OVP Rattle is this bad or a myth?
 

Hi guys, i hav an 1989 300TE with a rumbling idle. I pulled my OVP tonight and it appears to be a newer model with red top and 2 fuses. Fuses are fine but i noticed a rattle when i shook it which alarmed me a tad. I have searched high and low and it would seem to indicate a faulty OVP but i have also read that this symptom isn't necessarilly a fault and a bit of a myth. Admittedly i thought a rattle = bad. I can't imagine the relays in this are that sloppy that they would open and close when you shake it lightly. Can anyone shed some light on this?

Nope but others here can.

One thing I can say though is that the 2 fuse relay should only be used on the 90 and later cars. Your 89 should only have the 1 fuse relay.
Regards, Eric

not a myth.....at least in my experience..... all of our 124's have a spare in the trunk...

so the OVP should rattle when shaken?

This runs counter to all the advice I've ever read and heard on the subject. In fact, my 1988 was specifically "upgraded" to the 9-pin, 2-fuse version by my long-time MBz mechanic many years ago.

Ned, a few years ago my parents' 1995 E320 started running poorly and the OVP relay buzzed ... probably due to weak solder connections. Replacing the OVP relay resolved the problem.

no...should be rattle free

cool, mine definately rattles so hopefully i am heading down the right path in fixing this dicky idle. I am running out of things to replace to rectify this as well as money. I have replaced, 2 new fuel pumps, injectors, dist cap+ rotor, alternator, recond head and guides etc. I have only owned it 6 months and it des have a elatively new battery, perhaps the old one died and someone jump started it and blew the OVP?

What are others opinions on this? Meaning no slight here but I'd be interested to hear more opinions.

On this thread: http://www.peachparts.com/shopforum/tech-help/268191-m-103-too-many-issues-title.html at post number 10, GSXR, who we all know is one of the sharpest guys around, said this: "Early OVP's have one fuse, later OVP's are a different design and have two fuses. They are NOT interchangeable."
Regards, Eric

Hmmmm..... Not Interchangeable. Where did he get this info? Considering that a dealership specifically sold me a two fuse version specifically mentioning that M.B. had updated the OVP and FPR over the series of cars that they were used in and that the latest version of each is the proper unit to use.
My car works perfectly fine with either version - one or two fuse.

You're down under...... everything is different down there lol.... just kidding. :D:P

I dunno. But I do know that GSXR is the man.:cool: Hopefully he will weigh in here.
Regards, Eric

The early & late OVP's have totally different pinouts. They are NOT interchangeable, period. I believe the early style was used through model year 1987 in the USA, and the late style was used starting with model year 1988, but I'm not sure if that applies to all models of W124.


Early, p/n 201-540-08-45:
http://img.eautopartscatalog.com/hir...300&height=300

Late, p/n 201-540-37-45:
http://img.eautopartscatalog.com/hir...300&height=300


:scholar:

My 89 uses the early style so the changeover year must have been 90 which makes sense cause a lot of changes occurred in 90.

Edit: Well this is weird. I went out and checked and I have a relay on the 89 that looks like the top of the older one complete with only one fuse but looks like the bottom of the newer one but with only 7 pins instead of nine! Maybe there was a third "in between" one? Part number on this one: 201 540 32 45! It looks like my 89 could accommodate the 9 pin one but those last 2 pins wouldn't be going anywhere as the sockets are empty. Sorry, not gonna check the bottom of the 88's OVP cause as some of you know, I had an issue some time back with keeping one of the sockets from recessing. I don't even want to lightly disturb that area! It's definitely a one fuse style one too though.
Regards, Eric

I have 1988 300se--2 fuse OVP.

The EPC indicates that -08-45 was used on the .030 chassis through model year 1987. From 88-up, it was originally -32-45, which superceded to -30-45, then -38-45, and finally -37-45.

What I think happened is that all 88-up models use the late 9-pin socket, but early versions (maybe 88-89?) only used some of those sockets, and only needed one fuse. Later versions used all 9 pins with two fuses, adding another circuit. The 2-fuse relay is backwards compatible with the 1-fuse, as long as it's from 88-up with the same pin layout. You still cannot use the 88+ OVP in an 86-87 car.

Bottom line - not all single-fuse OVP's have the same layout! Interesting - I didn't know that. Thanks for the info, Eric!


:stuart:

i have a 32 45 spare... it has 7 pins and one 10a fuse.... the 38 45 i have is identical.

the 37 45 spare has 9 pins and two fuses....

Note that not only the number of pins is important, but also the layout of the pins. The early OVP will not plug into the late socket, or vice-versa, regardless of pin quantity.

:1eye:

Is the single fuse version still available ?

I would think so since Dave got those pics from an auto parts web site. Plus there are still plenty of MBs that use them. I'm too cheap though, I've been nabbing mine from the JYs.
Regards, Eric

engine died on my wife..... intermittent.... replaced fuel pump relay... seemed fine....

then the problem again last night...

pulled the double fuse ovp.... fuses ok..... rattled..

replaced ovp.... we'll see today...

I am running out of spares!!! this is for the 89 coupe..


several years ago...she had the ovp go out on a different 89 couple... go figure.

Based on the frequency of OVP problems reported, it does seem to be a design weakness. I'm told that the location of the OVP on the firewall directly under the windshield makes it highly susceptible to moisture and corrosion.

same problem happened today with a new ovp.... i still think its an ovp issue...[B]here's why.... i pulled the new ovp and got the car to start up.[/

i think i have one more ovp and two fuel pump relays

fortunately these parts are spares.... it will cost me real money if i have to replace the fuel pumps

I'll second that on the location. That was my thinking when I just very recently replaced mine, but off the cuff, I couldn't come up with a better place! Although mine is a 190 & lots less space for sure.

my 300se 1989 .It is fitted with a single fuse OVP.

Occasionally a jump start blows the solder junction of the zener diode leaving the top fuse intact. i was able to resolder mine back .
mak