Hey everyone. I'm new to the site but I've owned my monte for 3 years now. I have a 03 monte 3.8 3800 & I've just recently replaced the lower intake manifold gasket because it was leaking I've replaced the plynom (idk how u spell it) gasket thermostat thermostat gasket and water pump gasket cuz the water pump seemed to be in good condition. My heater core is bad and I'm replacing that within the next few days for now I just bypassed it. The fans are working properly but my question is why do I have to continue to put water I. The radiator every other day? (Water because I refuse to put coolant in it u til I put in the new heater core.) I don't see any visible leaks but I do hear this slight hissing noise as if air or something's was escaping when the car is on but I have yet to pin point it. I just want to know if there's something else I need to be looking at or is it because its water and not coolant? Please help a sister out! Thanks guys

 

Its 1 of 2 things....

Coolant elbows that go into the belt tensioner... and or the upper or lower intake gaskets.

Heres where the coolant elbows attach...

Have you replaced them?? How many miles on your Monte? This is a very common problem on our 3800's.... along with the upper and lower intake gaskets...

I'm sure someone will chime in with other idea's fixes...
Thanks for joining the MCF!
Pls feel free to join in on the conversation in the daily Blog!

 

FlyThai,

If you find it's those "famous" elbows, find the aftermarket aluminum ones. I just installed them. They have to be a lot better than the stock plastic ***t ones. Also use some of that "Bars Leaks", it is good for plugging small coolant leaks. I have a 99 Monte with the 3.8 liter with 193,000 miles. In the past I saw some evidence of coolant loss and I threw some Bars Leaks in and it stopped. I've never had the intake manifold off (yet) (knocking on wood).

 

if your losing coolant and its not getting burned then its going somewhere.

I'd check the condition of the oil.. a tan or milky color oil means water/coolant is mixing with the oil. Not a good thing.

You can rent/borrow a cooling system tester and put pressure on the system and see if there's any leaks into the engine or out onto the ground

 

So you say there are no obvious leaks of the water, i.e. no puddles under the vehicle etc. And yet your adding water daily? And there is a hissing sound whenyou turn off the engine. I agree with AO5C, it has to be going somewhere which would be into the block if not onto the ground. Are you seeing any unusual smoke from the tail pipes? How hot is your motor running, normal, overheating? The hissing is possibly a bad radiator cap or a leaking radiator.

 

I've replaced both coolant elbows already & as I've stated before I just replaced the upper & lower intake gaskets. I've also replaced the thermostat & gasket and radiator cap. Not only is it still going thru water every other day now it's developed this cough. But no smoke coming from the exhaust besides steam

 

The hissing is a sign of a pressure loss..

Pressure test the cooling system and note where the hissing is...and or leaks!

I would never ever put Bars leak in the cooling system..!!!!

The problem could also be there's a crack in the radiator! Tank or Seam. or where the upper or lower radiator hose connect.... Possibly when its warm and pressureized the crack opens up enuff to release the water/coolant and its not nearly enough to to see visually as it cools down...the crack closes ...Thus, not leaving any visual signs of leaks!

When you replaced the lower intake gaskets....did you use plastic or aluminum gaskets? If you used the plastic one....Theres your problem...
Did this problem showup the moment you replaced the lower/upper gasket? Or did it start after using the car for a while?
What kinda timeline passed between the repair and the start of coolant loss?

 

- never add a stop leak problem (as they promote clogging the system).
- Go to a parts store, get a radiator pressure tester. Car off, engine cold, hook the pressure tester up, bump up the pressure, look and listen for the leak. If you can here it then you should hopefully be able to find it.

Common issues (some already noted):
- Not cleaning the debris from old coolant elbows (not getting a good seal).
- Hole in a hose
- Old gasket material not cleaned from items flowing coolant
- Loose hose clamps
- Worn t-body gasket
- Holes worn in the UIM around the EGR stove pipe (allowing coolant to spray in the UIM, if it's a small enough spray, you won't get much steam out the exhaust).

Plus, if you bypassed your heater core, you should be able to add antifreeze not water to the system (as you should not be leaking it anymore).

 

The hissing sound: You guys have to remember that if you have been using the air conditioning or a defrost mode that turns on the compressor that when you turn off the engine there is a hissing sound as the freon equalizes pressure in the system. This is a normal sound and does not last long.

I have had good luck with Bars Leaks over the years. I'm convinced that it has helped me delay the dreaded intake manifold tear down so far. When I noticed a small coolant loss a couple of times over the years I added some Bars Leaks and the loss stopped. If it "clogged" up the system they wouldn't have been able to sell so much of it over the years. My '99 3.8 has 193,000 miles on it and I've done the elbow replacement twice, once with NAPA plastic and then recently with NAPA aluminum when I had it apart to replace the belt tensioner. I did install a new radiator this Spring, unrelated to BL, it was just old. One thing I hate, BL does turn our pretty red anti-freeze ugly brown!

 

I can't say I've noticed that significant a sound from the A/C system. But two things to keep in mind, I doubt the A/C is being used currently this time of year and using the defrost is limited. But ultimately, the idea of doing a pressure test on the cooling system is the best way to chase the leak down (as the car will have been sitting for a while and should be nice and cool again ruling out all items like the A/C system).

Some people have hard luck with Bars Leaks and some haven't. I look at it as you run a gamble and if you loose, it can be a painful gamble. I can't speak about their sales on a product like that. I don't know how many people buy it, and of those people how many had larger problems vs solved a problem. When you understand how that product works, it's attempting to "clog" you leak (that's how it seals it). Once your leak stops, the remainder of the product has to go somewhere. Some of it will keep flowing with the coolant, other parts will collect on the walls of the parts of your cooling system, and if you are having a bad day, it will clog your cooling system. For example, I know someone who had luck with the product solving his leak until he could get the car properly serviced, come winter, he had no heat because the stuff blocked off parts of the heater core. Added a lot of time and cost to his problem.
In my book, too risky a product, asking for trouble. Just my thoughts.