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Registered
Join Date: Oct 2004
Location: CA
Posts: 5,861
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Brake fluid in the engine ??? Educate me please
I took my 1983 SC to a reputable shop for a cold start problem... No CIS troubleshooting for me... Results:
- Tested fuel pressure (OK) - Cleaned and checked Auxiliary air valve (OK now): was cleaned ! - Check various vacuum systems, smoke check, no leaks found (found brake fluid being pumped into the engine)... Ugh, brake fluid in my engine??? How does that work exactly? Boosted brakes, failed M/C that leaks fluid in the vacuum system? Where in the "engine" does it go, anyway ? how do you spot that while doing CIS checks? Is this something I should change the oil for ? I must say something was fishy with the M/C because the pedal feel is a lot better with the new master cylinder ! Only thing is the car now cold starts beautifully but it's idling at 1100 rpm, and fluctuates a little at idle, which it did not do before. Damn CIS, change one thing, screw up another ! Tempted to go back, but right now I've dropped idle back to 800 by hand, we'll see if that does it... Please educate me on that brake fluid thing though - I had never heard of that !! |
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08-21-2009, 09:44 AM
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Friend of Warren
Join Date: Oct 2000
Location: Lincoln, NE
Posts: 16,494
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I imagine the diaphram in the power brake booster had a hole in it and allowed brake fluid to get sucked back through the vacuum hose to the engine intake.
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Kurt V No more Porsches, but a revolving number of motorcycles. |
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08-21-2009, 09:51 AM
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Most brake booster are vacuum actuated. If the SC's system had a bad booster which results in internal leaking of brake fluid into the vac line (going to the engine intake ) then that's a plausible explanation for finding brake fluid in your engine.
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08-21-2009, 09:52 AM
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MBruns for President
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but it's really not accurate as it gets sucked - not pumped in
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Current Whip: - 2003 996 Twin Turbo - 39K miles - Lapis Blue/Grey Past: 1974 IROC (3.6) , 1987 Cabriolet (3.4) , 1990 C2 Targa, 1989 S2 |
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08-21-2009, 09:54 AM
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UNDER CONSTRUCTION!
Join Date: Jul 2008
Location: ALASKA
Posts: 1,508
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Quote:
change the oil as brake fluid will swell the seals and creat a real mess of the rubber pieces in the motor. and the fluid had to be getting in there via vacuum unless someone poured it in. and if you replaced your booster that had a vac. leak now your cis is running a bit rich thats what the idle change is. someone at one point tuned this to run with the booster leak. cheers ed
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Sometimes the first thing that comes to mind should be the last thing that you do! 
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08-21-2009, 10:39 AM
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Location: CA
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All good points - no telling how long there might have been fluid in the oil, but I guess not long since I never noticed low fluid... So instead of lowering the idle (screw on left of airbox) I should have leaned the mixture ? If so, hmm, I can't guess that, it would have to go back...
Great point about the vacuum leak now "resolved", that probably means I need to also recheck my ignition timing !! My SC distributor has vacuum lines going to it ! Off to buy oil then ! |
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08-21-2009, 11:36 AM
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UNDER CONSTRUCTION!
Join Date: Jul 2008
Location: ALASKA
Posts: 1,508
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sounds like your off to a good start. your ignition timing is probably ok. but you may as well check it all while your going over things.
correct on the leaning it out some. SOUK here on the board has some good info on this without a co meter. cheers ed
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Sometimes the first thing that comes to mind should be the last thing that you do!
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08-21-2009, 12:05 PM
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Registered
Join Date: Oct 2004
Location: CA
Posts: 5,861
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Oil change done, along with my usual 1/2 qt overfill - 13 years and I still do it everytime...
I attempted to buy a CO tester but got outbid on a cheap Gunson unit, and after some more research figured out the Innovate LM1 is better anyway, but $269 or so... Given that I won't use it much, I figure a quick visit to the shop to stick a sniffer up the car's tailpipe is cheaper ! I raised the idle a bit again, but right now it sits at 800-850 and does not surge anymore, so no great urgency. The car does brake a lot better though, funny how you get used to something that goes bad slowly ! |
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08-24-2009, 03:36 AM
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Now,..change the oil AGAIN...(and filter, with NO overfills (intake's clean, right?) ).
Best, Doyle
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Recording Engineer, Administrator and Entrepeneur Designer of Fine Studios, Tube Amplifier Guru 1989 Porsche 911 Carrera Coupe 25th Anniversary Special Edition Middle Georgia |
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08-25-2009, 04:06 PM
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Registered
Join Date: May 2003
Posts: 3,346
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The brake fluid was being sucked into the intake not the crankcase. 1/2 quart overfull doesn't matter as long as the oil isn't so full that it gets sucked into the intake.
-Andy
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72 Carrera RS replica, Spec 911 racer |
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08-25-2009, 04:51 PM
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Registered
Join Date: Oct 2004
Location: CA
Posts: 5,861
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Yeah, the overfill is kind of a joke, I mean I'm shooting for mid-dipstick and/or mid-gauge, and I *always* overshoot (cold) and when hot hit the top mark ;-) It's ok, I just never learn when to say "when".... 1000 miles from now it'll be perfect at my current burn rate ;-)
That's what I thought about the fluid so is another oil change really necessary? |
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08-25-2009, 06:16 PM
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Gone to California
Turbo
