How often should you change the radiator cap. Mine seems fine but I have lost almost 1qt. of coolant since the last time filled it at 158k now I have 160k.

I know I have to worry about the intake gasket problem. At 160k I am but I don't think it's the problem. It has been using a small amount of coolant since I've had it. But I have noticed that once it drops to about halfway under the cold mark on the coolant resevoir it seems to stop. So It seems to be a pressure thing to me.

I going to change the radaitor cap becuase it can't hurt but I just wanted some imput as to if bad or not so good radiator caps will display these signs.

Also I have mentioned before that radiator is original by I have found no leaks at all from it.

Why dont you get the system checked using a pressure tester be sure,I dont think it costs much,do it cold and do it hot.

These kind of leaks are often due to old hoses or clamps. As the above poster said do a pressure test (cold) and I'm sure that you will see some leaks.

How often should you change the radiator cap. Mine seems fine but I have lost almost 1qt. of coolant since the last time filled it at 158k now I have 160k.

I know I have to worry about the intake gasket problem. At 160k I am but I don't think it's the problem. It has been using a small amount of coolant since I've had it. But I have noticed that once it drops to about halfway under the cold mark on the coolant resevoir it seems to stop. So It seems to be a pressure thing to me.

I going to change the radaitor cap becuase it can't hurt but I just wanted some imput as to if bad or not so good radiator caps will display these signs.

Also I have mentioned before that radiator is original by I have found no leaks at all from it.

You can watch the volume as a function of time the car is run when the radiator system is fully heated and under pressure. Longer drives and warmer environmental temperature will increase the amount of time the system is pressurized to the cap limit.

When the car has been driven on a longer run and you park it, do the sniff test around the engine compartment after shutdown to see if you can smell coolant seeping or leaking. I get a slight scent at times but can't find it. I keep wondering if it's around the radiator tanks but can't find any stains from coolant plus the organic leak stopper GM puts in.

If it's going into the intake manifold through EGR tube or seals, if you pull spark plugs you should see white deposits on some of the plugs that are getting the coolant sucked through occasionally, if its volume is high enough and often enough. Others had taken off the throttle body for cleaning and can check inside the UIM while it's off for leak from the UIM.

If the car has no leak sealant pellets in it, stop at the GM dealer and buy a package of 5 pellets and crush a couple of them and put into the radiator. I drive car, let cool some, open radiator cap with a towel over it, suck out some of the coolant with a hydrometer and dump in the crushed pellets. Close up and drive for a long period of time. Do this before you're going to do a longer drive.

See if the organic leak stop slows your coolant loss.

Hey I like that idea. There is oil making its way up the lower manifold and sitting in one of the wells in the front of the engine so I'll check those two spark plugs to see if coolant is leaking and that is a failure point.