Coolant overflow height question

[olmytsi]

All,

I've been running my stock overflow relocated to the stock sidemount location since late 2004.

Lately, I've been pushing coolant out of the overflow just cruising around, car doesn't overheat but I need to top it off a lil bit (maybe a cup) everytime I drive it (which is once or twice a week).

2 days ago, I raised it a bit (still in the sidemount location but higher up), filled it up (it was low) and I rerouted the hose going to the water neck and it seems to be holding the level.

I just wanted to know if having it so low can affect the system's ability to suck back the water in or maintain level.

It's been working fine since 2004 but who knows...

Radiator is new as of earlier this year, and so is the rad cap.

Thanks,

T

 

[kthackst]

How low was the overflow before? Can you add pictures?

A pin hole in the headgasket can prevent the system from pulling coolant back in.
A bad radiator cap can also prevent a system from pulling coolant back in.

I suggest a leakdown test just to rule out headgasket. Dont worry about the numbers but just apply 75-90psi at TDC for each cylinder while looking for bubbles in the coolant.

 

[19Eclipse90]

Remember that the system isn't "sucking" anything.

Basically, coolant is pushed into the overflow reservoir when it heats up and expands. Atmospheric pressure pushes the coolant from the reservoir back into the cooling system when the coolant cools and condenses.

Though atmospheric pressure differs with elevation, the difference in pressure at elevations only inches apart is negligible. So to answer your question, the install height of the overflow is a non-factor.

 

[ed1380]

And when you're sucking through a straw, you're not sucking. You're just creating lower pressure and atmospheric pressure pushes the drink up

 

[olmytsi]

I think I may have a HG issue cause it's still dumpin some water out although it runs really cool and pulls great.

Leakdown and comp test are in order

Thanks guys!

 

[nek]

And when you're sucking through a straw, you're not sucking. You're just creating lower pressure and atmospheric pressure pushes the drink up

Just what I was about to say. Sorry wiseman.....

 

[olmytsi]

Just to update, I pulled the head on feb 15, the HG was done for, had the head ported and stuff and put it back together on feb 26. So far, I have driven it 3 times and all seems well. The boost is set at 18 for now, I wanna play with the tune at that level and then eventually raise it and see what kind of airflow gains I see from the headwork.