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

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 07-26-2011, 07:46 PM
ps2cho's Avatar
Registered User
 
Join Date: Jun 2006
Location: Chandler, Arizona
Posts: 3,523
Checking timing on M103?

How can I check the timing on an M103 motor?
Factory spec should be 9deg at idle right?

I have a timing light, but not sure how to use it exactly.

Thanks guys.

__________________
2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k
Reply With Quote
  #2  
Old 07-27-2011, 12:09 AM
ps2cho's Avatar
Registered User
 
Join Date: Jun 2006
Location: Chandler, Arizona
Posts: 3,523
Ah spotted the marks on the crank pulley....

Looks like its reading 19deg at idle Isn't it supposed to be ~9deg @ 650rpm?
Its somewhat difficult to tell though...I spot a 10 mark, but not the next notch -- does the pulley go: -10, 0, 10, 20 etc...? So could I have been technically spotting a -10 making it a -1deg retard?
Either way though, its definitely -1deg, or +19deg so it doesn't quite seem right?

Does that seem very wrong or is it just me?
For reference: I DO have that R16/1 timing resistor plugged in. It has not been removed.

I used this as reference too:
__________________
2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

Last edited by ps2cho; 07-27-2011 at 12:28 AM.
Reply With Quote
  #3  
Old 07-27-2011, 06:38 PM
Registered User
 
Join Date: Jan 2003
Location: Dallas
Posts: 790
Yes, it does have minus/negative marks. Once in a land far away I carefully checked TDC with the head off against the damper marks and the little tang.
As I remember, it was off a bit, but can't recall which way - big help Huh?

But, the system works off the rear crank position sensor, not the front one, and it's all adjusted electronically. So, in theory, timing should not be a problem; nothing to move or wear.

Of course, the cam can get retarded due to chain stretch; but tht won't affect the crank timing.

DG
Reply With Quote
  #4  
Old 07-27-2011, 06:43 PM
ps2cho's Avatar
Registered User
 
Join Date: Jun 2006
Location: Chandler, Arizona
Posts: 3,523
So then for my low power issue I should probably get the crank @ TDC and make sure the cam is aligned in the correct position too (the hole and line lined up?)
__________________
2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k
Reply With Quote
  #5  
Old 07-28-2011, 12:18 PM
benzworldrefuge's Avatar
Registered User
 
Join Date: Apr 2011
Location: Bayshore, NY
Posts: 44
Worth verifying the cam is timed right. Just a thought on the timing. How about the hose running to the ignition module on the driver's wheel well. It is supposed to affect the timing when vacuum is sensed. Should this be on or off when checking the timing?
__________________

88 300e
89 300e
93 400e
93 500e
77 308 GTB
Reply With Quote
  #6  
Old 07-28-2011, 06:23 PM
Registered User
 
Join Date: Jan 2003
Location: Dallas
Posts: 790
Yeah, always good to verify the cam position; but....
- highly unlikely a 103 chain will stretch enough in 200k miles to appreciably affect cam timing (very rugged) - unless it's been worked on and reassembled wrong.
- still gotta find that exact piston TDC, and not knowing exactly where the damper/tab marks should align makes it a bit of a guess. The best way is to use a piston stop and go forwards-measure, backwards-measure, like when degreeing a new cam. But, I don't think the experts recommend turning a 103engine backwards, as it really stresses the chain tensioner.

I glanced thru the book, and the timing spec for the 103 at idle is 7-11 with the vacuum line either attached or plugged. Easy to check, though, just check the timing and then plug it and see if it changes.

One commet, years ago I did unplug my resistor, and the timing at idle did not change. It also didn't change at 2500 RPM in neutral. I assume it might cause a difference under load.
Comment - I left the resistor in and switched to regular fuel about 12 years ago - zero issues.

DG
Reply With Quote
  #7  
Old 07-28-2011, 08:47 PM
Registered User
 
Join Date: Oct 2004
Posts: 3,611
When I was testing out different trim resistors for my turbo install I found that they all idled at the same timing 8-9 degrees. They were all pretty close at 2000 RPM without load. To simulate load at 2k I pulled the vacuum line from the EZL. That's where you see the difference. I measured a 10 degree spread between the different value trim resistors with a simulated load.

FWIW 750 ohm is stock for our US cars and it tested nearly identical to an open circuit (resistor removed) at the points where I was testing.
__________________

90 300TE 4-M
Turbo 103, T3/T04E 50 trim
T04B cover .60 AR
Stage 3 turbine .63 AR
A2W I/C, 40 LB/HR
MS2E, 60-2 Direct Coil Control
3" Exh, AEM W/B O2
Underdrive Alt. and P/S Pulleys,
Vented Rear Discs, .034 Booster.
3.07 diffs 1st Gear Start

90 300CE
104.980
Milled & ported head, 10.3:1 compression
197 intake cam w/20 advancer
Tuned CIS ECU
4 ignition advance
PCS TCM2000, built 722.6
600W networked suction fan
Sportline sway bars
V8 rear subframe, Quaife ATB 3.06 diff
Reply With Quote
  #8  
Old 07-29-2011, 01:21 PM
benzworldrefuge's Avatar
Registered User
 
Join Date: Apr 2011
Location: Bayshore, NY
Posts: 44
Quote:
Originally Posted by S-Class Guru View Post
Yeah, always good to verify the cam position; but....
DG
I suggested it because IIRC, the head was off this engine recently. I could be wrong because PS2CHO has been working on both of his W124s and I know one of them had a cylinder head refresh. I would agree, chain stretch wouldn't impact cam timing enough for it to be felt on acceleration.
__________________

88 300e
89 300e
93 400e
93 500e
77 308 GTB
Reply With Quote
  #9  
Old 07-29-2011, 11:41 PM
ps2cho's Avatar
Registered User
 
Join Date: Jun 2006
Location: Chandler, Arizona
Posts: 3,523
I had the head off my 300TE, so not the engine I am dealing with.

Chain stretch on 95k mi engine is unlikely wouldn't you say so?
__________________
2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k
Reply With Quote
  #10  
Old 07-30-2011, 08:59 AM
benzworldrefuge's Avatar
Registered User
 
Join Date: Apr 2011
Location: Bayshore, NY
Posts: 44
I would agree. Chain stretch has no doubt occurred but it would be measured in microns ;-)

From my own experience I can relate that my 88 300E Daily Driver has been a dog for most of its life. Interestingly it never suffered the dreaded EHA failure until it got to 290k miles late this past fall. I replaced plenty of parts trying to get better acceleration but never found the cause until replacing the EHA.

I had replaced two on the wife's 89 300E and never had to adjust them. But when I put the new EHA on the '88 I never thought to adjust it and didn't. The car woke up! It would chirp the tires on the third gear shift at WOT! It also, however was running too rich and overheated a cat.

I had always attributed the difference between the '89's strong acceleration to the dogginess of the '88 to the '89's low mileage (115k vs 290k at the time for the 88). But it was fuel that made the difference.

Although I believe you have gone through much of the fuel system if not all of it and have adjusted your EHA, I would suggest richening it all up to see what the reaction is.

__________________

88 300e
89 300e
93 400e
93 500e
77 308 GTB
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 06:22 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2020, 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