Hi Everybody! I have not visited this site in a long time because my computer died. However, I just replaced my computer and I’m glad to be back. That is not the case, however, with my baby (83 300SD Turbo Diesel). Except for some minor inconvenience, the car is fine. The only problem is that I have a lot of difficulty starting the car in cold mornings. I also had a problem shutting the engine off. (I had to shut the engine off manually.)
If I plug the engine heater at night, I normally do not have a problem starting the car in the morning. Can someone give me a hint? I already know that my shut off valve must be replaced.


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Have you checked the vacuam line to the shut off valve on the injection pump? It is somewhat common for it to get knocked loose when changing the oil filter. You can also use a vacuam guage to ensure that it is getting vacuam to shut it off.

The cold start problem may very well be the glow plugs. An '83 has pin type glow plugs and I have had to replace them every year or two. Even if they are still making continuity, they will still sometimes need replacing, and I live in Texas. The temperature sometimes gets into the twenties, rarely lower. If you are in a cooler climate, it proabably presents even more of a problem. Just to make sure that the relay is okay, you can connect a voltmeter to one of the plugs when cold, turn on the key and ensure that it is getting voltage.

Good Luck,


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Larry Bible
'84 Euro 240D, 516K miles
'88 300E 5 Speed
Over 800,000 miles in
Mercedes automobiles

Thanks for the input. I'll tell my mechanic to check those things that you pointed out for me.

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Other reasons for starting problem in cold temperature:

1. need valve adjustment
2. engine low compression.

David

David. I recalibrated the valves a few months ago. Afted the calibration, I noticed that the cold start vecame smoother than before. However, I've never check the engine compression.
The light for the glow plug does not always comes on when I start the car. Therefore, I velieve that the problem may be that the diesel is not getting warm enogh to start. Also, the car starts up with no problem if I plug the electric heater at night.

If the light for the glowplugs doesn't come on, I would eyeball the glowplug relay.

Twice in the last 9 months my light did not want to come on, the first time (somewhat out of frustration ) I gave the relay box a little "love-tap"...this motivated it enought to get things glowing again.
I imagine my relay is getting a little old, but I'll wait till it gives up the ghost before I replace it.
Might be worth checking out in your case.

-Larry



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03/83 300D
07/73 280

Cisco,

As Larry indicated, I think the relay is likely the cause. The contact points burn out. You can open the relay box and try to clean the relay contacts and check all the soldering joints. If the 80A fuse is old, you may, as well, replace it too at the same time. The glow plug light is also a diagnostics tool by the way the light is turned on. The service menual has a section to check the system by watching the light. Also, the coolant temp sensor which is a part of the glow plug system may be faulty too.

David

Thanks for the input. Yesterday I tested the plugs that actually heat the diesel (the plugs that look like the spark plugs). I conducted the test with a light tester and each plug had electricity. I was told that the carbons in each of the testers might not be generating enough heat to facilitated the start up.

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[This message has been edited by Cisco (edited 02-28-2000).]

Cisco,

I think that you're halfway there. If you're getting voltage to the glow plugs, the relay, fuse, temp sensor, etc are probably okay. Before my experience with parallel glow plugs, I would've said to use an ohmmeter to see that they have continuity (are not open). However, I've found that with parallel, also called pin type, glow plugs, they will have continuity, but if I replace them, everything is okay again. They have gone up considerably in price in the last few years, and are now around $8 to $10 each. But I believe that if you replace them, you're problems will go away.

Good Luck,


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Larry Bible
'84 Euro 240D, 516K miles
'88 300E 5 Speed
Over 800,000 miles in
Mercedes automobiles

I just found a good Europeam diesel mechanic. Sice he has a long watting line, the earliest that I can bring my car will be in a week from today. However, all the recomendations and suggestions that I got form you guys will be very helpful to understand what is involved with this problem.
I'll keep you post on the outcome.

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If the preglow light does not come on then first check the glow plugs. On these engines when a glowplug goes bad the light will not come on. On later engines around 1990 (= or -) the glow lamp will blink after the car starts, telling you that a glowplug is bad. But the older cars the light just will not come on.
To test the glow plugs, the easiest way is to use an ohm meter, less than 1 ohm is normal for a good plug. Test them thru the large connector on the preglow relay. If you have more than one abd, you might as well replace them all.

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