Fogging the 'hood on start

boosted79 · 07-01-2017, 07:47 AM

And I figured out what it is. I drained the turbo pot after I shut it down (let it idle a few min b4 SD) After one day there was 1 1/4" of oil in the bottom of a 6" coffee can so that is 35 cu. in. The drain pot outside dimensions are 2.5 OD by 4 " long which is 20 cu. in. Add another 4 for the drain pot feed and scavenge line up to the bottom of the turbo and you get 24 cu.in. total drain capacity at the most so that leaves at least 11 cu. in. of excess oil that ends up in the intake and exhaust. I pulled the IC and found oil in the IC, intake manifold,etc. I have the ball in the oil feed fitting but no spring. I ordered one of those ridiculously expensive Rothsport S hose check valves to prevent drain back to the pump from the tank hopefully that takes care of it. I suppose I could have just put a spring to close that ball check in the feed line on sd but I also checked how much oil I got out of the sump when I did oil change at 100 mi. I got 4 1/4 qts out of the sump after a day sitting. I calc capacity of sump up to level of oil drain tubes from head to be roughly 3.5 qts IIRC so the valve will help with that too.

gsxrken · gsxrken's Garage

We don't all have this problem so I wonder why you need a somewhat unique solution. Post up some links and photos. Curious to learn if this works for you. Good luck!

boosted79 · 06:37 AM

This has me re-thinking my dumping scavenge pump into the breather. That is add'l oil in the sump that the scavenge side of the main pump has to take care of. But it doesn't appear to be a problem during running since there is no smoke after the initial oil burns off. But it would mean the level in the sump is higher on SD than if scavenge pump goes into the tank.

Rawknees'Turbo · 07-02-2017, 07:11 PM

Quote:

Originally Posted by boosted79

This has me re-thinking my dumping scavenge pump into the breather. That is add'l oil in the sump that the scavenge side of the main pump has to take care of. But it doesn't appear to be a problem during running since there is no smoke after the initial oil burns off. But it would mean the level in the sump is higher on SD than if scavenge pump goes into the tank.

Boosted, even if that were the case, I don't see how that little bit of additional oil that might be in the engine sump at shutdown would make it into the turbocharger oil feed (and then end up in the compressor housing, intake, etc). Extra oil in the sump could make it down the cylinders, past the stationary pistons and rings, and into the combustion chambers, but then you're talking about a lot of oil (such as happens when the engine has not been run for every long periods of time - like years), but that doesn't seem to be what you've got going on . . .

boosted79 · 07-03-2017, 03:06 AM

Rawknees - I'm going for state safety inspection this am, then I'm going to do some more research into this. I took this K27-7200 turbo and drain pot of my 1988 and put it in this one. The '88 didn't do this and it has the stock scavenge return line into the tank. The only thing I can think of is the level in the tank is higher than the turbo and it drains into the pump and then siphons into the turbo until the tank level drops to the same level as the turbo. I drove it Friday then put the coffee can under the drain pot after SD and it sat all w/e. I checked it last night and there are 2 1/4 in. of oil in the 6" diameter can, that's about 63 cu. in. or a little over a liter, almost a qt. The Rothsport valve should be here Wed.

scottrx7tt · 07-03-2017, 05:37 AM

just wondering.... Obviously, i don't have a REAL 930, but it should not make any difference. I drain my oil return line gravity fed into the sump plate, with no pump whatsoever. No problems at all. I wonder why i hear of so many of the 930 guys with these kind of problems.

boosted79 · 07:14 AM

Update - got the safety inspection done no problem and went for a ride. Got back home, let it idle for a few min., SD and drained the turbo pot. After only 1/2 hr there was 1" oil in the can or about 28 in3. So I'm already over the capacity of the drain pot and lines which is about 22 in3. I got to the dealer at 730 like they told me to but had to wait 1/2 hr for the grumpy old German mechanic to get there (been working on them for 35 yrs) and I watched when he started it and it blew a nice puff of blue smoke . He told me "oil level too high". I set it right above the min line when I changed it at 100 mi and it is still there. Scott - I agree, I've already looked at how I can run a piece of stainless tube from the turbo into the sump plate, that is the best solution I think. Well I already have that $300 Rothsport valve coming so I guess I'll stick that in and see what happens. I have to order a set of 3000- 3800 pills for my rpm switch, I have a 4200 in it now and I'm getting .8 bar in 3rd just over 3k.

Scott - did you use the stock steel sump plate or an aluminum aftermarket to tie your drain line into? Any pics?

mooney265 · mooney265's Garage

Quote:

Originally Posted by boosted79

He told me "oil level too high". I set it right above the min line when I changed it at 100 mi and it is still there.

It was set there when "hot" or when "cold" ?? I ask this because your problem sounds similar to mine about 8-yrs ago. Turned out to be a 2-fold solution:

1. The oil level was too high. Now, it never gets above 3/4 when Hot. Also, I've added a 'catch can' after the breather...
2. The ball bearing was not in place after a rebuild. This was an easy diagnosis and fix.

Since then, absolutely now smoke on start-ups. Good Luck!

boosted79 · 06:30 AM

Solved it and it's my own fault! I decided to go back to the source and look at the fittings that the turbo oil supply line attaches to. The check ball was there but I put it in the wrong spot, I had it right under the oil pressure switch instead of under the fitting that clamps the banjo fitting on the oil line. I remember looking at that on assembly and checking if the ball restricted the supply to the turbo when it was open. No problem there as you can see in the pics. Interestingly the ball still sealed when I blew into the hole where the pressure switch screws in, but obviously it doesn't seal enough to keep the oil from siphoning on SD. Anyway after I assembled it correctly I took it for a run and then drained the pot after SD. This morning there is only 1/4" of oil in the coffee can.
How I assembled it the first time - wrong.

Ball open

Rawknees'Turbo · 07-04-2017, 10:38 AM

Nice find!

So the low oil pressure idiot light was not on the whole time (with ball blocking the switch's hole

)?

Quote:

Originally Posted by boosted79

Ball open

Exactly how Jeff's are, all the time (full commando), so I hear!

boosted79 · 07-04-2017, 12:30 PM

No, idiot light never came on, must have been enough leakage to pressurize it.

scottrx7tt · 07-04-2017, 01:59 PM

Are you running the spring also?

Quote:

Originally Posted by boosted79

Solved it and it's my own fault! I decided to go back to the source and look at the fittings that the turbo oil supply line attaches to. The check ball was there but I put it in the wrong spot, I had it right under the oil pressure switch instead of under the fitting that clamps the banjo fitting on the oil line. I remember looking at that on assembly and checking if the ball restricted the supply to the turbo when it was open. No problem there as you can see in the pics. Interestingly the ball still sealed when I blew into the hole where the pressure switch screws in, but obviously it doesn't seal enough to keep the oil from siphoning on SD. Anyway after I assembled it correctly I took it for a run and then drained the pot after SD. This morning there is only 1/4" of oil in the coffee can.
How I assembled it the first time - wrong.

Ball open

boosted79 · 07-04-2017, 02:33 PM

No spring, seems to be ok w/o it. I still have that Rothsport valve coming for the S hose, probably don't need it but it will keep the sump from filling up over the long winter nap.

scottrx7tt · 07-04-2017, 07:16 PM

If I remember correctly, when I put all of that on my car, I'm thinking the ball is smaller than the banjo fitting, so it should automatically locate down to the bottom of the bore even if installing it last before putting the oil switch in. I ran the check ball with the spring though that turbokraft sells.

Rawknees'Turbo · 07:53 PM

Quote:

Originally Posted by scottrx7tt

If I remember correctly, when I put all of that on my car, I'm thinking the ball is smaller than the banjo fitting, so it should automatically locate down to the bottom of the bore even if installing it last before putting the oil switch in. I ran the check ball with the spring though that turbokraft sells.

Scott, there is a very small orifice (

) in the bajo fitting (either just above or below the point of the large holes - can't remember which) . . . much smaller than the 9mm ball. That prevents the ball from traveling up to where the switch is screwed in.

BTW, here is the installation order, in case someone comes upon this thread in the future and is wondering . . .

boosted79 · 07-05-2017, 02:36 AM

Rawknee where did you find that? I looked in the PET for that diagram and couldn't find it anywhere. My new rpm pills will be here tonight so I can get on the boost pipe!

scottrx7tt · 07-05-2017, 04:21 AM

Hmm, interesting.... I wonder if the turbokraft kit is different, or I have mine in wrong also... BTW, I just checked the turbokraft website, and it does not show a spring anymore.

Rawknees'Turbo · 07-05-2017, 02:44 PM

Quote:

Originally Posted by boosted79

Rawknee where did you find that? I looked in the PET for that diagram and couldn't find it anywhere. My new rpm pills will be here tonight so I can get on the boost pipe!

Have fun boosting, boosted!

That pic has been posted in various threads here for years, so I did a google search for "Porsche turbo oil restricter ball" and the pic came right up. I think it is from the workshop manual.

boosted79 · 07-05-2017, 05:28 PM

Somethings not right, I put the 3200 pill in and no change to AFR at .8 B at 3200, more troubleshooting. Got the cruise running at 14.1, idle 13.3 @1000, will try adjusting the boost CP tomorrow. Still @ 14.1 @.8B, too much time there and boom.

Rawknees'Turbo · 05:38 PM

^^^

Are you using a Leask adjustable WUR (can't remember if you have something more advanced for fueling)? If so, all you'll need to do is use the special tool (not THAT "tool") to draw the disc on the bottom of the WUR outwards about 2mm from where it is now and you will be close the the high 11s/low 12s for boost/full throttle enrichment. If you go too rich, then use a large c-clamp to push the disc back in and raise pressure (the instructions say use a drift and hammer to do that but a c-clamp works way better - Jim Fairman's idea, BTW).

Also, you can run much leaner during cruise (like 14.8-15) and then have better cruising fuel economy. Usually there won't be any lean missing at those numbers, butt each engine is different, obviously . . .