Blowing Oil After Top End Rebuild

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Ron LaDow
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Re: Blowing Oil After Top End Rebuild

#106 Post by Ron LaDow » Mon Jan 14, 2019 2:46 pm

Rusty Ferrell wrote:Got on the highway and at 70 started building press after having a steady 4 inches of Water column. Got up close to 10 inches and I pull to the side of the road at idle, I didn't time it but pressure came down slowly to zero, got back out to the next exit and got to 3.5". Returned to the shop, pulled the oil can off the breather an had about two tablespoons of oil in it. It seems to me that the beather is flooding with oil and when I let it idle the breather emptied the oil back into the case and pressure came back to zero. When I first pulled over the blowby held at its highest point and went up slightly before coming down.
Even given the pressure rise, how can it not return to zero the instant you shut it off? Is the end of the breather submerged in the oil?
Added by edit:
Wes is leaning the way I am; this seems more like a case breathing issue than a blow-by issue. A 'road-draft tube' of dimensions not far smaller than the 616 part vented millions of SMCs and they are not noted for good ring seals out of the factory.
I'd do a really close look at the venting from one end to the other.
Last edited by Ron LaDow on Mon Jan 14, 2019 4:39 pm, edited 1 time in total.
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Wes Bender
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Re: Blowing Oil After Top End Rebuild

#107 Post by Wes Bender » Mon Jan 14, 2019 4:08 pm

That just doesn't sound right at all. Something has got to be blocking the breather. Maybe not completely, but blocking it nonetheless. If it isn't obvious on he outside, I'd pull the engine and remove the third piece for a look in there. Too much oil is another suspect. Drain it and measure how much it has in it.
Some days it just isn’t worth the hassle of chewing through the restraints......

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Re: Blowing Oil After Top End Rebuild

#108 Post by Rusty Ferrell » Mon Jan 14, 2019 7:05 pm

Ron, I believe the crankcase pressure taking a little time is due to a restriction I put in the system to difuse the oil a bit and allow it to drip back. It was blowing approximately a half a quart prior to the diffuser (scotch brite). We'll pull the engine in a week or so and remove the third piece. We had a bit of binding when we first installed your full flow filter had to finesse it to tighten it down.
There are no locating holes in the third piece for the cover pins. Don't seem how but the general thinking here is that something may be blocking the high vent on the left side of the case. Other than taking the third piece off the main case was left alone, P&C, heads and both crank seals.
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Re: Blowing Oil After Top End Rebuild

#109 Post by Norm Miller » Tue Jan 15, 2019 5:53 pm

Many years ago I had car in the shop with a blocked #1 main bearing oil drain hole, in the case.
It blew oil severely.

Just a long shot.
Norm
 

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Re: Blowing Oil After Top End Rebuild

#110 Post by Robert Vaughan » Tue Jan 15, 2019 6:45 pm

Regarding the Ron LaDow integrated full flow oil filter and the oil pump cover slignment pins:
I found that four custom thin tubular brass spacers between the M6 bolts securing the pump cover and the inside diameter of the pump cover fastener holes located the pump cover better than the small alignment pins. I recall removing the small alignment pins and leaving them out. Working with the third piece, separated from the rest of the engine, with the integrated full flow oil filter accessory fastened in place, with the oil pump gearset inside, dry, I could prove that this pump cover position was best because turning the drive tang by hand was easy and smooth. In other words, Ron's four M6 fastener holes are in the right place. You can not necessarily depend on the position of the small alignment pins sticking out of the third piece.

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Craig Richter
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Re: Blowing Oil After Top End Rebuild

#111 Post by Craig Richter » Tue Jan 15, 2019 6:56 pm

Been following your woes here, Rusty, because your problem is really baffling. Lots of motors have gone by these posters, stock, race and everywhere in-between, and none of us can come up with any fixes you haven't worked on. I was sure Wes and Ron were on the right track, because holding any crankcase pressure after the motor is shut-off seems impossible without some major restriction at generator stand/oil filler. Maybe Norm's "long shot" isn't so long. I think I remember the Maestro had a pretty long chapter on #1 main bearing weirdness. Good luck, because you're not done yet...
 

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Re: Blowing Oil After Top End Rebuild

#112 Post by Greg Carter » Fri Jun 14, 2019 7:29 pm

SOLVED

After a few months of head scratching and trouble shooting we finally figured out what was going on.

Bottom line, the small rubber O-ring that seals the main case and third piece nose (crank pulley) bearing oil galley was missing. I either failed to install it or it fell out at some point during reassembly.

The oil galley passes through the bottom portion of the oil breather passage (where the generator tower mounts to the case). The O-ring not being there allowed the breather to fill up with oil under sustained RPM loads and, once it reached a point where the oil blocked the vent, the case would over pressurize and pump oil out everywhere. After it did it, it would take more sustained RPM driving to do again as the case pressure had effectively returned to normal once the oil was no longer blocking the breather passage. If I drove in stop-and-go traffic (ie: around town) I was never at a sustained RPM long enough to build enough oil in the breather passage for it to pump out as the time at idle at stop lights allowed the oil to drain back down.

It doesn't appear there was any real damage to the crank shaft and we replaced bearing. At this point the engine runs well with no oil issues.

I guess I'll go re-read the Maestro's book to avoid anymore bone-headed mistakes........

Greg

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Re: Blowing Oil After Top End Rebuild

#113 Post by C J Murray » Fri Jun 14, 2019 8:27 pm

Thanks Greg for posting the solution. That is really weird! Funny how a tiny mistake with a tiny part can cause so much trouble. Glad you figured it out. :D
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Re: Blowing Oil After Top End Rebuild

#114 Post by Don Gale » Fri Jun 14, 2019 9:46 pm

3 piece oil rings? Me thinks 1 or more of them didn't go in right.
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Re: Blowing Oil After Top End Rebuild

#115 Post by Harlan Halsey » Sat Jun 15, 2019 4:58 am

Robert Vaughan wrote:
Tue Jan 15, 2019 6:45 pm
Regarding the Ron LaDow integrated full flow oil filter and the oil pump cover slignment pins:
I found that four custom thin tubular brass spacers between the M6 bolts securing the pump cover and the inside diameter of the pump cover fastener holes located the pump cover better than the small alignment pins. I recall removing the small alignment pins and leaving them out. Working with the third piece, separated from the rest of the engine, with the integrated full flow oil filter accessory fastened in place, with the oil pump gearset inside, dry, I could prove that this pump cover position was best because turning the drive tang by hand was easy and smooth. In other words, Ron's four M6 fastener holes are in the right place. You can not necessarily depend on the position of the small alignment pins sticking out of the third piece.
There is a reason that Porsche put those alignment pins in the oil pump cover. It is because the cover also has the outer bearings for the oil pump gears. Oil pump covers are not interchangeable, unless you happen to be very lucky. (Two covers I happen to have out of engines differ by .010" across the dowel pins.) If for some reason you want to change covers, then you have to do as you suggest: with the third piece off the engine and the pins out, move the new cover around until, "turning the drive tang by hand {it is}easy and smooth." Then you pin the new cover in place. (I know of an engine where the builder just tightened the nuts after getting smooth rotation, but that made it tough on the next guy.) Same procedure would seem to be necessary with any different cover, but how one accomplishes that without having hand access to the oil pump drive tang as the Pre Mat web instructions seem to imply, baffles me. Unless of course, the aftermarket cover has a whole lot of clearance in the bearings?

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Re: Blowing Oil After Top End Rebuild

#116 Post by Craig Richter » Sat Jun 15, 2019 5:30 am

Greg, more thanks for sharing the solution to your problem. Sometimes posters fix their issue, but are so happy they forget to tell the Forum the whys and hows, leaving us, collectively, no smarter than before.
Don, 3-piece oil rings are the best, but if those center "squigilly" pieces don't get clipped together correctly, or get knocked apart during assembly = big smokey problems!
 

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