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The reservoir on my 2000 Olds Silhouette (220000 km) draws down about 1/2 inch a week or about a cup of 50/50 mix. There are no drips under the car, no smell in the cabin, the oil looks good and the car doesn’t overheat. Radiator cap was replaced last year. Is my next option a flush and pressure test?
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Start with a visual inspection for any obvious leaks under the hood at all the hose connections and water pump. Also, if memory serves the lines to the heater core run over the right front axle. There might be enough rust on the underside of the lines for a pin-hole leak not very apparent from the top side of the lines.
These lines were the location of my leak on my 92 Lumina before any other cooling system component.
When replacing the radiator cap did you go with an OEM or 3rd party? Sad, but I have had nothing but trouble with 3rd party caps and highly recommend going with a replacement GM.
Due to issues with Dex-Cool causing corrosion to the cooling system components and engine this vehicle may have been converted back to the old school green ethylene glycol 50/50 mix. Using a third party tracer dye and black light might be advantageous to use with to the pressure test.
If using Dex-Cool which should be orange or sometimes pink using the ACDelco Dex-Cool Tracer Dye and a black light will do the trick for the pressure test.
A pressure test on the system at the operational PSI would also confirm a leak in the system; operational pressure should be on the radiator cap.
Eric has a great video on pressure testing – http://www.ericthecarguy.com/engine-videos/403-pressure-testing-cooling-systemsGM was bad about running heater lines through brackets as I remember my 1996 Buick Power steering bracket contained one of the heater lines and was cracked. If the coolant leak is small enough and falls on the exhaust it will just evaporate. When the system is at full operating temp just squeeze the upper radiator hose to verify that the system is pressurized. If not, you have a leak somewhere.
Thanks for the replies. I’ll look at the heater lines. Neat trick about the squeezing the hose to check for pressure. Its definitely a very small leak but I’d like to catch it before it goes big. Radiator cap is a Prestone. Seems to work but I’ll look for an OEM cap just to be sure. Coolant is still Dexcool 50/50.
Honestly, I think it’s normal. A 50/50 mix is just that, antifreeze and water. The water WILL evaporate and cause the reservoir to get low. I usually top them off every oil change.
To find a leak, you can use this method as suggested if you don’t get any traction squeezing hoses.
More info on finding leaks here.
http://www.ericthecarguy.com/faq/finding-and-fixing-leaks
Good luck and keep us posted on your progress.
[quote=”joinaunion” post=148875]With it running and temperature is normal do you see a leak at water pump?[/quote]
No. Everything looks dry.
[quote=”EricTheCarGuy” post=148866]Honestly, I think it’s normal. A 50/50 mix is just that, antifreeze and water. The water WILL evaporate and cause the reservoir to get low. I usually top them off every oil change.
To find a leak, you can use this method as suggested if you don’t get any traction squeezing hoses.
More info on finding leaks here.
http://www.ericthecarguy.com/faq/finding-and-fixing-leaks
Good luck and keep us posted on your progress.[/quote]
I wouldn’t mind topping off every oil change but I would have thought a cup a week a bit steep. I know my reservoir is being used, however, as the level changes back and forth from cold to hot and the line is always wet inside so you could be right and the water is evap’ing through the reservoir. If that is the case, wouldn’t the remaining fluid continue to get more and more concentrated?
Could be intake gaskets,the 3400 has plastic intake gaskets that split and cause a coolant leak.Luckily Dorman has a kit with upgraded intake gaskets made out of metal instead of plastic.Use a pressure pump to find the leak.The intake gaskets are a common problem in the 3100 and 3400 engines.Does it miss?could be a bad headgasket if this is happening.You don’t want to burn up the engine up,the engine comes out from the bottom for engine replacement.
The intake gasket was replaced at about 100000km under warranty. I believe they replaced it with a metal gasket. The engine doesn’t miss but has a slightly rough idle that I put down to a dirty MAS.
FOUND IT!!!
Its the overflow hose. When under pressure, a **TINY** leak starts to form. It drips maybe once every ten seconds down onto a lower cross beam (hence no driveway spillage). It also blows back onto the serpentine belt if the radiator fans are on. It all stops a minute or so after the engine is turned off.
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