Oil in air box, '78 928 125k miles
#1
Rennlist Member
Thread Starter
Oil in air box, '78 928 125k miles
How much is too much? I'm getting about a thimbles full of clean oil in the air box after a 100km drive. Anybody know if this is normal or an issue? I was thinking piston blow by causing high crankcase pressure? Any other likely causes, hopefully something easier to fix
#2
Oddly enough that is normal for these early cars, although not desirable. Try doing a full throttle run up through the gears and watch the smoke billow in your rear vew mirrow. There are more than one vendors who supply a corrective kit for this. I got mine from 928 motorsports and it worked like a charm. The downside is you will have to unbolt the waterpump housing to get that deflector plate in properly---at least I did. with 928MS kit there is the plate (goes in the oil fill /separator assy) and you have to drill a hole in the cam chamber for oil return (which is not difficult). I have no problems now, I can go full bore through the gears with nothing spitting back to the filter housing.
#5
Rennlist Member
You'll find a few iterations of a baffle for that location. Worth considering the one that Greg Brown makes, which I believe Roger at 928'sRus stocks. Here's a thread with a pic ... https://rennlist.com/forums/928-foru...tallation.html
#6
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Well...
I was having the same issue on my 79 as well.
When doing a top end refresh, I installed this kit.
I also put a wad of stainless steel wool packing in the port on the airbox where the heated vent hose attached. I then put a small drain tube in the bottom of the port to drain any excess oil caught by the packing.
I also removed the god awful heated vent hose that had seen several kilos of silicon, tape and hose clamps from a PO. Replaced it with a Goodyear heavy duty flex hose.
I was just in the states several weeks ago to have a weekend drive in the mountains of Wests Virginia. Got on it coming on an entrance ramp to I64. Backed up before running up someone's tailpipe.
I could not see ANYTHING out the rear view. Car ran fine after a few minutes. No real difference that I could tell after all that work. But I have the satisfaction of at least attempting to solve the issue.
But I don't have anymore oil in my airbox!
I was having the same issue on my 79 as well.
When doing a top end refresh, I installed this kit.
I also put a wad of stainless steel wool packing in the port on the airbox where the heated vent hose attached. I then put a small drain tube in the bottom of the port to drain any excess oil caught by the packing.
I also removed the god awful heated vent hose that had seen several kilos of silicon, tape and hose clamps from a PO. Replaced it with a Goodyear heavy duty flex hose.
I was just in the states several weeks ago to have a weekend drive in the mountains of Wests Virginia. Got on it coming on an entrance ramp to I64. Backed up before running up someone's tailpipe.
I could not see ANYTHING out the rear view. Car ran fine after a few minutes. No real difference that I could tell after all that work. But I have the satisfaction of at least attempting to solve the issue.
But I don't have anymore oil in my airbox!
#7
Rennlist Member
Thread Starter
Thanks for the replies. Now that I know this is not uncommon I might just monitor it for awhile. If it becomes a problem I'll definitely be looking into one of these solutions.
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#8
Rennlist Member
Yes, not a problem, just messy. I have one of the baffles, and it helps some, but does not eliminate the blow back by any stretch.