OVP rebuild? - PeachParts Mercedes-Benz Forum

JamesDean · #1 11-14-2007, 02:27 PM

I was just wondering if anyone has ever attempted to rebuild their or actually has any picture of its internals..

Just curious.

kpb · #2 11-14-2007, 02:54 PM

I investigated this issue cuz I thought my OVP may have been wacky. A search should reveal that some have opened theirs up and resolder connections. I could not figure out how to open mine without destroying the casing.

If you do not find such threads here, I may have been on the MBCA site when I found some info.

lee polowczuk · #3 11-14-2007, 03:02 PM

i wouldn't mess with it, personally.

shingleback · #4 11-14-2007, 05:53 PM

I just did mine today; remove the fuse, bend back the 2 tabs at the bottom (by the pins) and slide the relay assy out of the housing. Remove the cardboard cover to reveal the printed circuit board, solder side. Clean the board (you will probably see loads of contamination here; I used a small bronze brush). Resolder all the connections to 'fix' any cold solder joints. Assemble in reverse order.

sbourg · #5 11-14-2007, 09:30 PM

I couldn't get ours to come apart, so I installed a new one. That solved the problem - for about 2 months, and the problem started up again. At this point, I tried harder, and got the old one to come apart. The solder joints to the board all had hairline fractures. I removed the solder, added wire bridges from pads to pins, then resoldered. That one is still working fine after several years. I then took apart the 'new' one, found the same problem, so same repair. So, now I have a good spare too.

Steve

shingleback · #6 11-15-2007, 02:21 PM

Quote:

Originally Posted by sbourg

I couldn't get ours to come apart, so I installed a new one. That solved the problem - for about 2 months, and the problem started up again. At this point, I tried harder, and got the old one to come apart. The solder joints to the board all had hairline fractures. I removed the solder, added wire bridges from pads to pins, then resoldered. That one is still working fine after several years. I then took apart the 'new' one, found the same problem, so same repair. So, now I have a good spare too.

Steve

Hey Steve: putting a wire bridge is a great idea, thanks. My relay is still in my pocket today (a spare I got from a junkyard), so I will do the same before putting it in the car. Then I will give the other one the same treatment and put in on the shelf with other spare parts. Thanks for sharing.

sbourg · #7 11-15-2007, 03:36 PM

As a circuit designer and prototyper I found the kind of poor mechanical design incorporated in this relay is unfortunately common, so I had need to devise a rework that would hold up to normal mechanical stresses. The pity is that such design errors were never corrected at the factory - the replacement OVP's still are a faulty design.

Steve

JamesDean · #8 11-15-2007, 05:22 PM

im starting to think that maybe that's what happened to me a few days ago..

i was driving, braked at a stop light..and the engine idle sunk and it stalled out..started back up..

did it again few miles later but was a PITA to start back up..

I took it to the shop that day, everything worked fine, left it there over night, everything worked fine cold the next morning.

I suspect a cold solder-ish problem on the OVP. I might pull it this weekend and look at its internals. Hopefully I dont break it. Thats my only fear when it comes to pulling this thing and trying to "fix" it.

That's why I was looking for pictures to see just whats inside there, If I do take it out and open it, I'll take some high resolution pics for everyone.

ejsharp · #9 11-16-2007, 12:14 AM

James... your situation sounds like bad solder (cracks) on your fuel relay. Circular hairline cracks cause it to shut down depending on temperature and G forces. To fix redo solder on back of board behind the heavier items mounted to the board.

JamesDean · #10 11-16-2007, 01:32 AM

Quote:

Originally Posted by ejsharp

James... your situation sounds like bad solder (cracks) on your fuel relay. Circular hairline cracks cause it to shut down depending on temperature and G forces. To fix redo solder on back of board behind the heavier items mounted to the board.

original thread...
http://www.peachparts.com/shopforum/showthread.php?p=1674379

ds190 · #11 11-16-2007, 11:44 AM

I just replaced the OVP in my 300TE. I opened it up for fun, and it had about a .25 inch layer of wet crud on the inside bottom that was like toothpaste. The design of that OVP, even with that seal around the cover over the fuses, allows moisture and dust to get in and corrode everything.

I had another one that went bad years ago, and here it is opened up. Corrosion around the inner connections, and the board clearly blew out somehow. I opened the case around the relays, and as it is completed sealed, the relays themselves look great with no environmental damage.

I am tempted to take silicon and seal the fuse cover shut, to prevent moisture and dust getting (but easy to open if fuse blows).

wbain5280 · #12 11-19-2007, 11:53 AM

Just jump the stupid thing. Its only function is to protect the ECU and ABS box in case someone hooks the jumper cables backwayds, and how often do WE let that happen?