Disappearing coolant - typical culprits?

[mwaldrp]

I have a '97 Jimmy SLT with 134,000 miles. Several years ago (about 4 or 5) I developed a gurgle in my coolant system which turned about to be a faulty water pump. I replaced the pump and the gurgle went away for about 2 years. It started again and I added about a gallon of coolant to top of the system. Since then, I have had a steady but slow leak that requires about a half quart of coolant every 3 to 4 months. After reading through the forum I decided to replace the radiator cap as I read in several posts that the OEM radiator caps tend to not properly seal the system and let in too much air. After four months the new cap hasn't made much difference so I assume I have a leak elsewhere. Before I go and replace the water pump again (it doesn't seem to have any problems) I want to look at the whole system to see if anything else might be leaking. I have added UV dye and am set to go searching for leaks. Are there any typical leak locations for these engines?

[MT-2500]

Originally Posted by mwaldrp

I have a '97 Jimmy SLT with 134,000 miles. Several years ago (about 4 or 5) I developed a gurgle in my coolant system which turned about to be a faulty water pump. I replaced the pump and the gurgle went away for about 2 years. It started again and I added about a gallon of coolant to top of the system. Since then, I have had a steady but slow leak that requires about a half quart of coolant every 3 to 4 months. After reading through the forum I decided to replace the radiator cap as I read in several posts that the OEM radiator caps tend to not properly seal the system and let in too much air. After four months the new cap hasn't made much difference so I assume I have a leak elsewhere. Before I go and replace the water pump again (it doesn't seem to have any problems) I want to look at the whole system to see if anything else might be leaking. I have added UV dye and am set to go searching for leaks. Are there any typical leak locations for these engines?

Keep a eye on engine oil.
If coolant is leaking into it it will show under leak dye test.
Pressure test system cold and warm and hot and check for leaks all over top and bottom of engine and rad and all hoses and water fittings and also over flow tank and hose..
And do not forget to check inside cab under heater on floor.
Has the intake gasket ever been replaced?

[mwaldrp]

Originally Posted by MT-2500

Keep a eye on engine oil.
If coolant is leaking into it it will show under leak dye test.
Pressure test system cold and warm and hot and check for leaks all over top and bottom of engine and rad and all hoses and water fittings and also over flow tank and hose..
And do not forget to check inside cab under heater on floor.
Has the intake gasket ever been replaced?

Is there a way to examine the oil for dye without changing the oil?

Is there any equipment required for a pressure test? How does a pressure test work exactly?

There is no coolant inside the cab so I don't think the heater core is leaking.

I don't think the intake manifold gasket has ever been changed. This was my next step if I couldn't find the leak elsewhere.

[inafogg]

take n blacklight the dip stick
youll need a radiator pressure tester(pumps system up to normal pressure)
then you can black light cooling system
Good Luck