How to Repair Cadillac Head Gasket Using Sealant

A leaking head gasket can become an expensive problem if you don't do something to stop the leak. A quick fix is to use an engine block sealer, but generally you'll need to replace the head gasket if you want the repair to last. Either way, if you don't do anything at all to stop the leak, you run the risk of ruining your engine.

Quick Fix

1. Make sure that your engine is cool, and then drain the radiator and flush the system. You can use a flushing agent if you like. Follow the kit’s directions.
2. Add water to the engine and leave room for the additive.
3. Add head gasket sealant according to direction.
4. Add more water to top off the cooling system, and bleed out the air. Repeat this until you have it completely full.
5. Put the radiator cap back on.
6. Based upon the sealant's directions, idle your Cadillac for half an hour or as recommended. You may need to leave it in the vehicle for a couple miles.
7. Let your engine cool and drain out the water and sealer. Leave all caps off, and let your vehicle dry out for 24 hours.
8. After 24 hours, flush the system out with water again, and then drain it out.
9. Once you have flushed the system and drained it, fill it back up with the correct water to coolant mixture for your vehicle.
10. Do not forget to bleed out the air from the system by using the bleeder valves. You open the bleeder valves and take the radiator cap off, and then run the engine until it is warm. Keep topping it off until it can't hold any more water (or, more precisely, until the cooling system indicates that it's full).

Leaving Sealer in for a Week

1. With your engine cool, drain the coolant system of all fluids. Refill it with water and leave room for the sealer. Add it to the radiator.
2. Do not tighten the radiator cap; leave it loose. Start your engine and let it idle for 15 minutes. Then you will tighten the cap and continue to idle for another 15 minutes. Shut off the engine and put your hand on the radiator hoses on the top and the bottom. If the hose on the bottom is cold, twist the radiator cap loose once the engine is cool. Top off the radiator with water.
3. Leaving the cap loose, restart the engine and rev up the engine until you have the idle at 2500 to 3000 RPMs. Do this for five minutes. Tighten the cap. Drive the car for five to ten miles. Take your hand and feel the hoses again. Both hoses should feel hot, so if they didn't feel hot after either idle, there may be an air pocket. Use the bleeder valves to bleed the air out of the system, and top off the radiator.
4. Leave the sealer in the vehicle for one or two weeks.
5. After you have had the sealer in the vehicle for a week or so, drain out the system, but don't use a chemical flush.
6. Refill the system with distilled water and less than 50% antifreeze. The less antifreeze you use, the better. Do not use a product like Dexcool or Extended Life.

If, for any reason, you don't see any results or you continue to have problems with your head gasket leaking, then you may need to consult with your local Cadillac dealership to get professional help. A leaking head gasket cannot be ignored, so fix it as soon as you can.