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Old 04-12-2002, 10:05 AM
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Question OVP Relay

I have read many posts regarding the OVP relay, but I would like to get an opinion of my situation. My 87 300E runs rough for no more than 5 seconds on a cold start, and then runs fine. It will start right up if driven, parked for a brief period, and re-started. Would the OVP relay be the most likely culprit? Please advise
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Old 04-12-2002, 10:14 AM
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Join Date: Mar 2001
Location: Evansville WI
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Sounds like what typically happens when the valve stem seals are worn out. On the OVP problem, it also starts hard, but the idle speed will be incorrect also, and most times you also have the ABS light on (dash light).
I'd inspect the spark plugs for signs of deposits being caused by worn or hardened valve stem seals. How many miles on it?
If you replace the spark plugs and then it starts OK for a week or so, then starts doing it again, probably the valve stem seals. Although I have had a few cars that acted this way and it ended up having resistor spark plugs in it, replacing them with the proper spark plug fixed it. You don't have any of these fancy spark plugs in it do you? Need to run the recommended non-resistor plugs, preferably Bosch Super. Or for that matter, it may be just worn out spark plugs.
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Old 04-12-2002, 10:29 AM
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I am not exactly sure of the true mileage, but I believe it to have over 200,000. The car runs very well for the age and mileage. I will replace the spark plugs, and see if that helps. Thanks!
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Old 04-12-2002, 10:44 AM
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When you replace the plugs, be sure to examine the grounding lug for signs of crusty deposits on them. It's caused by oil, but isn't black looking, had a fairly normal yellowish-gray look to it. Sometimes also has like a "glaze" to it.
Again I really recommend only the correct plug, a local parts store may not have them in stock, unless it's a European specialty parts store. You may need to get them at the dealer. it's worth the extra work to get the correct plug. Don't let yourself get talked into a "fancy" spark plug, such as platinum tipped, dual (or more) electrode, split fire, etc, as these are typically resistor spark plugs, and this engine has resistors in those metal plug wire ends, don't need resistance twice.
At 200,000 miles I wouldn't be surprised if it needs valve stem seals. If the maintenance hasn't been paid attention to, it may even need valve guides, which is a big job. The valve stem seals however can be done by pressurizing the cylinders, no need to remove the head.
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Old 04-13-2002, 10:00 AM
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Join Date: Dec 2001
Location: Nashville, TN
Posts: 551
Gilybenztech, you and the original poster have just diagnosed my problem. What is the exact reason, though, that this would cause the problem? I am supposing that it runs rough a few seconds because the plugs have to burn off the oil and don't spark correctly?

Plus, I'm using 1 qt of oil every 750 miles with NO smoke and NO leaks.

1994 C280, dark green metallic
105k miles

1991 190E 2.6, Black
191,500 miles
(sold to another forum member)

2003 Chevy Tahoe LT, Redfire Metallic
105k miles

1989 Mustang GT Cobra Convertible
43k miles
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