Dreaded 5.3 coolant leak?

[cdub2010]

Im almost done with my junkyard 5.3/4l80e/np241 swap into my 1977 K25. Its been a long 6 months, with christmas, work and winter. Im finally to the fun part, starting it up. I just topped off the fluids in the engine a few weeks back. Did a quick test start and it fired right up. Been busy since then, noticed some coolant on the ground tonight.

I took a chance on this junkyard 5.3, with unknown history, I just found out i have 706 heads, Coolant is coming from the drivers side exhaust bolt holes. I had to remove some broken exhasut bolts, I welded nuts on and didn't drill them. Not sure if any one drilled before me and hit water jacket. Pulled the rocker covers, looks clean with no sludge or goop. Drained oil got around 5 quarts out without dropping filter. Same amount I put in a while back. So no coolant in the oil.

Im thinking I Should just get some hi temp sealent on the header bolts and drive it, or is this enough signs to tear it down to inspect/replace the heads.

[mongocanfly]

id try that 1st and see what happens...if it doesn't leak it should be ok

[homemade87]

What you have is not the coolant leak problem prone from the 706 heads . The 706 will crack around the center head bolts under the valve cover and put water in the crank case . Seems you have already eliminated it as a problem

You have a different problem . Either the exhaust bolt was to long and bottomed out and cracked the head or it may have froze or previous owner did something .

I would keep an eye on it . Once it heats up and is pressurized it may push some fluid out . If the crack is internal as well it could fill the cylinder as well and hydraulic and do some damage .

[rapid49]

I would put pipe sealant on the bolts and try it. Closely monitor for leaks or issues elsewhere.