Beginning to rebuild 308 engine when visually inspecting block found small cracks in the relief area between pistons and valve seats, 4 out of 6 cylinders have visible hairline cracks, cracks don't seem large enough to leak, is this a common occurrence?
Since you mention a relief, I assume this is a 1954, 55, or 56 block? Do the cracks go all the way to the cylinder? The issue is: if the cracks go deep enough to enter the water jackets around the valve seats or cylinders, the exhaust gas can blow into the coolant, which is very bad.
Ive rebuilt many 308's over the years and rarely found one without hairline cracks. Ive had them repaired several different ways from machining
pinning, replacing valve seats, and sleeving cylinders. The right way is to fix but if they were minute Ive left them alone at times then poured in K& W Permenant Block Sealer when starting with no problems. It took decades to begin the crack and may take decades before ever reaching water jacket.
The Key is to pull out the long water Distribution Tune below the valves to ensure the Holes are Open.
Recently I read an Article about old Ford Flathead V8's usually are all full of cracks a nd rarely fix except in extreme cases.
Leave a reply
