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Batwood
06-01-2013, 11:33 AM
My buddy is having a coolant issue on his car. After a long WOT pull, the car will puke coolant from the overflow cap. Its been properly bled a few times and there shouldn't be any air or other issues causing it (unless his headgasket decided to go).

Its a 4.6 DOHC with the overflow mounted at least a foot lower than the vent cap for the coolant crossover. Low enough that when you remove the overflow cap, it just fills up the jug and leaks out on the ground. Add to that, the fact that its the size of a pop can.

In general, you want your overflow mounted above or at least at the same level as the rest of your coolant system, right? On most cars, the overflow cap is level with or higher than the radiator cap or other vent plugs on the motor... yes?

Can it even function properly as an overflow if its low enough to be filled by gravity from the motor?
It just seems strange and hes having lots of problems.

Deimos
06-01-2013, 04:44 PM
Drain coolant and hook up the old smoke machine to a vacuum port or rad cap.

Batwood
06-01-2013, 05:05 PM
Its been bled and tested.

Deimos
06-01-2013, 05:41 PM
Only trust the tests you perform as to not overlook something.

AutoMods
06-01-2013, 11:09 PM
probably several different types of systems out there. .. but I think the main radiator cap is what needs to generally be at the highest point . the overflow tank does not. overflow tank is not pressurized. overflow should not get any coolant unless the radiator cap opens to let excess coolant temporarily go into the overflow while hot.

http://www.howstuffworks.com/how-does-radiator-cap-work.htm

TbTalon94
06-01-2013, 11:29 PM
I had a problem with my DSM puking coolant all the time. Had my coolant overflow tucked down nice on my tranny. Figured it out and moved it up above the cap and never had a problem again. It's worth a try.

Batwood
06-02-2013, 07:25 AM
probably several different types of systems out there. .. but I think the main radiator cap is what needs to generally be at the highest point . the overflow tank does not. overflow tank is not pressurized. overflow should not get any coolant unless the radiator cap opens to let excess coolant temporarily go into the overflow while hot.

http://www.howstuffworks.com/how-does-radiator-cap-work.htm

There is no other cap, just the vent plug.

And thanks Trevor. Good to know.

sparkles
06-02-2013, 08:17 AM
Because Ford