Temp Gauge on RED and coolant boiling over

[ScottinNJ]

Hello all: Last night, while driving home, the temp gauge on the dash was red. I pulled over to find that coolant was boiling out of the overflow reservior. The water pump was replaced by the prior owner, and no hoses appear broken. In reading the posts, it appears that it could be the thermostat, radiator cap or head gasket. Any thoughts and advice are much appreciated. Cheers.
P.S. It's a 1997 RR 4.6

 

[joey]

Easy way to check the radiator cap is change it.

Check head gasket will require a pressure test or chemical test of the antifreeze.

Thermostat easy check is to remove it and see if the issue goes away.

 

[xlgrover]

change the thermostat first. Its the cheapest thing to do. If you see the fluid bubbling in the overflow resevoir, its likely the headgasket.

 

[ScottinNJ]

Thanks for the good advice. I will replace the cap and t-stat and go from there. I will post a follow up in a few. Thanks much. Cheers.

 

[ScottinNJ]

T-stat replacement

Does anyone have any detailed instructions on replacing the t-stat? I have a 97 4.6. Once again, thanks guys.

 

[ScottinNJ]

Follow Up

I got lucky. Bad overflow cap. $25 Fix. Expect the worst & hope for the best. Thank you all for your insight.
Cheers.