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Jerry Newton
Jerry Newton, Cadillac Technician
Category: Cadillac
Satisfied Customers: 4608
Experience:  ASE Master Technician, L1, Master GM Technician. Over 20 years of bumper to bumper GM experience.
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98 cad with northstar engine, temps running 225, and the

Customer Question

98 cad with northstar engine, temps running 225, and the coolient disapears and I NEED TO REFILL tank, and lucky to find someplace to park and let cool down, and takes at least one gallon, need to use 2 most times. New radiator, thermsadt . Using a new 14 # ***** cap. In a short drive Maybe 5 miles, it went to 200 quickly and stayed there, Until I idled for 10 minutes and it went down to 196 and stayed there is that normal? I'm 84 , and have no talent on how to work on my car, and your help.
Submitted: 2 years ago.
Category: Cadillac
Expert:  Jerry Newton replied 2 years ago.

Don't do any more work on this car until you've had the engine tested for a head gasket leak.

Your local repair shop can do this, or you can buy the tool and do it yourself. The test is called a block check, and it's a chemical test that detects the presence of exhaust gases in the cooling system. If it fails this test, you have a leaking head gasket. The reason we test this first is because head gasket failure is very common.

If it needs head gaskets, it's a very expensive repair, potentially ending with engine replacement, because sometimes we find that the block is cracked or the threads are stripped in the block when we take them apart. Plan to spend anywhere from $2500-5000 to repair this, if if fails the block check. You should not be losing coolant, and if it's not leaking onto the ground, it's going into the engine, which is another giveaway that the head gasket is leaking.

The temp of 225F is not terribly bad, this engine routinely runs at 220 without an issue. But the coolant loss is significant, you need to get a handle on that.

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