Antifreeze leak im stumped

[98 gmc 4x4]

I'm loosing antifreeze some where but cant figure out where, ive done a pressure test and it holds good for about 10mins then slowly drops a few psi. Ive checked all my hoses put rags around where the heater lines do into the fire wall around my overflow tank and by my radiator cap all drie. My water bump weep whole is not wet and its not leaking out threw the bolts. I dont think its burning it because i have no white smoke and it has power. Ive been reading about the intake manifold gasket leaking but if that would leak wouldnt my oil level rise? Also how would i narror it down to the intake manifold leaking what test can be done to see if thats leaking? Thank you for taking your time to answer my question.

 

[sewlow]

If your oil looks like a nice yummy chocolate milkshake, then chances are the H. gaskets are leaking.

 

[ls6firebird]

If your oil looks like a nice yummy chocolate milkshake, then chances are the H. gaskets are leaking.

this was what i was thinking. happened to mine, hopefully you are luckier than me!

 

[98 gmc 4x4]

My oil looks fine.

 

[radical7]

what about the raidiator u check it

 

[98 gmc 4x4]

Radiator was fine last time i checked it, tomorow im going to re check everything and report back with an update.

 

[DRAGGIN95]

Sure sound's similar to vortec intake gasket's!

 

[Balzer]

I would bet its the intake manifold gasket! My 97 would just loose coolant over about a months time, like 1/2 to 3/4 of a gallon. Never saw any white smoke (steam)out the exhaust, and never saw any drips anywhere. Then one day noticed a little tiny bit of steam at the back of my engine bay. I changed the intake gaskets and it stopped loosing it.

 

[98 gmc 4x4]

Blazer my truck does the same thing i will have to watch for steam, did you notice it when it was warm or cold or before or after the thermastat opened. Thanks for the imput guys! But how do i know for sure its the intake manifold gasket?

 

[Balzer]

On mine I had just got home and popped the hood for some reason and saw the steam. It was at op temp for sure. Apparantly its a VERY common problem on vortecs.