Vannin' Home Forums Chevy How to.... blown head gasket :eek:

"To do leanbh" . You speak Irish Catfish?

If you do a pressure test on the cooling system and it shows losing pressure, do a leak down test on the cylinders and it will show you which one or if they are all good, then it is the manifold or some other source.

Naw. But my grandfather did. And his father, and his father, ......

I did a compression test and all cylinders seem good. Gonna do a pressure test on the cooling system and a leak down test and see if I can pinpoint where the issue is.

Heater core ....

Yeah that's what I was thinking frscke1. If I bypass the heater core by just connecting the hot-in and cold-out water lines back to back and refill the radiator overflow bottle then I can see if the level drops over time and that should tell me.
I have a feeling I ran it like that before though and was still losing coolant.

So ... the heater is disconnected /bypassed so it can't be a leaky heater core. I guess that means inlet manifold is the most likely culprit.

Lilse tools makes a kit 75500 which is an exhaust tester for the cooling system so if its impossible to do a cylinder leak down test its always another option to help determine if you do have compression loss into the cooling system.

Hidee Ho Shaggy,

Long, long ago in a Land far away, a wounded 1969 327 smallblock rebuilt by my FIL, was losing coolant, powering a 1970 Chevy C10 down the road. This was unacceptable on a 90 mile daily commute. Take a quick look into the radiator with the engine running, at operating temperature, radiator cap off. Check for exhaust entering the coolant. It will be readily apparent. Have a friend apply throttle, engine in park, parking brake on, safety first. Look for tiny bubbles! If you see them increase when the motor revs up, hate to say, but the heads probably should come off that motor. Mine were still fine, but don't let that motor overheat.

Yes you can reuse intake bolts. Clean all inspect threads well, pay special attention to the proper gasket installation, torque, and don't misalign the intake valley gasket putting the intake on. That Sucks...

Just use proper attention to detail upon reassembly, and you'll be fine, (FIL Leonard at Precision Engine...)

Lucky for me, since I knew who rebuilt mine, I brought it up on occasion! The fun part upon reassembly on a Chevy smallblock is hydraulic valve lash adjustment!

Chevy Tip: Take an old pair of steel valve covers, and cut the tops off, bolt them on first, way less smoke that way.

Good Wrenching!