Leaky radiator cap

[signart]

Got a friend in a nearby town, has an Interstate and is suffering a radiator cap leak. He just ordered oem cap and replaced it, but claims it is loose and won't seal. I checked mine and it takes quite an effort to press down and turn to lock, in no way could mine be considered loose. Haven't had a chance to check his yet, but does anyone else have any ideas what could be causing this?

[F6Dave]

Try bending the tabs on the cap very slightly.  My Interstate did that.  I placed the cap on a rag on the workbench, then tapped each tab a bit with a hammer and wooden dowel.  It fit tighter and stopped the leak.

[signart]

I'll let him know, but I think he has tried that with his old cap. He said the new cap is worse than the old one after tinkering.

[Jess from VA]

It can be either the tabs on the cap or the tabs on the radiator neck need tweaked.... carefully.

Also, the set screw on the Show Chrome cap cover can create a leak if too tight. 

[signart]

Yeah, I'll probably have to ride down and take a look. Sounds like it's got to be the lip on the radiator fill since the new oem cap is not sealing. Thanks

[drpete65]

Had the same prob, bending the tabs, nor a new cap helped. The dealer told me I needed a new radiator. I took it to a radiator shop. They filed the fill neck and put a bigger gasket in the cap. 40 bucks and done!!!!

[Ricky-D]

When ever you have a leaky radiator cap, one of

the first things to do is to check the coolant

recovery line for blockage. This can be the

cause of coolant leaking from the cap since

this function of the cap is not a pressure

sealed area but rather only sealed to allow

for capture and recovery of the coolant

during times of heating and cooling of the

radiator.

***

[signart]

Good point.