1992 Merc 230CE - FrankSm
Hi folks

My '92 W124 coupe has started to suffer a rattle/groan from the engine area when idling and when the steering is turned. I'm guessing the PS pump is expiring.(will do some work with a stethoscope to make sure it's not the waterpump or alternator). The PS resevoir is up to the "full" mark, has never leaked or anything - although the fluid itself is rather murky (and not the pink/red colour you would expect to see).

Can anyone tell me what fluid the Benz takes ? Most other cars take auto-trans-fluid, but I'm not sure about the Merc. I'm going to bleed the old fluid out and try some new fluid before opting for a new pump.



Frank Smyth
\'95 Vauxhall Omega CDX 2.5TD
\'96 Mazda MX5 1.8 turbo
1992 Merc 230CE - Aprilia
Ideally you should use MB's OEM PS fluid - available from their dealers for about £7 a pint! Its a light golden colour. You may find ECP also stock an equivalent under the 'Febi' brand. Some people use Dexron II/III with no obvious ill effects.
If its the Vickers pump (cast alloy all-in-one with reservoir) then you'll find that there's a filter in the bottom. Undo the little nut that hold the white plastic tube in the midddle, lift of the tube & spring and then hook out the filter with a piece of wire. Remove all the old fluid (well, as much as you can) before removing the filter. Filters are under £5 from ECP (well, they were last time I bought one, might have gone up).
1992 Merc 230CE - FrankSm
Thanks Aprilia ! I'll have a look for that filter. I can't see the part# on ECP's site, nor on KMSparts. Interestingly, neither site lists a specific fluid/oil for power-steering on the Merc... I don't think I have anything to loose by using Dexron II at this point.
1992 Merc 230CE - Aprilia
If its a 'good' car then personally I would stick with the correct MB or Febi oil. Dex II might be a little agressive for 15-year old seals. Make sure you get the correct Febi oil - on later cars MB went to rack and pinion steering and specified a Pentosin (green) PS fluid.
That filter is definitely in there - it lies flat on the bottom and is not obvious. ECP or GSF should stock them - they are made by both Hengst and Mann and well as of course MB OE branded.
1992 Merc 230CE - FrankSm
Will do - the car is definitely a keeper.

However... just went out to it there now for a drive, and did two things I have ingrained in my head never to do:

1. with engine on turn the steering wheel to the left and to the right (not nice for the steering nor the tyres). The goaning/creaking is still there.

2. coasting along at about 10mph, switch off engine; turn the steering left and right. With the engine off the steering still creaks

That makes me think it's not the pump (since engine is off) and therefore must be steering rack/box or track-rods, or other suspension parts.

Think I need a second person to help with the diagnosis while I'm under the car with it on axlestands ! Another job for The Wife :-)
1992 Merc 230CE - Aprilia
A favourite for creaking on the W201, W124 etc is the idler arm bushing. This is located on the passenger side firewall. A new bushing kit is around £15-20 IIRC, and easy to fit. Don't overtighten the bolt otherwise it will creak again after a few months.
There are other things too - tie rods and steering damper spring to mind. If steering damper is original then relaplace it anyway - well worth the money.

Ask Honest John

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