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Pete, Cadillac Technician
Category: Cadillac
Satisfied Customers: 28717
Experience:  17 years Cadillac experience as a technician.
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1996 Cadillac DeVille: the 4.6 Northstar engine.I..coolant

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Hi There,
I have a 1996 Cadillac DeVille with the 4.6 Northstar engine.
I Have noticed the car is using coolant.(adding approximately 1 gal. every week or so)
I have pressure tested the system and find no visible external leaks. No drips on the driveway. Pulled the plugs and found no coolant in the cylinders and there is no sweet smell in the exhaust. I also checked the oil dipstick and found no signs that it is entering the crankcase. SO any ideas????????????
Thank You George
Hello,I will be glad to try and assist you with this,Welcome to Just Answer.

Hi George,

Even with no excess smoke or smell to the exhaust your engine could be slowly burning it in the exhaust system most likely from a head gasket as these are fairly common on these engines.

This engine also has a water crossover manifold that connects between the two cylinder heads under the throttle body.The gaskets on these are common to leak as well and can sometimes be hard to detect if they are leaking.We have had to use dye in some of the cooling systems on these vehicles to locate leaks on these engines.

I would check the crossover manifold to see if the coolant is slowly leaking out at the gaskets and if so then the gaskets need replaced.

Let me know if you need anything else,click accept if you feel satisfied with your answer as this is how I get credited for my time,Thanks Pete!
Customer: replied 6 years ago.

Just A quick question about the crossover manifold?

can i get to it without removing the intake or is it buried?

Do you have a Diagram. I cannot find one in my service manual.

Thanks again George

I don't have any diagrams or pictures to post for this manifold but you should see it under the throttle body on the engine on the drivers sides of the cylinder heads.It sits above where the transmission mounts up to the engine.

Here are the instructions on how to remove this manifold to replace the gaskets.It is about an 8 hour job at a shop.


1. Drain the engine coolant.
2. Remove the engine sight shield.
3. Remove the upper filler panel.
4. Remove the air cleaner assembly.
5. Disconnect the shift selector cable.
6. Remove the throttle cable bracket
7. Remove the throttle body.
8. Remove the left engine torque strut and bracket.
9. Remove the EGR pipe at the throttle body spacer.

10. Disconnect the upper radiator hose from housing.

11. Disconnect the lower radiator hose from the thermostat housing.
12. Remove the water pump belt cover.
13. Remove the water pump belt tensioner.
14. Remove the water pump belt.
15. Remove the throttle body spacer.
16. Remove the EGR.
17. Disconnect the EGR pipe from the water crossover.
18. Disconnect the park neutral switch.

19. Remove the water pump cover.

20. Remove the water crossover from the engine.


1. Install the water crossover on the engine.
- Water crossover bolts to (18 lb ft).
2. Install the water pump cover.
- Water pump cover to (89 lb in).
3. Connect the park neutral switch.
4. Connect the EGR pipe to the water crossover.
5. Install the EGR.
6. Install the throttle body spacer.
7. Install the water pump belt.
8. Install the water pump belt tensioner.
9. Install the Water pump belt cover.
10. Connect the lower radiator hose to the thermostat housing.
11. Connect the upper radiator hose to the housing.
12. Install the EGR pipe to the throttle body spacer.
13. Install the left engine torque strut and bracket.
- Torque strut bolts to (37 lb ft).
14. Install the throttle body.
15. Install the throttle cable bracket.
16. Connect the shift selector cable.
17. Install the air cleaner assembly.
18. Install the upper filler panel.
19. Install the engine sight shield.
20. Refill the engine cooling system.

Let me know if you need anything else,click accept if you feel satisfied with your answer as this is how I get credited for my time,Thanks Pete!
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