Coolant Level

[cashflow50]

I have a 03' 4.8L GMC Yukon. Yesterday after coming home from work, I was prompted with a message coming from the dash that I was low in coolant. I would like to add more coolant to the surge, but I'm debating if I should flush/drain the whole system or just add new coolant. Why is it low I dont know. Is there a leak? I don't see any puddles under my vehicle I know when the coolant level is low, you add coolant to the surge. If I were to flush then what would the procedure be. Where do you add H2O to get the 70/30 mixture with the coolant? I cant seem to find the radiator cap.

 

another question- where is the thermostat located? I want to change that also. I dont want to have that freeze on me and flush the system again.

 

I hope a tech can help me with a step by step procedure to get the correct amount into my autos system. Thanks in advance.

[cammiller]

First you need to find out where it is going. I would check the water pump gaskets and water pump. What is the mileage on your Yukon?

[cashflow50]

It has about 57,000 miles. I checked those areas and no significant leak. I was reading some posts in this forum and someone stated that it might be a bad surge cap or radiator cap. air leaks.

[waltv]

Be sure and take a look at the wiring loom that runs across the front of the oil pan. Usually, if you have leaking water pump gaskets, which is pretty common, there will be some residual fluid in the loom. It tends to evaporate off the block and oil pan just leaving 'stains'.

If you can't find any evidence of a leak there, you'll need to perform a pressure test on the system to find the leak. You can also pressure test the cap if you have/can get an radiator cap adapter.

The thermostat is located in the water pump inlet. It is not servicable seperately. You must replace the water pump inlet/thermostat housing and thermostat as an assembly.

The pressure cap on the surge tank is the only pressure cap required for the cooling system. The surge tank provides the coolant fill point and the central bleed location.

[corinthian-brad]

I agree w/ walt.... I just replaced the water pump on my 2005 Sierra 5.3L. I was loosing coolant on a regular basis. I really couldn't see a whole lot of leak staining until I removed the water pump, and discovered rust staining on the block / front of heads that wasn't really visible with the water pump in place. It's a fairly easy procedure to remove the pump, and check the gaskets. It took me about 2 hours start to finish. I reinstalled w/ new gaskets and some high temp RTV - so far so good!