Can a Non-DIY'er Replace the OVP?
 

Help!
After several hundred $$$ in "guesswork" I am at my wits end. I have been experiencing the same problem several members have with my '93 300E 2.8. Surging idle of RPM and oil pressure guage. My car will loose pressure then cut off. All the dash lights come on. If I'm able to restart it that's when the surging idle begins (and continue). After looking through the archives it seems like the OVP should be replaced. My question is: Can a non- DIY'er like me replace it and if so what type of instructions are available? Thanks in advance for your help.

Give it a try!
 

Ignition OFF.

Nothing could be easier. On my 107 Euro it is located just over the right passenger kick panel above the fuse box. Pull the OVP and it comes right out. Push a new one in. The hardest part is removing the interior panels. You might have to lie on your back in the passenger foot well. Anyone can do it.

Steve
'85 500SL Euro.

Umm on your car the OVP relay is located behind the black plastic panel behind the battery. It usually has a red top. You should check the fuse(s) on top of the relay first before you replace it.

The OVP resides in a different location for the W124 series (wish it were THAT simple, though).

If the 2.8L underhood layout is similar to my 3.2L, then the OVP is actually located behind a black plastic shroud behind the battery. Push the top of the shroud down below the firewall lip and remove completely. The OVP is silver and has a clear top with a 10 or 20 amp fuse. It is bolted down on one side, so you will have to remove the nut before you can pull the relay off.

I disconnected and removed the battery for easier access. Total installation time: 15 minutes, including reinstalling the battery.

The part can be obtained for around $65 at FastLane. Not sure that the OVP is the cure (I had a different set of problems), but I hope it works for you.

Wire harness?
 

Didn't that year model have problems with the wire harness? I would look into it, if your OVP turn out to be OK. Also do a search on the fuel pump relay.
Just some friendly advice...

Forgot about that. MB will replace it free of charge under the goodwill program if the car has less than 100K on it. Mine was replaced way back when I had some acceleration/performance problems.

BTW, I am still fumbling with an idle surge problem. The OVP solved my "hot start" issue. You may or may not have success in that area.

why don't you to have someone you trust diagnose
the problem? it will save you time and money!
cheers!!

I had not yet considered the wire harness. I do have the car at my local MB dealer being diagnosed. The serviceman all but guaranteed me the problem was the OVP (even before I suggested it). He said if he took it off and it read "Austria" on it that he was 95% sure that was probably the problem. Were Austrian-made OVPs bad? Does this sound right? Thanks for all the great advice!!

He's right about the OVP

I had a tech look at it and he indicated the wire harness is frayed. My car has 117,800 miles on it. Can I still get MB to repair it free under the goodwill program?

recent consensus here seems to be that MB has tightened up on free (good will) replacements of the wiring harness (especially on vehicles over 100k miles)

you may wish to pose this question to your MB dealer, and MBUSA and obtain guidance for your particular situation

let us know what turns out and good luck
-fad

give it a shot. you wouldn't lose anything. nothing is
cut in stone. it would be an opportunity for the dealership
to gain your business, and for you a new resource of sales
and service. good luck!

But...
 

What about the OVP? Did you replace it? Did it fix your problem?

I did replace the OVP. Seemed to ride ok for about a month. Recently, the same problem reoccured; idle dropped then surged and eventually cut off.