98 4.3 4dr 4x4 Blazer. Top to bottom completely rebuilt. Ready to fire her up for first time after adding fluids and noticed bright green dripping from oil drain plug. Best i can tell is that its somewhere above the starter, making its way down along the seam of the block and bellhousing. No visible pools or puddles up top anywhere that i can see. Cant see a darn thing, know its coming from above because there is the occasional drip that runs down the side of the oil pan. Guess next step is to pull starter and see what i can see. Any and all thoughts or suggestions much needed and appreciated.

 

Check heater core hoses on firewall could be something simple like cracked hose or loose clamp. Hopefully its something simple especially after a rebuild. but other things to check are intake gasket at the rear of the heads, maybe intake is loose, or on the sides of the block there is small metal threaded plugs into the water jackets.


I would just take a bright flashlight and check everywhere that you can before you take the time to take anything back apart.

 

Thnx Chuck!
Hoses and clamps are all new and were one of the first things i checked. Upper and lower intake were done by me...positive that propper torqueing sequence and values were done. When i got the block back from the machine shop one of the coolant plugs was only finger tight so i went thru and put sealer on threads and torqued em to spec. I was so carefull putting it back together....wasnt in a rush; i have been tinkering on it since november or so. The list of what all i have done and dollars spent are extensive. Keeps me out of wifes hair and her out of mine...lol.

 

When you did the coolant plugs, you checked the ones in the head too correct?
I have also seen a thermostat housing leak, run the length of the intake and run down the back of the block. But you should see puddles on the intake.

 

I found my leak when i took the t stat off when i did the spider......someone did not put the gasket on the lip of the t stat they just laid it around the t stat and put the housing back on..........I could not find that leak.........it must have ran down the back of the housing and then????............I wouldn't notice any pooling until I parked on the slope of my driveway.......it was damning up somewhere....

It is just so damn hard to see anything, with all the tubes, wires and hoses on these engines.........probably the hardest chevy that i have ever worked on ......

 

this is so frustrating last night I was all over under all in everything that I could think of to check every fitting every sensor every hose every everything I didn't take any parts off I didn't get that far yet but I almost feel stupid I can't find this damn leak I'm not sure where to go or what to do next I'm at work I'll be home in a few hours and if somebody's got any thoughts ideas or game plan I'm all ears

 

Leak dye. Or pressure test and look for or hear the leak.

 

I agree with above, UV dye and/or pressurize it and force it to leak.

 

Borrowed pressure set up from a buddy. We have 2 parts houses here in town and neither one has cooling system dye...so I'll do it without. If I still cant find leak I think I'm gonna pull the plenum and see what I can see then...hopefully it wont come to that. Gonna put on grubbies and head out to the garage here in a few minutes. I'll let ya know what happens...thnx guys for the help!!