Issue with coolant

Need to find out where the coolant is leaking out. Low coolant level can cause these issues. Do pressure test on cooling system to find the leak. Small inspection mirror comes in handy while looking for the leak. If the weep hole on the water pump shows any signs of leaking replace water pump and therm.

Radiator cap or thermostat. If the cap can't hold sufficient pressure (about 15-16 lbs) then it is allowing coolant to flow into the overflow bottle needlessly. If you have a stuck thermostat it is allowing the car to run too hot, again causing coolant to expand and overflow into the reservoir bottle. Hopefully replacing one (or both) of those items fixes your problem, and it's not something serious like a gasket issue in the engine.

I've been fighting months on my DeVille with leak after leak and car overheating.firat thing mechanic told me WAS head gasket. I panicked. Before u panic when someone says must b gasket FIRST go to AutoZone, rent a tool that u put down in overflow, car running,add liquid u have to buy, ifs liquid turns yellow means YES u do have the head gasket issue But if the liquid stays blue u DO Not have a blown gasket. I did this test 4 times to make sure it kept giving same answer I have all problems that points to gasket Check that first It is 25.0 0 to rent that test apparatus take back full refund.just liquid u do have to buy

Regarding the thermostat issue yes if the thermostat is stuck or blocked that blocks water to flow through correctly

How can you resolve thermostat being nlocked

Replace a bad thermostat.

have a 2002 Deville caddy 5.7 L CHECK COOLANT LEVEL light keeps coming on. I had pressure test new water pump new thermostat installed flushed system. Everything checked out fine 2 days later light keeps coming on . The tank has a sensor but I can't find it. Is it in the reservoir or below it ?

Northstar engines are notorious for leaking head gaskets due to a bad head bolt design.

My temp is normal and coolant level normal but check coolant level keeps coming on. Had head pressure test normal new thermostat new water pump. Only thing left is to change coolant tank reservoir. My question is where is the tank sensor inside or on the bottom of reservoir ?

Unplug at the bottom of tank.take a wire and jump the plug.warning light will go out.But you need to check your coolant level yourself after that.I bought a new tank and it still said same thing so I jumped it out

Put new water pump thermostat radiator overflow bottle and still overheats and does not have blown head gasket doesn't lose water but gets hot what could it be please help I have to North stars going it what could be the problem I do not have any head gasket I have checked no water in the oil still overheat fans come on everything replaced them still you're taught after about a half hour

I have a 2000 Cadillac Deville. Will a low coolant reading shut down the alternator from charging the battery because that's what happened to me.

@Timmy6641: no

Check your surge tank return lines for blockage!!! These lines get blocked cause the vehicle to overheat then blow a head obviously water pump,thermostat are good and there is coolant in system!

Refer to youtube under cadillac overheating Star Gaimazz. Was having overheating problem and this method works. My car no longer overheats

I'm not a GM tech but my understanding is Northstard don't leak antifreeze into the oil. You could have a blown gasket if your idle is rough on startup and you can't keep the level of antifreeze up. Still not a nail in the coffin so best bet is rent the tool and check for combustion gas in your coolant system. If your just leaking coolant and can't find a source add some bars no leak (pills are the best). GM may still carry them but I don't know if there is a difference and oddly enough in the service bulletin have even recommended when you change a major component..

My 2000 Cadillac has been down for a year and a half , it was over heating and i replaced everything possible for circulation and coolant pump etc. Remembered i didnt have this problem untol i changed my alternator, low and behold a yr plus later i tare it back down to the alternator and take first coolant hose off and notice the back hoes was completely kinked cutting circulation off ,,, im replacing it in the morning with 2 new elbow hoses and im almost positive this was yhe problem the whole damn time !!! Wish me luck ,, circulation is critical on these motors..

had the same issue with my car having overheating problems so I had a mechanic look at it you took the line out cleaned it out and it was run in front up until I found out that the coolant I was using was recalled for Cadillac DeVille the same coolant that's in the manual that I was buying a gunked your system up and that's where the overheating starts .I know what the line looks like in my 1998 Cadillac DeVille looks like that is clogged it's a long skinny line there was a lawsuit on this antifreeze and they also tried to sue Cadillac but they couldn't if u have your Manuel and u are using the antifreeze from Manuel dont

@pell726 what is the name of the original coolant in the manual you was using ? & what are you using now? And can you upload the line you are talking about that was blocked

My parents gave me their 1999 Seville because of the overheating issue. After many attempts I removed the return line from the reservoir that runs across the valve cover and goes down into the thermostat ,housing unit. It was occluded . I blew it out with the air compressor and put it together. I added 50/50 silicate free antifreeze. My engine doesn't get over 196 and it runs like a kitten. The return line from the reservoir is fairly small in diameter and bends in multiple places. When you add pellets it has the potential to clog. Hope this tid bit of information helps.

1969 DeVille coup battery capacity amps?

775 Cold Cranking Amps (CCA). Group size 34. Hope that helps! Jim