The facts: I'm leaking coolant, its not coming from the hoses, radiator, or water pump. i put a new water pump on my car in the beggining of summer because that was leaking, i then filled the the radiator with water so i been using water all summer and no cooling problems/ issues. So monday i decide to drain and refill my radiator and engine with coolant, no problems untill the next morning i find a damp wet spot under my car below the compressor and water pump, i look at the coolant resivor and its half full, so i originally think its probably coming from the water pump but then i realized the leak was to slow the wet spot was damp not puddle like the leak was much slower, when my water pump was leaking it drained the whole resivor tank. Now this is what i have noticed the last couple of days, i have not had any cooling problems other then the leak for example i'm not overheating , i think i found the leak its coming from above the waterpump high and to the right and below the pcv valve bracket housing thing to the right ( to the right i mean standing on the passenger side with my body parallel to the car with my left hand closer to the rear and right hand pointing towards the front of the car), its gathering in this area and collecting . Now i noticed the coolant forming droplets around a gasket, the gasket looks like a silicone gasket, i personally think i might have a bad head gasket, Heres the catch when i drive the engines heat dires up the coolant in this area and it takes a good two hours before it starts to noticably collect again. i had my uncle look at it while the car was warm we might have messed around looking for the leak for about and hour , he put this pump thing with basically a radiator cap connected to it with a gauge to the radiator top opening and applied pressure, no leak it didn't force out any coollant. he said everything looked fine but now i'm going to ask him to look at it after it sits for a while to get a better analysis. What do you guys think is going on here? and if you guys are pretty sure whats gong on what do you think it would cost ($$$$) to have this repaired rough estimate would be great, also i noticed once the reivor tank is about a quarter full the leak starts to slow down a lot. If anybody could give me some input here i would greatly appreciate it, thanks

I'll skip giving a lecture about using just water in the cooling system. From what you're describing, it sounds like the leak is coming from the coolant elbow that runs from the lower intake manifold to the belt tensioner. It'* right about where you're describing.

There are three weak spots that can lead to coolant leaks on your L36 engine: the plastic coolant elbow that Archon described that provides a path for coolant from the aluminum lower intake manifold (LIM) to the tensioner assembly; the plastic upper intake manifold (UIM) around the exhaust gas recirculation passage; and the plastic frame of the LIM gaskets that make a seal between the LIM and the cast iron cylinder heads.

The plastic coolant elbows typically crack and begin to seep before they break and spill all your coolant on the ground. Coolant does not enter the engine as a result of a coolant elbow failure. Replacing the elbow requires removal of the tensioner assembly or the Lower Intake Manifold.

From your description, it sounds as though your leak gets worse when the engine is cold and tightens up from thermal expansion as the engine warms up. See if you can get the same coolant system pressure test done with the engine cold.

If you confirm that the leak is not coming from the coolant elbow, but from between the LIM and one of the heads, the probable source is a failing LIM gasket. The silicone bead seals and plastic frame that holds them in place against the cylinder heads are notorious for deforming over time, and have caused many an engine failure. Often, the coolant leaks into one of the cylinders, but the leak can occur from a coolant passage to the outside of the engine, too. These plastic frame LIM gaskets have been known to fail in as little as 40,000 miles, but typically last two to three times that long.

The durable fixes for these weak spots all involve substituting metal for the plastic in these vulnerable areas. Aluminum coolant elbows (about $6), aluminum frame LIM gaskets (GM dealer - about $60), and replacement plastic upper intake manifolds with steel heat shields in the EGR bore (APN - about $130) are all available for your engine.

On my L27, a front cover (what the water pump mounts to) bolt was loose that caused a leak similar to that. It would leave a spot on the ground in the morning only. The bolt was near the lower hose inlet on the fron cover. Had to take the motor mount off to tighten.

thanks for the info, another question how urgent is this problem to be fixed can i get away driving it untill the weekend.

It depends on what is causing the problem.

Check the oil for indication of coolant or contamination. If contaminated with coolant, the oil will appear milky, or chocolaty, i.e., opaque rather than clear. Even though your leak appears to be external, you may also have an internal leak at the LIM gasket. If you find the oil contaminated, drain it quickly and repair the problem. Don't drive the car. Coolant in the oil will destroy your engine bearings.

Smell the exhaust to detemine if coolant is going through the cylinders - if so it will smell sweet, like ethylene glycol. If you find that, and drive the car, you are taking a chance on hydrolocking the engine if a small internal leak suddenly opens up into a big one. In the best case, a hydrolock will happen when you try to start it and the starter won't spin. In the worst case, you will bend a connecting rod.

If the oil looks OK and the exhaust smells normal, you may just have a cracked coolant elbow. If you know that is the problem, you could chance driving the car. But you will be chancing a very rapid loss of coolant and a rapid overheating of the engine. If you try this, keep a very close watch of the coolant level. With the car cold, before you start it, open the radiator to check the coolant level. It should be all the way to the top. You will need to watch the temperature gauge very closely. If the car begins to overheat, shut it off. Don't try to drive it home, just get it off the road safely and have it towed. Driving an overheated engine will destroy it. That will cost you a whole lot more than a towing bill.

all right i will check those things now, should i tackle these repairs my self, im not a mechanic by no means but on the other hand i am very mehicanical and have the tools and have a good idea what i'm looking at. if i do send it to the shop how much am i looking at worst case senario right now and best case senario right now if i dont drive my car untill i take to the shop, a rough estimate would be greatly appreciated

is it possible to have a cracked elbow and a leak at the LIM gasket because i think i do where the elbow goes into the tensior pulley area i see a coolant droplet on the bottom of the elbow and when i looked at my oil it has a hint of green on the edges of the oil dipstick and the exhaust definetly smells different i don't know if its a sweet smeel but it smells like gas with a differnet kick if i had to guess like contaminated gas

When it comes to the coolant elbows, and manifold gaskets, anything is possible.

To have the gaskets taken care of at a shop, I'd guess $400 - $500 for the cost. You say you have the tools, and ability...I'd say go for doing it yourself. It'* not that hard of a job. Cleaning everything up is what takes the longest for me. If you're going to do it, do it right, and do the whole job. Upper and lower intake gaskets, valve cover gaskets, coolant elbows, and throttle body cleaning.

i took it to the shop its there right now the guy gave me an estimate of 450 bucks, i really wish i had the time to do this job but with school and work forget about it and now since its football season i don'nt feel like wasting a saturday or sunday working on my car i want to relax. any way the guy at the pontiac dealership said it was the plenium gasket, i asked about the LIM gasket and he gave me a weird look he said lim was probably a quick name for it, anyway thanks for your guys input