2000 olds silhouette is overheating. i have replaced the intake gasket, radiator and cap. there seems to be a pulsing in the electrical system, and the fan seems to be sporadic as to when it comes on. i dont know if any or all are related.

indicates blown head gasket
do a compression test to confirm then replace head gaskets and have the head/s shaved as they will be warped

take off the cap
remove the hose underneath the radiator
put your hosepipe in the radiator cap
and allow water to flow through till its clear
then replace the radiator hose and refill with coolant

Time for Intake Gaskets and possibly head gaskets, very common problem with these, the intake gaskets go bad and the coolant actually burns in the cylinder and of course the cylinder pumps air into the coolant system because of intake gaskets being bad. :-(

In so far as it is a 10 year old automobile, and not knowing the maintenance history, my first area of concern would be the Radiator. The buildup of scale in the radiator core is a gradual process, and slowly reduces Radiator efficiency. What may seem like suddenly is, in fact, the result of long term process.
First step is to verify that the vehicle is actually overheating, or is the gauge just reading higher than normal?
Is the engine losing coolant? Then pressure test the system and Radiator cap, repair as necessary.
Are the cooling fans operating normally, both of them?
Has the radiator been checked for flow? Is airflow through the radiator restricted by dirt , bug debris, or plastic bags?
Finally, you may want to have the system block checked for the presence of exhaust gasses indicating Head Gasket leakage.

could be, but you can verify. First make sure there is no air bubble in your cooling system. Recommend you park on an incline, remove the radiator cap, start the car and let it warm up until there is flow in the radiator. Fill the radiator and keep it full while the engine continues to run. Look for any bleed ports the system may have either in the hoses or at the attach point housings. Crack any bleeders open to allow any air out. Top off the radiator all the way to the neck and make sure there are no bubbles coming up. Bubbles coming out the radiator are an indication of a blown head gasket. If no bubbles, close the cap. Check to see if the car is still overheating. When overheating is due to a blown headgasket, the bubbles are usually easy to see. Please let me know if you have any questions and thanks for using FixYa.

Unless you haul heavy loads or tow a trailer just replace it with the same type that was in there. If the car is overheating in ordinary service the problem is most likely not the radiator. There are many causes for overheating that do not involve the radiator. If the truck is a six and it has brown or yellow oil and the coolant mysteriously disappears you have another problem. The engine needs the intake manifold gaskets replaced. That is a major and rather nasty job. Do yourself a favor and have the truck checked out before you buy any radiator. You could save yourself the cost of a radiator that will do no good.

First is to check to see if it's your intake gasket, pull the dip stick and look at the condition of the oil. Look for excessive sludge and milking, look under the oil cap and look in to the valve cover, also pull the PVC valve and look at the condition. Check to see if there is sludge and milking, if there is then you have antifreeze leaking in to you engine crank case which is very bad. The antifreeze is corrosive to the engine bearing and will soon cost you a new engine if there is no indication of antifreeze in your crank case, then it's a leak somewhere else through out your cooling system. If you see the leak from the out side then that's good, it may just be a bad hose clamp that needs to be tightened. If your not sure and want to buy some time, add about 3 table spoon of common kitchen Black Pepper. The black pepper will work it's way throughout the cooling system and will plug up the leak for now and the great thing about pepper is that it will not leave any residue when you flush out the system, not like the radiator stop leaks out in the market. Good luck and keep me posted, it could be the heater hose to the heater core.

first of all what engine. does it sport ?

This is basicly a very time consuming job rather than a physically hard one to complete. In order to replace the gasket you must remove the intake plenum,throttle body, and misc. vacuum hoses. The wiring harness connections must also be disconnected. Finally the intake manifold is exposed. The bolts holding the manifold to the block are removed exposing the leaking gasket. After removing the push rods and placing them in the correct order to be replaced the gasket and sealants can be removed. Finally replace everything in reverse order. Be sure to consult a GM manual for correct bolt torch specs. The correct specs for the manifold bolts usually come with the gasket. Make sure to change your oil a few times after this job in case any coolant entered the block. Also,change the thermostat and the oil seal on the distributor half shaft cap while you have everything off. Good Luck

I have a 2000 montana and mine was doing the same thing. I replaced intake manifold gaskets, thremostat, and water pump. Turns out it my heads were warped. I had them taken to a machine shop and it has seemed to fix my overheating problems.