W108 Relays

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Haris
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Model you own: w108
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Location: UK

W108 Relays

Post by Haris » Tue 11 Jun, 2019 4:10 am

Hi,

I wanted to refresh/service all the relays in the engine bay to make sure they going to be reliable going forward.

The auto electrician is intending to charge £24 for each relay to give them a once over.

Are there any suitable modern relays that can be adapted instead?

Original part no 0332008001

Thanks in advance!

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John Green
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Re: W108 Relays

Post by John Green » Tue 11 Jun, 2019 1:04 pm

Apart from cleaning up the contact points there isn't much that can be done to "service" these. They are plenty of new modern relays, but your challenge will be to find ones that share the same pin pattern for the plug. Not to mention they will be made in the PRC, so in the long term the old ones will most likely be more reliable.
M.B Spares & Service 14-16 Lyell St, Fyshwick ACT. Ph 02 6239 1099

http://mbspares.com.au - Supporting Australia's Mercedes-Benz Enthusiasts.

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John Green
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Re: W108 Relays

Post by John Green » Tue 11 Jun, 2019 1:05 pm

Hang on, this sounds like you are in the UK? (fill in your location on your user control panel) This does possibly change the story with corrosion being an issue we don't have here in Oz.
M.B Spares & Service 14-16 Lyell St, Fyshwick ACT. Ph 02 6239 1099

http://mbspares.com.au - Supporting Australia's Mercedes-Benz Enthusiasts.

Haris
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Posts: 17
Joined: Mon 05 Jan, 2015 5:28 am
Model you own: w108
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Location: UK

Re: W108 Relays

Post by Haris » Tue 11 Jun, 2019 6:05 pm

Hi,

Yup I am in the UK.

Car is from California though so has been dry most of its life!

I was hoping I could use a modern relay and adapt the pin pattern if needed. I'd simply use the original metal housing but have a modern relay inside.

I have a laser cutter so I reckon I could create new plastic casing for the bottom bit.

It looks like a very simple 4 pin relay that cost almost nothing these days, just wanted to make sure of any specs I should be aware of when picking a modern equivalent.

Thanks,

Haris

CraigB
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Re: W108 Relays

Post by CraigB » Tue 11 Jun, 2019 7:32 pm

It would mainly be the amperage they can carry and matching that. Mind you, I can only remember replacing one relay out of all my Benz's (on a W126), but have certainly replaced the cheaper plastic units on other cars......you might be replacing very robust, 'made like no other car' units with something lesser but newer. Inside its just the contacts and the winding to go wrong.... haven't had one apart but if they have big and nicely hardened contacts and good solid winding.... The one i just replace on my 2002 Peugeot 406, for the a/c comp clutch, was all swollen around the winding and the tiny contact welded together..... others for lights say on my Landy the contact had burnt away...... just thinking out loud!
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Haris
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Re: W108 Relays

Post by Haris » Tue 11 Jun, 2019 10:29 pm

Sounds like I might be better off testing and opening them myself to clean with some electrical contact cleaner.

Maybe just buy a spare to keep in the car. I think I'm just being paranoid as my friend wants to use the car for his wedding and the last thing I need is for it to break down.

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Bartman4800
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Re: W108 Relays

Post by Bartman4800 » Wed 12 Jun, 2019 11:24 am

Lucky for you, there are no relays that stop the engine from running (except the starter solenoid)

If you want to improve the reliability, think about changing the ignition to a "123 ignition system" (not W123), as well as a fresh coil.

https://www.123ignitionshop.com/gb/22-mercedes

Breaker points are know to corrode, and capacitors are known to give up without usage.


Bart
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Haris
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Re: W108 Relays

Post by Haris » Wed 12 Jun, 2019 4:26 pm

Thanks everyone for the advice

That's already sorted, I bought an aftermarket electronic ignition kit.

It now has a rebuilt starter motor
Rebuilt alternator
New alternator regulator
New warm up device thermostat - most recent thing to go wrong!
Valve clearances have been adjusted
New thermostat
It has fresh fluids apart from brake fluid which is left on my list

The rest of my list is aesthetic bits to tidy up.

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