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  #1  
Old 01-14-2005, 11:20 PM
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Join Date: Jun 2002
Posts: 60
w126 Start Problem

I have an '89 420 SEL. Two days ago I attempted to start it and the only response I received was the fuel gage registering how much gas was in the tank. No lights (internal or external), radio, climate control, etc. worked. I wiggled the shifter and shifted into nuetral - no luck. I tried to jump the car as well. I pulled the battery and checked it - registered a good battery. After putting the battery back, it started right up. From there it ran for over fifteen minutes before I shut it off. I started it up several times after that without a problem.
The next morning it would not start. Tried the same steps as before without success. The battery and regulator brushes are recently new. Regular tuneups, fuel pump relay replaced, good ground from the engine to the body, battery terminals/ wires are in good condition and all fuses appear to be fine.
Any thoughts? I am an average DIYer so try not to get too technical with suggestions. The other problem is that I have recently moved and have not unpacked my CD's and repair manuals.

Thanks in advance for any help.

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  #2  
Old 01-15-2005, 12:07 AM
goldstone's Avatar
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Join Date: Oct 2002
Location: Dutchess County, New York
Posts: 158
You'll track it down. The fact that you got it to start in the interim implies that it's almost certainly a faulty ground somewhere.

I'd check the starter connections first...

Good luck! (Let us know when you find the problem.)
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1991 560SEL-Euro (214,000 miles)
1989 420SEL (Retired from daily use at 325,000 miles; Use as donor vehicle)
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  #3  
Old 01-15-2005, 02:10 AM
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You can do it
 
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Location: OC S. California
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Based on the information you provides I will try 2 paths of troubleshooting to get you started at least.

Does engine turns when you turn the ingnition key?

1. If not try to jump start, make sure you let it charge for few minutes before you crank it up. If it fires up, culprit could be one of these: your battery, Alternator, or Your charging circuit. Since you started and ran it for 15 minutes, car sat for overnight and did not started in the morning. You might have slow current drain in your electrical circuit.

2. If it turns but do not fire up, you could have Fuel related or Electrical related problem.
2a. Fuel related, do you have gas comming to injectors? if no it could be blockedfuel filter, empty fuel tank (sorry), FPR or Fuel distributor. If gas is reaching to the injectors move on to next step

2b. Do you have spark in the plugs, take one spark plug out leave the wire connected provide the ground to it, crank the car and look for the white spark in the spark plug electrode. if No spark, it could be one of these; ignition coil, distributor cap, rotor, ignition wires etc.

Please provide more data after doing the above step to further investigate the issue.

If you want a blind shot, I will go for distributor cap and rotor.

I hope it helps, feel free to ask any more questions.
Good luck and keep us posted.

Thanks
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87 420 SEL
Looking for a nice mid 80's MB diesel.
87 BMW 528e (Sold)
99 TOYOTA 4Runner
1989 Honda Accord (Sold)
1988 Honda Accord (Total)
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  #4  
Old 01-15-2005, 01:01 PM
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next step

Tried to jump start the car today, waited for about 5 minutes and although she struggled, it started and is currently running.

Goldstone - I checked the starter connections and everything appears to be in working order.

BenzMatic - the engine didn't do anything yesterday at all. It was as though I didn't even have a battery connected at all.

Since the car did start from the jump, you suggested the battery, alternator, or charging circuit as problem areas. I have checked the battery and it is registering properly (and is only two years old). I am attempting to find someone locally who can check the alternator. What can I do to check the charging circuit? I did notice that the first layer of insulation on the wire going from the battery to the alternator had begun to fray but I could not see any wires showing through.

Thanks for the initial replies.
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  #5  
Old 01-15-2005, 02:06 PM
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Join Date: Jun 2002
Posts: 60
aternator repair cost/diagnosis

I was able to have my alternator checked by a local mechanic. He said that the meter he was using should register 14 or better and it showed 13.65 after I started the car. When I turned on the lights, blower motor, etc. the number went down to 13.25. He told me that the parts in the alternator had worn (bare with me, I am not adept with the technical terms) over time and that it needed to be repaired. He would charge $160.00 out the door to remove, I am assuming rebuild, and button it back up. Does this diagnosis sound legitimate and how about the price?

Thanks.
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  #6  
Old 01-15-2005, 02:40 PM
300sel(88)
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Could be ignition switch.
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  #7  
Old 01-15-2005, 05:16 PM
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ignition switch?

Quote:
Originally Posted by 300sel(88)
Could be ignition switch.

How do I check the ignition switch?
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  #8  
Old 01-16-2005, 01:04 AM
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You can do it
 
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Location: OC S. California
Posts: 120
Most probably the Alternator is not charging the battery properly and battery dies after initial starts. I will bet that it will not start in the morning again, if it is the alternator issue. It should put out 14v when car is running, most probably the carbon brushes are bad which comes with the voltage regulator. It is about $33 and it takes 10 minutes to change it, so I think $160 is a little too much but still not that steep. Does you machanic gaurantee that this will fix you issue? I do not think it is your ignition switch, here is the test: try to turn off the car and start right away for 5 times. If car starts or engine turns 5 out of 5 times, your switch is good.
If you are up to doing it yourself, it is very simple DIY job, just open 2 screws and take old one out and put the new one and tight the screws.

See the attached pic for the part, it will give you an idea how easy it is to put it in. You can buy it from the sponsor of this board, FastLane.

As for as the ignition switchis concern,

Good luck and Keep up posted.
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w126 Start Problem-vol-reg..jpg  
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87 420 SEL
Looking for a nice mid 80's MB diesel.
87 BMW 528e (Sold)
99 TOYOTA 4Runner
1989 Honda Accord (Sold)
1988 Honda Accord (Total)
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  #9  
Old 01-16-2005, 02:40 AM
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Join Date: Dec 2004
Location: Seattle WA
Posts: 82
I agree that 13.25 volts may not be the optimum charging voltage but dont think with 13.75 running voltage that its the actual fault you are sufering from. So if you hade the car running and when you parked it the battery voltage was good then read on.

This is an easy way to aproch a no cranking diagnosis even though its harder to write it up then it is to do it.

1. At night make sure the battery has a full charge. In the morning before you start the car put a volt meter on the battery if you dont still have 12.something for voltage suspect the battery.

2.If the batt. voltage is ok then leave the hood up and place the meter where you can see it from the drivers seat then turn the key on it shouldn't affect the voltage much then watch closley as you try to crank the engine if the voltage drops (way) down and the engine doesn't crank you have a battery problem or the starter is drawing to much amperage. If the voltage doesn't drop skip to #3 if it did keep reading.
If that is the case then you need to boost/jump start with a amp. meter on the battery cable to see how many amps are passing through the cable when cranking. I would think 300 to 350 would be your max# if the amp# drawn from the battery is lower than that when it was boosted/jump started then the problem would be that the battery wasn't capable of supplying the amperage that the starter needed to crank the eng.

3. If the voltage didn't drop when you tried to crank the engine then that meens that somthing like the starter sylinoid/ignition switch/bad wire/ relay/etc never gave the starter the comand to crank the engine that would make 300sel(88) the hero of this thread. lol... There are a few ways you can go about it but I would just go to the starter and find the exciter wire for the sylinoid there may be more than one small wire sorry dont know the color of hand but when you test it remove it from the starter and place meter on it and if your meter leads are not long enough have someone crank the motor. If it has power when the key is in position #2 then its the wrong wire if it only has power when the key is turned to the cranking possition then the starter is the problem if the large 6.gauge wire has power also(sorry forgot to mention that first)
If you never get power to the exciter wire then you will need to go to the switch plug and check for power there if there is no power in the wire there than its prob. the switch if there is then its poss. relay/wire and remeber you had mentioned wiggling the shifter? Not sure your model has a nutral start switch but wouldn't be suprised if it did.

OK well that should keep you busy for a while and post back with the good or bad news.

Sorry everone for the long post but some things have to be said completely to minamize confussion.

Dave..................
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  #10  
Old 01-16-2005, 04:17 PM
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Fixed?

Well I pulled the trigger and had the local mechanic pull the alternator. He ended up rebuilding it and replaced the brushes on the regulator. The temperature's been in the low 20's over the past few days so the car has had to start cold everytime. When I went to pick it up last night, it had sat for some time. It started right up. Checked the voltage and it read 14.4 versus the 13.65 or 13.25 with a load the day before. I drove it home and it sat overnight outside until this morning. When I turned the key, it fired right up again. It appears that the problem has been fixed - a total of $160.00 + tax for the rebuild.

Thanks for all the replies - I have printed out the other avenues referred by several of the members in case the problem resurfaces. At least I will have a starting point.
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  #11  
Old 01-16-2005, 07:15 PM
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You can do it
 
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Location: OC S. California
Posts: 120
Good to hear that you are up and running again. Hopefully it will not surface again but if does, just follow Dave's instruction to narrow down the problem.

Happy motoring.

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87 420 SEL
Looking for a nice mid 80's MB diesel.
87 BMW 528e (Sold)
99 TOYOTA 4Runner
1989 Honda Accord (Sold)
1988 Honda Accord (Total)
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