E30 M3 Relays

[ringmoor]

hello I am new to this Forum and having probs with relays changing numbers and finding replacements.
One is black - retarding relay original on 13901311772 and can’t find what else to use as this is discontinued.
Similarly for the DME relay and the orange relay which is a common relay in the car this ends 774
I have been told the white relay ending in 700 will work as a DME relay.
So everyone help please
David

[HenryM3]

Found this on the net
This post may belong in the NO-START, so my apologies. A few weeks ago my '91 M3 was dead. I hooked up the charger and immediately heard the culprit...a buzzing relay. Turns out to be the evap purge valve relay, PN 1390-1311-772. Found an old thread concerning the relay here, and just thought I would update it with info that I recieved from my BMW dealership, after a consult with the main service and tech people. PN 61361-388-911 relpaces PN 6131-1-373-916, which replaces PN 1390-1311-772.

[ringmoor]

Thanks but I know this is wrong as there is a later post in the same thread saying why
Also I tried one of the suggested relays and it is wrong but thanks for the post

[HenryM3]

I,ll check what the p/n is on my relay (dme) tomorrow and let you know. Mine is a white one. Don’t know what the retarding relay is for.

[HenryM3]

BB7C7D25-1074-4AC0-A2F3-08BF8ADCE8B7.jpeg

I’ve put some pictures up of my DME relay which doesn’t match any of your numbers, they are listed on eBay and cheap. The one on the left was bought years ago to try and solve a problem that was nothing to do with the relay, hence why I have the spare. You know the story, throw some new parts (money) at it instead of coming on here and getting advice from people with knowledge. What you do with this information is down to you

[ringmoor]

Thanks for all the effort
I actually have one of these from somewhere -cant remember- but i never throw anything- will go and try it !
Hopefully one problem solved.
I have also got 2 used of the orange coming from Ebay.
The problem left is that Retarding relay which is proving to be a pain cant find anything anywhere so far on replacement alternatives or used ones.Hopefully someone will have the answer.
Will let you know when i have changed out the DME in the car which i will do in an hour or so and if OK will get a couple more for the drawer as apparently its a common problem

[ringmoor]

well your efforts have resulted in SUCCESS ! Thank you -the car is now going-- so with ordering some more and fuel pump relay spares coming the world is a happier place in my little part of the world !
So one really to go
Thank again

[HenryM3]

Surely, if you have the old one they normally have a layout of the pins and how it operates. Can this not be used to find a similar operating relay. BMW probably stopped supplying not because they were special but because no one was willing to pay their inflated prices. It’s quite likely a standard 4pin relay.

[Brianmoooore]

I'd no idea what a retarding relay was, so I've done a little Google research. It appears to be a perfectly ordinary 12 volt, single pole, normally closed relay, apart from a capacitor wired across its coil to give a time delay on its release.
First of all, unless its 'potted', I suggest you open up the original relay and see what's happening inside. They are simple devices, and a simple cleaning of the contacts may bring it back to life. I'd advise checking out any capacitance value written on the capacitor, and possibly replacing it, as electrolytic capacitors deteriorate over time.
I don't know the part numbers of any BMW normally closed relays, but I'm sure they exist, and a change over relay, such as the blue one under the LH side of the dash, could be used at a push. The capacitor can be added to the underside of the socket externally. The pin position of any replacement relay needs to be carefully compared with the original, and the bucket connectors moved in the base to suit.
https://www.ilcats.ru/bmw-classic/?func ... anguage=en Looks like 3 is a direct replacement, but without the capacitor.

The DME relay you show is a simple 12 volt double pole normally open relay. The BMW supplied 'equivalent' is a blue-green colour, and is a direct replacement for M40 and late M20 engines, and although it will 'work' on early M20s, it does not work as intended, because the pins positions are different from the original. If used with an early M20, the buckets should be moved around the base to suit. The M3, while an iconic engine, is fairly primitive electrically, so possibly the same applies.
If the fuel pump relay is a four pin orange one, then it's just a simple 12 volt, single pole, normally open relay, the same as any of the other orange ones in the fusebox, except for the moldings on the case to engage with the retaining clips. This applies to the DME relay s well.

[ringmoor]

Thank you
The relay numbered 3 you refer to is a BMW motorbike relay no longer available hence it has no P/N on the car pares in the catalogue.. You can get it from Portugal and USA as a copy or original respectively but at a silly price.
So the plan is to firstly clean and check /clean the old one-- as you can open it and get the capacitor value .If it works good if not then get a normally closed 4 pin 20A same pin configuration and add a capacitor externally as you describe .This relay would seem to me to fit the bill ?
DURITE 0-727-02 12V 20A AMP 4 PIN NORMALLY CLOSED MINI RELAY

s-l500.jpg

You can also get this with the connector base with wires attached to plug in so to speak. £4-6 each
So hope i got it right !

[Brianmoooore]

That relay looks suitable, and assuming the diagram in the link I posted is correct, all you need to do is swap over the wires to 30 and 86 on the existing base. This will leave 85 an 86 swapped over, but as long as the relay contains no spike suppression diodes, that makes no difference.
On a single pole relay, it doesn't matter is 30 and 87 are swapped over either, but in this case they end up where they should.