No need to measure, 1/8" difference is noticeable. If the front seal didn't squish when tightened down, required a lot of sealants to fill the gap, easily slipped from its position, as Bob mentioned post #2, it's the problem. Myself, I'd have applied sealant to the gaskets setting them into place on the pan. Once into place, taped them in position allowing them to dry in place, inverted on a flat surface to apply pressure to keep them flat. Once dried, I'd apply a light coat to the gasket edges and the surface and snug the bolts into place. Once it set up a bit, tighten down. That Permatex a great product. When I did more, I was also a fan of GM's engine sealant. Similar product. I would like to clarify however the RTV comment and my understanding of it. Room Temperature Vulcanising. Difference Between RTV and Silicone | Compare the Difference Between Similar Terms Different products for different applications. That's the Chrome one. Driver side dip stick tube. Far as I know, factory steel, passenger side dip stick tube. I'm going to guess that's Permatex Grey under that gasket. 22074.pdf (itwgbpermatex.wpenginepowered.com)
If the dip stick is on the passenger side, you have a later pan. Stock 283 pan would have the dip stick on the driver or left side.
Over the last few years GM has been progressively selling more and more "AC Delco Original Equipment" parts in place of "GM Genuine Parts" at their dealership parts counters. To the best of my knowledge the quality of these parts and the warranty coverage has been good. But I wouldn't be surprised if GM now sold only the later design oil pan that used the thicker seal as a replacement for both the older and newer style oil pans. Or that most of the people selling these parts are even aware of the actual difference between the two styles of oil pans and their seal requirements. (Lord only knows how the aftermarket "stock" oil pans are cataloged!) It also doesn't help when the engine in question has been out of production for 30 years or more.
Spent half the day Friday replacing the pan with a new 1-piece. Still leaked. Maybe worse. Got under there Saturday morning, snugged all the pan bolts again, thought i had it. Nope. Today i dropped the pan again. Found this. This is the fel-pro 34509 gasket. Should be for this pan. Look at the gap when relaxed. the other pic also looks like that front seal never did seal, as there is flash rust on the lip. No where else. Not sure what to do now.
find an old used original oil pan, and an old used original timing cover, install them with the correct gasket. But seriously....how does the timing cover look? There's a trough on the bottom of it that the front of the pan gasket fits into. If it's deformed, or missing, or made wrong (such as most of the aftermarket timing covers were), it will never seal.
Thank you for all your help. I’m dumb, and didn’t measure the openings Friday when i dropped the pan. The opening is clearly 2-3/8” deep, thus the thick gasket. Not the one i thought it was.
I know people love those FelPro one piece pan gaskets but when I had my 427 small block built it leaked right on the dyno.
The one piece gasket makes installing the pan when the engine is in the car, a lot easier. And they usually don't leak, but having original old Chevy tin is a big part of it.
Did the timing covers change in that lower seal area when the oil pans changed to the thicker front seal? I don't recall that being the case, but who knows.
I really don't know. I do know that the timing cover is "original" to me and me having the motor. I did replace the pan with an new one a few years back when putting this all together. since we are just now starting to drive the car, the couple drips has turned into puddles.
The hose from the valve cover or filler neck to the air cleaner was to let clean air flow into the crankcase it is not to vent fumes out. The fumes were vented though the pcv valve. On a Chevy or other GM you had/have a filter that clips in the housing of the air cleaner This is a 61 Chevy C 10 road draft tube setup . Note that air is supposed to flow in though a breater, flow though the engine and be drawn out by air passing the tip of the road draft tube at road speed, it is totally ineffective at an idle. My experience with oil leaks in an 283 involve running two breathers on the engine and no pcv or even road draft tube. You have to get the pressure out and breathers alone don't cut it. In that 283 there is a more than good chance that the front seal has cut a groove in the damper too.
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