Manifold gasket questions

I've read most of the posts about coolant leaks at the intake gaskets and wondered if GM ever did anything to fix this problem. Most of these posts seem to be about engines of the late 90s and early 2000s vehicles. My particular interest is my 97 that had 77K when the previous owner melted down the engine due to coolant loss 2 years ago. I picked the car up and replaced the engine with a 2003 version out of a Bonneville with 70K.After alot of swapping components(oil pan,oil filter adapter,throttle boby,fuel injectors and rail) I had an engine the PA would accept. Today I noticed the resevoir a little low and found the plastic by-pass elbow leaking going into the tensioner assy. I'll be fixing that little problem next weekend but should I also be worried when the intake gaskets are going to go? Is this an age or mileage problem? The first engine that was in this car had relatively low miles but was 11 years old when it failed. The current engine has about 85K and 7 years old.Thanks for your ideas.

I've read most of the posts about coolant leaks at the intake gaskets and wondered if GM ever did anything to fix this problem. Most of these posts seem to be about engines of the late 90s and early 2000s vehicles. My particular interest is my 97 that had 77K when the previous owner melted down the engine due to coolant loss 2 years ago. I picked the car up and replaced the engine with a 2003 version out of a Bonneville with 70K.After alot of swapping components(oil pan,oil filter adapter,throttle boby,fuel injectors and rail) I had an engine the PA would accept. Today I noticed the resevoir a little low and found the plastic by-pass elbow leaking going into the tensioner assy. I'll be fixing that little problem next weekend but should I also be worried when the intake gaskets are going to go? Is this an age or mileage problem? The first engine that was in this car had relatively low miles but was 11 years old when it failed. The current engine has about 85K and 7 years old.Thanks for your ideas.

The incidence of upper manifold leaks at the EGR tube are much fewer after 2000 (1999). It's not impossible, but I wouldn't lose sleep myself. You're more likely to have the elbow leaks (use silcone sealer on the o-rings) and a water pump leak. The 1995-1998 motors seemed the most affected. The lower intake gaskets were a problem early in those, but seem to have dropped greatly with the 2000+ motors. The supercharged motors seem to have some trouble with lower gaskets more than normally aspirated.

That's good news. Is there a particular sealer you prefer(Brand or color). It seems to be a good idea because this elbow is only a couple years old and already wants to leak although once the engine warms up it doesn't seem to leak as bad.

That's good news. Is there a particular sealer you prefer(Brand or color). It seems to be a good idea because this elbow is only a couple years old and already wants to leak although once the engine warms up it doesn't seem to leak as bad.

From reading about other people and suggestions for replacing them. They suggest cleaning the groove for the o-ring with wood or plastic to get it smooth without scratching and to use a silicon sealer just to help make sure the o-ring does seal. Not being cleaned well enough and sealed well enough probably describes why they are a couple years old and are seeping again around the o-rings. Just from reading other forums, you are not alone with a leak in a replacement elbow due to o-rings.

I do not remember a particular brand of sealer.

AND
as for a leak in the UIM, I still feel the number of posts drastically reduced at 2000 model year. People tend to over emphasize the problem now, in my humble opinion. The availability of quality, re-engineered replacements even over the GM EGR metal tube reduction in size makes this an easy fix. Posts after 2000 seem to involve lower manifold gaskets on the super-charged models more than uppers on the normal intake engines.

You are well-protected by being alert to any change in volume in your coolant. Remember to check radiator for full level occasionally and consider the shrink in volume with colder ambient temps when the whole motor is stone cold; check reservoir level at about the same ambient temp because it will drop slightly in volume if the motor is 40 deg on morning and another check is at 10 deg.

You caught the leaking elbow by being alert. If owners of 1995-1999 had started questioning drops in volume that continued after refilling a cup or so per month, they would have had their cars checked and replaced the failing UIMs before they caused more problems in a few cases. So awareness is your best protection.