I have a 1972 Mercedes 250. I believe that the OVP is out. I have one from a 1987 that I can get for free. Are they interchangeable? How much would a non-working OVP effect the overall performance of my car? It stalls at traffic lights and seems to be missing a bit. Thanks!

You have been reading too many OVP Cure-All post.. cars of your vintage do not have/use OVP circuits , as they are not needed.
OVP technology is for Cars with Engine Controlled Mangement computers [ ECU] and systems........

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A Dalton

Sounds like you have old sparkplugs and/or leads causing weak and missing sparks. New leads, plugs and points is where I would start.

Bert

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'70 111 280SE/c 3.5 (4 spd manual) - sold
'63 MGB
'73 MGBGT V8

Well, there is a relay on the firewall on the passenger side. I was told that it was the OVP. What else could it be?

It's probably the relay that controls the timing's vacuum advance/retard. Figures out coolant temp and RPM and decides if timing can be retarded for better emissions.

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Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

So if that failed, how would I know?

Basically, I've changed the spark plugs, fuses, distributer rotor, air filter, cleaned the carbs, and it is helping but it still is stalling at traffic lights, and especially has problems after I get off the highway and slow down my RPM's...any ideas? thanks in advance.

The relay should retard the timing when the engine is warm and with RPM above (I think) 2500 or so.

If the relay failed, it might leave the timing advanced when it should be retarded, or vice-versa. So conceivably you could get a small loss of low-end power or a slightly rough idle if it was retarding incorrectly. But I don't think it would cause the engine to die.

You can eliminate this as a cause if you disconnect the retard side of the vacuum and plug it. Then set your timing to whatever the spec is.

Some other things to look at are

- the idle solenoids - do they click when you plug/unplug the wires with the ignition on?

- is the dashpot, instead of the idle stop, controlling the idle speed? If so, it may be "pulled in" too far after a high vacuum condition like a run on the freeway.

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Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

Thanks! I am changing the points and wires today!

If it's on the firewall, might be the voltage regulator.

It's not integral on the W114.

Jim

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14 E250 BlueTEC black. 45k miles
95 E320 Cabriolet Emerald green 66k miles
94 E320 Cabriolet Emerald green 152k miles
85 300TD 4 spd man, euro bumpers and lights, 15" Pentas dark blue 274k miles

Thank you Arthur!

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Regards

Warren

Currently 1965 220Sb, 2002 FORD Crown Vic Police Interceptor

Had 1965 220SEb, 1967 230S, 280SE 4.5, 300SE (W126), 420SEL

ENTER > = (HP RPN)

Not part of the in-crowd since 1952.