[bricktron]

hi all, my mechanic (finished the swap, now doing loose ends) told me that the '85 filter housing has an electrical oil pressure sender instead of the classic tube. i am really excited not to have the engine oil coming into the passenger compartment after reading several horror stories about cluster repair. however, i have the wrong kind of cluster gauge unit, with the old style of gauge.

what models had an electrical oil pressure sender/gauge?

while researching this, i found this photo of a gauge unit with an "economy" meter at the bottom:

this is from a late 280e, i'm guessing?

 

[Euro W123]

All w123 oil pressure gauges are mechanical unless someone modified it. The cluster in the picture is from a 9/82 up Japanese market 200 or 230e.

 

[frans-c]

Can't help with the electrical gauge, but I can tell that my '85 230E still had the mechanical oil pressure gauge.

On the instrument cluster: that belongs to a 230E - redline is at 6000 rpm and maximum indicated speed 200 km/h. 280E is 6500 rpm and 220 km/h respectively. It could also belong to a 200 carb. First time I've seen the orange-only numbers, though.

 

[300Dman]

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[yzn]

i was thinking the same thing since the engine i swapped use electric one.
Can w124 gauge be used??

 

[chasarms]

Having just disassembled mine yesterday to deal with the dead odometer issue, I can certainly say that my U.S. '85 300D has the oil tube running to the oil pressure unit. It's not electrically actuated.

 

[Stretch]

Perhaps there's confusion with the electric speedo?

It could also be a W126 thing - those SDs are cutting edge!

 

[bricktron]

very interesting, guys. I see two possibilities - either the 85 Cali setup is different,or else we are (accidentally) using a 126 oil filter housing. thanks folks!

 

[DeliveryValve]

The only way to get a 617 oil filter housing with an electronic oil pressure gauge is to get it from a w126 300sd.

The simple solution is to swap housings. The hard solution is to adapt the w126 gauge guts to the w123 gauge face plate.


.

 

[mach4]

very interesting, guys. I see two possibilities - either the 85 Cali setup is different,or else we are (accidentally) using a 126 oil filter housing. thanks folks!

'85 Cali is mechanical

The 126 filter housing uses electrical - I've replaced the standard one on my engine with the 126 filter to clear the steering gear.

 

[Stretch]

I knew it!

S - class - class!

 

[bricktron]

thanks all, that was very helpful. paul, I can't see the wire in your photo, so did you adapt the gauge, or roll with no pressure gauge?

I am interested in the gauge swap. has anyone tried retrofitting 126, or 124, gauge guts into a 123 cluster? please let me know if you have one on hand to sell me; I'd take a look at this before acquiescing to use the stupid oil line into the cabin.

cheers!
aaron.

 

[Stretch]

Well here's my steep learning curve for a W126 tachometer

Help identifying diesel tachometer req'd - want to fit it to my car! - PeachParts Mercedes ShopForum

Basically (from what I can see) if you were stubborn you could probably get it to fit but it is a whole load of work...

 

[mach4]

thanks all, that was very helpful. paul, I can't see the wire in your photo, so did you adapt the gauge, or roll with no pressure gauge?

I am interested in the gauge swap. has anyone tried retrofitting 126, or 124, gauge guts into a 123 cluster? please let me know if you have one on hand to sell me; I'd take a look at this before acquiescing to use the stupid oil line into the cabin.

My situation is a bit different than what you are facing. My 617 was swapped into a 380SL which comes with an electronic oil pressure gauge. The mounting for the electronic tach, oil pressure, temp and fuel are all interchangable (and I believe that the movements are the same as well), although they are all different based on the components around them (and the tach circuit board for that gauge). Also had to epoxy the gauge face from the 123 tach on the 107 faceplate to provide the proper calibration.

I took a cursory look at the manual oil pressure gauge in the 123 donor car, and it appears to be different such that it wouldn't take an electronic gauge internally without some modification. If I get a chance later, I'll open it up to make a better assessment.

Even if it won't screw right in, it might be possible to take an electronic oil pressure movement and adapt it to the back plate by drilling some holes. The spacing is probably pretty close and shimming might make up any difference.

 

[mach4]

I just went out and opened up the cluster, and from everything I can see, the manual oil pressure gauge has the same mounting arrangement as the electronic one. It should screw right in. You can test this theory by opening up yours, removing the manual movement and swapping the fuel movement into the oil position. Like I say, it should just screw right in. The tricky part is going to be hooking up the wires from the sender. On the clusters with electronic gauges, the signal comes in through the round connector and brings the signal to the gauge through the PCB back plate. You'll need to solder leads to the connectors and bring the wiring from the sender separately. Check the wiring diagram for more information. Assuming that everything fits and you can figure out the wiring, just grab an electronic pressure movement from a 126 or a later 107 and you're good to go. You might need to drill some holes in the back plane for the wires and to provide clearance and you might need to rig up something for the bolt to attach to.

I attached an image showing the movements for temp, fuel and oil. You can clearly see that the movement itself seems to be the same, but the coil and other components are different and in different locations.

Good luck!

 

[PlaneCrazy]

Excellent news! I suspected as much.

 

[bricktron]

hey very helpful! thanks for all the details. time to get the other gauge....

 

[DeliveryValve]

I got a w126 gauge to part with and extra w123 gauge to mess up . Pm me if interested.


.

 

[bricktron]

really informative post, paul, thank you for checking for me. it is admirable that the same movement would be used several times over and a good hint that the electrical unit could be fit in there too. i am confident about wiring it too.

is that a blue coil which is in a different spot on the rearmost movement?

anyone know what the signals look like on a scope? is it a DC fraction of some base voltage?

 

[PlaneCrazy]

From what I've learned on this thread, the fuel gauge uses 5VDC as a reference, with a DC voltage signal. From what I've learned about "electricks", the same components can use an assortment of signals for different purposes...