Chev k1500 5.7L - 1998, 200k miles - leaky antifreeze

[BoxMN]

So I put in new water pump. It had been sort of leaking now and then, but I never really could tell exactly where it was coming from. I figured the water pump was due, so put i new one. Check it very close afterward, no leaks around it, ran it and no puddles or drips. Then the other day, after that little cold snap, I came home and saw a wet spot under the engine... ugh... It had been sitting without being run for days and was bone dry under it until last Saturday night.

So now I am thinking maybe a leaky frost plug or something?... I haven't really gotten to inspect it yet. Long ago I did have a heater plug leak and the shop fixed it for me - this was about 60k miles in. I have also read that with this engine is known to have a leak at the heater hose coming out back of engine area somewhere.... not sure where that is but wondering and hoping that it is something easier than a frost plug hidden behind stuff.

Any advice on where to look first, next, etc.? Ay tips on how to spot where leak is coming from? Coolant system is new to me... Thanks, and everybody have a Merry Christmas!!!

Edited December 24, 2015 by BoxMN

[Macgyver55]

Has it ever had the intake manifold gasket replaced?  If not, its possibly, if not very likely the problem.

[jmd1]

Have you checked all the clamps you removed to replace water pump?  could simply be a cold water leak, where the clamp is not quite tight enough.  good luck

[BoxMN]

It did have the intake fixed at about 60k, supposedly with the "new" fixed gasket. I will get under it next week and see if I can find where I is coming from, funky thing is that it just doesn't seem to leak consistently so far. Wondering now that the water pump was not the prob at all. 

Will check clamps for sure  

Thanks!

[jmd1]

So one other thought is if you notice it leaking while engine is cold, then warm it up and it goes away i would bet it is a loose clamp.  I see this type of leak on most of my engines (industrial) when we have a cold spell here in AZ.  Same goes with tires, my pressure is set in Phoenix but when i come to Tucson where it gets colder at night my TPM will come on in Tucson.  Happy holiday