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1990 W124 230CE Coupe
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Discussion Starter #1
Where to start... Need help as nearing the end of my patience.... I have a 1973 450SL . European car .. Good but not great. 5 years without any big difficulties but has let me down 3 times in last 5 months .. New fule pump and new coil were the first 2. *Couple of weeks ago it started to run really rough. *When driving it was ok but when coasting and then accelerating it chugged a couple of times before taking off ... Then started to run rought in traffic *finally had to abandon it at a garage ... They said they were familiar with 107's so seemed like a good idea.

They bypassed the electronic ignition .. New coil and points and said this should solve the problem.. They also did a pressure test on fuel and said pressure was not holding for long enough when the engine off and suspected an injector leak.*

Took it home 50 miles .. Now back running rough.. Even on tick over

Have tried the following..
Fuel addetive to see if it will clear injectors but no more than 10 miles since added
Checked all connections to ECU based on 07.4-035 from manual
vacuum hoses and connection seem fine
Trottle switch clicks OK
Temp sensors are within spec
Injection valves resistance is OK

I plan to check trigger points and timing using a timing light but this is outside my comfort zone

Question ?... Beside the air valve there are 2 connections .. One is the temp sensor coolant connected to ECU.. The other has a rectangular dark brown connector .. 2 brown wires .. Engine dies when disconnected ? Whats this for .. Reads 32 ohm when engine cold...

I really shoud take it back to the garage but I dont think it will struggle that far.*
Any suggestions on where to go from here. *

Sent from my iPad
 

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Outstanding Contributor
450slc5.0cab 280sl5sp 280se4.5 500se+500slAMG +250seStkW108 350sl4spdX3 500secEuro
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I my car is not smooth in the 1500-1700 range with low throttle, and I wonder if my resistor spark plugs are the issue. The local mb dealer has somecorrect non-resistor plugs for about $36 and I need to pick them up to see if that makes a difference. My idle and higher Rpms are quite smooth. If plugs don't solve it, my fuel strainer is next.
 

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1975 450SL
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You may want to check the gap of the points. I had a lot of problems with mine before I gave up and replaced them with an electronic unit.

You would need a dwell meter to do this correctly, but you can get close by gapping them to .014", about the thickness of a business card.

To set the points, you would have to remove the distributor cap and the rotor. The points are there on top of the dizzy. The object is to get the little "rider" pad at the top of one of the 8 lobes on the distributor shaft, and measure the gap.

The use of a timing light is pretty simple; once you've done it, you'll wonder why you were so worried about it. Most modern timing lights have 3 wires; Red and Black with clamps on the end, (these go to power and ground respectively) and another lead that has a weird looking clamp on the end with a hole in it. The odd looking clamp goes around the wire of the #1 spark plug, try to get within 6 to 8 inches of the plug end of the wire.

Hook the clamps up and start the engine. Making sure not to drag any wires near pulleys, belts, and fans, point the lamp end at the little pointer next to the harmonic balancer, then pull the trigger switch. The light should start to flash rapidly, and you should be able to see numbers and marks next to the pointer on the balancer. These numbers and marks indicate the degrees of engine rotation from #1 TDC that the spark plug is firing. Adjust by rotating the distributor to the specifications for your engine.

There may be some requirements in the specs for your year/model that say to remove and plug vacuum hoses, so check them out first. Just don't tell your wife, she'll probably not be able to emotionally handle the fact that guys actually DO read instructions, contrary to what every Womens' magazine says.:D

Good luck,
Scott
 

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'72 350SL, '85 300D, '98 E320, '19 Subaru Outback (sold '14 GLK250)
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Question ?... Beside the air valve there are 2 connections .. One is the temp sensor coolant connected to ECU.. The other has a rectangular dark brown connector .. 2 brown wires .. Engine dies when disconnected ? Whats this for .. Reads 32 ohm when engine cold...
There are pics with component locations in the D-Jet section of Encyclopedia Germanica (the stickies) The post by Proctologist is a very useful place to start.

However, the pic of the sensor with the brown connector is not correctly indentified (I notated the pic but put a ? next to that part). I believe it is actually the Thermo-Time Switch which is associated with the cold start valve. ***

I wouldn't "think" pulling that plug would stop the engine, unless teh wire is perhaps grounding out. Check the leads.

*** we should get that fixed! Ok - rough job, but done. How do we get this into Procto's stickie? It should be there in a few places and elsewhere on forum.
 

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1972 350SL 148,000 miles
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If Dave or Dig or someone lets you in to my thread you have my full permission to fix that pic Graham

Personally I'd switch to Pertronix and see if that fixed the issue, if it didn't I'd start going to the trouble shooting sections of the D-Jet section in the Encyclopedia, theres a great troubleshooting guide in one of those threads, a big chunk of it is my thread but theres some I missed on page 2 of the d-jet and Kjet thread
 

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'72 350SL, '85 300D, '98 E320, '19 Subaru Outback (sold '14 GLK250)
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If Dave or Dig or someone lets you in to my thread you have my full permission to fix that pic Graham

Personally I'd switch to Pertronix and see if that fixed the issue, if it didn't I'd start going to the trouble shooting sections of the D-Jet section in the Encyclopedia, theres a great troubleshooting guide in one of those threads, a big chunk of it is my thread but theres some I missed on page 2 of the d-jet and Kjet thread
Hi procto,

Tomadaly should probably get the whole troubleshooting pdf in this link in case I have to remove it:

http://www.benzworld.org/forums/r-c107-sl-slc-class/1667167-d-jet-training-manual.html

There is not a lot of info in his post, but seeing they already converted to conventional points (assuming they also put ina conventional coil), then the ignition should be OK.

After that, I would first look at injection - that takes doing all the tests for leakdown and measuring individual injector outputs. No magic solutions, just do everything.

After that, I would pull the trigger points and compare measurements with those on your EG summary. I had a heck of a time before I discovered one rubbing block had worn out.

Then, or maybe first, I would make sure all grounds are good and that nothing is grounding that should not be!

But your thread covers most of this.
 

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Always Remembered RIP
1979 280sl 4 sp w/ac 1957 MGA 1998 volvo xc/70 2004 F150
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Egv-107 got the 73 running and probably the most important point is to check the basics: plugs, timing, cap/rotor, grounds, relays - just read it, then re-read it !!
 

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1990 W124 230CE Coupe
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38 Posts
Discussion Starter #10
Hi guys ... Thanks for all input ... Appreciate the training manual .. I will use it to trouble shoot.

As the rough running clears some of the time im not convinced its timing and amy be related to injectors. I see lots of good reports on pertronix ... Most related to 1975 versions..
Is there much difference for a 1973 version... ??
Is it the same 1885 model . Are the distributors the same. ??

Im thinking of pulling all the injectors and having them ultrosonically cleaned .. Anyonu tried this ??
 

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R/C107 Moderator
1986 560SL: '84 500SL: '84 280SL 5 speed: other 107s
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Hi guys ... Thanks for all input ... Appreciate the training manual .. I will use it to trouble shoot.

As the rough running clears some of the time im not convinced its timing and amy be related to injectors. I see lots of good reports on pertronix ... Most related to 1975 versions..
Is there much difference for a 1973 version... ??
Is it the same 1885 model . Are the distributors the same. ??

Im thinking of pulling all the injectors and having them ultrosonically cleaned .. Anyonu tried this ??
I cleaned my '73 injectors in injector cleaner and ultrasonic jewelry cleaner. Worked Okay. The pros are a better choice because they will also test the spray pattern and flow.

I pulled the entire fuel rail with injectors connected. Be careful removing the injector clamps. The bolts may be frozen. Spray with PB Blast or similar.

I took a picture of the rail and injectors on the concrete floor. Can you guess which injector was leaking?
 

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1990 W124 230CE Coupe
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Discussion Starter #12
Thanks rowdie... Cool name ... Must try and figure out how to change my name...

Just had the car out ... Running better since yesterday. Put additive in about 20 miles ago to see if it would clean injectors and i suspect thats the improvement ... Ran well but coasted downhill towards the end of my trip chugged a bit when i gunned it. Tick over better but seems to down on power.

Have you replaced your ignition or is it still the original
 

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R/C107 Moderator
1986 560SL: '84 500SL: '84 280SL 5 speed: other 107s
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Thanks rowdie... Cool name ... Must try and figure out how to change my name...

Just had the car out ... Running better since yesterday. Put additive in about 20 miles ago to see if it would clean injectors and i suspect thats the improvement ... Ran well but coasted downhill towards the end of my trip chugged a bit when i gunned it. Tick over better but seems to down on power.

Have you replaced your ignition or is it still the original
Rowdie was my late Border Collie and best friend.
The ignition in mine was already changed to the Crane system. A few here have used it also but there is more info. on the Pertronix install and it seems a better choice.
 

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'72 350SL, '85 300D, '98 E320, '19 Subaru Outback (sold '14 GLK250)
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10,340 Posts
I see lots of good reports on pertronix ... Most related to 1975 versions..
Is there much difference for a 1973 version... ??
Is it the same 1885 model . Are the distributors the same. ??

Im thinking of pulling all the injectors and having them ultrosonically cleaned .. Anyonu tried this ??
This place in UK might be a possibility for injector cleaning. Or you could do it yourself (see Proctologist thread in stickies where I did it at home. I also used a Jewellery ultrasonic, but not sure if it did much good.) It puzzles me why pulling the thermo-time switch would stop the car. It should make no difference unless it is grounding out and fuel is squirting in through cold start valve. Maybe disconnect cold start valve, start with spray, warm car up and then see how car runs. If you are getting fast leakdown, it could be the cold start valve and not the injectors.

Pertronix installation on 73 is easier than on 75. In fact on 75 it is not easy at all! If shop installed a conventional coil instead of the blue Bosch coil, then it should work with the Pertronix 1885 (which replaces both points and transistorized switchgear). If you decide to go this way, there is a hand drawn sketch on Proctos thread that shows how to make connections
 

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1990 W124 230CE Coupe
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Discussion Starter #16
took out the injectors ..

:confused: as I was told I had a leaking injector - i pulled them out last night - 6 came out with ease - and 2 took me about an hour - they were really stuck . didnt want to use too much force but kept lightly hammering them with a wooden dowel eventually they freed.

Seems I have 2 different types. 4 of them are bosch 0280150024 with removable hoses and 4 are 0280150036 with crimped hoses. one is rated at 490cc and the other at 495cc. Hope this is not a problem - there off to a local shop to be ultrosonically cleaned - new seal etc.

should have them back next week - if no improvement - plan to try a pertronix 1885 - seems its suitable for my distributor,
 

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1986 560SL: '84 500SL: '84 280SL 5 speed: other 107s
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It sounds like 4 have been replaced and 4 had the hoses renewed. They are originally crimped on.

Do you know when the valves were last adjusted?
 

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1990 W124 230CE Coupe
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Discussion Starter #18
seems the 024 version has a a hose connection and the hoses can be changed - while the 036 version is crimped - from investigation both are similar rating with only 5cc in flow rate different.

no idea when valves last chacked - not in last 5 years - or 4000 miles. I will put on my todo list - but as the rought running only happens under certain conditions I dont think valves can be a significat problem..:thumbsup:
 

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1986 560SL: '84 500SL: '84 280SL 5 speed: other 107s
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When renewing the hoses the crimp connection is cut off and replaced with a hose clamp.
 

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'72 350SL, '85 300D, '98 E320, '19 Subaru Outback (sold '14 GLK250)
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Don't forget the 9th injector. Also known as the cold start valve or injector. If you had done the leak down tests as outlined in the manual, you would have been able to determine where the leak down was. But I have suggested this twice now, so good luck .......
 
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