My 2003 STR has a leak somewhere around the radiator or under the expansion tank. Coolant leaks, I can smell it and see the steam around the radiator but there's nothing dripping on the ground. Its obviously a very small leak, but I'm just curious if this happened to anyone else. Trying to determine where to start looking as I take it apart.

It leaves very visible orange stains so I'd poke a borescope around and look.

Try a pressure test, you will see the leak.

Borescope, great idea thanks! Much easier than taking it all apart.

I will do this in combination with the boroscope. Thanks. I'm thinking radiator.

Also check the tightness of the hose connectors.

Expansion tank prone to leak at the base of the overflow nipple. Can't say for the V-8's, but 3.0L radiators are prone to leak at the plastic tank seam, right hand side, aft (engine bay side) about 3/4 of the way down from the top.


From the experience I have made, with a 2003, if your radiator is original, you are about 2-3 years beyond the expected failure point. You should also not be surprised if you are on the 2nd or 3rd expansion tank and it is the culprit. These will all seem minor niggles once your under-super-charger hose springs a leak. Depending where you find the current leak, you may want to consider a complete hose-renewal, including DCCV and under supercharger hose. It'll be expensive... and total B...(itter ex-wife) to complete.... but the 4.2L doesn't suffer overheating well...

Sometimes smell is just fluid that was not washed off after servicing it. I would rinse the area well with a low pressure hose and cover and avoid wiring as much as possible. And it does not come off really quick, you might have to do it a couple times.
If you do have an actual leak then you should be rinsing the area anyways because its nasty stuff.
Remember low low low pressure not high pressure

Probably a heater hose. I have had 3 separate pin hole leaks in hoses over the years. Just plan to change your hoses. All of them! There are about 22 coolant hoses on an STR and they all need to be replaced.

The one under the super charger is the worst!
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