I have a 91 305 tpi.

Last year I replaced the radiator, thermostat and water pump.

It boils coolant after a drive, kinda smells like burnt coolant, but doesn't smoke any from the exhaust. The temp gauge seems wildly inaccurate, it will be pinned one moment, then fly back down the around 230 within a second. Mechanics looked at it last year after I worked on it and said it was running hot, but not overheating hot.

I'm about to bust it open and do the headgasket, wondering if you guys had anything to say that would make me think it's something else.

Appreciate any helps guys. Thanks.

 

Have you pressure tested the cooling system yet?
The spikes might be from an air pocket in the engine. Steam can be a lot hotter than boiling water.

 

Thanks for the response. How would I go about checking the system or clearing air pockets in there?

 

I would say air pocket also.

1) Raise the front of the car safely. Probably enough to get front tires just off the ground.
2) Remove radjator cap.
3) Start car & watch for fluid flow when thermostat opens. Be careful-- fluid will be hot!!!
When t-stat opens, it is very possible a " burp " of fluid may gush out the open radiator.
4) Add new coolant as needed to top off. May need to do this a couple times or more.... Until
there are no more " burps ".
5) Let engine cool down & replace the rad cap, or if the cap is old, get a new one.
6) When cooled down very well, rinse radiator & radiator lower mount with water hose to rid any coolant so it will not find its way onto hot engine making it smell bad.

Some ppl will add water from a hose to the radiator, some will get a couple gallons of distilled water to add. IMHO I add distilled.