NO start no idle - Mercedes-Benz Forum
 
LinkBack Thread Tools Display Modes
post #1 of 8 (permalink) Old 07-26-2018, 05:48 AM Thread Starter
BenzWorld Junior Member
 
Date registered: Dec 2009
Vehicle: 1979 450SL
Location: SE Ohio
Posts: 6
Mentioned: 0 Post(s)
Quoted: 2 Post(s)
(Thread Starter)
NO start no idle

Hello I am a fairly intuitive mechanic but am a bit stuck, I am not very familiar with Mercedes. I recent bought a 1979 450sl that has been sitting 5 years. The fuel pump was bad so I replaced it . The only way I can get the car to start and idle is to take a business card and slide it between the air intake disk and housing thus creating a air gap. The car will then idle ( not a good idle but will idle ) The throttle is responsive when worked by hand but again it does not act right. If I remove the card the plat closes and car stops. I have attached a picture of the idle mixture screw area just as I have found it. Does it look right or am I missing parts. I am trying to attach I should say
Attached Thumbnails
Click image for larger version

Name:	IMG_8013.jpg
Views:	10
Size:	40.8 KB
ID:	2443741  

Last edited by jeepman; 07-26-2018 at 05:51 AM. Reason: add photo
jeepman is offline  
Sponsored Links
Advertisement
 
post #2 of 8 (permalink) Old 07-26-2018, 05:53 AM
BenzWorld Elite
 
Weather Man's Avatar
 
Date registered: Dec 2008
Vehicle: 1984 380SL
Location: Key West FL USA
Posts: 2,268
Mentioned: 4 Post(s)
Quoted: 298 Post(s)
I'm no expert but it sounds like the fuel distributor is jammed up. It connects with the throttle plate so if the one does not move then the other must be preventing it. This is consistent with sitting for a long period of time.
Weather Man is offline  
post #3 of 8 (permalink) Old 07-26-2018, 05:59 AM Thread Starter
BenzWorld Junior Member
 
Date registered: Dec 2009
Vehicle: 1979 450SL
Location: SE Ohio
Posts: 6
Mentioned: 0 Post(s)
Quoted: 2 Post(s)
(Thread Starter)
Thankyou I will look that up, the car is quite the puzzle but that's a enjoyment to me, figuring it out and talking with other enthusiast
jeepman is offline  
Sponsored Links
Advertisement
 
post #4 of 8 (permalink) Old 07-26-2018, 06:29 AM Thread Starter
BenzWorld Junior Member
 
Date registered: Dec 2009
Vehicle: 1979 450SL
Location: SE Ohio
Posts: 6
Mentioned: 0 Post(s)
Quoted: 2 Post(s)
(Thread Starter)
I also would like to mention that if the switch is on and the car not running, when I shove down on the air intake plate I can hear fuel being dumped into the engine. Is that a sign the plunger is working ?
jeepman is offline  
post #5 of 8 (permalink) Old 07-26-2018, 02:21 PM
Premium Member
 
Jyuma's Avatar
 
Date registered: May 2017
Vehicle: 1983 380 SL
Location: Long Island, New York USA
Posts: 2,099
Mentioned: 15 Post(s)
Quoted: 743 Post(s)
Premium Member
Garage
Quote:
Originally Posted by jeepman View Post
I also would like to mention that if the switch is on and the car not running, when I shove down on the air intake plate I can hear fuel being dumped into the engine. Is that a sign the plunger is working ?

The fact that you can "shove" (be gentle) the air metering plate down means by definition the plunger is working... if the plunger wasn't working (moving up and down) then you wouldn't be able to press the air metering plate down (unless the plunger is stuck in the full up position, but that would supply maximum fuel flow through the injectors and I would think you would notice that). However, that doesn't mean the barely visible fuel slots are open and free of gunk, ditto the fine mesh screens on each port or the ceramic valves or paper thin diaphragm.

The fuel is continually sprayed at the back of each intake valve via the fuel injectors. It is not likely that you are hearing the spray. You may be hearing the fuel circulating through the fuel distributor on it's way back to the tank but the spray should be far too subtle for you to hear. I suppose it's possible if you have very good hearing. I don't.

With the key on and the engine at idle, the air metering plate should be slightly open.... the thinness of a business card sounds about right (maybe a bit more). With the air metering plate fully closed there will be insufficient air entering the system to support combustion.

Have you by any chance checked the fuel pressure? If you haven't you might want to start there. You might also try running some Techron through the system to help clean it out. Once you get the engine running well enough to drive the car, it would be a good idea to add a bottle of Techron to you next few tank refills. More is not necessarily better... don't exceed the recommended amount.

Any chance you could post a video of the engine running? As it stands now we're painting with a very broad brush, we'd be in a better position to give advice if we could see and hear the engine running.

Nobody gets out of this life alive.
Jyuma is offline  
post #6 of 8 (permalink) Old 07-26-2018, 05:03 PM Thread Starter
BenzWorld Junior Member
 
Date registered: Dec 2009
Vehicle: 1979 450SL
Location: SE Ohio
Posts: 6
Mentioned: 0 Post(s)
Quoted: 2 Post(s)
(Thread Starter)
Thank you for the reply, it was very informative, The good news is that I decided to try something, with the car idling and the card in place I stuck a Allen wrench inside the air mixture hole and was able to locate the bolt I thought missing. As I turned the wrench the idle smoothed a bit and raised so at that point I pulled out the card and was able to adjust the the bolt and gain a reasonable idle and throttle response. before this I did take a video as you suggested but now I believe the whole problem in that area was someone had the car so out of whack it would not run.

Now the next issue I was not mentioning till I saw if the car world run. it has a vey loud tappet noise on front right bank. I pulled the cover to find what many on here have talked about. Broken clips and to my disappointment a wiped cam lobe. Can I change this one cam while leaving the chain in place? My next venture is to locate a cam and the one rocker assembly. Any thoughts.
Attached Thumbnails
Click image for larger version

Name:	IMG_8024.jpg
Views:	14
Size:	61.8 KB
ID:	2443857  
jeepman is offline  
post #7 of 8 (permalink) Old 07-26-2018, 05:55 PM
BenzWorld Elite
 
jsebastian's Avatar
 
Date registered: Sep 2011
Vehicle: 1967 250 S (sold) 1986 560 SEC 1987 560 SL
Location: San Diego, CA
Posts: 1,229
Mentioned: 3 Post(s)
Quoted: 117 Post(s)
Garage
Maybe find a junkyard cam. Do your timing marks line up? Reason I mention is you might want to replace the chain/tensioner maybe guides too since you are already in it. I have replaced my guides since they are plastic in the 560, don't know about the 450. Good luck.
John
jsebastian is offline  
post #8 of 8 (permalink) Old 07-26-2018, 06:34 PM
Premium Member
 
Jyuma's Avatar
 
Date registered: May 2017
Vehicle: 1983 380 SL
Location: Long Island, New York USA
Posts: 2,099
Mentioned: 15 Post(s)
Quoted: 743 Post(s)
Premium Member
Garage
Quote:
Originally Posted by jeepman View Post
I pulled the cover to find what many on here have talked about. Broken clips and to my disappointment a wiped cam lobe. Can I change this one cam while leaving the chain in place? My next venture is to locate a cam and the one rocker assembly. Any thoughts.
Yes you can change the one cam but by the looks of that chain guide I see in the photo it's time to change the chain guides as well. May as well change the tensioner while you're at it, ditto the oilers.

Before removing the cam sprocket take 3 tie-wraps and clamp the chain to the sprocket. Once you do that you can remove the sprocket from the cam (single bolt). You'll need a 3 jaw puller.

It is best to keep tension on the chain... I use bungee cords to hold tension on the chain but any way you have of preventing the chain from developing too much slack is fine. Once the chain and sprocket are secured you'll need to remove all the rockers (it requires a special tool) each one has it's own spacer so be sure not to mix them up. Being that you'll be replacing the cam you may need to perform the procedure for selecting the correct spacer size for each valve. Finally you may need to remove the cam towers. Make certain that the Allen sockets you use are top quality and sunk all the way into the Allen head bolts before you apply full removal pressure.

Full disclosure... I've never actually removed a cam from one of these engines so I don't know if it's necessary to remove the cam towers or if the cam can slide out once a retainer has been removed. Others here will be able to direct you.

Good luck.

P.S. Is that a crack I see in the injector seal?

Nobody gets out of this life alive.
Jyuma is offline  
Sponsored Links
Advertisement
 
Reply

  Mercedes-Benz Forum > Mercedes-Benz Roadster Forums > R/C107 SL/SLC Class

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Mercedes-Benz Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may 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 Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 

Title goes here

close
video goes here
description goes here. Read Full Story
For the best viewing experience please update your browser to Google Chrome