Antifreeze Overflow Leak

[KolaWonder]

Hello -

I have a 1972 FJ40. It is just starting into warm weather around here. Yesterday I found the the FJ leaked some antifreeze after driving. I am wondering if there is a thermostat adjustment or something that can be made. It is coming from below the radiator somewhere - as I did not see any antifreeze at the cap. It dropped a small puddle and then stopped. Any ideas?

Cheers - KW

 

[65swb45]

Do you have an overflow bottle?

 

[JohnnyC]

do you have an overflow tank added?

 

[73FJ40]

@KolaWonder

My '73 has a thin metal tube attached to the side of the neck to the radiator cap, and runs down the passenger side of radiator.

Fluid flows from the tube to the ground, out of sight if the cap relieves pressure for any reason.

 

[Vandal FJ]

Mine had terrible overheating issues until the overflow tank was added. Problem solved. But it's a newer radiator...

 

[KolaWonder]

@KolaWonder

My '73 has a thin metal tube attached to the side of the neck to the radiator cap, and runs down the passenger side of radiator.

Fluid flows from the tube to the ground, out of sight if the cap relieves pressure for any reason.

So mine has a. rubber overflow tube - no bottle. This drips onto my garage floor. I also just found some under the drivers side tire - not sure what that is about. Is there a way to adjust the thermostat so that this overflow does not occur?

 

[KolaWonder]

Do you have an overflow bottle?

No overflow bottle, can someone recommend one?

 

[65swb45]

You can buy a generic overflow bottle and cage from almost any auto drone store for less than $15. Or you can buy an Uber-cool Toyota bottle and bracket that a MUD vendor has made to fit the FJ40:

VintageTEqParts.com

vintageteqparts.com

 

[73FJ40]

@KolaWonder

If the coolant is leaking from your rubber overflow tube, then an overflow bottle would catch it.

If the coolant is leaking from elsewhere, then the overflow bottle won't catch it.

To double check if leaking is from the rubber overflow tube, it would be best to run the outlet of the tube into a temporary plastic bottle wedged into the engine compartment. You may want to consider a temporary hose instead of dislodging the current hose from its retainers. You really have to confirm whether or not the coolant is coming from this tube or elsewhere.

Note that the coolant may channel along the radiator frame and/or chassis and drip onto the ground somewhere other than directly below the leak.

Also, if you had 'topped off' your coolant by filling the radiator to the top of the neck, the cooling system will naturally spit out excessive coolant upon thermal expansion. "Classic" cooling systems like FJ40's up until the early 1970's relied on the top tank of the radiator to be the "expansion" tank, forcing excess coolant out the overflow to be replaced by air upon the cool-down. After a few cycles, the coolant level reaches an equilibrium.

Your recent hotter-weather driving may have resulted in higher coolant temperatures, causing more expansion, leading to the release of more coolant.

Possible leaks:
1. Hoses or hose-clamped connections
2. Water pump seal (there is a weep-hole in the casting below the water pump shaft that will let coolant drip out if the seal is shot.)
3. Radiator
4. Head gasket

 

[65swb45]

Everything @73FJ40 wrote is true.

An overflow bottle is always a good idea, regardless.

 

[Vandal FJ]

My 350 stopped overheating in the summer pretty much completely with the addition of the overflow tank. Probably should have started with that, then I might not have needed to replace my radiator!

 

[73FJ40]

Later model overflow bottle retrofitted to my 1973. Bottle bracket (and NOS coil, resistor) sourced at http://www.marksoffroad.net/ (thanks @65swb45). New bottle and cap sourced at City Racer LLC (thanks @Racer65).

Note that there is a specific radiator cap intended for overflow bottle systems that may not be the same as the standard cap.

 

[middlecalf]

The only way an overflow bottle would help with overheating is when the overflowed coolant that’s in the bottle is replaced (drawn) back into the radiator upon cooling - if the bottle is set up correctly - rather than dumped on the ground and therefore a low coolant condition develops. It in itself has nothing to do with the cooling function of the cooling system.

 

[KolaWonder]

Thank you everyone! I am going to start with the overflow bottle. Just trying to decide on which one I would like.

 

[73FJ40]

@KolaWonder

Excerpt from the 1973 Owner's Manual regarding fill level for the radiator:

 

[B1oodyBuzzard]

Asking for a friend… did the 72 have a overflow res? I just started searching and I only see retro fits.

 

[73FJ40]

No reservoir on my January 1973.

The overflow tube from the radiator neck ran part way down the passenger side of the radiator, directing overflow to the ground.

 

[B1oodyBuzzard]

thanks