99 SE non-turbo 220K on the clock

I took the UIM and LIM off and there was lot coolant under the UIM. The LIM gaskets looked to be not leaking, looked good, UIM gasket no so much. The UIM has a date code of '02, but I can't remember the year and mileage when we had the dealer do the last job.

So my question is: I can't figure out how coolant gets in the upper intake. The stove pipe area did not look all that bad. Maybe I just don't understand how and where the water flows. When I filled the radiator the coolant just flowed into the cylinders. Can some one explain the water flow? Take a look at the pic'*. The large ports seem to have warped inwards or is normal?

Second question: Is there some place online that sell both the APN UIM and the GM lower gaskets?

Looking at the underneath of the UIM, the two coolant ports go into it to the throttle body. They pass the EGR area, usually the heat cracks the EGR area and coolant pours into the motor. Check the UIM by the EGR.

My 95 SSE bonny has the following symtoms that seem related to this topic:
1) very slow coolant leak,
2) EGR error code P1406, Check engine light comes and goes (last for a few weeks then stops for a few and repeats)
3) see small amounts of white smoke sometimes in the morning coming from up from front of hood when stopped waiting for light to change
4) Sometimes runs a little rough after reaching desired highway speed

Now it seems very close to being related to a coolant leak around the UIM/LIM gaskets that have also caused the EGR issue.
Question is:
1) Can I continue to ignore this until things get worse? I see some white film buildup on the inside of the oil filler tube, does this indicate a coolant leak into the engine?
2) How much would it cost to change the UIM/LIM gaskets?
3) Is there a way to confirm its a gasket issue from just looking under the hood?

Iggy...your problem doesn't necessarily sound like a UIM leak.

Reasons behind that are smoke under the hood is probably an external leak of oil or coolant. Internal leaks like the original poster had appear as white smoke from the tail pipe. The EGR is not typically a code that one gets when the UIM bursts.

Your problems sound a bit like a vacuum leak (P1406) and possibly some gaskets that need to be replaced. A look around under the hood should confirm or deny these suspicions. Changing the UIM itself and the LIM gaskets is a good idea and preventative maintenance on these engines.

If you have a UIM failure beginning to happen, ignoring it usually results in cylinders filling with coolant and hydrolocking them. This leads to bearing failure in many cases. It'* kinda like what happens when Homer ignores the emergency sirens at the plant, except the motor doesn't come back for the next episode.