I am working on my 2003 Monte Carlo with the 3.4L engine. I have what I belive is the common Lower Intake Manifold gasket failure. I am getting fluid from somewhere unexpected though. I had not drained the coolant yet when I was taking off the alternator bracket. When I removed the bottom bracket bolt I saw coolant come out of the hole. I was able to make more come out by squeezing a coolant line. I am guessing that this is from the lower intake manifold gasket leaking. I know have the lower intake off and do not see any problems with that gasket itself, however, I do not think the sealant was run far enough up the gaskets and may be the source of the leak.

Here is a pic showing where it was leaking.
IMG_20130509_040603_552_zps456f1bde.jpg

Just a little more perspective.
IMG_20130509_040554_686_zpsb71a7a19.jpg

Has anyone seen coolant come out of this hole before?

Should replacing just the LIM gasket stop the leak there or should I be looking at doing the Head gasket?

Additional Info
At around 75,000 miles I had the rocker arm bolts strip out of the heads and both heads were replaced. The car is now at 132,000 miles. Other than the leak the car is in great shape. I am cleaning throttle body and replacing all orings and the thermostat while it is broken down.

Thanks for the help!!!!

 

Change the LIM and the UIM ...you should be fine.

 

I am unable to properly determine what hole you are saying has coolant running out. But in general, if the LIM gasket began failing (which the nylon ones do around 80-120K on them), the coolant may travel from the beginning of where it was leaking and show up somewhere completely different.

Since you already have the car tore down, when you replace the LIM gaskets, get the Fel Pro aluminum ones (otherwise, IMO it's a waste of time and money). Also, if you post pics of the LIM gaskets, I could give some feedback based on there condition.

 

The first picture is now displaying like I expected it too the leaking hole is circled. I have to clean the parts before I start reassembly, I am working on it nights. I will take some pics of the LIM gasket before I start cleaning. I did inspect them pretty well and did not see and tears or cracks. I will post the pics when I take a break from cleaning.

Thanks

 

That hole may go into a water jacket you could put Permatex on the threads
of the bolt when you put it back together .. That will keep coolant from wicking up the bolt threads..

 

I'm actually a little concerned. Based on the 3400/3100 design, if my memory serves, that bolt hole is opposite a water jacket BUT that hole should not go through into the water jacket. If it does, I wonder if someone drilled/tapped it and went a little too far.

That being said, leaves limited options. Replace the head or coat the threads are two options.

Also, if I am correct, you should be able to compare the front and rear heads (facing the same direction, as I believe they should be identical, including the location of bolt holes).

And lastly, maybe it's not leaking from that hole, maybe coolant is traveling form elsewhere (such as that freeze plug).....

 

Here are some pics of the LIM gasket on the leaking side.
IMG_20130509_223252_021_zpsb23bf75d.jpg

IMG_20130509_223321_922_zps95fc5ce7.jpg

IMG_20130509_223325_507_zpsd8e04244.jpg

IMG_20130509_223329_756_zps869fef4e.jpg

I would not expect to have a fluid passage where the bolt goes through. The heads all have bolt holes at the same locations it just happens to be the one with the alternator bracket bolt in it that is leaking.

 

X 2 ,That's what I was thinking he should look at freeze plug ..

 

I took this video before I removed the intake. I was squeezing the coolant hose to make it come out.


I am confident it is not the freeze plug.

 

That is really, REALLY odd. But I give you points on making the video!!

And the LIM gaskets don't look damaged like I expected. I assume that the valley (the spot on the LIM and block between the front and rear LIM gaskets) had the RTV gasket maker/sealant too when you took it apart?

I hope when it comes together that this was just some weird and freaky situation solved by changing the LIM gaskets.

Keep us posted!