'88 300SEL stalled when started to stop on the road... also ABS question. - PeachParts Mercedes-Benz Forum

86560SEL · #1 05-05-2018, 10:51 AM

Hi all,

Still have my old trusty '88 300SEL that has been mine for about 11 years now. It was my moms car for about 4 years, but she has since bought a new car and gave the MB back to me. I have several cars, so this one does not get driven much, but the other day (Tuesday) I was going to take it to get an alignment. Started up fine, ran smooth as usual. I drove on the highway about 6 miles, then when I got into town, a car in front of me stopped to turn. I applied the brakes and just before I got stopped, the car stalled on me with no warning and all of the dash light came on. The car started right back up with no issues, but I didn't want to go in into town, so I headed on back home, ran fine even when I had to make stops back home. Now this isn't the first time we have had stalling issues with this car, in the past it did this, but had been awhile, then a couple of years ago we had the issue where it would stall with no warning and all would go black and it would take it awhile to start back, if at all and had to be towed. We had since had the battery and alternator replaced and that seemed to take care of that issue.

I have read about the OVP relay on these numerous times (about how this COULD be the issue), but for the life of me, I cannot find out exactly where it is located on this car. If I knew, I would replace it and go from there. Can ANYONE tell me exactly where the OVP relay is on a 1988 Mercedes 300SEL? A photo would be awesome.

Any other advice/info appreciated. I am selling a couple of other vehicles as I have way too many, but really want to keep this car and make it my run around town on the weekends car.

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Also, my ABS light is on and sometimes when coming to a stop, the ABS will activate even on dry roads. I have not been able to find anyone that can read codes (if that is even possible on a car this old) to tell me what the exact issue is), but would like to get it fixed obviously. I have driven cars with years without ABS (and still own 3 older cars that were not even optioned with ABS), so if I could even disconnect the system, I could safely drive it like a car with non-abs brakes, which I think is safer than the ABS activating for no reason, even on dry roads with light braking.

Any advice on any of this greatly appreciated. It is an older MB and it has been a very good car for us over the years, but starting to need some attention and not easy to find a mechanic around here that will work on older Mercedes, so trying to do what I can on my own so I can start driving this car again and not let it set and ruin.

Jorn · #2 05-05-2018, 02:47 PM

It's at the firewall, the top is red and you can see the 2 replaceable fuses.

https://www.google.com/search?q=Mercedes+M103+OVP+relay&num=20&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiPsK3Kne_aAhXszFQKHdYkDrMQ_AUICygC&biw=1645&bih=1200#imgrc=FDtQZaKvZJGDYM:

Sugar Bear · #3 05-05-2018, 04:46 PM

Stalling as described can be a sticky/slow to close EGR valve causing a temporary large vacuum leak when backing off the throttle.

ABS light, yes try an OVP relay.

Good luck!!!

86560SEL · #4 05-07-2018, 09:40 PM

Thanks for the replies!

Will try replacing the OVP relay and see what happens with the ABS light/stalling.

I will do some research on the EGR valve to see where it is located on these. Shew they are not cheap are they? lol.

86560SEL · #5 05-10-2018, 11:49 PM

Hmm... I do not see one with a red top on mine. I snapped this pic of mine this evening... is this it?

Sugar Bear · #6 05-10-2018, 11:55 PM

Yep!!!

Hit Man X · #7 05-11-2018, 12:22 PM

All OVPs I have seen use a 10A fuse.

Early M103 had no EGR, nor AIR. Well, at least Federal cars. No idea about CA ones.

My now dead 1989 300E would stall often like that. New fuel pump relay fixed that.

I much prefer the 88/89 300SE/L due to the easier electronics.