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northstar head or gasket check

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I have a 95 SLS w/ a northstar engine. Lately the engine has been consistently running in the 230's atemp wise, and above on short trips. the fans due come on. I replaced the hoses , water pump gasket and thermostat. The water pump turns and the belt is working. Even if I don't see coolant loss it gets low. How can I check for a blown head gasket and cracked head. I'vew tried some of the sealants and I don't have much faith in them. I didn't replace the water pump as I couldn't keep enough pressure on the tool to keep it from slipping off the pump locking ears. Anyone with ideas?

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A cracked head is pretty unlikely. Signs of a bad head gasket can be: coolant loss with no visible leak, white steam from exhaust particularly when first starting the car (this steam will smell sweet, like coolant), a misfire, or overheating. One thing you could do to verify a leaky head gasket is to take the cap off the coolant tank and give it a sniff. If it smells like exhaust fumes, then odds are it's a head gasket. You can also buy a combustion byproduct test kit from NAPA and probably some other parts stores to test the coolant.


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Did you say that you tried a sealant?????


If you did, you could have clogged the purge line. Pull the 3/8" hose off the top of the tank, when the engine is cool, start the engine and check for coolant, if no coolant the AIR purge line is clogged and MUST be cleared, or the water pump will cavitate, and the engine will overheat

Make sure the cap holds pressure, if the cap does not hold pressure coolant will be blown out of the system and it will boil

Make sure the coolant is at least at a 50% concentration

Pressure test the system

Smell the coolant in the tank, if you smell exhaust fumes you have a head gasket problem

Test the coolant with a NAPA combustion by products tester

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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