: Cadillac Overheating Issues



JimMayor007
09-27-07, 02:35 PM
Most of the time the engine that has this problem is the Northstar. Overall this is a great engine and is listed in the top ten best engines. However, they are very expensive to repair. Overheating is a symptom of a larger problem, in other words, the overheating is not the problem, why it is overheating is.

1. The Northstar has a feature known as "limp home mode." This feature allows the car to be driven without a drop of water for up to 100 miles. It accomplishes this by shutting down the cylinders in an alternating fashion, this blows outside air through the engine, hence the engine becomes air cooled instead of water cooled. You need to know that if the car is driven at high speeds or longer distances, internal engine damage will result.

2. Overheating can be due to a myriad of things, here are a few: Blocked Radiator-usually caused by excessive dirt buildup. This is fairly easy to see and very easy to fix. Thermostat-these are designed to open and allow water through at certain temperatures, if it is not opening, overheating will result. This is rare on these cars. Clogged Radiator Inside-look inside the radiator (if you can, later models are sealed) if you can't, then look in the coolant canister, if the water or canister (if it is empty) looks muddy, usually means a sealer has been put in, this is DEATH to these engines as it clogs up the internal water ports. Head Gasket-this is fairly easy to diagnose, look at the base of the heads (will take a flashlight and some effort) if there is leaking here, the gasket is blown. Look at the oil on the dipstick, if there is antifreeze there, or if the oil looks milky or if the oil has bubbles in it, this could indicate a blown gasket, it can also indicate a cracked block. Fans-these cars have at least two fans on most models, crank the car and let it idle, the fans should come on shortly, if they do not, it is probably a relay, if one fan comes on and the other does not, it's likely the fan motor.

These are just a few of the things you can see for yourself. Be aware however that if the car will not crank and the seller tells you it was overheating, you can plan on a new engine. This will cost you about $3,000.00 for the engine and around $2,000.00 for the removal and installation. Also the intake manifold on the Northstar is plastic and cannot be repaired, it is not included on the new engine, so plan on buying one. Of Course, you can buy an engine on ebay for less, but it will still cost you to swap the bad one.

misfit6794
09-27-07, 04:53 PM
Look at the oil on the dipstick, if there is antifreeze there, or if the oil looks milky or if the oil has bubbles in it, this could indicate a blown gasket

Northstars WILL NOT have milky oil,even if the hg is blown, the oil on the dipstick will not show you if the hg is blown or not.

The ONLY way to be sure of a blown hg is to have the coolant tested for exhaust gases or have a cylinder leak test.

Or you can look for coolant (white smoke) in the exhaust.

Good post though.

Ranger
09-27-07, 10:05 PM
Lots of misinformation though.


The Northstar has a feature known as "limp home mode." This feature allows the car to be driven without a drop of water for up to 100 miles.
Manual says 50 miles.


look in the coolant canister, if the water or canister (if it is empty) looks muddy, usually means a sealer has been put in, this is DEATH to these engines as it clogs up the internal water ports.
That is normal when the sealant tabs are used. It is NOT death and does NOT clog anything but small external leaks or porous castings.


Head Gasket-this is fairly easy to diagnose, look at the base of the heads (will take a flashlight and some effort) if there is leaking here, the gasket is blown. Look at the oil on the dipstick, if there is antifreeze there, or if the oil looks milky or if the oil has bubbles in it, this could indicate a blown gasket
True on most other engines, but as mentioned, the Northstar rarely if ever puts coolant in the oil when a head gasket goes.


Fans-these cars have at least two fans on most models, crank the car and let it idle, the fans should come on shortly
The fans do not come on till the coolant temperature reaches 224 degrees or the A/C is on.


Be aware however that if the car will not crank and the seller tells you it was overheating, you can plan on a new engine. This will cost you about $3,000.00 for the engine
If you know where to buy a new Northstar for $3000, post it. Many people here would be greatfull.