Radiator overflow bottle

[diverant]

Have an 86 cj7 with the 6 cylinder. I am changing out the radiator and there is not an overflow bottle. Just a hose to nowhere going down by the side of the radiator.

I bought the bottle. Looking at pictures on line it looks to be installed next to the washer fluid but there are not any holes for it?

Do I need it? Did it come without one originally? Or is there another OEM style bottle that gets installed somewhere else?

 

[JPNinPA]

It is needed. As fluid is heated it expands and pressure builds increasing the boiling point. The radiator cap limits the pressure to 16 psi that in turn limits the boiling point. While a higher boiling point sounds good many components will fail at high pressures. As the fluid pushed past the cap it gets caught in the expansion tank until the engine cools and sucks the coolant back into the system. Without the tank you lose the fluid and gain air in the system. Air allows more internal expansion and boiling to occurs at lower pressures.

 

[TLCJ5]

I agree with JPNinPA...You need it.
Many older CJs did not come from the factory with an overflow bottle. I'm not sure about 1986, that may be why you don't have existing mounting holes, but it would be well worth the effort to add one on.

 

[elstx65]

I have an 84 CJ7 and it has an overflow bottle next to the washer fluid bottle.
On that not, the cap on it doesn't snap on. Should I get a cap that works correctly?

 

[JPNinPA]

I have an 84 CJ7 and it has an overflow bottle next to the washer fluid bottle. On that not, the cap on it doesn't snap on. Should I get a cap that works correctly?

the cap keeps dirt out and fluid from evaporating. It might be a good idea to put a cap on it.

 

[TerryMason]

They are on ebay for $30 shipped (new).
jeep cj overflow bottle | eBay

 

[diverant]

Great thank you for advice. I'll drill the holes. The bottle is shaped to go over what I believe is the Ignition Module (?). It looks like an aluminum housing that is pitted pretty bad. Does this part ever go bad? Should I change it before burying it?
It is not a show jeep just a seasonal daily river.

 

[greg92jeepxj]

Not a great place for an ignition module near an overflow . Less likely to happen in a well maintained cooling system but should the radiator back feed coolant to the reserve under substantial pressure and cause any over flow out of the tank , the module gets it. Possible to reroute module without too much wiring harness issues ? Just thinking ahead . After all , it is a jeep and subject to low speed high revving which will cause hotter temperature .

 

[TLCJ5]

I agree with greg92jeepxj. The Ignition Module would normally be mounted on the drivers side fender near the rear of the fender(under/in front of the brake MC).I would expect the overflow bottle to mount closer to the radiator. If I remember right(which only happens on occasion) the washer fluid bottle mounted on the rear side of that fender(near the IgMod).
Maybe somebody with an original "86 could post a picture of the location.

 

[JPNinPA]

If the cap of bottle has a overflow spout run a hose from it to below the radiator and don't worry about it anymore.

PS the expansion or overflow bottle should always have some fluid in it.