Coolant system test

2000 S10 Blazer 4x4 with 4.3 has a slight odor of antifreeze while running. Has 110,000 on it with religious maintainance. I see no signs of leakage anywhere as everything seems pretty dry. So I decided to rent a coolant pressure tester from autozone today to see if this thing holds pressure.
My results where pumping the tester to 16psi. After 15 minutes it leaks down to 12 psi. I see no leaks or hisses while under pressure. Is this normal or is this a sign that I have a slow internal intake leak. Keep in mind I have no antifreeze leakage so far as I haven't had to add any, my reservoir tank is a couple inches low though so I was just about to add some. Is it time for a LIG replacement yet or am I over thinking this? Also The water pump has 75000 and doesn't appear to be leaking from the weep hole.No coolant in oil.
Just tested it a second time pumped it up to 17 pounds and after 15min it's at 13 psi? Is this small amount of leakdown normal?

2000 S10 Blazer 4x4 with 4.3 has a slight odor of antifreeze while running. Has 110,000 on it with religious maintainance. I see no signs of leakage anywhere as everything seems pretty dry. So I decided to rent a coolant pressure tester from autozone today to see if this thing holds pressure.
My results where pumping the tester to 16psi. After 15 minutes it leaks down to 12 psi. I see no leaks or hisses while under pressure. Is this normal or is this a sign that I have a slow internal intake leak. Keep in mind I have no antifreeze leakage so far as I haven't had to add any, my reservoir tank is a couple inches low though so I was just about to add some. Is it time for a LIG replacement yet or am I over thinking this? Also The water pump has 75000 and doesn't appear to be leaking from the weep hole.No coolant in oil.
Just tested it a second time pumped it up to 17 pounds and after 15min it's at 13 psi? Is this small amount of leakdown normal?

A little leak off is normal.
But coolant smell and reservior tank going down is not normal.

Hints on pressure testing.
Always test cold and warm and hot and sometimes in between.
Some leaks are very tempt sensitive.
Always look on underside of everything.
Water pump weap hole and under and back and front of engine and under rad.
And all heater hose and couplers rad hose clamps and along top of intake.

If pressure test does not show any leakage add some leak test dye to coolant and drive some andthen run the leak dye test light on system and check engine oil with the light to.
If intake is leaking inside engine it will show up in engine oil.
And always check the heater core and floor board carpet for leaks.
Can you smell coolant inside cab or engine copartment or at rear out of tail pipe?

A little leak off is normal.
But coolant smell and reservior tank going down is not normal.

Hints on pressure testing.
Always test cold and warm and hot and sometimes in between.
Some leaks are very tempt sensitive.
Always look on underside of everything.
Water pump weap hole and under and back and front of engine and under rad.
And all heater hose and couplers rad hose clamps and along top of intake.

If pressure test does not show any leakage add some leak test dye to coolant and drive some andthen run the leak dye test light on system and check engine oil with the light to.
If intake is leaking inside engine it will show up in engine oil.
And always check the heater core and floor board carpet for leaks.
Can you smell coolant inside cab or engine copartment or at rear out of tail pipe?

I just started smelling the antifreeze about 3 days ago. Check the fluid in the radiator and was to the top, however the overflow bottle was a couple inches low, it's been years since i've had to add any. Pass side floor is dry.
However I think the coolant tester from autozone needed broke in after about the forth test I only leaked down 1 psi in 10 minutes, The first couple test showed several psi in 10 minutes(Also engine had time to cool)?.

So now I'm going to do a complete system flush, refill and keep an eye on it. I still don't no why I can smell anifreeze. I'm sure it was me I've been smelling it for at least 3 days and always when I exit the truck never inside.

Now you say always test hot and cold so I suspect I could have a problem when it's hot being I have minimal leakdown when it's cool. When I tested it warm is when it leaked the most probably 2 or 3 psi in 5 minutes?

I just started smelling the antifreeze about 3 days ago. Check the fluid in the radiator and was to the top, however the overflow bottle was a couple inches low, it's been years since i've had to add any. Pass side floor is dry.
However I think the coolant tester from autozone needed broke in after about the forth test I only leaked down 1 psi in 10 minutes, The first couple test showed several psi in 10 minutes(Also engine had time to cool)?.

So now I'm going to do a complete system flush, refill and keep an eye on it. I still don't no why I can smell anifreeze. I'm sure it was me I've been smelling it for at least 3 days and always when I exit the truck never inside.

Now you say always test hot and cold so I suspect I could have a problem when it's hot being I have minimal leakdown when it's cool. When I tested it warm is when it leaked the most probably 2 or 3 psi in 5 minutes?

Yes always test cold and warm and hot.
Some leaks are very tempt sensitive.

2000 S10 Blazer 4x4 with 4.3 has a slight odor of antifreeze while running. Has 110,000 on it with religious maintainance. I see no signs of leakage anywhere as everything seems pretty dry. So I decided to rent a coolant pressure tester from autozone today to see if this thing holds pressure.
My results where pumping the tester to 16psi. After 15 minutes it leaks down to 12 psi. I see no leaks or hisses while under pressure. Is this normal or is this a sign that I have a slow internal intake leak. Keep in mind I have no antifreeze leakage so far as I haven't had to add any, my reservoir tank is a couple inches low though so I was just about to add some. Is it time for a LIG replacement yet or am I over thinking this? Also The water pump has 75000 and doesn't appear to be leaking from the weep hole.No coolant in oil.
Just tested it a second time pumped it up to 17 pounds and after 15min it's at 13 psi? Is this small amount of leakdown normal?



Take off the plastic cap on the valve cover where you add engine oil.
Do you see droplets if coolant on the inside of the cap? Almost like condensation? If so, your lower intake manifold gasket is leaking. Check this both hot and cold.

No amount of leak is acceptable , if it's leaking then it is leaking.
If you don't find a/f in the oil,floor,ground, ect like mentioned above then continue to pressure the system for long periods of time , and check the exhaust when you re-start the engine. It may even have a slight dead cyclinder at first , but go away quickly.

Your dealing with a tiny leak none-the-less. If you don't ever see any a/f during all these tests and don't use any during these tests then the leak is probably above the level (in the vapor space)

The tools themselves are prone to leaks as well. If want to pursue it further there's some more to do like isolate systems , and external leak test with leak detector. I'd keep driving it, it'll get worse.

you never said if you smelled the coolant inside the cab or outside. you could have a small leak in the heater core but not enough to flow out and onto the carpet.if you smell it outside, use a bright flashlight and a mirror and check the corners of the intake manifolds for droplets of coolant (a very common problem)also look at the front side of the inlet tank on the radiator(you may have to loosen the radiator and push it forward a little).It is common for the tank to crack. sometimes it will only look like a white line and it may only leak as the coolant warms up

you never said if you smelled the coolant inside the cab or outside. you could have a small leak in the heater core but not enough to flow out and onto the carpet.if you smell it outside, use a bright flashlight and a mirror and check the corners of the intake manifolds for droplets of coolant (a very common problem)also look at the front side of the inlet tank on the radiator(you may have to loosen the radiator and push it forward a little).It is common for the tank to crack. sometimes it will only look like a white line and it may only leak as the coolant warms up

Yesterday I got her on the hoist and found the oil cooler line on the bottom of the radiator seeping a little, It appears to be coming from the fitting screwed into the radiator. It was wet with dexcool around it and appears to be a very small leak. Can You take the fitting out and seal the threads? Maybe tephlon tape. I'll try to tighten it up but I don't think it will help as most likely it needs more attention. Maybe a couple tablets would plug such a small leak.

No , you won't be able to use thread sealant on it.there is a rubber gasket inside the tank on each oil cooler fitting.you may be able to tighten the nuts.they probably won't move much,use a socket or box end wrench. if you can't get it to seal, you can get gaskets from a radiator shop and if you are careful, you can replace them without removing the tank.

Thanks I will try to tighten the fitting and go from there, it just started leaking So I suspect the o ring needs replaced.