Radiator cap?

[99Montana]

Hi everyone -
99 Montana - coolant down a little - filled up the radiator and reservoir - let it get up to temp - find out there is a leak - wiped things dry and small leak appears to be coming from the cap.
Do these go bad ? It looks a little slimy.
Factory or aftermarket parts?
Thanks for the help

[GTP Dad]

Welcome to AF!

Yes they do go bad usually the seal around the surface that contact the radiator itself. You can get one from your local parts place or the dealer whichever you perfer.

[cdru]

I would go to the dealer. It's only a few bucks more and is guaranteed to be the correct specs. I found that the aftermarket cap at my local Auto Zone to be more along the lines of a generic model. It fit, but it wasn't a great fit. It also was 1 psi off from what the factory spec called for...I beleive lower then what it was suppose to be.

[99Montana]

OK guys - bought one at the dealer over the weekend - topped off AF - just checked it and it still leaks !!
Any ideas or fixes to this minor but annoying problem ?
Thanks

[gkindub]

99Montana, I have seen my rad cap leak for a day or so after I've removed it. I think the crazy angle of the radiator neck contributes to this by trapping fluid in the upper channels of the cap while its being twisted down. Then the trapped fluid slowly drains out of the channels and appears to be a leak but isn't. My $.02...Check the overflow hose connection at the neck for leakage as well.
Regards, gb

[cdru]

Give it a day or two. Also make sure that the cap isn't on crooked and that both "ears" have be caught.

[99Montana]

yes that is a strange angle !!
no leak at overflow connection and cap on tight.

Is it possible to have a small crack ? I'm looking but can't find one.
Also - I've heard the OEM caps are junk and I should have bought a Stant.
Any thoughts?

[gkindub]

99Montana, I'm still using the OEM cap and have no idea whether the Stant caps are any good, but if you're still leaking somethings probably amiss. Certainly the cheapest and quickest route to go on this is simply to replace the cap if there is nothing visibly wrong w/ the one in place now.
Regards, gb

[pspierce]

I think I also have the same problem. The only thing with mine is that I just finished changing the intake gaskets which if you read about this from other members that this is a very common problem. I wish I had checked out this website sooner! Good Luck!
Steve

[99Montana]

I'm still working on this prob
will post results later...

[Glen_T]

One more thing to check....since the radiator is plastic in that area, I wonder if the sealing face is distorted a bit. You might get some fine emory cloth that is wider than the opening, and glue it to a piece of wood that is very flat. If you sand very lightly and then inspect it, you should see "witness" marks where the neck sealing face was sanded. If the sanding mark is even all the way around, the the flange is surely flat enough to seal. If not, I don't see why you could use this same arrangement to touch it up a little.

I assume you are sure you have the cap all the way on. I only say this because I've only had my cap off once, and I think it took me 5 minutes to get it back on - I could not seem to get it to twist all the way back to where it was supposed to be.

Otherwise, you could have a small crack, but I'd think it would be obvious.....Good luck, Glen

[99Montana]

Originally Posted by 99Montana

I'm still working on this prob
will post results later...

Sorry for the late reply... I know you guys must have been on the edge of your keyboards and losing sleep at night over my problem

Glen, I did use your suggestion (about 8 months ago!) and it looked as if it was distorted. A little sanding revealed a nice smooth even surface. The cap seemed nice and tight after I fought getting it back on... a GREAT angle indeed ... but no leaks!! YEA!!

Thanks again for the help