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  #1  
Old 02-13-2017, 09:50 PM
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1972 MERCEDES 280 SE W108 ENGINE LOOSE POWER AND SHUTS OFF AFTER 15 MINS

Hi Guys
I have 1972 Mercedes 280 SE 6 cylinder w108. I am having issues with the engine loosing power after running 15 minutes and finally shuts itself off. I have to wait until the car completely cools off for to be able to restart the engine again? It wont start until engine cools off. What do i need to do?
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Old 02-13-2017, 10:49 PM
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Quote:
Originally Posted by apozar View Post
Hi Guys
I have 1972 Mercedes 280 SE 6 cylinder w108. I am having issues with the engine loosing power after running 15 minutes and finally shuts itself off. I have to wait until the car completely cools off for to be able to restart the engine again? It wont start until engine cools off. What do i need to do?
First, remove the gas cap, and drive the car without the cap. Any change?
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Old 02-14-2017, 12:44 AM
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When it dies, does it have spark? Check that so you can narrow it down to fuel or ignition system.
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  #4  
Old 02-14-2017, 06:29 PM
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Frank's gas cap idea is a good place to begin. If that doesn't make a difference I'd look at the coil.
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  #5  
Old 02-14-2017, 07:02 PM
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Let us know what (if any) troubleshooting was done. When it won't start / run, is it getting the three critical conditions required TO run?
  1. Compression
  2. Fuel
  3. Properly timed spark

Report back and let us know which is missing. If you have all three, it will run. So one of the three is missing. One is very easy to test, one easy with a timing light - but if you have no timing light, you can at least verify spark in general without one - and the other would require a compression test tool.

It could be anything... Vapor lock, valves too tight that heat up and cause you to lose compression, a failing ignition system (such as the pesky electronic ignition box going out), etc.
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  #6  
Old 02-18-2017, 10:17 PM
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As weird as it sounds the removing the gas cap trick will tell you a lot.

Be careful when driving it as you can't imagine how much gas just sloshes out when the gas cap is not down tight.

Also, when you do removed the gas cap is a a 'woosh' of pressure released? This is all a part of the 'remove the gas cap' test.

I cannot remember if an electronic ignition was used on this car. I know it has a conventional distributor with points and such but right in there somewhere these electronic ignition systems were coming on line to boost the spark voltage. If this is faulty it will fail when it is hot and then, when it cools, act normally.

If your car has one of these, and I am not sure if they were used on a car that early, then check the wiring connections and see that they are clean. I once had a '75 doing the same thing and it was nothing more than a tarnished connection in the ignition module.

Also pull the coil wire out of the top of your distributor and look for a blue powder. If it there then your coil wire is arcing and this will cause a fail when it heats up, expands and breaks the circuit. After it cools it will then make the connection and you will be OK.

Until it heats up again.
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  #7  
Old 02-19-2017, 06:32 AM
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I had a vw that did this.
Turned out to be rotor arm.
As coil got hot the spark reduced and wasn't enough to bridge worn rotor arm.
Not mentioned in any manual!
Good luck.
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  #8  
Old 02-20-2017, 12:09 PM
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Quote:
Originally Posted by W109Driver View Post
I had a vw that did this.
Turned out to be rotor arm.
As coil got hot the spark reduced and wasn't enough to bridge worn rotor arm.
Not mentioned in any manual!
Good luck.
I talked this over with a mechanic friend of mine and he said he had seen this with a cracked distributor cap.

I asked him how could he know for sure since some Mercedes distributor caps were rather expensive. He said he hooked it up to an ignition analyzer, and old Sun Scope unit he had, and it told him everything the ignition system was doing.

It may be hard to find someone with this equipment these days but if such a shop could be found the test results could pinpoint the problem without a lot of guesswork.
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  #9  
Old 02-22-2017, 02:49 PM
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check the fuel filter
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  #10  
Old 03-16-2017, 07:16 PM
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we figure it out finally.. it was the fuel filter.. we replaced both the filters car is running strong now.. Thanks for the help guys
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