I want to preface this by saying I know the right answer to my question... Anyway, I've had a small drop of antifreeze on the passenger side front of my block for years. This is on my '65 Skylark, iron heads. This is the most reliable old car I've ever owned; I bought it 15 years ago with 71,000 miles, and it now has 108,000. The previous owner had the heads off because he broke some of the exhaust manifold bolts, so the heads have been off the engine, but all I've ever done to the engine is replace the valve cover gaskets, clean out the oil pan, and rebuild the oil pump. That's it. Anyway, I have a small dribble of antifreeze coming out of the head gasket at the lower passenger front corner (near the water passage). I certainly would have no problem with tearing the heads off this winter and doing the head gasket thing (and checking the heads), but the idea of mission creep scares me on this car. It is so reliable that I don't want to jinx it. Once the heads are off, I'm going to want to clean up the valve seats, and it does seem to have a small rear main leak, so why not check that? Oh, there's some copper showing on the main bearing, should I do something about that??? All of a sudden, I'm rebuilding one of the nicest running engines I have. Anyway, I drive this thing about a thousand miles a year, and I'm wondering if anyone's used anything that'll seal up a non-compression based head gasket leak. I've used GM sealing pellets to good effect over the years, but I don't know if it'll seal a head gasket. Any ideas would be appreciated. Aaron
Re-torque the heads. I had a small leak like that ONLY when the engine was cold. Re-torqued the heads and it was gone.
I would not try those gasket sealer additives . But if need be, head gaskets are a Saturday job on that car. Just remember to drain oil and add fresh to make sure there’s no coolant into oil pan.
Thanks guys...I'll try retorquing the head today, and if it doesn't seal, I'll probably just pull both heads and do the gaskets without touching anything else (other than checking flatness).
Mill the heads, bigger cam n carb.... I wish you luck fighting the more is betta theology. Gits me every time. ....Jim/Rott
I know the feeling, may as well fix this do that, upgrade that thing ruin the other thing NOOOOO, Im doing a head gasket and that's it!!!!!!!!!!!!!!!!!!!!!!!
With six old cars and no real penchant for speed, it's easier to just say no than it otherwise might be. Oh, but these old cars have so many worms in the can!
I just retorqued the head and it still seeps. Argh.... Well, a couple questions since I don't have a ton of mechanical experience with 300s: 1. Are there any block drains? I can't really see any, but I didn't look all that carefully either. 2. Do the head bolts hit water? If so, I'll probably just use Permatex 3 on them, which is my personal favorite. What a drag. I can only hope the heads aren't warped at this point.
Warped heads not a big deal because you're taking them off anyway and having them milled will be helpful to get them to seal if you're going to use steel shim head gaskets that it probably has now? Swapping to composite gaskets will seal easier but will lower compression slightly probably to around .75:1 lower plus or minus .25:1. If they are warped, you can have .020" taken off and use the composite gasket and get close to the same compression and lifter preload.(composite head gaskets are more forgiving to surface imperfections than steel shim heads gaskets are if the block doesn't look as good as it should for a steel shim H/G) While you're in there if it hasn't been done before, you may want to change the timing chain and gears to get the time bomb nylon coated factory gears out of there. And check the came while it is down that far for worn out lobes, over 100,000 miles on a flat tappet cam is a lot to ask for and you past that! You may also want to consider a valve job while its down that far to freshen the heads up while they're off? Upper end rebuild perhaps? GL
The early LS motors in the C5 Corvettes had a porosity problem. GMs fix....alumaseal. If I bought a new Vette and they wanted to fix it like that I think I would object.
I forgot to mention that I did the timing chain and gears when I did the oil pump; it still had a nylon gear that was in surprisingly good shape. Of course I replaced the whole set anyway because the chain was flopping around a little more than I'd like. It looks like it has composite head gaskets on there right now. I'll take a straightedge to the heads, but if they're in spec they are going back on the same day. This thing runs just about perfectly.
