Oil Pan Gasket Issues

[1968CHEVYC10]

the rear main seal was leaking pretty bad on my 350. According to my suffix code the block is a '75, but the gasket they gave at oreilly's didn't look like it was the right one, it looked like this: http://www.autozone.com/autozone/par...74451_0_12292_ (the oreilly site was down but it's the same part) There should've been only one of the two larger holes on the sides, for the dipstick. So I took it back and they gave me one for a '74 350 that had it only on one side. Anyway I got it in put oil in it and now it's leaking way worse than it was before, especially bad at the front near the timing cover. I've heard that GM changed the thickness of the gasket where it meets the timing cover in 81, but also switched the dipstick to the other side. Anyway I'm just wondering if anybody has had this problem and how they fixed it. Thanks Yall!!

[67ss&99ss]

Originally Posted by 1968CHEVYC10

the rear main seal was leaking pretty bad on my 350. According to my suffix code the block is a '75, but the gasket they gave at oreilly's didn't look like it was the right one, it looked like this: http://www.autozone.com/autozone/par...74451_0_12292_ (the oreilly site was down but it's the same part) There should've been only one of the two larger holes on the sides, for the dipstick. So I took it back and they gave me one for a '74 350 that had it only on one side. Anyway I got it in put oil in it and now it's leaking way worse than it was before, especially bad at the front near the timing cover. I've heard that GM changed the thickness of the gasket where it meets the timing cover in 81, but also switched the dipstick to the other side. Anyway I'm just wondering if anybody has had this problem and how they fixed it. Thanks Yall!!

I dealt with the same problem this week on my uncle's 65 Nova. He had a one piece gasket on his engine and it leaked really bad. I ordered the gasket for a 55-74 sbc and put it on and there was a huge gap at the timing chain cover. I didn't even try to start it. Anyway, I went back and got a gasket just like you have pictured. It is thicker at the timing chain cover area. It will work correctly on your engine. What you need to do is get that gasket, and a tube of red RTV silicone. Pull the pan back off, clean the pan rails, timing chain cover and rear main area until its spotless. I like to use brake parts cleaner or acetone. Put a dab of silicone on all four corners of the block ( where the cap meets it and where the timing chain cover meets it. Then put a bead of silicone on the block where the dipstick holes are on the gasket. Put the gasket on, then put the pan on and really snug the bolts down. The gasket has a steel shim in it to "prevent" over-tightening. Just be careful not to strip the bolts in the block. This should solve your oil leak issue.

The thickness actually changed in '75.

http://www.cartechbooks.com/vstore/s...6&chapter=6898

[1968CHEVYC10]

Awesome, so there wasn't a problem with having the hole for a dipstick on both sides?

[67ss&99ss]

Originally Posted by 1968CHEVYC10

Awesome, so there wasn't a problem with having the hole for a dipstick on both sides?

Nope, you should be good to go.

[Lee H]

With your oil pan sitting on your work bench place a straight edge across the front and measure the depth of the dip that goes around the timing chain cover. 1 3/16s use the 74 and back thin gasket set, 2 1/4 use the 75 and newer thick gasket set. Almost all after market use the thick set. Keep in mind that just because your motor is a 75 does not mean it has the correct pan on it. I'll bet your pan needs the thick set but you have the thin set on it. Note that the only difference in the gasket set is the thickness of the front seal.