Radiator Cap Leaking

[cv2065]

Was getting ready for a maiden voyage today and noticed that the radiator cap was leaking as the engine approached operating temp at 180-185. This is your standard 16lb cap that came with the kit and I have the Boig cool tube upper radiator tube with the built in fill reservoir. I thought maybe the cap was bad so replaced it with another one and I'm still getting the same thing. I don't see any issues with the filler cap area.

Radiator is filled with the standard Prestone 50/50 premixed and I filled the system with the wheels up to remove any air pockets. I don't recall seeing this on my first start and warm ups a few weeks back. Any ideas why the caps might be getting too much pressure?

[Mike.Bray]

Might find some ideas in this thread.

https://thefactoryfiveforum.com/showthread.php?51426-Leaking-Radiator-Cap

[cv2065]

Might find some ideas in this thread.

https://thefactoryfiveforum.com/showthread.php?51426-Leaking-Radiator-Cap

Thanks Mike. I think Rich may have hit it on the head in that thread. The only thing I changed out since first start was having the overflow tank powder coated. I filled it about half way after reinstallation and it purged out a little bit the other day when I was working on the timing. Looking at it cold it's about halfway full. I'm going to take some of the fluid out to about 1/3rd full and see what happens.

Edit: Just reduced the overflow to 1/3rd full and all is well. Thanks Mike/Rich!

[rich grsc]

Glad it's working

[cv2065]

Thought I had this issue sorted, but am starting to get leaks again out of the cap. I changed out the cap with another 16lb vented cap and same thing. I get to about 160 degrees and it starts dripping. Because this started when I pulled the overflow tank to have it powder coated, I'm thinking that maybe I introduced air into the system and need to burb it again? I never drained the system, just tied up the tube and reinstalled.

I thought that maybe the t-filler edges are not sealing against the cap correctly, but that would have happened from jump. Checked the overflow tube and it seems to be clear. The tank has a puke tube so it's vented to air and is not pressurized.

Anything else I should check?

[RJD]

Check where the overflow tube attaches. I had a polishing bead stuck in there.


221608

221609

[cv2065]

Check where the overflow tube attaches. I had a polishing bead stuck in there.


221608

221609

Saw that. What a crazy find! I think I have some air and will use the funnel method tomorrow and see what we get.