Relief, Oiling system in a type 4 Options

[worn]

If anyone has read my previous threads my two week vacation turned from driving to lying on the creeper under the new engine and transmission. Low oil pressure after warm up. I ordered a new Melling 30 mm pump and we shall see, but at the same time I looked into the pressure relief system - especially where it shunts oil away from the cooler because it is easier to see in the car.

What I found surprised me. First, looking at two different cases (72 1.7 and 76 2.0) I found that the piston seats on a shoulder in the bore that is at most a mm wide, and is not at all uniform in width across the piston face. OK, maybe it isn't supposed to seal.

Second I found that by the time you have opened the valve to shunt past the cooler, you are also dumping into the sump. That is there is a small overlap between the outlet to the oil gallery and the grooves cut in the bore leading to the sump exit.

Finally, the piston is simply loose in the bore. I can understand a fear of seizing, but there is no way that with my system oil isn't streaming into the sump, and it will stream faster as it thins - much faster.

I also spent a long time cruising the Samba - they ought to know whats up. What I found is a recurrent theme of new engines built in a variety of ways making low oil pressure. Many people were happy with what I ended up with - 10 psi at idle. On a new engine.

It is steel against untreated aluminum, so wear would be expected, but mine do not look worn - just poorly made. Maybe they are worn and I cannot tell. I got a face full of oil on one attempt at examination, so I may have missed things.

It seems an ideal situation for machining or sleeving during the rebuild, and I actually found a manufacturer of a sleeving kit with a ball bearing valve.

Thoughts ladies and gentlemen? (IMG:style_emoticons/default/idea.gif)

[eyesright]

My (home rebuild) engine is back in the car, oil leaks from bad oil filter/case seal (D'oh!) and flywheel O-ring cured...pools of oil on the floor reduced to only a drop here and there.

I also changed the stock oil temp sender to the appropriate sender for the VDO gauge (miscommunication with the guy taking my order @ PP probably, whom I thought said just use the stock sender) so now I have oil temps, oil pressure, and head temp.

Okay, oil pressure is way low (less than 5 @ idle, 15-20 @ speed but 80 when cold.) and on my first drive last night (probably 70F outside temp) my oil temp worked its way up to 225F. So, higher than normal oil temps and lower than normal pressures suggest I'm losing pressure as the relief valve allows oil to return to the sump instead of passing to the cooler. I'll get some marking solution to see if that's the problem and probably figure out a way to hone the seat. I understand I don't want to take off too much, maintaining the chamfer

Warren, thanks for your research and work. If not for that and the gauges I bought just to be cool, my engine would be toast soon.

Tim