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Whistling coming from behind air cleaner

682 views 5 replies 4 participants last post by  viperjesse 
#1 ·
Hi guys, 85 380sl. replaced fuel dist, cap, rotor. Still have surging idle. When it warms up and is in gear the car feels like it's humping the road (best way to describe it). While trying to set the mixture I noticed a whistling coming from the back of the air cleaner. The air cleaner is in place and it sounds like it is coming from just underneath the rear of the air cleaner.
Any ideas? Is this just the air intake? Is there a vacuum hose back there prone to leak? I do have a K&N filter installed.
Thanks in advance.
 
#2 ·
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You got a vacuum leak, no doubt. Lots of stuff in that area, and no real way to point at anything from afar. You're just gonna have to get close up and personal with it. If nothing is obviously loose, get a can of starting fluid and just spritz it lightly at the various fittings etc. listening for changes in the idle.
 
#3 ·
The vacuum diagram would be in the manual. Use the online version from the E.G sticky, if you don't have a CD. Use it to make sure everything is in the right places.

You might just want to go through the engine vacuum system hose by hose and connector by connector, if you are REALLY worried about things. It could take a bunch of hose and a few hours, but the peace of mind is worth it.

Heat, oil, and time have a tendency to degrade the rubber. If you have the time, a few skills, and some patience, it's not a difficult job, just a bit time-consuming.

Good luck,
Scott
 
#4 ·
Thanks guys, I did spray some carb cleaner around, tomorrow I'll get the eather out and spray around.
Are all the vacuum lines rubber or are some back there solid tubing?
When the engine is cold it runs pretty good but when the warmup idle kicks off thats when the road humping starts.
 
#6 ·
Yes after it was warm and the high idle came down. Today I will remove the air cleaner assy and try with the starting fluid. I'm just wondering if I bumped something off when I replaced the fuel dist.
Otherwise the car runs great, no hesitation and pretty snappy on accel.
 
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