Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   PeachParts Mercedes-Benz Forum > Mercedes-Benz Tech Information and Support > Mercedes-Benz SL Discussion Forum

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 03-21-2011, 07:31 AM
Registered User
 
Join Date: Mar 2011
Location: Hummelstown, Pa.
Posts: 3
Whistling from behind air cleaner

Hi guys, 85 380sl 69k miles. Bought back in December, it ran great but developed a miss in #4 the day after I got it home. turned out to be the fuel dist. It cured the miss but created a surging idle at operating temp.
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.

Reply With Quote
  #2  
Old 03-21-2011, 08:16 AM
Registered User
 
Join Date: Mar 2010
Location: Orillia, Ontario
Posts: 217
Sounds like a vacuum leak. Have you examined all the vacuum hoses? Look for cracks, splits, etc at the little rubber elbows that join the hard vacuum lines to various fittings. Do you have a vacuum guage? If so, what vacuum reading are you getting at idle?
__________________
I choose to be happy, even when the Mercedes is being awkward, lol
Reply With Quote
  #3  
Old 03-22-2011, 07:23 AM
Registered User
 
Join Date: Mar 2011
Location: Hummelstown, Pa.
Posts: 3
Rechecked all the vac lines again, found no issues with any. The whistling stops when air cleaner is removed so I made sure it wasn't interfering with any lines. Sprayed starting fluid around, no change.
I know the mixture still needs adjusted since I replaced the fuel dist and it's rich. I pulled the plugs and they were heavily carboned black. Cleaned them all, leaned it out a bit and most of the surging went away. Just down to a lumpy idle.
Tried using a friend's old Sears diagnostic station but the dwell needle didn't change when tuning the mixture.
Reply With Quote
  #4  
Old 03-22-2011, 07:40 AM
Registered User
 
Join Date: Mar 2010
Location: Orillia, Ontario
Posts: 217
Quote:
Originally Posted by viperjesse View Post
Rechecked all the vac lines again, found no issues with any. The whistling stops when air cleaner is removed so I made sure it wasn't interfering with any lines. Sprayed starting fluid around, no change.
I know the mixture still needs adjusted since I replaced the fuel dist and it's rich. I pulled the plugs and they were heavily carboned black. Cleaned them all, leaned it out a bit and most of the surging went away. Just down to a lumpy idle.
Tried using a friend's old Sears diagnostic station but the dwell needle didn't change when tuning the mixture.

Sounds like you are doing the right stuff; except for the dwell meter. The dwell meter is used to set up points in a non-electronic ignition vehicle. Adjusting the mixture won't show on a dwell meter at all.

Does the diagnostic rig have a fuel mixture guage? The ideal mixture should be 14:1 Or if the machine has a c0 meter, somewhere around 1.5 to 2 5% would do it.
__________________
I choose to be happy, even when the Mercedes is being awkward, lol
Reply With Quote
  #5  
Old 03-22-2011, 10:35 PM
meltedpanda's Avatar
Certified Benzaholic
 
Join Date: Mar 2003
Location: Central Ky
Posts: 6,265
on mine ( djet) it was getting the co reading with a fuel gas analyzer meter that finally got her sorted out. It took a long time for me to find a unit , but I am glad I did!
__________________
Ron
2015 Porsche Cayman - Elizabeth
2011 Porsche Cayman - Bond,James Bond
Sadly MERCEDESLESS - ALways LOOKING !
99 E320 THE Queen Mary - SOLD
62 220b - Dolly - Finally my Finny! Sadly SOLD
72 450SL, Pearl-SOLD
16 F350 6.7 Diesel -THOR
19 BMW X5 - Heaven on Wheels
14 38HP John Deere 3038E Tractor -Mean Green
84 300SD, Benjamin -SOLD
71 220 - W115-Libby ( my first love) -SOLD
73 280 - W114 "Organspende" Rest in Peace
81 380 SL - Rest in Peace
Reply With Quote
  #6  
Old 03-23-2011, 12:27 AM
Registered User
 
Join Date: Oct 2008
Location: Phoenix, AZ
Posts: 349
Not to be a smartass, but could something as simple as the rubber gasket on the bottom of the air cleaner housing be the problem? There is a rubber gasket on mine to seal to the throttle body, if yours cracked, folded, broke from age/heat, etc...

Go for the "inexpensive" stuff first, you might just learn enough to know which expensive thing to buy.

Scott
__________________
Remember, it's not just a car. It's an Adventure.
Reply With Quote
  #7  
Old 03-23-2011, 07:38 AM
Registered User
 
Join Date: Mar 2011
Location: Hummelstown, Pa.
Posts: 3
Thanks guys, no smart ass at all, every suggestion is always appreciated.
The rubber gasket is soft and in great condition like all the vac hoses.
I read in some searched out posts that you use a Sears analog dwell meter attached to diagnostic pin #3 and adjust mixture till it reads 22 deg.? or 50% duty cycle? This one had no duty cycle reading, it looks like it may be from the 70's.

A littel background on me: I've built American muscle cars and engines for years so I'm very mechanically inclined, but I still have a lot to learn about these Benz engines.
When the air cleaner is off you hear the sucking noise from the intake, when I put it on I believe the noise is coming thru the air intake nose on the filter housing due to the increased flow thru the K&N filter.

Could the engine be getting TOO much air thru the K&N and acting like a vac leak?
Reply With Quote
  #8  
Old 03-23-2011, 11:40 AM
meltedpanda's Avatar
Certified Benzaholic
 
Join Date: Mar 2003
Location: Central Ky
Posts: 6,265
could be , I have been dealing with MB's a long time- for the most part , as designed is the way they should stay - messing with the design tends to cause a chain reaction of issues...

__________________
Ron
2015 Porsche Cayman - Elizabeth
2011 Porsche Cayman - Bond,James Bond
Sadly MERCEDESLESS - ALways LOOKING !
99 E320 THE Queen Mary - SOLD
62 220b - Dolly - Finally my Finny! Sadly SOLD
72 450SL, Pearl-SOLD
16 F350 6.7 Diesel -THOR
19 BMW X5 - Heaven on Wheels
14 38HP John Deere 3038E Tractor -Mean Green
84 300SD, Benjamin -SOLD
71 220 - W115-Libby ( my first love) -SOLD
73 280 - W114 "Organspende" Rest in Peace
81 380 SL - Rest in Peace
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -4. The time now is 06:34 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2024 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page