Oil Filter Gasket

[Michael J.]

I just changed the oil and filter cartridge in the can on my '67 L71, I had been putting it off for a while since it is such a messy job. I am wondering if anyone has a trick for removing the old gasket up on the engine block end of the can seat, which seems to be welded in place. I couldn't budge it with a small screwdriver blade, a punch, etc. Any ideas appreciated, thanks.

[Bob R.]

Re: Oil Filter Gasket

When you install the new gasket make sure you wet it with some fresh oil. I use an ice pick to remove the old gasket and have never had a problem getting it to come off. I push it in at an angle and the gasket comes off without a problem.

[Timothy B.]

Re: Oil Filter Gasket

Michael,

If you can get it with a ice pick remove the relief valve and take it off. The relief valve is held on with the two screws you see when looking up there.

[Stuart F.]

Re: Oil Filter Gasket

Tim has the right idea. Remove the relief valve and the ring seal comes out real easy. Gives you an opportunity to clean the valve as well. Go easy on the bolts though as over the years I rounded one off and had to use a special tool to loosen it.

If you happen to be in a hurry or are not inclined (lazy) to do this (like me), go ahead and reuse the old ring seal. I sometimes go two or three changes without changing it. I use two different canisters; one original and one repro (exchanging at each oil change). The gauge thickness of the two are quite dis-similar, but even that doesn't seem to matter. I've never had a leaker. For one thing, I always use just the right torque on the bolt. I believe many overtighten and crush the ring seal too much.

The worse thing you can do is to just add a new seal on top of the old (if one is good, two should be twice as good). This will leak for sure, big time!

Stu Fox

[Michael J.]

Re: Oil Filter Gasket

OK, thanks very much for all the tips!

[Ronald L.]

Re: Oil Filter Gasket

I'm following Stu's lead, change the gasket when there's a demonstrated need, you will know it when the motor pukes a couple of quarts on the ground after a filter change.

Question is - how do you know the oil is really going through the filter???

Can one verify the by pass valve function>

[Timothy B.]

Re: Oil Filter Gasket

Ronald,

When a cold engine is started the bypass will open and allow unfiltered oil to the engine until pressure is equal on both sides of the valve. The valve also opens if there is a restriction in the oil filter, same principle applies as there is not equal pressure on each side of the bypass valve.

[Ronald L.]

Re: Oil Filter Gasket

Tim,
This is the theory of operation, thanks for that detail.

Is there any way to check for proper function?

Or if someone has messed with the valve such that the oil is not generally being filtered?

[Timothy B.]

Re: Oil Filter Gasket

Ronald,

If you remove the relief valve assembly from the engine, the valve is just a plate with a small spring behind it. Just make sure it's clean on both sides and it shuts completely and I think your OK.

When pressure is on both sides that means oil is traveling through the filter and all is good. I think other than cold oil or a restriction in the filter, thick oil is probably the other thing that would cause the valve to open until this thick oil works it's way through the filter.

[Michael H.]

Re: Oil Filter Gasket

Ronald,

When a cold engine is started the bypass will open and allow unfiltered oil to the engine until pressure is equal on both sides of the valve. The valve also opens if there is a restriction in the oil filter, same principle applies as there is not equal pressure on each side of the bypass valve.

I think the valve remains closed until the pressure to route oil through the filter excedes the pressure required to open the bypass valve. That would occur if the filter is partially plugged.
I don't think the valve opens on cold starts.

If I remember correctly, the valve is designed to open at 11 PSI. In other words, if more than 11 PSI of pressure is required to force oil through the filter, the bypass opens.

The valve may also open at high RPM/pressure.

The valve operation can easily be checked by depressing the disk to make sure it is free.

[Wayne M.]

Re: Oil Filter Gasket

.... Remove the relief valve and the ring seal comes out real easy. Gives you an opportunity to clean the valve as well. ....

Another casting date to worry about . Here's the valve from my mid-May cast 396 block . Note the 65 and 5 dots. Same valve SB or BB.

The valve can be installed in two positions; with the valve nearest the hole in the block, or 180 degrees off. I don't believe it makes a difference (opinions ?).

[Timothy B.]

Re: Oil Filter Gasket

Wayne, I don't think it makes any difference which way the valve is installed. What's interesting is that the 1967 AIM calls for a gasket where the valve attaches to the block and earlier AIM's don't show this.

[William D.]

Re: Oil Filter Gasket

Great Post - Thanks for the info. Always have problems with that seal!!

Bill

[Robert I.]

Re: Oil Filter Gasket

" I don't think it makes any difference which way the valve is installed."

Shop manual says it's better to have the valve away from the engine.

How does one keep the washer in place when re-installing the pressure relief valve???

[John H.]

Re: Oil Filter Gasket

" I don't think it makes any difference which way the valve is installed."

Shop manual says it's better to have the valve away from the engine.

How does one keep the washer in place when re-installing the pressure relief valve???

Robert -

Which shop manual says that?

Which washer?