Oil Filter Bypass Valve

[6shark9]

I can't seem to find much information on this valve.

Does any forum member know if:

There is there one present on a '69 350ci?

Is it in the block (above) the oil filter?

Is it servicable?



I want to rule out that the valve could be stuck open causing low oil pressure at idle RPM.

Thanks for any help,

 

[GTR1999]

There is a bypass in the aluminum adapter the filter screws into.

 

[JohnZ]

There's also a bypass valve built into almost all modern filters.

 

[RonJ]

There's also a bypass valve built into almost all modern filters.

With the by-pass valve built into the adaptor, I don't think it's advisable to use a filter with a by-pass valve.

Ron ...

 

[Hib Halverson]

The oil filter by-pass valve will not cause low oil pressure. All it does is provide a path around the filter if the filter becomes restricted.

Now...if you've disabled the filter bypass and the filter is restricted low or no oil pressure is the result.

There is also a pressure relief valve in the oil pump. It is possible for it to stick and cause low oil pressure at idle but it would be very unusual for that to happen.

The first thing to do on a car that old which exhibits low oil pressure is to verify the reading on the IP gauge by installing a known-good gauge on the engine and comparing the readings. If you verify low oil pressure, there are a wide variety of problems which could cause it.

Check your gauge accuracy and report back.

 

[6shark9]

Thanks folks.

I planned on checking the guage for accuracy.
However, the oil pressure responds very quickly to engine RPM.

Idle (700 RPM) pressure reads 5 psi
1500 RPM pressure reads 40 PSI

A post a long time ago suggested that it may be due to a filter bypass valve being stuck open. Reason was, worn crank bearings cause low oil pressure but as RPMs increase there are two factors: Higher pressure from the oil pump running faster but lower pressure as the centrifigal forces spin oil out of the crank.

Because the oil pressure responds so quickly in my case, it was suggested that I may have the bypass problem.

I hope that I find that the 5 psi turns out to read 20 psi on another guage!

Motor was rebuilt 25,000 miles ago. I didn't do it, so I can't be sure that it was done right. Paperwork with the car leads me to believe that it was done with a good amount of care.

 

[Vettehead Mikey]

Idle (700 RPM) pressure reads 5 psi
1500 RPM pressure reads 40 PSI

So what's wrong with that? There's thousands of SBCs running around very happily with this pressure.

 

[mrvette]

So what's wrong with that? There's thousands of SBCs running around very happlily with this pressure.

I know from Pontiac daze it don't take much to float a bearing, but 5 psi seems really lo to me, more like 20 is more the norm on a fresh enough engine, my old tired 318 workhorse van with 250k miles on it runs at 15 or so hot idle, and that makes me nervous, as it's only 40 psi at full throttle running...

I also realize I"m old school about that.....

GENE