Oil Pressure Continued

I tried to use air up thru the front main oil hole but air comes out everywhere up front of the engine with a large amount of air and residual oil out of the bleed hole in the cam on the side of #1 cylinder. Even though it is AIR that I am using, the leak seems excessive. This then gets me back to the cam shaft retaing plate securing the cam with 2 small bolts in the block. Just what could be wrong with this plate that could cause such a leak?

I also removed and checked the oil filter and there is just the one little metering hole in the pipe tube; so nothing wrong there. The pipe had a few surface pits but the pipe was solid when I pressurized it with air. So oil filter is OK.

As for the probem no oil to the rockershaft, when blowing air down thru the rocker support hole in the head, residual oil comes out the aft main bearing, so nothing wrong there.

So the problem comes down to no pressure building up in the main oil galley. And it seems to be getting worse as I play with it. How long should it take cranking over the engine for pressure to build up in the main galley and pressure gauge. And should it build right up to the relief valve spring pressure? And that should be about 30+ psi for the relief valve that I have. I would expect the pressure to build up in 20 seconds or less and to the full pressure, just cranking with the starter (spark plugs removed).

Just what is it with the cam retaining plate that could cause such a pressure loss? The manual mention a copper clad plate but mine looked to be just plain steel. The governor shaft in the cam felt snug when assembling that part of the engine. But for the leakage from the hole, all the oil would have to come by the short governor shaft inside the cam shaft. So it looks like I am back to removing the cam cover plate on the engine. I just don't know what is left. Crankshaft, mains and rod bearings are all new.

I quit for the day.

Hal

Checking the relief valve with air will take a lot more pressure then if oil was used because the oil viscosity is so much greater than air. Recheck the spring and set it stiffer. I"m thinking that where your problem is.
Here"s some other thoughts.
Is the oil filter inplace and filled with oil. It will act as an accumulator until it fills partially up.

How does the face of the gears look relative to the pump housing? Any sign of excessive wear on the end faces?
Did you mic the cam journals and the bores to see what the clearances were before assembly? I can"t see how the cam retaining plate can cause the problem if the cam fore and aft clearnace is correct. All the thrust plate/retainer does is maintain that clearance. Did you check the cam thrust plate for wear and the fore and aft clearance when you assembled it? Did you check the pump inlet tube for leaks?

What good is this part-time oil filter with such a little flow? Seems would be better without it and change oil slightly more often.

The only suspect that I have left might be the cam journals but ... from the drawings, they are fed from the main bearing and not the galley so would would not be too detrimental to the main galley pressure. The mains would restrict the flow.

A lot of worn-out engine pressure problems are an accumulation of worn tolerances that then add up to a large bleed on the system.

Will know more when I pump pressurized oil thru the system.

Are you sure your oil pressure gauge is giving you a good number?

A good pump will have excess flow and can overcome some excessive leakage. Those gears are darn tough to measure for that tight a clearance both the gear backlash and clearance to the pump housing. For the cost of a pump rebuild kit, and the effort needed to pull the govenor housing and tear into the camshaft again, I'd recommend rebuilding your pump first before doing all that.

George

I keep telling folks that I have a NEW crank and NEW bearings so that is not suspect as the bearing fit quite snug. I have no spark plugs in the engine when cranking and using a 12 volt system, so it really spins it fast. At times I have had 10+ pound steady at the pressure gauge and other times get nothing. The least of my concern is a correct reading gauge as anyone doing this sort of thing would know that. So far no one has come up with any logical cause. My oil container was full when I took it off to check it for leaks in excess of the small orifice.

If one reads my whole thread so far, I have provided quite a bit of info on what I have and have done so far. Thanks to all for suggestions.

Will pressurize the system with oil from a 2 gallon paint pot tomorrow thru the pickup inlet on the oil pump and see just where the oil goes.

Working on a friends NEW VW engine on his airplane with defective valve seating on a NEW engine. All rusty so no compress. Pulling the heads and lapping the valves. The engine was setting for over 6 months. Rear spark plugs were real rusty. Never seen this happen so quick.

Good luck.

Question? How many of what thickness washers is need to raise the oil pressure from 20 up to 25-30 psi. I suppose that one could remove the old spring and measure the tension at 2 points and then calculate the K factor of the spring to get a scientific guestimate. Maybe I could take the tension specs in the manual and calculated what I need. But easier to find out from someone who knows the fractional number of lbs/inch. I plan on pulling the pan when I change the break-in oil shortly and crank up the pressure a notch. It is steady at around 20 idling or max rpm, so appears to be a minor weak relief spring.

Any idea what might be wrong with the filter housing? Maybe a crack? I even screwed out the pipe, pressure checked it, inspected the small orifice, etc. And what ever it is, it varies the pressure from about 10 psi down to none during all my testing. And in the later phases of it, I had no pressure. Using the same gasket between my blocking plate and engine block. Plate is in contact with the filter housing. Filter system is worthless anyway. Thanks again for all you inputs.