Can I make the M42 radiator self-bleed?

[iamsam]

I see everyone going through hell to bleed the air out of the coolant on their M42s, and i heard somewhere that the M20 has a self-bleeding system, where all you have to to is rev the engine and the coolant is continually self-bleeding, so you never get any air bubbles in the system, causing a bouncing temp gauge.

Can you somehow make it so that the M42 does that?

So i thought of something, and i am not sure if it will work or not. What if i was to get rid of the bleed screw and somehow attach a fitting in its place with a small teflon tube and run the tube back into the coolant reservoir? (see image below)



What would happen? as the engine runs, the coolant (and air bubbles) would continuously run through the tube from the bleed hole back into the reservoir. No coolant would be lost, but would that screw up the system? would that prevent coolant from flowing through the radiator?

[iamsam]

bumpity bump-bump. I edited the first post.

[Julien]

no. and no to your assumption about m20s.

[iamsam]

M20s don't have a self-bleed system? and why don't you think my idea will work?

[lennon]

bleeding doesnt work like that.

no the m20 system is not "self bleeding", there is a bleed screw on the thermostat. you should have no trouble bleeding your stock m42 system unless something else is wrong.

[iamsam]

how can a system be closed and self-bleed itself?

no the m20 system is not "self bleeding", there is a bleed screw on the thermostat.

well the theory is that i want to get the air bubbles out of the coolant stream from the upper coolant hose (via the bleed hole) and vent the bubbles into the airspace inside the expansion tank.

So no, the air does not leave the complete system, but becomes isolated in the airspace in the expansion tank.

does that make sense? its just a theory, i want to explore into it a bit more...

[lennon]

i understand your theory. i just dont see the need for such a system. once the coolant has been bled of air, it should stay that way. its not like air is constantly entering the system and needing to be removed...

[iamsam]

i understand your theory. i just dont see the need for such a system. once the coolant has been bled of air, it should stay that way. its not like air is constantly entering the system and needing to be removed...

true, true. its just that for the past several months i have been wrestling with my cooling system (i think everything is finally working now), and in the process I have changed the t-stat about 5 times (3 different t-stats), changed the water pump, flushed the coolant, pulled out the radiator to bring it to a shop to get cleaned out, and replaced both coolant sensors at separate times.

All together, that adds up to about 10 separate times i had to bleed the system, and it is a pain in the ass because coolant gets everywhere, and i have to hose off the driveway every time.

So If i did a one-time install of a self-bleed system, every time i did any sort of maintenance to the cooling system i could just fill it back up, bolt everything together, and let the system bleed itself just by running the car.

[rThor432]

If everything is working properly, there is no need for you to add a "self-bleeding" system. Dont over think this, it's just a cooling system on a 20 year old car.

[iamsam]

If everything is working properly, there is no need for you to add a "self-bleeding" system. Dont over think this, it's just a cooling system on a 20 year old car.

true, but every time you open the cooling system (take out water pump, t-stat, sensors, radiator, etc) you have to bleed the system.

Sure, this system will be operating continuously, even though it doesn't need to be, but i guess the amount that i have been taking the cooling system apart i wish i had a self-bleeding system.

Perhaps a better idea would be simply to install a "bleed nipple" where the bleeder screw is, kind of like the ones on the brake calipers, with a hose attached to it that you can simply place in the expansion tank when you take the coolant cap off, so that when you do have to bleed the system, you can take the cap off the expansion tank, loosen the bleed nipple, put the hose into the tank, and bleed the system without losing any coolant or making a mess.

heck, that would be a far easier solution. I'll do that and make a writeup.

[rThor432]

true, but every time you open the cooling system (take out water pump, t-stat, sensors, radiator, etc) you have to bleed the system.

Yeah, I know.. I did it once too. I bleed cooling systems all the time and havent ever thought that a system like this would make any sense. The stock setup works just fine.. And bleeding a cooling system takes what, 20 minutes tops if it wants to be a complete bitch?

Just do it, should be fun to look at anyway.

[iamsam]

i'll do the bleed nipple/hose idea, it will be super easy and cheap, and then i won't have to deal with a mess or loss of coolant.

A nipple should be easy to find on McMaster-Carr. Ok, no snide remarks... ;)