Thick vs thin front oil pan seals

[shuttermutt]

Does anybody remember which years used which versions of the front rubber oil pan seal? I'm wondering if this problem wasn't caused by using the wrong seal. The engine is a 1969 350 4-bolt, but heaven only knows where the pan came from.

[jhow66]

69 model should use the thin seal.

[PR454SS]

I THINK the thick seal was late 70's like 77 or 78, I always have to go with trial fitting.

[shuttermutt]

Turns out the switch was made in 1975. In other words, 57-74 use the thin seal and 75-up use the thick seal, for future reference. Personally, I spent a little time doing research and calling parts houses this morning. I'm going to have them use the new Fel-Pro PermaDryPlus 1-piece molded silicone rubber gasket (part number OS34509T). They're designed to install with the engine in the vehicle and are quite a bit more idiot proof from what I understand.

[shuttermutt]

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SUPPORT YOUR LOCAL SPEED SHOP!!!
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Apparently (keeping my fingers crossed and knocking on wood) my dip stick tube nightmare has come to a close. I did manage to locate the one-piece gasket from Fel-Pro. I called every parts house in three cities and nobody had even heard of it. It occured to me to call a local speed shop and race engine builder. Sure enough, he had what I needed in stock and he even matched Summit's price.

When you need to replace your oil pan gasket, do yourself a favor and GET ONE OF THESE GASKETS. Don't even think about the 4-piece cork and rubber crap. Sure, it's $35 or so, but the ease of installation, piece of mind, and overall quality are outstanding. Short of ordering the wrong part number, it's really tough to screw up this installation even with the engine still in the vehicle.

Since I'm so close to such a long trip, I didn't want to take any chances. I also bought a brand new GM oil pan ($70) and a new set of Moroso oil pan bolts ($4). Yeah, it all adds up to a hell of a lot more money than a stupid dipstick tube, but "in for a penny, in for a pound", as they say.

So far everything appears to be okay. We buttoned up the bottom end (I very closely supervised this time), cleaned everything up, and started the truck. The guy nearly crapped himself when he saw fresh oil coming from underneath again. I killed the truck, raised the lift, and pointed out that the crossmember was a channel with no drain and that he should probably sop up the oil that was in there before we try to determine if there's still a leak.

He did and I fired the truck up again. We crawled around with it up on the lift for about 5 minutes and didn't see even a drop of fresh oil. I drove home (about 10 miles), parked on top of a patch of virgin white snow, and let the truck idle for about 15 minutes. No oil to be found there, either. The best news is, of course, that there was over 2 quarts left in the pan when they dropped it this morning and the engine seems to be no worse for wear.

What a freakin' nightmare. I'm going to mount that stupid dipstick tube in a nice piece of cherry and show it to anyone that asks, "Why?" when I tell them to leave something well enough alone!