Top 10 1999 Cadillac DeVille Questions & Answers

The engine coolant temperature sensor is located on the driver side of the engine near the rear of the engine compartment

my husband did everything that everyone else did that had this overheating problem. It was so weird that my engine cooled at a light and heated up going down the road. I have a north star 4.6 engine and this is natorious for happening. my check engine light also came on and so I had a diagnostics done which told me my #1 injector wasn't firing , car ran like **** as well. After putting in a new water pump and plugs,ect. and realized injector was good a friend told him we could have a blown head gasket. So just to see if this was the problem I went to buy a bottle of glassbeads and the auto parts guy told us to purchase a bottle of BARS STOP LEAK BLOCK SEALER NOT RADIATOR BUT BLOCK SEALER $31.99 . He followed the directions and we waited 24 hrs. before driving it. What ever the problem was has stopped my car runs like brand new and I am loving it again. no over heating no injector problem, runs great.......I hope this helps. I know its probly a temperary fix but its a fix and now we know what the problem was. SASSY

There is no need to bleed air out of the system as the Northstar is self purging.

If you are having overheating problems the most common overheating problem with the Northstar engine is a blocked purge line. It's job is to purge air out of the cooling system.
There is a small diameter hose coming from near the top of the coolant tank(Not the cap!),this is the purge line.
With the engine idling,pull the purge line from the tank,if there is no coolant flow from this small hose,it is blocked and this will cause overheating.If the hose is clear, check for blockage at the nipple on the tank.

Air locks in the Northstar engine shouldn't be a problem as the system is self purging, given that all hoses are clear.

my caddy is running hot and i want to replace the head gaskets but i need to know how to set the timing

Rear of the vehicle by the fuel tank...by the frame rail:



Disconnect the fuel feed pipe (1) at the in-line fuel filter and return pipe (2) near the in-line fuel filter



Squeeze the plastic tabs of male end connector of fuel filter

I had the same problem. The mechanic could not get the compressor to take in new freon. It has to do with the car's memory. You have to reset it by disconnecting the hot wire from the battery which for thirty seconds. This resets the cars internal memory, so it won't remember that it's out of freon. Reconnect it turn on the car and turn on the air the compressor will start.

Northstar belt routing diagram.
This diagram should also be on top of your engine somewhere, usually on the plastic cover on the radiator.

One is in the trunk on the driver side be hind the rear seat. Second is under the hood on the driver side by the air filter..

Hello,

Here is detailed solution on how to replace the heater core in the 1999 cadillac deville;



STEP 1 Disconnect the negative battery cable.


STEP 2. Drain and recycle the engine coolant.

STEP 3. Disconnect the heater core hoses using tool J-37097 or an equivalent.

STEP 4. Remove the right side sound insulator and the glove box module.


STEP 5 Remove the programmer shield, if equipped, and disconnect the air mix valve link.

STEP 6 Disconnect the programmer vacuum and electrical connectors.

STEP 7 Remove the heater core cover, leaving the programmer attached.


STEP 8 Remove the heater core retaining screws and the heater core.



have a nice day..

Make sure your engine is breathing properly, by regularly changing air filters. Flush your cooling system once each year and pressure test. There are cooling lines that cross over the rear of the engine that get corroded and may begin to weep antifreeze..you can view these lines by removing the engine cover....if you've had a consistent odor of antifreeze after running,with no drippage evident, this area is probably the culprit.....love my 99...