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Same problem Don!!
Hey Don,
Your experience with no turbo boost AFTER the oil change on the front engine is the same scenario on this end, except the turbo on mine finally came alive after rotation to about 30" and then VERY slowly came up to 35" in the downwind climbout. I was surprised to hear you're having the same problems. You'd think that with fresh oil and a new oil filter that the problem wouldn't be there. How many hours on your front engine? Mine sat quite a bit too before I got it. Our front engine is 1250 TTSN.
And Bob... NO, it's still not sorted out but I'm sure glad to hear you NEVER have these turbo problems, as it is apparently only Don and I that have the "Carbon Gunk Meister" in our engines (HA!-HA!). And BTW, when you comin' out this way??
Anyway, FRONT engine: FIRST FLIGHT after oil & filter change, no turbo boost on the takeoff roll until after rotation, then slow spool. After climbing to 4000', 29"/2400 RPM cruise, then pushing the throttle up turbo responds but it spools up more slowly than the rear engine, which has 140 hrs TT. Came back and landed after an hour-long flight, belly clean as a whistle. I'd put 7-quarts in during the oil change.
SECOND FLIGHT a few days later... oil level during preflight was 5.5 quarts, so added 1-quart. OK turboboost at the initation of the takeoff roll, although 35-36" is all she'd do with 126PPH on fuel flow. Did a 33"/2450 RPM/92 PPH climb @ 125-130 KIAS up to 17,500 and began noticing a slightly nervous MP needle going through anout 14,000. Hit the yellow boost pump and releaned to 92PPH and MP seemed to stabilize. In cruise at 17,500 with OAT of 20 Degrees F, ran 30" MP, 2400 RPM, and 82 PPH. Cyl head temps about 2 needle widths of 400 degrees. Now, here's what was interesting: while in cruise at 17,500, pushing up the front throttle (with some enrichening of the mixture too), I notice the MP begin oscillating back and forth between 30" and 37/38" with fuel flow following. Oil pressure at the edge of the top green and steady, no fluctuations seen. Bring throttle back to 30" and with yellow boost on, everythings fine and steady. Does this sound like maybe a dirty controller?
After a slow descent with power up to keep the cyl head temps constant, and upon landing, noticed the breather let loose a whole bunch of oil down the belly. 30-Minutes after shutdown oil level is back down to 5.6 quarts, so it appears almost a quart sprayed down the belly, up into the rear wheel area and across the top and bottom of the rear stabilizer. Checking the front oil cap, it's wet underneath and down the sides of the oil filler neck, and I discover also that the dip-stick O-ring is missing. Wonder if that had anything to do with the oil loss?
Anyway, waiting for a new O-ring for the dipstick and a new oil cap gasket as it doesn't feel like its tight enough, maybe its allowing upper plenum pressurized air to exert some effect on the breather. And yes, I have separators.
Don, do you get any oil scum and where do you run your oil levels???
Still sorting out the problems. BTW, during the oil change, just a couple of bits of carbon in the recessed portion of the oil plug. Have yet to cut the filter open, but I'm sure we'll find some carbon. Gee, did I leave anything out? 1977 P337.
SkyKing
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