Radiator leak= me dumbfounded

[vtach]

Okay, my bobbed truck never overheats (according to the gauge), but it leaks coolant out through the overflow tube. Its not a lot, but I can find small spots under the truck. I can also see some spray on the bottom of the motor. I gave traced this to the overflow tube. I have cleaned the radiator neck out, tried 3 different caps (1 brand new), all with the same leak.
Any ideas?

 

[dlawbrey]

If you fill it all the way to to top and then run it the collant naturally heats and expands. It has to go someplace which is the overfow. Don't top it off and then run it, bet it stops.

 

[FMJ]

I had a the same prob, the filler neck had a defect around the overflow inlet. It was a raised area that did not allow the gasket on the bottom of the cap to seal completely against the surface on the inside of the filler neck

 

[vtach]

So if in fact this is the problem, is there a way to fix this? I will examine the neck tomorrow.

 

[FMJ]

So if in fact this is the problem, is there a way to fix this? I will examine the neck tomorrow.

I used a brass drift, and a small hammer to remove/flatten the raised area.

 

[BEASTMASTER]

don't overfill it. if antifreeze is in the radiator neck there's enough in it. it will spit out what it doesn't want and leave it like that.

 

[Lex_Ordo]

Yes, my M35A2 does the same thing. I replaced all the hoses, thermostat, and radiator when I first took delivery back in October '08. Flushed the system with fresh water, drained and replaced all the antifreeze. To this day, the coolant is still sitting in the neck, and I still get the slight overflow from time to time.

Remember this.
Coolant, and blood are similar in that the smallest amount looks like a lot more than there actually is. It is both the color and consistency.

The truck is finding its natural bablance. This is why you should check both you coolant and Master cylinder once every coupple of weeks.