Oil Filter Question

[ironridge]

Does anybody know if there is supposed to be a hole about 3/32" drilled in the expansion plug that is located in the passage above the oil filter next to the threaded adapter?(where the filter screws on) What would the purpose be? Also has anybody changed the filter bypass valve?

Thanks in advance.

[Hubert]

Yes the orifice is suppose to be there. As for the purpose its never been explained fully. I believe its to vent pressure to the oil gallery side of the bypass valve. I sometimes think the oil filter bypass valve is a differential valve and opens during big swings of oil pressure at start up and at engine revs etc. The orifice helps pressure build on the backside of the bypass valve to close it so oil will then only pump through filter unless a big differential builds and opens the bypass again. Other times I question operation.

I have posted a few times on the oil filter bypass valve and have never been fully satisfied with why and when it opens.

What would you change it to, why, and for what purpose remote mount filter maybe?

[ironridge]

Thanks for the response on the orfice. As for the filter bypass I am concerned that when the block was hot tanked it may have been damaged.

[JohnC]

Any chance it is allowing oil to flow around the oil cooler bypass valve? Otherwise, congealed oil in the cooler might prevent flow even if the oil in the engine got hot.

[Hubert]

I bought a GM oil filter bypass valve to look at a good while ago to see what it is and how much pressure opened it and learn more about it.

It has a little spring, plastic pieces, and is a stamping assembly. If "hot tanking" gets really hot(?) it could have have done something maybe but I think the oil gets anywhere up to about 270F ish (when towing) so the valve should be able to at least tolerate that much heat. Unless the hot tank chemicals would damage the plastic???

There is a cooler bypass that I think is similar to the oil filter bypass too.

Did I miss some other info in another post that you are worried about oil bypassing the filter or oil pressure issue?

[ironridge]

I never thought about the cooler bypass, I am thinking now that might be what I'm looking at, as it would be located on the outward side of the filter(oil filters from the inside of the filter out ) I better have another look at the passages and what goes where.

I was just concerned with it being damaged. Now I'm not even sure that it has a filter bypass.

[Hubert]

You can see the bypass for the filter in the base of the filter pad. Here is a diagram of the oil passages. Oil pump to cooler (or bypasses) then to filter (or bypasses) then to oil gallery and distributes to cam, crank bearings etc.

http://www.thedieselpageforums.com/photopost/showphoto.php?photo=930&ppuser=18766&sl=h

Can be found in my photo gallery.

I think it filters outside is dirty side or clean oil flows through threaded knipple. But I'll look again to make sure.

[Hubert]

I looked again and dirty oil is on outside of filter element clean oil goes through knipple.

You can't see the oil cooler bypass from underneath but the filter bypass is in the area between the knipple and the filter gasket. It appears you would have to pull a plug out of rear of engine then the cooler bypass is seated down in the oil passage way pretty much above the oil filter inlet path such that if oil bypasses the cooler it comes right down into the dirty side of the filter.

If you want I can send you a full size scan of the page out of the helm manual. Just send me your email in private message.

[Hubert]

Aaahaa

Man I am slow sometimes and forgetful othertimes. Its seems so clear now. The diagram is a bit misleading and I think missing a path down from the oil cooler bypass to the filter.

Oil flows from pump to cooler then to filter then to galleries etc or bypasses cooler or filter depending. Looking at it AGAIN I now interpret it as the oil cooler bypass is above the cup plug with orifice.

Such that I think the oil pumps towards the cooler but when too cold it doesn't want to flow oil through lines and cooler fast enough. When cold enough it bypasses the cooler lines and cooler through this oil cooler bypass. Then some but not all the oil comes down through the cooler bypass because after cooler bypass valve it is restricted by this orificed cup plug. Or in other words it can bypass some around the cooler but has to squeeze oil through this orifice such that the orifice restriction allows pressure to stay pushing towards the intended oil cooler path.

Once oil has circulated and warmed enough the oil cooler bypass should close and all oil pass through cooler and the cup plug orifice does nothing.

What do ya'll think of that?

[Hubert]

uhhgg OR

The helm manual says "the oil cooler bypass valve is located in the engine block oil gallery to oil cooler passage".

So maybe oil can flow directly from pump to oil gallery when it bypasses the cooler during cold start. And the orifice cup plug helps pressurize one side of the oil cooler bypass valve to help control the differential pressure across the cooler and or cooler bypass valve???

Man it is tough to interpret that diagram due to size and lines so close. I think there are other passages suppose to be shown but someone edited them out to try to clarity due to overlap in the orientation of print. Its just not very clear how the cooler is bypassed.