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 > Tech Help

Closed Thread
 
LinkBack Thread Tools Display Modes
  #1  
Old 12-02-2008, 04:42 PM
pantherpaw's Avatar
David
 
Join Date: Dec 2006
Location: Roswell, Georgia
Posts: 130
Hard to start when warm

My 1991 300CE (M104 engine) starts instantly when cold; however, after driven awhile and engine is up to temp, it takes about 5 or 6 seconds to resart. Its giving my starter a hell of a work out.

I recently removed the intake and throttle linkage, fuel lines, injectors, etc. to clean intake and pcv, air valve system. Replaced all the pipes and hoses under the intake.

What could be wrong? Anybody?

Thanks,
David

__________________
1991 300CE Sportline
1983 300SD TurboDiesel (Gone but not forgotten)
  #2  
Old 12-02-2008, 05:33 PM
Moderator
 
Join Date: Mar 1999
Location: Tucker, Ga USA
Posts: 12,153
Assume you have checked distributor cap & rotor???

Fuel pressure bleed off is the most likely problem.

The fuel distributor must maintain pressure after shutting off.

Fuel pressure accumulator OR fuel pressure regulator are common issues.
__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator
  #3  
Old 12-02-2008, 05:49 PM
pantherpaw's Avatar
David
 
Join Date: Dec 2006
Location: Roswell, Georgia
Posts: 130
Thanks, ...no i didn't even think of the cap and rotor. I will go back in my records and see when it was replaced last. I have every receipt since the car was new. The other two items to check, I didnt even know about those items. I will check all of these and go from there. Thanks again for your help.

David
__________________
1991 300CE Sportline
1983 300SD TurboDiesel (Gone but not forgotten)
  #4  
Old 12-03-2008, 10:05 AM
Registered User
 
Join Date: Aug 2002
Location: Southeastern PA
Posts: 3,018
David, check the condition of the spark plugs too. They should be replaced every 30,000 miles. If the spark plugs are not that old confirm the gap is correct.
__________________
Fred Hoelzle
  #5  
Old 12-03-2008, 10:42 AM
pantherpaw's Avatar
David
 
Join Date: Dec 2006
Location: Roswell, Georgia
Posts: 130
problem started after recent engine work

I've had the car for almost a year, and I've put only 8,000 miles on it since then. The problem started when I removed the entire fuel and air intake system to replace the air pump tubes/hoses, and cleaned the pcv 2mm hole and cleaned the intake. After I put it all back together, it started right up after it primed itself again.

Long story short, I'm inclined to think that it must be some adjustment in the linkage that I didn't get back in the right position or something. (I mean, it started warm just fine before I did the engine work).
__________________
1991 300CE Sportline
1983 300SD TurboDiesel (Gone but not forgotten)
  #6  
Old 12-03-2008, 11:59 AM
pantherpaw's Avatar
David
 
Join Date: Dec 2006
Location: Roswell, Georgia
Posts: 130
Don't get me wrong, the suggestions from you guys make the most sense here; however, its just such a coincidence that it started after I screwed around with it...(I'm not a proffesional mechanic by any stretch of the imagination)...is it possible that it could be something in the linkages or fuel lines that I didn't put back together correctly????

I just wanted to eliminate that as a possiblity, before I spend the bucks on the accumulator, dist. cap, etc.
__________________
1991 300CE Sportline
1983 300SD TurboDiesel (Gone but not forgotten)
  #7  
Old 12-03-2008, 02:20 PM
pantherpaw's Avatar
David
 
Join Date: Dec 2006
Location: Roswell, Georgia
Posts: 130
Update

My records indicate:

Distributor Cap, Rotor, Ignition coil, and spark plugs replaced @ 197534 miles.

Fuel Pressure Regulator replaced @ 218404 miles.

current mileage is 227,000 miles.

That leaves the accumulator; Is there a test to determine if the accumulator is bad, or do just replace it?
__________________
1991 300CE Sportline
1983 300SD TurboDiesel (Gone but not forgotten)
  #8  
Old 12-03-2008, 05:59 PM
Registered User
 
Join Date: Jul 2008
Posts: 1,236
Take an ohm meter and check your temperature sensors. Recent experience has shown me that starting the car can be extremely difficult without working coolant temp sensors. You can check this in 3 minutes.

If you need info on how to do this, post back or pm me and I will tell you how it's done.


-tp
  #9  
Old 12-03-2008, 06:09 PM
Registered User
 
Join Date: Oct 2007
Location: Greater Metropolitan Beaverdam VA
Posts: 2,596
hard when warm

I think you messed up when you reattached your throttle linkage. I did this once a few years ago on a 123 when I separated the linkage for cleaning and lubrication. It manifested itself in a similar way.

In my case, the car was driveable and I took it to my indie who saw the problem right away and reconnected the lingage joints correctly. Didn't even charge for it.

Let us all know what you find out when you fix your problem, no matter what it is. Feedback is important to the integrity of the forum.
  #10  
Old 12-04-2008, 04:25 PM
pantherpaw's Avatar
David
 
Join Date: Dec 2006
Location: Roswell, Georgia
Posts: 130
tinypanzer,

coolant sensor replaced at 125,419 mi. (current mi. = 227,561) so I guess thats plenty of time for the sensors to go bad.

I would like to know how to check these. How many sensors are there, and where are they located, etc. What resistance should I be seeing across the poles?
__________________
1991 300CE Sportline
1983 300SD TurboDiesel (Gone but not forgotten)
  #11  
Old 12-04-2008, 04:36 PM
pantherpaw's Avatar
David
 
Join Date: Dec 2006
Location: Roswell, Georgia
Posts: 130
Quote:
Originally Posted by rocky raccoon View Post
I think you messed up when you reattached your throttle linkage. I did this once a few years ago on a 123 when I separated the linkage for cleaning and lubrication. It manifested itself in a similar way.

In my case, the car was driveable and I took it to my indie who saw the problem right away and reconnected the lingage joints correctly. Didn't even charge for it.

Let us all know what you find out when you fix your problem, no matter what it is. Feedback is important to the integrity of the forum.

Yes, it would not suprise me to find something out of place, or a spring.
The coincidence is compelling. I work on it, problem starts. MB Doc says fuel accumulator, and I believe him; however, I would like to eliminate as many simple (cheap) causes before I spend the money on the part. He showed me how to test the accumulator, so I'm going to try that this weekend. I'll stop by BenzWerks, and let, Mike take a peek as well.
__________________
1991 300CE Sportline
1983 300SD TurboDiesel (Gone but not forgotten)
  #12  
Old 12-05-2008, 07:20 PM
Registered User
 
Join Date: Jul 2008
Posts: 1,236
Hi,

There are two coolant temp sensors, both located on the top of the engine near the back. The single pole sensor goes to the temp. gauge in the instrument cluster. The 4 pole sensor contains two elements, one for the timing and one for the fuel injection. The elements are identical, and should both read the same value.

As far as what resistance you should measure, that depends on the temperature. These sensors have a negative temperature coefficient. That means that as temperature goes up, resistance goes down.

Check out these images.... Measure across the points shown on the diagram then compare the value to the chart. You should be very close to the value listed for your given temperature. It will be much easier if you do this at ambient temperature since then you will know exactly what value you SHOULD be getting.

Again, both sensors should give you the same value. If they are significantly different, replace it.

If you wanted to be really thorough, you could get the car warmed up and see if the temp sensor matches a reading from an IR thermometer or similar.


Good luck!
Attached Thumbnails
Hard to start when warm-sensor.jpg   Hard to start when warm-chart.jpg  
  #13  
Old 12-05-2008, 07:34 PM
Registered User
 
Join Date: Jul 2008
Posts: 1,236
One last thing - Be careful pulling the plug off the sensor. When I pulled my plug off, half the sensor came off with the plug!!

Also - MB doc is probably right.....


-tp
  #14  
Old 12-05-2008, 07:44 PM
Registered User
 
Join Date: Jul 2007
Location: USA
Posts: 2,156
Hope this helps:

Check fuel system for leaks
check fuel pressures
check zero postion of air flow sensor plate
__________________
1986 300SDL, 211K,Dealership serviced its whole life
1991 190E 2.6(120k)
1983 300D(300k)
1977 300D(211k)
  #15  
Old 12-09-2008, 11:09 PM
pantherpaw's Avatar
David
 
Join Date: Dec 2006
Location: Roswell, Georgia
Posts: 130
update

pulled air cleaner and studied linkage, vacuum lines, wires, etc. I checked to make sure the hose clamp wasn't catching on the linkage (per cd manual).

I found two obvious things that were absolutely wrong:

1. vacuum line, coming from fuel pressure regulator, is connected to the pressure regulator; however, the other end is as free as bird. Couldn't find where it is supposed to go. I'm hoping the right person finds this post again and knows about this particular vacuum line.

2. At the rear of the valve cover, a large wiring harness comes around from the passenger side to the drivers side; and turns to run beside the valve cover toward the front of the car. Well, right at the turn (left rear corner of valve cover) a wire lead breaks away from the harness and goes directly toward the "area" that i worked on. It has a round plug on the end of it with a "rubber boot" on it. Its free and hangin out in my engine compartment. I absolutely cant find where it goes. HELP.

I feel confident that one or both of these is my warm start problem (i hope); so, if anybody can help, I would really learn alot and would be very appreciative.

Thanks,
David

__________________
1991 300CE Sportline
1983 300SD TurboDiesel (Gone but not forgotten)
Closed Thread

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 08:28 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page