TOPIC:

If that oil filter bolt was in place at one time and worked well I would see no reason to shorten it. Perhaps you can measure the overall length of the bolt and compare it to a new one, or a known "good" bolt to see if any stretch has taken place. I am certain someone on the forum has a new oil filter bolt and can give you the overall length. Take a close look at your bolt and make sure it has no cracks in it especially around the head or thread area. Otherwise put it all back together properly, install the oil pressure gauge and see what happens.

Rick H.

Many times when I do an oil change the O ring is big and it does not fit properly, so I cut the O ring and make it a perfect fit.

When I had Jeff weld the crank journal it distorted the case a little so oil was leaking past the O ring between the cases. Oil pressure was way down. I could see it leaking past it with the filter out. I loosened all the small bolts, installed the filter tightened it then tightened all the pan bolts. Oil pressure came back up. I wound up using a thicker O ring I cut to size at a steep angle and glued it using Super glue for plastic. Worked great. I doubt the bolt is the culprit but it may have had a ham handed PO that tightened it too much. Normally the head would be stripped if that were the case. I'd try using the washer on the outside to see if that's the problem. You can buy new bolts from a number of places or maybe a good used cover. A member here had a issue of the cover breaking. It was caused by a plug installed by the PO for his Micky Mouse oil cooler setup. Removed the plug and all was well.
Steve

I was thinking about that today. There is a big O-ring, same size as the one on the bottom of the filter cover. It's between the cases. Maybe it's missing?

hardrockminer wrote: I was thinking about that today. There is a big O-ring, same size as the one on the bottom of the filter cover. It's between the cases. Maybe it's missing?

so cases have to be split to see if it's there? Why is it there? To seal oil passage between the two case halves?

If the engine is full of oil and the cover is off there shouldn't be any oil getting past the O ring. If there is it might be missing or cracked. You would also have very low oil pressure if any.
Steve

hardrockminer wrote: I was thinking about that today. There is a big O-ring, same size as the one on the bottom of the filter cover. It's between the cases. Maybe it's missing?

There isn't a large 'O' between the cases.
Only on the filter and breather covers.
There is a small squared profile 'O' ring between the cases the same as on the oil pump to that seals the join up to the oil pressure switch.
If that was missing the oil would leak back into the sump and the oil pressure would drop so that would not be the cause of the leak.

Apologies...I was wrong. It's on the inside of the oil pan.

There is also a small O-ring inside the cases at the top of the oil filter.

If either one is leaking it would reduce pressure to the mains.

No there isn't a large o-ring between the cases, but there is a large 91mm o-ring above the oil filter area of the oil pan that is compressed against the case when you tighten the oil pan bolts. That shouldn't be the issue unless the oil pan was disturbed. The o-ring on the filter cover is 105mm. If it is properly installed and the components are in good condition and correct, I don't see how the o-ring could simply blow out.

Rick H.

Rick H., that is what got me in the first place. Just now ordering a new filter and something caught my eye. The photo of the filter I just bought shows one with more holes in the shell, larger and more densely spaced than the one I have pictured earlier in the thread. I wonder if I have the wrong filter. TBH, I really don't remember when or where I got that filter. This has been a very long term project,as mentioned earlier. All I remember is being quite surprised when, just before I first started the engine, checking and finding that brand new filter in place.

I am not familiar with the bigger KZ engines but bear with me. Anyone check the oil pressure relief valve? Or do these engines not have one. I haven't read where it was mentioned.

Yes there is a relief valve as such, but even if that was defective I don't think there is enough pressure build up to force the o-ring out of its location between the filter cover and the oil pan. If there is enough pressure to do that I would be super surprised. If the components for the oil filter cover, bolt and o-ring are correct and properly in place it should make for an almost seamless joint. I am not at home while this thread has been running, but I wish I were. I would like to see if there is any gap whatsoever between the filter cover and oil pan on my KZ-1000 just to verify what I believe is correct. Moreover, excessive pressure will/should take the path of least resistance. I am not so sure that path would be through the oil filter cover o-ring.
Rick H.