Cadillac Owners Forum banner

1 - 20 of 31 Posts

·
Registered
Cadillac
Joined
·
103 Posts
Discussion Starter #1
1994 cadillac sts heating up flushed radiator and replaced thermostat and still heating up u think it could be the temp sensor
 
K

·
Guest
Joined
·
0 Posts
Probably a blown headgasket. Time to dump the car. Big big $ to repair:bonkers:
 

·
Registered
2006 STS-V, 95 Sierra Z71
Joined
·
351 Posts
Go buy a block tester from NAPA or rent one from AutoZone. Follow the directions, and post your findings. Check the purge line on your coolant surge tank too, it must be clear.
 

·
Registered
Cadillac
Joined
·
103 Posts
Discussion Starter #4
where exactly is the purge line exactly located and if it is plugged how do u unplug it ,so if that line is blocked could that cause it to overheat
 

·
Administrator
2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
Joined
·
67,976 Posts
The purge line runs from a nipple on the top side of the coolant reservoir to a hollow bolt nipple on the thermostat housing cover. It removes air and gasses from the high point in the cooling system in order to prevent bubbles in the coolant and water pump cavitation. Hundreds upon hundreds of posts on its function and cleaning.
 

·
Registered
Cadillac
Joined
·
103 Posts
Discussion Starter #6
I cant find the thermostat housing cover so i can connect it. can anyone help
 

·
Super Moderator
White Diamond '03 DHS (with DTS floor shift)
Joined
·
86,619 Posts
It's at the engine side of the upper radiator hose.
 

·
Registered
1997 Cadillac STS (BOSE w/AUX In, Massage Seats, URPAS, "Z")
Joined
·
6,405 Posts
Just disconnect that small hose in the top (front) corner of the coolant tank (engine off - and be careful not to brake the coolant tank nipple is pretty fragile). Then put the hose end in a 2l bottle (place it away from the accessory belt but with in the hose reach) and turn on the engine (idle). You should have a steady laminar flow (no bubbles and such) with a debit of about 1/2 litters a minute. If no flow or very slow flow then the line is plugged (follow the hose and then the metal duct until goes into the housing). If flow with bubbles then likely that is exhaust gas entering into the cooling system (head gaskets).
 

·
Registered
Cadillac
Joined
·
103 Posts
Discussion Starter #9
where exactly is the purge line on a 1994 cadillac sts

is it the line right by the radiator cap if it is where does it connect to car is overheating
 

·
Registered
94 Eldorado, and a 99 ETC
Joined
·
3,887 Posts
Re: where exactly is the purge line on a 1994 cadillac sts

It's this one. It travels under the intake plenum to the throttle body then to the water pump crossover. Disconnect it from the surge tank and start the car to check if it's plugged. It should trickle coolant while the engine is running. If it doesn't then it is plugged and is likely the reason for your overheating.


The one right by the radiator cap is the overflow tube. It doesn't connect to anything.
 

·
Registered
Cadillac
Joined
·
103 Posts
Discussion Starter #11
Re: where exactly is the purge line on a 1994 cadillac sts

ok purge line ok it is clear u think it might be water pump or rad that is causing the overheating
 

·
Registered
1997 Cadillac STS (BOSE w/AUX In, Massage Seats, URPAS, "Z")
Joined
·
6,405 Posts
Radiator unless has lots of passages clogged or is covered or coated with a layer of heat insulator material can not cause any overheating. If you have normal coolant flowing on the purge line with engine on then the water pump is working. Check your WP belt tension, clean up the front of the radiator (bugs, leafs and other derbies - that would give you maybe 1% better heat transfer). Water pump 99% of the time when is bad starts leaking.
1) Does it heat up when idling in traffic or driving slowly (city) and cools down once you are moving faster (above 30MPH)?
2) Does it heats up on HWY or up the hill?
3) Does it heat up no matter what in the first 5-10 minutes after start up?
4) What is the temperature?


1. Is normal if it does not go above 228*F. If goes consistently beyond that then check your radiator fans.
2. Is bad, is generally sign of head gasket but could be also loose WP belt, clogged purge line or low coolant level. Head gasket can be detected with an exhaust gas test or if coolant level is dropping but no external leaks, idle is rough and has lot of white vapors out the tailpipes.
3. That is a clear indicator of a stuck thermostat.
4. Temperature variations between 194*F and 226*F are normal.
 

·
Registered
Cadillac
Joined
·
103 Posts
Discussion Starter #14
how do u check ur radiator fans and radiator or could it be heat sensor if it was heat sensor i would have a service light on right
 

·
Registered
1997 Cadillac STS (BOSE w/AUX In, Massage Seats, URPAS, "Z")
Joined
·
6,405 Posts
Moezy, witch one of the situations applies to you?
There are 2-temperature thresholds that dictate the fan speed. At normal coolant temperature both fans spin on low speed (are connected in serial connection so each fan see ~6V DC). At 224*F the PCM switches the fans on high speed (are connected in parallel rather than serial so each fan operates on 12V DC). The fans should work with the A/C on regardless of the coolant temperature.

No lights for fans...
 

·
Super Moderator
White Diamond '03 DHS (with DTS floor shift)
Joined
·
86,619 Posts
Re: where exactly is the purge line on a 1994 cadillac sts

It's not the water pump. Unless it is leaking, it's fine. Do or have a block test done to check for exhaust gases in the surge tank.

Define overheating.
 

·
Registered
Cadillac
Joined
·
103 Posts
Discussion Starter #17 (Edited)
its going up to 260 then a light comes on stop engine i just noticed a slow drip around the water pump i am not sure if it is coming from the waterpump going to have a mechanic look at it tomorrow how long does it usually take to replace waterpump
 

·
Administrator
2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
Joined
·
67,976 Posts
its going up to 260 then a light comes on stop engine i just noticed a slow drip around the water pump i am not sure if it is coming from the waterpump going to have a mechanic look at it tomorrow how long does it usually take to replace waterpump
2 hours and $200.
 

·
Administrator
2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
Joined
·
67,976 Posts
This applies only to Northstar equipped cars correct? I have a 4.9 that overheats while idling.
If your 4.9 has one or two electric fans just behind the radiator, you need to begin checking fan fuses and relays. Locations are either on the diagram in the (underhood) fuse box top or owner's manual.
 
1 - 20 of 31 Posts
Top