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2004 Monte Carlo SS (not supercharged)
3.8L series II
76,000 miles

So I noticed today the smell of burning coolant. I checked my coolant and it was pretty low (I check it regularly).  It's dark out now and I'm parked on dirt so I can't see much.  After sniffing around it's coming from the belt side of the engine.  Water Pump is dry, radiator hoses are dry, thermostat housing is dry.  I found some wetness around the gasket that goes on top of the intake manifold.  What is this? And could it by my problem?  

usually a radiator coolant pressure tester is used to pressurize the radiator and system with the engine off to check for leaks...

some cars like yours take a special adaptor for the pressure tester...  many stores rent the tester..






there could be several places for it to leak from....

there seem to be enough problems that the aftermarket companies have come out with intake manifold kits..
this is a dorman 615-180  this is around 130 bucks.. and must be popular.. as my local az hub store stocks it..




since i normally work on older models.. i have not had to work on one of these yet..  i would imaging that there are coolant passages in these...  

I'll run the test to see if it's an internal or external leak.  However, if it is the intake leaking, I'd find coolant sitting on top of the manifold.  I obviously can't leave that there so would I have to remove the whole manifold to get it clean? If so it seems like replacing the lower gaskets too would be a smart idea.  Also, I have no signs of coolant in my oil.  

Before anything else, I took of the radiator cap and my heart sank.  Brown sludge under the cap, but as far as I can tell it doesn't go down very far, just around the cap area.  Head gasket????

So I rented a pressure tester with my special adapter.  My car has a 1" deep fill tube.  It comes with a 1/4" gasket that fits in there and covers the hole for the overflow tube.  However, when I screw the adapter on the radiator top, there is nothing pushing on the rubber gasket so I have 3/4" of space sitting in there and all the air goes into the overflow reservoir when I use the pump?  Am I just an idiot or would you think I'm missing something?  I feel like there should be something pressing against that 1/4" rubber gasket to prevent it from leaking.  

i have not run into this adaptor problem...

as i have a different style of adaptor that has an expanding stepped rubber sleeve.. so it plugs the round hole in any size of plastic tank..




you can post pictures to photobucket  dot com..  and paste the IMG link here in a reply..


with brown mess in the cooling system..  you could have blown head gaskets.. bad transmission cooler .. bad engine oil cooler..

pull the dipstick and see what you have in the tube...     pull the oil filler cap...  see what you have there..


can you post some of the part numbers from the side of the adaptors.. and a brand.. along with photos..

i will be in and out this afternoon..

buick V6s are known to blow head gaskets when over heated..  

this is what your cooling system adaptor should look like..  this is a stant 12032



 

Dipstick = normal.  Normal color and about 1/4 quart low after 2400 miles.  I check it once a week and haven't been losing any oil.

Oil Cap = normal.  No milky residue or anything

The pressure tester is a rental from autozone.  It's a motorad MT-300.  It comes only with the pump, a standard radiator cap adapter, and a 1/4" rubber gasket.  I looked this tester up online and it is supposed to have a red and a blue piece that seems to be what I'm missing. I also have an OEM brand radiator cap adapter  set.  The only part number I find on it is 27118.  It has two adapters in it.  One with female threads and the other with male threads.  Nothing looks like the picture you showed above.  I'm not so much concerned about the pressure tester because I can just plug the hose to the overflow tank if need be.  I'm more concerned about the 'sludge' around the radiator cap.

I can give you a little more history on my car.  I had the car in Texas for about a year and went through the hot summer there.  I never overheated the car, or even came close at any point.  I actually replaced the thermostat because it didn't want to run hot enough when it wasn't 106 degrees outside. I recently drove it to Michigan where I've been for the last month.  While in Texas I did notice my coolant was a bit discolored and I've been meaning to flush it but just haven't gotten to it.  Does Dexcool sludge up if it doesn't get flushed regularly?  

is it orange dexcool...  or pink/red dexcool...

none are supposed to sludge up..

its hard to say...

i don't like the idea of it  being a little low...

a pressure test is still in order...

talk to the manager.. see what he has in different adaptors..

different chains stock different pressure testers...



i came up with a test a long time ago.. requires a lot of work.. and some tools..  a sure way to check for head gasket leaks...  not for the average person...

requires... compressed air ... and lots of it..

a compression tester set with an adaptor to hook the hose to the shop air hose...

a remote starter button to be able to crank the engine remotely in tiny increments...

a breaker bar with a properly sized socket to turn the crank to position each cylinder one at a time at TDC for that cylinder...

a radiator pressure tester with a clear vinyl hose on it.. the system filled to part way up this hose... so one can see any coolant level changes...

i disable the ignition system..   disable the fuel injection system.. block the throttle open or remove the PCV hose so air can escape from the intake with ease...


i remove the valve core from the end of the compression tester and store it safely.. its not the same as a tire valve stem core..
even though it looks the same..

i pull ONE spark plug at a time..

install the compression tester hose...

use the remote starter button.. usually by pounding it into something solid.. i can make the starter bump the crank around to get to the absolute TDC compression stroke..    i normally mark the damper in six or 4 positions.. depending on the engine..

i then charge the cylinder with air..  if the coolant does NOT change level.. the head gasket is good.. on that cylinder..

if the coolant level does change.. i have an instant test i can show the car owner that there is trouble with that cylinder..

as everybody can understand.. that air into the cylinder should NOT come out the radiator..


the reason that a cylinder leak down tester won't work.. as this is a similar test..  it there is a calibrated restriction in the end of that hose that limits the amount of air flow..  so you cannot pump enough air to really get a good idea of gasket sealing.. its designed for testing the rings and the valve seats..


warning.. the engine can spin when applying the air..

just reset..  its complicated...

but it works...

there are also other tests that can be done..

disconnecting the water pump belt..   hooking up the same type of radiator tester with a clear vinyl hose.. to monitor pressure while the engine is started..  if the coolant changes level   you have a leak...

professional mechanics have an even cooler system..

they take an old fuel tank pressure sensor.. wire it with a 9 volt battery.. run the wires to their expensive digital storage scope.. hook up the spark plug clamps to know what cylinder is firing..
use the pressure sensor in a tee with the radiator pressure tester hose.

start the engine again with the water pump belt off so there is no movement..

the scope will pick up the pressure changes as any leaks from combustion are pushed into the cooling system

it only costs 3 to 10 grand in a digital storage scope..
and 5 bucks worth of wire and a battery...

i like mine better..

on.. off..  bubbles .. no bubbles..

hope this helps..  

...after all the usual locations where coolant might be lost...Consider
that your head gasket might have cracked. The coolant might be entering one
cylinder and steaming through the exhaust. I realize that no one wants to hear
about the cost to remove the head, mill and replace the gasket. An alternative
is an additive made by 'Barr' that fixes head gaskets quite quickly and costs
about $30. You need to pour directly into radiator and not the recovery tank.
This may involve disconnecting the upper radiator hose. Follow the directions
on the container.
and Good Luck !