I have a 1993 S10 Blazer 4x4, it has a 1 year old radiator, 1 year old premium crate motor, I replaced the upper and lower oil coolant lines and the heater core. After replacing the lower oil coolant lines, I have added coolant every day for over a month. Last week my father-in-law ran a pressure test on the radiator, it showed the drain plug leaking and the radiator cap was bad. We replaced the drain plug...I have now purchased 3 radiator caps from 3 different auto parts stores, and I still loose almost a 1/2 gallon of coolant on a round trip to work about 120 miles each day. I do not find any coolant on the ground where I park, I never see coolant leaking or dripping on the ground when the motor is running or not. I am out of ideas. Any suggestions would be appreciated!

 

As a last resort... Put a bottle of stop leak in and see if it makes a difference.

 

Add some black-light sensitive fluid to the coolant and run it for a day, then purchase a basic black-light and see if maybe that shows you the leak. Even if its all evaporated, it should still glow from the residue left behind.

 

Ok 1st check your oil see if it has a milky color and if it is over full (head gasket)
is your trans auto and dose it cool threw the rad check your trans fluid for the same milky color
But usually your trans would dump in to your rad
How about your hose that gos to the overflow tank if that is bad your rad will push it out but not suck it baack in
It also may be burning in the exhaust and steaming out the pipe or driping on the pipe and burning off before it hits the ground

 

I would not use stop leak

it could clog other things like the heater core


Id check the engine oil

if its milky i would not run the motor till fixed

 

Thanks to all who replied, will begin checks tomorrow

 

That is not even close to true... Apparently you are not familiar with stop leak... lol.

 

not my problem

Ive seen stop leak plug up lots of things

Like the heater core
I was just saying

 

I call BS as well! Lots of things...very doubtful. You obviously do not understand how radiator stop leak works (Bar's Leak or the stop leak tablets from the dealer are the only ones I would recommend)... Manufacturer requirements for radiator stop leak products include that the product must be able to pass through a 24 gauge screen which represents a passage size MUCH smaller than any radiator & heater core used in the automotive industry.

Your "experience" with a product was likely due to another failure that lead to your inaccurate assumption; in which case, I don't fault you much, you just don't have the "experience" to see the root cause and/or take what others say as fact when it, in truth, is just opinion.

 

I would check trans fluid. If it's contaminated, might look like strawberry milkshake. If that's the case it's quite possible that the trans cooler in the radiator has been compromised some how.