that too. On my 68, the top of the thermostat appears to be the tallest thing in the system. I decided to drill a hole in the thermostat top and tap it with a plug. To make sure I drilled the hole at 90 degrees and did a good job, I went and bought a drill press!! Bought a Sears that maybe cost $170. Drilled the hole, tapped it for an aluminum pipe thread plug. When I loaded my engine with coolant (a mint never wetted ZZ4), I filled it until coolant bleed out of the opening.
.......................

My thermostat housing is a Billet Specialties housing with a 45 degree neck. The Billet Specialties aluminum housing is horribly constricted inside. I would imagine that this could cause some real heating problems that people wouldn't guess was due to a thermostat housing constriction. I ground out the interior restriction. I probably doubled the interior opening. Now..how many people do you know that have ported a thermostat housing???

Also.......I have a Be Cool radiator in the 68, and the radiator has a radiator cap opening for a...you guessed it...a radiator cap. Or a 68 Corvette you don't want a radiator with a radiator cap. The overflow tank on a 68 (Ok,OK is it the expansion tank?, can't keep it straight) has the radiator cap for the system. For the Be Cool radiator, I used my Dremel disk cutter to remove the radiator cap spring so it just became a rubber gasket sealed cap. Now the radiator cap on the overflow/expansion tank works like a stock cap and the radiator cap on the radiator just seals the hole in the radiator.

Also, I could go on and tell what I use for radiator coolant, but this just causes a lot of controversy. Lets just say I don't have a heating problem with the 68. It runs cool. The radiator is actually for a big block and with an electric fan, the engine runs as cool as a witch's tit. (About 180 degrees on the engine temperature gauge, although I know this temperature reading may not be accurate, and also, on my ZZ4 I had to install the temperature gauge on the intake manifold next to the thermostat housing, not in the cylinder head due to fitment problems.)

Am I getting into too much detail here??? You know, ask some people the time of day, and they'll tell you how to design a watch. Yes drill the thermostat housing and install a bleeder plug. Somewhere in the early 70's (?) there was a Corvette thermostat housing that had a hole on the top to screw in a thermostat sensor the for smog system. This would be an option also.
 
Last edited:
IMO, it don't matter, as the system is closed and the water level is over any area of the engine that needs cooling, IE the heads first and foremost....

so it pumps up and over a hill, so what??

:twitch::thumbs:
 
68/70Vette said:
Noticed that too. On my 68, the top of the thermostat appears to be the tallest thing in the system. I decided to drill a hole in the thermostat top and tap it with a plug. To make sure I drilled the hole at 90 degrees and did a good job, I went and bought a drill press!! Bought a Sears that maybe cost $170. Drilled the hole, tapped it for an aluminum pipe thread plug. When I loaded my engine with coolant (a mint never wetted ZZ4), I filled it until coolant bleed out of the opening.
.......................

My thermostat housing is a Billet Specialties housing with a 45 degree neck. The Billet Specialties aluminum housing is horribly constricted inside. I would imagine that this could cause some real heating problems that people wouldn't guess was due to a thermostat housing constriction. I ground out the interior restriction. I probably doubled the interior opening. Now..how many people do you know that have ported a thermostat housing???

Also.......I have a Be Cool radiator in the 68, and the radiator has a radiator cap opening for a...you guessed it...a radiator cap. Or a 68 Corvette you don't want a radiator with a radiator cap. The overflow tank on a 68 (Ok,OK is it the expansion tank?, can't keep it straight) has the radiator cap for the system. For the Be Cool radiator, I used my Dremel disk cutter to remove the radiator cap spring so it just became a rubber gasket sealed cap. Now the radiator cap on the overflow/expansion tank works like a stock cap and the radiator cap on the radiator just seals the hole in the radiator.

Also, I could go on and tell what I use for radiator coolant, but this just causes a lot of controversy. Lets just say I don't have a heating problem with the 68. It runs cool. The radiator is actually for a big block and with an electric fan, the engine runs as cool as a witch's tit. (About 180 degrees on the engine temperature gauge, although I know this temperature reading may not be accurate, and also, on my ZZ4 I had to install the temperature gauge on the intake manifold next to the thermostat housing, not in the cylinder head due to fitment problems.)

Am I getting into too much detail here??? You know, ask some people the time of day, and they'll tell you how to design a watch. Yes drill the thermostat housing and install a bleeder plug. Somewhere in the early 70's (?) there was a Corvette thermostat housing that had a hole on the top to screw in a thermostat sensor the for smog system. This would be an option also.
Click to expand...

Interesting, is the fluid level in the expansion tank higher than the thermostat?
 
Mercedes and BMW have a little bleed valve, similar to a brake bleeder, beside the tstat forever, same deal, higher than the radiator and the recovery/expansion tank pressure cap. Other mid engine exotics also have a bleeder on the remote (front) radiator.
As Gene said, it's a closed system, so the pump will eventually force all the air to the radiator and then to the recovery tank. Then the system will only suck back coolant and not air and the top hose and housing will stay full of coolant.
The bleed valve is used to solve the problem immediately and until a BMW is driven for a while and a few hot/cold cycles, it will often overheat if it is not bled first.

You can use the tstat housing from an emissions chevy that already has threaded ports in the housing for sensors.
You can also buy block off caps in place of a radiator cap.
 
i bought my thermostat cover at oreillys for $8.00 and it has 2 threaded holes with plugs in it already. it's a thick aluminum high quality piece. i unscrew one of the plugs to get air out and add water.
100_1622.jpg
 
You must log in or register to reply here.

Latest posts

Back
Top