964 low oil pressure solved, new question

[Don Settergren]

Okay, so the ball is part of a check valve system as suspected. Check valves are used to keep fluids from returning backwards through them. So I guess Tom, the author of this thread may have a squirter that squirts the back-side of the piston and lubes the wrist pin bearing. It works at high bar\psi but also at low pressures. That doesn't seem all too bad to me. I'm still at a loss as to why Porsche used a check valve in the squirter.

[TomUban]

Don, Unfortunately it is my thread and I am the one with the engine in question. I guess the term "check valve" is a bit of a misnomer as it is really a pressure regulator that does not allow the squirter to operate until there is enough pressure to open the valve. As I understand it, the squirter's purpose is primarily to reduce the operating temperature of the dome of the piston up which it squirts (by 100 degrees or so). If the pressure regulation ball in the squirter comes out, then presumably the squirter is operating all of the time rather than just when the pressure is above 3 bar (off idle). So if the remaining "nozzle" which the squirter fell out of is still able to hit the back of the piston with oil, then the cooling effect should still be present, however as the pressure regulation is no longer pressent, other areas of the system may be starved for oil (e.g. main bearings?), particularly during idle conditions. Sigh...

--tom

[Don Settergren]

Thanks for the information. I've always had a sneaky suspicion that some of my squirters were malfunctioning as they were way easier to clean than all the instructions on Pelican suggest. Maybe I have the same problem and will be pulling my engine just like you. Three of the squirters are on the same oil line as the main bearings so trouble looms. Anyway, I didn't mean to hijack your thread on this fantastic public forum. Sorry!

[ekessel]

Is there any update on this engine problem?

-Eric
90 C2

[TomUban]

I swapped in a '92 engine and the '90 is sitting in the front of my garage waiting for me to decide what to do with it. I won't know if the metal fragment was from a squirter or somewhere else without either opening the case myself or sending it out for a rebuild.

[john walker's workshop]

maybe it's a plug from a crankshaft oil passage.

[TomUban]

I wish that I had more knowledge or a better diagram of the oil flow for a 964 so that I could better speculate without disassembly. The metal bead was found in the pressure regulator which as I understand is after the pump, which is after the screen. So unless a larger than normal hole developed in the screen, how would anything this size from inside of the case end up where it did?

[ekessel]

It could have fallen into the tank.............

-Eric
90 C2

[DW SD]

Tom,
The 964 diagram looks very much like the 993 posted by Bill Verburg. However, the oil filter, fed by the outlet of the oil pump does not exist.

Also the bridges (to feed the top end) are smaller in size since the 964 uses a solid lifter cam, where the 993 uses hydraulic lifters.

Doug

[Don Settergren]

I can send you a ball from a squirter assembly if that'll help... Just PM me.

[TomUban]

Sorry if I'm asking a stupid question here, but I would just like to be clear. the pump draws from both the tank and the sump, passes through the pressure relief valve, then to the engine's oil ways. If the metal object fell into the tank or was a loose scrap from the brazing of the tank, etc. it would just pass through the pump and end up in the relief valve, never having to go through the sump screen. This sounds likely.

Right, the 2nd oil filter does not exist on the 964, so that oil flow is non-existent.

Thanks for the offer Don, but I'm not sure that it would help. Do you have a picture of the squirter assembly? That would be interesting to see...

[Henry Schmidt]

Originally posted by john walker's workshop
maybe it's a plug from a crankshaft oil passage.

That would be my thought as well.

[TomUban]

But wouldn't a plug from the crankshaft oil passage have to flow through the oil pump screen in order to arrive at the pressure relief valve? I believe that the hole size on the screen is smaller than the size of the metal bead.

[DW SD]

Originally posted by TomUban
Sorry if I'm asking a stupid question here, but I would just like to be clear. the pump draws from both the tank and the sump, passes through the pressure relief valve, then to the engine's oil ways. If the metal object fell into the tank or was a loose scrap from the brazing of the tank, etc. it would just pass through the pump and end up in the relief valve, never having to go through the sump screen. This sounds likely.

Right, the 2nd oil filter does not exist on the 964, so that oil flow is non-existent.

Thanks for the offer Don, but I'm not sure that it would help. Do you have a picture of the squirter assembly? That would be interesting to see...

Tom,
The oil pump is really two pumps sharing a driveshaft. One pumps clean oil gravity fed from the oil tank to feed the lubrication system, which includes bearings, cams and moving parts.

The second is to scavenge oil from the crankcase and send it out to the oil cooling system and on to be filtered prior to re-filling the tank.

Doug

[Don Settergren]

Going back to your original photo, the ball from the squirter looks too small to be your stray part. Attached is a photo of a dime and a disassembled squirter (sorry, the camera doesn't have a zoom).

Could the stray part be part of the oil pressure sender you replaced? If I had one, I'd probably cut it in half just for fun...

[freddie911]

Originally posted by TomUban
I wish that I had more knowledge or a better diagram of the oil flow for a 964 so that I could better speculate without disassembly.

Oil flow diagram for engines with on engine cooler, should be same as 964



Fred