C2 _ oil pan (?) leak

[Steve D.]

63 _ 327

I know that leaks are a pain to locate; my question is _ does the following description sound more like a pan gasket leak or something else?

This is a leak, not a drip; estimate between 1/2 pint in 15 mins. It appears to be coming out right at the bottom of the timing chain cover where oil foams out; suggesting pressure. I have a single piece pan gasket.

[Joe L.]

Re: C2 _ oil pan (?) leak

63 _ 327

I know that leaks are a pain to locate; my question is _ does the following description sound more like a pan gasket leak or something else?

This is a leak, not a drip; estimate between 1/2 pint in 15 mins. It appears to be coming out right at the bottom of the timing chain cover where oil foams out; suggesting pressure. I have a single piece pan gasket.

Steve------


That's a serious leak. It's unusual for an oil pan gasket to leak at that rate. There is no pressurized oil in the vicinity you describe. How is the engine's oil pressure? If there is a serious leak in the pressurized system there should be a noticeable drop in oil pressure.

[Steve D.]

Re: C2 _ oil pan (?) leak

Oil pressure is ok: 55 psi

[Joe L.]

Re: C2 _ oil pan (?) leak

Oil pressure is ok: 55 psi

Steve------


Did this leak begin right after you installed the oil pan gasket or has the gasket been installed for some time with no leak problem until recently?

[Steve D.]

Re: C2 _ oil pan (?) leak

Joe

Recently installed after replacing main and rod bearings.

[Harry S.]

Re: C2 _ oil pan (?) leak

Steve, Did you install the correct gasket? Check the attached picture. Do you have a new style oil pan on your 63?

[Richard M.]

Re: C2 _ oil pan (?) leak

There are 2 differently sized seals at the front of the pan where it seals against the timing cover. The 2 sizes are due to the different oil pans, where the dimension from the front arc center to the flat surface of the pan rails is slightly different.

I am thinking the wrong front seal was used, and if there is a sizable gap at the seal it could cause your issue.

Stock pan on your '63 should be 2 1/4" height. If a service replacement was installed at some point it could be 2 3/8".

Joe Lucia posted these differences in post# 8 of this thread. The photos in post #1 show some measurements.
https://www.forums.ncrs.org/showthre...t=oil+pan+leak

Rich

[Gene M.]

Re: C2 _ oil pan (?) leak

63 _ 327

I know that leaks are a pain to locate; my question is _ does the following description sound more like a pan gasket leak or something else?

This is a leak, not a drip; estimate between 1/2 pint in 15 mins. It appears to be coming out right at the bottom of the timing chain cover where oil foams out; suggesting pressure. I have a single piece pan gasket.

What do you mean by "oil foams out"? Do you have pressure in the crank case? If so it suggest rings blow by.......

[Steve D.]

Re: C2 _ oil pan (?) leak

Rich _ Thanks; I missed that thread when I checked the archives. _ Steve

[Steve D.]

Re: C2 _ oil pan (?) leak

Harry _ I will check the number. I have used the one piece successfully before and thought I bought the same one. _ Steve

[Steve D.]

Re: C2 _ oil pan (?) leak

Gene _ At the point where I can see the oil dripping, there appear to be fine bubbles. I haven't used a gauge, but I can't detect any blow from the breather in the back of the block, or see a high reading on the dipstick from oil being pushed up the tube. _ Steve

[Joe L.]

Re: C2 _ oil pan (?) leak

Rich _ Thanks; I missed that thread when I checked the archives. _ Steve

Steve-------


I think the wrong gasket, as others have suggested, is exactly the problem. There are two different one piece gaskets for 63-79 small blocks. The one used for 1963-74 small blocks with original oil pans has a front gasket thickness of 0.22". The one used for 1975-79 small blocks has a front gasket thickness of 0.41". The latter is also used for 1963-74 Corvettes with GM replacement oil pans sold after about 1976. These replacement oil pans are identical to the original 1963-74 oil pans except for the front gasket radius.

I strongly suspect that you have the 0.22" thick gasket but you also have the pan that requires the 0.41" thick gasket.

[Richard M.]

Re: C2 _ oil pan (?) leak

Joe, Curiously......

Reference from your previous post...
1955-74 small block (Corvette and otherwise)-----2-1/4"

1955-74 GM SERVICE oil pans after about 1976 (i.e. pans with 6 digit part numbers)----2-3/8"

1975+ oil pans------2-3/8"

Was there ever a definitive reason why the later years oil pans(1975 +) had this dimension change to the front seal area? I think I can understand due to this change that the service replacements for the earlier years followed suit with the new dimension.

It seems so frustrating to many that this change happened. So many years later those that are not aware of this oddity continue to have these problems. I too have been surprised and frustrated by this over the years.

Rich

[Harry S.]

Re: C2 _ oil pan (?) leak

A quick way to identify a 63 oil pan, besides the measurement, a 63 oil pan has a nut plate welded on the inside. It is threaded to accept the drain plug. The later oil pans have a large hex nut welded on the inside. Here are a few pictures. I had to replace my nut plate as it was stripped.

[James W.]

Re: C2 _ oil pan (?) leak

A quick way to identify a 63 oil pan, besides the measurement, a 63 oil pan has a nut plate welded on the inside. It is threaded to accept the drain plug. The later oil pans have a large hex nut welded on the inside. Here are a few pictures. I had to replace my nut plate as it was stripped.

Harry,

Is the nut plate only for 1963? I bought the same GM nut plate that you have pictured to repair my original 1964 Corvette oil pan that has a leak at the oil pan drain.

Thanks,

James