Drain valve question

Dean Lemoine

Dean Lemoine

Senior Member
I’m looking for the thread type and size of the radiator drain valve. I’d like to make a radiator level sight glass (actually clear tubing) and install it at the drain valve. Thanks in advance for any information
 
1/8" NPT. Drain valve located on the bottom of the water return pipe on the driver side of your car. If you have some sort of after market radiator with a drain valve, then the thread size may be different.
 
And you can't open the top fill and see the water inside?


Perhaps yours is a "pressurized" system? In which case you'll need both a bottom connection AND an upper connection to the gauge.


Dobbin
 
The top of the tube would have to be open to atmosphere to work, so how are you going to keep water from pushing out? By adding a valve or plug that could be opened? Then you would need to add the drain valve back into the system along with a long snaky line to above the water level in the upper tank.
 
All good points:
It isn’t pressurized
Once the level goes below the baffle, I don’t know where it is
I saw the Snyder product, seems a bit pricy
I’ll leave the drain valve in place
It’s an experiment, if it doesn’t work, I’ll take it off
Thanks for the responses.
 
Do not know if this will work, think it should. Just get some clear tubing that will fit tight over the drain valve outlet, cable tie it or super glue onto the outlet. Cable tie/mount the other open end of the tube somewhere above the full expected level. Open the valve when you want to check, close the valve after you check.


Cost would be for the clear tubing, and a couple of cable ties or superglue.


If you want to drain via the drain valve, cut the cable tie on the high part of teh tube and place the tube below the level of the motor.. Re-cable tie when done.



Mark the tube for full hot, and full cold, the level hot should be higher than when cold, and the cold level should indicate slightly above the radiator core.
 
Why does it have to be a permanent installation? Just stick the hose on the valve, hold it higher than the tank, open valve, check level, close valve, place finger over end of hose, remove hose, drain hose into radiator.
 
Posts # 8 and 9 might on to something, thanks guys. I know everyone says, “let it seek it’s own level”. I agree with that, but I want to know where that is.
 
Dean Lemoine said:
All good points:
It isn’t pressurized
Once the level goes below the baffle, I don’t know where it is
I saw the Snyder product, seems a bit pricy
I’ll leave the drain valve in place
It’s an experiment, if it doesn’t work, I’ll take it off
Thanks for the responses.
Click to expand...

I think this is a brilliant idea, Dean, just to see what you see. Please be sure to report back with some photos after you play with it a while.

At high RPM, if there is any restriction in the radiator tubes at all, you should be able to see the coolant level in this tube go down, compared to the level at low/idle RPM. I'd like to know by how much.

Fun and games!

:D
 
Is there enough space below the baffle to allow one to "carefully" drill a small hole through the baffle so the water level could be seen?
 
That’s a really good idea. There probably is room, but I’d hate to drill a hole through the tank of my brand new radiator. You’ve got me thinking though.
 
Dean Lemoine said:
Posts # 8 and 9 might on to something, thanks guys. I know everyone says, “let it seek it’s own level”. I agree with that, but I want to know where that is.
Click to expand...

Posts 8&9 sounds good, I was thinking Tee into the overfill tube up near the radiator neck, it's open to outside air and above the coolant level, with the lower drain valve open could you keep it open and run the engine ???
 
1crosscut said:
Is there enough space below the baffle to allow one to "carefully" drill a small hole through the baffle so the water level could be seen?
Click to expand...

If you go to a coffee shop, like Starbucks, you can get some small wooden stir sticks. I keep a stack of them on my bench (in a coffee mug) for all kinds of uses.

Use a wooden stir stick as a dip stick, going in through the radiator cap opening at an angle, off to the left or right of the baffle, and touch the bottom of the radiator tank. Now remove the stick and read on it how deep the coolant is above the top of the tubes.

The stick is at an angle, so you need to adjust it a bit in your head to account for that. I mostly do this on a cold engine to confirm I have some coolant above the top of the tubes before I take off.

I have also used a flashlight to look to the right or left of the baffle, then you can see the tubes and judge how much coolant you have above the tubes.

On a cold engine, I shoot for 1/2" above the tubes. On a hot engine, I shoot for having the coolant just at or just below the baffle.

Hope this helps.

But I still want to hear about Dean's experiment. :D

.
 
Here’s what I did, right or wrong. Thanks to all for the ideas and suggestions.
 

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