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  #1  
Old 02-16-2007, 05:54 PM
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Just spoke to a Mercedes tech about my cars issues....

And he said for me to call back Tuesday and he will see if he can work me in on Thursday. I explained all of my issues and at first he mentioned something (like a sensor or something - he was talking fast) and said it was very expensive to replace. He also said that I should not use platinum plugs on that car around here. I do not recall what I replaced them with 2000 miles ago, but I know that they were Bosch.

He also said it could be the injector seals causing it.... we will see.

It will be going next week to see what is going on. If its something cheap/simple, I will get them to fix it and keep on driving it. If not and its something complex/expensive, I will likely junk it out. I was only keeping it because it offered much better MPGs than my truck when it was getting 21 mpg in the city, but then it dropped to 14 mpg and now 12 mpg. Its getting worse and worse.

I will post the results later. Thanks to all for the advice over these past few weeks.
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  #2  
Old 02-16-2007, 06:32 PM
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Quote:
Originally Posted by 86560SEL View Post
And he said for me to call back Tuesday and he will see if he can work me in on Thursday. I explained all of my issues and at first he mentioned something (like a sensor or something - he was talking fast) and said it was very expensive to replace. He also said that I should not use platinum plugs on that car around here. I do not recall what I replaced them with 2000 miles ago, but I know that they were Bosch.

He also said it could be the injector seals causing it.... we will see.

It will be going next week to see what is going on. If its something cheap/simple, I will get them to fix it and keep on driving it. If not and its something complex/expensive, I will likely junk it out. I was only keeping it because it offered much better MPGs than my truck when it was getting 21 mpg in the city, but then it dropped to 14 mpg and now 12 mpg. Its getting worse and worse.

I will post the results later. Thanks to all for the advice over these past few weeks.

He's right about not using platinum plugs because your engine calls for non-resistor plugs.

All platinum plugs are resistor plugs.

Mercedes has the resistance in the spark plug wire boots, so it you are using platinum (or regular) resistor plugs, you are doubling the resistance, which diminishes the spark.
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  #3  
Old 02-16-2007, 08:27 PM
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Hmmm. Next chance I get I will remove one of them to see what I have installed. Thanks!

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Originally Posted by suginami View Post
He's right about not using platinum plugs because your engine calls for non-resistor plugs.

All platinum plugs are resistor plugs.

Mercedes has the resistance in the spark plug wire boots, so it you are using platinum (or regular) resistor plugs, you are doubling the resistance, which diminishes the spark.
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  #4  
Old 02-17-2007, 12:05 AM
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One cause of suddenly bad gas mileage is a failed or disconnected O2 sensor.
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  #5  
Old 02-17-2007, 06:12 PM
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You should really sell that car while its worth something, well $500 maybe. At the rate your going its going to the crusher in a few months.
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  #6  
Old 02-17-2007, 06:24 PM
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Yeah, thats the thing he said it could be, but I did not mention that it had bad MPG.... I never got a chance. He said it was an expensive repair.

Stalling... yes, it does this, but only when temperatures are above 70. Its really a problem in the spring and summer and fall. Hard starting is never. It always starts at the turn of the key.... starts instantly, no matter the temperature. Even if its bitter cold... like 18F, it starts instantly.

That is one thing that is so puzzling.

Someone said O2 sensor.... I am assuming its OK, because the warning light is not illuminated.

My main problem is the rough idle (like a miss) when in park/neutral and when it initially shifts into 2nd-3rd and 3rd-4th it will miss. Not always missing, but often. Sudden MPG decrease has also occured. I am now getting 12 mpg and was getting 21 mpg.

Also, power is low, which it always has been since I have owned it. Maybe its normal though.... I had a 90' Lexus LS400 before this, that was quite powerful at low RPMs.

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Originally Posted by user name View Post
a sudden decrease in gas milage on a 380 is somtimes a defective warm up compensator ,, stalling and hard starting also are symptoms..
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  #7  
Old 02-17-2007, 08:08 PM
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Thumbs down Not all are resister plugs

Quote:
Originally Posted by suginami View Post
He's right about not using platinum plugs because your engine calls for non-resistor plugs.

All platinum plugs are resistor plugs.

Mercedes has the resistance in the spark plug wire boots, so it you are using platinum (or regular) resistor plugs, you are doubling the resistance, which diminishes the spark.
Look up the Bosch sight,www.boschusa.com there is a non resister plug marked for the 2s and 4s platinum.
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  #8  
Old 02-17-2007, 09:39 PM
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I e-mailed my neighbor across the street, who is a master guild Mercedes technician, and works at Penske Mercedes Benz in Covina, CA.

He tells me that all platinum plugs have a resistor built in the spark plug. Its value is about 5.8 K ohms.

The issue is not "platinum" versus conventional copper core plugs. It's resistor versus non-resistor and Bosch Platinums HAVE RESISTORS. This must be the sixth time in the last year I've made this point!

Most aftermarket manufacturers list resistor plugs for Mercedes which have non-resistor plugs as OE. They just don't care. Most don't offer non-resistor plugs in the correct heat range and geometry, so they just list resistor type plugs.

I copied the following post from Duke 2.6:

"Take a look at the service CDs. They have several examples of both normal and anamolous of secondary wave form traces and show at least one with excess secondary resistance. It may not result in any noticeable difference when the plugs are new, but as they age - wear and build up deposits, the number of misfires will increase resulting in more idle roughness and higher emissions than if the proper non-resistor plugs are used.

Bosch H9DCs (for M103 engines) cost about two bucks each and have a normal service life of 30K miles. The H9DC0 has a "heavy duty" electrode. They were OE, but they are more expensive, and the standard electrode H9DC work just as well over the 30K service interval.

Spending more money to by the WRONG plug is just plain foolish!"



Also, to further illustrate that pre-1998 Mercedes engines were not designed for platinum plugs, there was the following Q & A in the Technical & Restoration Forum in the March / April 2003 The Star Magazine.

There is a question about platinum plugs and an interesting reply. It doesn't say who exactly wrote the reply, but Stu Ritter usually answered most questions:

"After I put Bosch Platinum +4 spark plugs in my 190E 2.6, a dealership advisor reprimanded me, saying they aren't recommended by Mercedes-Benz. He said that a service bulletin indicated that they should not be used. Is this so?

Some time ago a Mercedes-Benz service bulletin recommended against using fine single-wire platinum electrode spark plugs in their engines. The electrode on these plugs was so thin that the spark could be blown off the plug, causing misfires. Thin-wire plugs (platinum plugs) could cause poor idle quality and misfires at high rpm under full throttle. Mercedes-Benz has not recommended the newer +4 plugs, which have four electrodes and could cause the spark to be blown off."
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  #9  
Old 02-18-2007, 12:00 AM
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Thanks. As soon as the weather breaks, I will remove one of the plugs and see what I installed. It is supposed to be 61 on my next day off (Thursday), so I would remove them then, but I am supposed to take it to that MB tech that day. I will probably get him to check it.

Hopefully he can find out whats wrong with it. I really do not want to junk it out, as I still love driving it, but it has become a headache with the low MPG, the winter time missing, summer-time stalling. I also occasionally have that RPM "dance" when in park.... the rpms will slightly go up and down, up and down, up and down, up and down (with warm engine).
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  #10  
Old 02-22-2007, 05:13 PM
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Well, I just heard from my psychiatrist......

Well, well. I just got back from taking the car and really not much better off now than before. The plugs were indeed platinum and he changed them out to standard Bosch plugs. Its not missing nearly as bad now, but still is occasionally when it shifts and still is not idling completely smooth when in park.

He hooked it to machines, checked for vacuum leaks, etc. Seems as if the injector seals are indeed leaking (discovered by spraying brake cleaner?)- which he said it why it is still not smooth and why it is stalling in warm weather. Also, he said the thermostat needed changed (which I knew). I told him it was running very cool when cold and very warm when hot.

To check it and change the plugs was $90.00. I was thinking it was going to be $50., but it was worth it to find out what was going on and get the proper plugs in there and hopefully get better mpgs. He also noticed the noise that the valves/lifters were making on the passenger side of the engine- that, tick, tick, tick, sound. I also told him that it had a knock between 1500-1700 rpms and he said that the camshaft was likely worn, which I thought so, from the info I have gathered here. At first he said it could have a burnt valve because of it and causing the roughness, but when I returned, he did not mention it. He said it was the injector seals. I went back to pick up the car and he had made an estimate sheet. Seems as if it is going to be MUCH more to have this done there than I want to put into this car. $183. for the injector seals, $71. to replace the valve cover gaskets/INSPECT the camshaft/lifters/rockers and I think around $95. for the thermostat/gasket. He also said that the "engine electrical" checked out perfectly. He had some sort of huge "1980'ish" looking machine he hooked up to the car. I am assuming it was what they used back when these cars were new?

I spoke to my uncle, who has owned several Mercedes and he said that other than electrical, most anyone could/should be able to do this type of work on a older Mercedes themselves and recommeded the normal mechanic we normally use. I think he would do all of this for 1/2 the price.

If this does not work out (him being able to do it much cheaper), it may become more clear that I should just sell this car to someone that has the time/knowledge to put into this car. Everything else is fine.

Thanks again for all of the info you folks put in.

Last edited by 86560SEL; 04-05-2007 at 05:21 PM.
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  #11  
Old 02-22-2007, 05:29 PM
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If it were mine, one of the cheaper things to look at would be the idle control valve (on top, up front, to the left of center) - these can get gunked up, and a vigorous (and I mean vigorous) cleaning can be helpful.

Here is a picture: http://catalog.eautopartscatalog.com/mercedesshop/sophio/image.jsp?title=Idle%20Control%20Valve&url=http%3A//img.eautopartscatalog.com/live/C403011604VDO.JPG
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  #12  
Old 02-22-2007, 05:57 PM
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Idle Control Unit might also need to be re-soldered.



Cams wear due to the oiler tube keepers becoming brittle and breaking (it's $8 to replace)

Be sure to also check the gasket under the steam that controls a/f ratios. A quick spray with PB will help in the meantime. My 380sel had some issues starting and idling, these helped.
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  #13  
Old 02-22-2007, 08:30 PM
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Isn't that the thing that if you disconnect and the idle increases, then its OK? If so, I did that (upon recommendations) and the idle increased, so I was assuming that it was OK.

I asked this once, but never got a reply... I do not know how to remove it, or what to even clean it with.

He (MB tech) said that the "engine electrical" was in proper working order. Would this also include the idle control valve / unit?

Thanks again!


Quote:
Originally Posted by Larry Delor View Post
If it were mine, one of the cheaper things to look at would be the idle control valve (on top, up front, to the left of center) - these can get gunked up, and a vigorous (and I mean vigorous) cleaning can be helpful.

Here is a picture: http://catalog.eautopartscatalog.com/mercedesshop/sophio/image.jsp?title=Idle%20Control%20Valve&url=http%3A//img.eautopartscatalog.com/live/C403011604VDO.JPG
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  #14  
Old 02-22-2007, 09:29 PM
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I still think you should sell it while its worth something. Buff it up, list it on ebay and maybe you will get $1k.
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  #15  
Old 02-23-2007, 12:01 AM
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$1K would be nice, as thats what I paid for it, but had sunk about $200 in it since then... mufflers, brakes and most recently this latest "repair" bill. Cannot complain, I guess I have got my monies worth out of it.

I think that the rust free body, good interior, good tranny and all other good electrics, it should be worth that. If someone had one of these cars that was crashed or something, with a good low mileage engine.

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I still think you should sell it while its worth something. Buff it up, list it on ebay and maybe you will get $1k.
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