I have a 2004 chevy monte carlo my 16 year old daughter ran it hot, I allowed it to cool down, put coolant then drove it and it started overheating and the red hot coolant light came on and it died so i pulled over added water and when i cranked it was loud and making a tapping noise. My brother in law told me to add liquid glass to the radiator and fallow the directions on the bottle and i did cranked it and it still was tapping and running rough so my boy friend took the valve cover off and collant had gotten into the oil and one of the bolts in the first hole to the right had came out rethreaded o and broke the first bolt off in the hole and it took 3 days to get it out it ; ( changed the oil let it sit 24 hours and i cranked it and once again it's making a tapping noise still and over heating. So yesterday morning I put another thing of liquid glass, changed the thermostat changed the oil let it sit 8 hours flushed the radiator and added coolant then cranked. I cried last night because it's still doing the same thing. My boyfriend is now saying I need a new water pump. I just replaced the water pump 4 months ago. Do anyone have any advice. I'm going on two three with no car. ; (

 

Before you read, with out inspecting the car in person, it's tough to say EXACTLY what is going on. A trusted professional may be your best bet moving forward. But here's my input.

The 3100 and 3400 does have a "valve tick" (some are hardly noticeable, some get louder over time). Since the car was over heated the FIRST thing that should have been done is change the oil and filter. The oil after an overheat changes it's properties and is no longer the lubricant the car needs.

Second, don't add any more stop leak, liquid glass or any garbage like that. They can clog systems in the car, waste your money and time. I can say, I've known one of these engines to have a crazy loud tick, resolved by adding a product seen in the parts store called "motor honey" (it's a small bottle of basically a thick oil, it's purpose is to "thinken" your engine oil but not to a dangerous condition). Had to add one bottle of the stuff with each oil change between 3000-5000 miles (after about the 3rd or 4th oil change, no more need for the additive, the problem actually resolved itself and we used the car happily another year or two before selling it).

NOW, the problem you have. These cars are KNOWN for the lower intake gaskets blowing out (crappy nylon that lasts maybe 80,000-120,000 miles). When they fail, coolant goes both out of the engine and into the oil. By the fact you said there is evidence under the valve covers, this tells me you lower intake manifold (LIM) gaskets are done for (probably done for before the big overheat).

You may want to have a trusted professional look this over. What I'm about to say is from a guy in '09 with a 180,000 changed head and LIM gaskets on a '94 Grand Am (has a 3100, the 3400 was based off it, they are near identical), the car runs AWESOME with 215,000 on it now!

If the car is in good enough condition, because of the over heat, I would consider having both the LIM and head gaskets changed. You MIGHT get away with JUST LIM gaskets, but you are also VERY close to having the heads done too (it would seriously suck to have find the head gasket bad after doing the LIM gaskets). If you go forward, the heads need to be inspected to ensure they are not warped. In most cases, that can be done at home with a trusty straight edge. If you go forward, you want FelPro gaskets and get the aluminum LIM gaskets (they cost a small amount more then the nylon garbage and worth the money).

Make a point of teaching your daughter the value of understanding gauges, especially the temp gauge. Proper use of the instrument cluster can avoid making a bad situation worse.

BTW - you have a 6th gen Monte (you posted in a 4th gen section).

Best of luck and keep us posted!