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Amedee, Cadillac Technician
Category: Cadillac
Satisfied Customers: 24101
Experience:  ASE certified Technician advanced level specialist. Wisconsin certified emissions state inspector
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1997 Cadillac Deville: going down..leaks..pavement..driven..parked

Resolved Question:

1997 Cadillac Deville with Northstar engine. The coolant level keeps going down, but there appear to be no external leaks. No coolant appears on pavement under the car after it has been driven several miles and parked with engine hot. It is not overheating according to the instrument panel thermometer. A local mechanic did pressure test and says it needs a new water pump, new heater hose and new radiator hose. It seems to me that there would have been some indication of leakage below the car if there were perforations of the hoses or leakage from the water pump. Should something else be checked out?
Submitted: 5 years ago.
Category: Cadillac
Expert:  Amedee replied 5 years ago.
Hello there!

YES.. if you suspect you are looking coolant and it is not dripping on the ground, you can have the cooling system checked for Hydro carbons. It is possible for the intake gasket or head gasket to leak coolant internally. THis test will confirm if the head gasket is in fact leaking. In addition, they can check to see if the cooling system has excessive pressure. THis will also point ot a blown head gasket. THis is done with a cooling system pressure checker. You can install the cooling system pressure checker to the cooling system and instead of pumping it up to look for leaks, just start the engine and let it warm up and watch the gauge. Excessive pressure building up too fast would indicate a head gasket problem.
Customer: replied 5 years ago.
<p>I don't just suspect that I am losing coolant; the car definitely is losing coolant, and as I said before, there is no drippage at all on the concrete pavement below the car. Shouldn't the mechanic have done a cooling system pressure check like you described in addition to just pumping up the system and looking for leaks? And is it possible that the problem could be something as simple as a defective radiator cap?</p>
Expert:  Amedee replied 5 years ago.
YES.. it could be a bad radiator cap. However, if this were the case, then you would see if leak when the engine gets warm. Coolant will be coming out of by the radiator cap.

The shop I have been working at for years will not do this test unless the technician suspects a problem with the head gasket or if unless the customer requests this specific test.
Customer: replied 5 years ago.

I am still puzzled. Since there is NO leakage under the car when parked hot, and since the shop seems to have found leakage in the hoses and pump, WHY would that leakage not show up under the car when parked fully warmed up after many milles driving? It does not seem to make sense that absolutely no leakage would be seen if there are flaws in the hoses or something defective about the water pump. I do not know if the hoses ever were replaced, and I suppose that the wise thing to do would be to get them repoaced anyway, just to be certain that they are ok.

Expert:  Amedee replied 5 years ago.
Sometimes when you have a slow coolant leak, you will not see if on the ground. This is because the coolant will evaporate before it hits the ground. Especially if the leak is a slow leak. Sometimes when there is a coolant leak, it will drip onto the hot motor or hot exhaust manifold and just burn right up before it hits the ground. THis too is very common!
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