be sure you are not over filling your radiator. Full cold level is just above the top of the tubes.
I run an original 50+ year old radiator 180 thermostat and a 7 lb cap. Runs just above 180 all of the time.
never pukes any coolant.
if you have an overflow hose on it and are getting coolant on top of the radiator you must have a leak between the cap and the top of the radiator.
factory cap was 13 lb.

 

I have an overflow tank and the level is staying right between cold and hot after driving. It may be a tad overfull so I’ll check it when cool in the morning. Thx!

 

I think Father Brown needs to be called in.

 

Just an anecdote, I have sworn off buying ANYTHING ever again that says "Mr.Gasket" on it. Period.

 

Try a Stant cap from pep boys.

 

I swapped my coolant today and took the family out for the first drive of the season.

Once at home, I saw a little puddle from under the car and went to inspect. I found a small drip from the radiator cap which was pooling coolant in the lip of the radiator. Once I cleaned that up, it made a high pitch demonic pressure sound. The cap was new last year, I think Mr. Gasket brand (cant remember) and is a 15 lb.

Do I hire a priest to exorcise the evil from it? Possible this cap went bad already?!

Otherwise it was a successful first trip of the year.

Two videos below. Dunno why the first wont load in the thread but whatever....

- YouTube

Enjoy the videos and music you love, upload original content, and share it all with friends, family, and the world on YouTube.

youtube.com

Obligatory first pic of the season from Ghost Isle Brewery in New Buffalo Michigan.
View attachment 890386

looking at the video you posted it looks like the over flow tube to the top is leaking.
resolder the tube to the cap receiver.

 

There are actually two seals on the cap. The lower one seals the radiator. The upper one seals the cap to the upper radiator lip so anything that leaks past the lower seal goes out the overflow hose. Check the sealing faces of the radiator, don't overfill the radiator and buy a new cap. (They don't last forever.)

I bought a new cap once. It only had a good seal on the bottom and leaked like a sieve on the top from the get go.

 

Take a 6 inch and a 12 inch ratchet extension and tape them together like a cross. Carefully move towards the cap. If the screaming gets louder, you need a priest...

 

It's possible your leak is the tube connection to the radiator fill neck coming from the expansion tank. The noise could be the valve in the cap vibrating as coolant is being pulled back into the radiator as it cools.

 

Had to add a clamp to my overflow hose to stop a leak like that.
I guess I could drill out the passage into the overflow tank to make it larger, thus less pressure.

 

Thanks for all the help. The rad fluid level dropped overnight to about 1/2”-3/4” below the lower lip opening. Here’s a pic of the cap also. No rubber seal for the upper lip.

 

There's your problem. No rubber seal on the upper lip.

 

I also just pulled some more fluid out of it so now the level is just above the cores and about an inch exactly from the lower lip. We’ll see how that works.

 

It should have a seal on top like this one.

 

Well, now that’s dumb isn’t it. Wtf? Time to go shopping.

 

If you have the coolant at the correct level it will never loose any coolant. I have run them with the cap barely on and they dont leak. I have never had a cap with a rubber seal on the top. anything that leaks past the bottom seal is supposed to go out the overflow tube. The fact that you have added a recovery bottle and the level in the radiator is now low tells me there is a leak in the over flow line. and the coolant dripping in your video is most likely the source of the leak.
the leak may be the hose to the nipple or the nipple leaks at the neck.

 

You have the wrong cap for use with an overflow tank. You need a cap designed for coolant recovery.

 

What does said type of cap look like?

 

I think yesterday it was overfull and coming from under the cap and not overflow nipple. It worked perfectly fine last year pushing/pulling fluid as needed from the tank. The only change was me swapping fluid yesterday and probably putting too much in it. I’ll see how it does after sucking the level down.

 

Like the one you had but with the top seal, the metal check valve lets fluid flow back into the rad under vac when it cools down. kip

 

It looks like the one in answer #15

 

Went to my local speed shop at lunch who sold me the original cap. He agreed there should have been a gasket there and neither of us can sort how it would have "fallen off" so figure it didn't have one since new and we both missed it. Either way, he gave me a nicer quality cap with a gasket for no charge. Local cruise-in tomorrow night so I'll see how it goes.

Thanks everyone!

 

Went to my local speed shop at lunch who sold me the original cap. He agreed there should have been a gasket there and neither of us can sort how it would have "fallen off" so figure it didn't have one since new and we both missed it. Either way, he gave me a nicer quality cap with a gasket for no charge. Local cruise-in tomorrow night so I'll see how it goes.

Thanks everyone!

So where is our local speed shop?

 

"Local Speed Shop" for "Ricers" is the AutoZone sticker aisle...

 

These places are drying up out there. Sad, but happy to see ours still going.

 

I had a faulty radiator cap take me out of a auto cross event just 2 weeks ago!
The spring had lost tension and was not holding enough pressure for when the car was under load, hot, and spinning to 6,500 RPM.
Borrowed a cap from another racer after the event to run some practice laps and sure enough it was just the cap that caused all my problems.
From now on checking the spring pressure will be on my pre race check list!
I think a good cap will fix your problems!