1989 deville slow overheat
 

ok, im new, just registered. got my father caddy after he passed. and it was overheating for him, well he didnt know for sure.

anyways i took it to the mechanic to check the system at the same time as the safety, and said it was working fine, thermostat coming on when it should fans working as they should. passed the pressure and leak tests.

so after driving it longer than usual it starts to overheat, the coolant is shooting into the overflow boiling hot. level is right up to the top. tried changing the cap, to no avail. which was my last ditch effort to not have to rip the whole thing down, as in the rad and waterpump.

anyways first planning on checking the rad, what kind of tests are there to see if its clogged up, in one of these hanyes manuals it says to put a hose down the upper part of the rad, and see if water flows from the top of the engine.

also with the waterpump, gonna remove the belt and replace it, but it seems to be working fine?

the heater core was recently replaced last year or so

WOW, long post

anyway thanks

Overheating
 

Some things to check as well would be heat riser valve frozen closed, make sure timing is bang on, plugged cat converter, is the front of the rad free of bugs and dirt?? A good rad flush would work wonders I'm sure but you may have to replace anyway. Is it the Olds engine?? Post some pics if you can.

heat riser valve never heard of that before, gonna have to find out what it is. its a 4.5 liter. if i doesnt rain tomorrow, i wanna at least drain the coolant, and remove the rad. i will try to take pics if i remember my phone.

thats the dumb thing, theres no gauge just a light. so i cant see what its doing. if it over heats a few times, i shouldnt damage the engine right? i only drive it long enough to get it off the road.