W123 oil pressure gauge to W124 electric gauge. - PeachParts Mercedes-Benz Forum

ah-kay · #1 11-16-2018, 03:00 AM

My W123 oil pressure gauge is leaking. Any one has done a conversion to the W124/W126 pressure gauge which is not mechanical. I want to rid of oil leak once and for all. I have a spare sender and a W126 dash I can hack.

if6was9 · #2 11-16-2018, 07:18 AM

If you can make the connections it should be doable. As I recall the electronic sender is a M10 X 1.0 with an aluminum seal ring at oil filter canister housing. The analog system the connection is a plastic pipe with some sort of compression seal to a threaded boss on the canister.

So you might find another place to connect to live oil pressure, maybe the top of the oil filter canister can be drilled and tapped for the electronic sender. This would allow you to get it rigged up and operational before making anything permanent and if you get hold of a spare canister cover you can quickly and easily go back to the original configuration if you ever want that. You'll have to come up with a way to seal shut the analog pressure port if you don't use that as your access to live oil pressure. Or maybe you could fabricate a an adapter with the pipe connector on one side and maybe a block of brass modified to accept the electronic sender.

I don't have any oil filter canisters in front of me but is there someplace in the cast structure on the rearward side where a cover plate of sorts with the attaching point be unbolted and swapped out for a cover plate from an electronic gauge installation?

Of course you'll need a cluster gauge that is capable of reading the electronic sender signal and is interchangeable with the analog gauge.

t walgamuth · #3 11-16-2018, 07:29 AM

Are you sure it is not just a hose leak? Those mechanical gauges are among the most rugged reliable devices on the car. If you need one I'm pretty sure they are easy to find. I probably have 2 or 3 of them lying about.

ah-kay · #4 11-16-2018, 11:40 AM

Quote:

Originally Posted by t walgamuth

Are you sure it is not just a hose leak? Those mechanical gauges are among the most rugged reliable devices on the car. If you need one I'm pretty sure they are easy to find. I probably have 2 or 3 of them lying about.

The analog mechanical gauge is very prone to leak, albeit very slowly. I may consider your offer.

moon161 · #5 11-16-2018, 11:44 AM

The connection of the oil pressure line to the filter is an easy one to break, take your time or have a spare handy.

sixto · #6 11-16-2018, 04:21 PM

A painful option is to swap in the oil filter canister from a 126 SD. Something to consider if your canister and/or oil cooler lines are weeping.

Sixto
98 E320s sedan and wagon
02 C320 wagon

ah-kay · #7 11-16-2018, 04:47 PM

Nothing is weeping, line or the canister assembly, only the damn gauge in the dash. I am looking at my options, fixing it or changing to electronic like the w124. I made a fixture to pressurize it with compress air and found the leak. I may try to resolder it and check it out. I have all the parts to do a conversion but it is a lot of work and try and error. We will see.

JHZR2 · #8 11-16-2018, 06:44 PM

Ive often wondered how much more of a liability the line and gauge will be as these cars age.

Diesel911 · #9 11-16-2018, 10:16 PM

Might be some info here: http://www.peachparts.com/shopforum/diesel-discussion/213681-w126-oil-filter-housing-w123-housing.html
There is a picture of the 2 Oil Filter Housings in one pic and the one on the left is the W123 housing.

moon161 · #10 11-16-2018, 10:38 PM

I'd rather put a new guage in than mess with the connection at the cannister filter. I've got a spare cluster or two in the garage. I think I'd have things apart and back together in a couple few hours, and I'd have justified keeping a pile of crap in the garage, at least to myself.

ah-kay · #11 11-16-2018, 11:09 PM

Well, I soldered the leak but I torched up the spring when I used the blow torch. The leak was fixed but the needle spring is deformed. It still works ok but I may not reused it.

I also found another gauge in my junk bin. I pressurized the gauge to 100 psi and I see no bubbles when immersed in water. So I think it is good to go. I am going to drive the car with the gauge exposed to check for leak.

Diesel911 · #12 11-17-2018, 12:38 PM

You can solder it but the gauge cracked because of metal fatigue. 30+ years of flexing.

It would crack again.

Diesel911 · #13 11-17-2018, 02:47 PM

Since someone else is going to look at this thread because of the title I thought I would post the thread size of the electric sending unit. M12X1.5

The info came from this site Oil Pressure Sensor For Benz(01039), OEMNO:0065429417/0055421817, Application:Mercedes-benz
A Chinese manufacturer of the electric oil pressure sending unit.

When I get home I have a new W123 Oil Pressure line I never installed and I can get the threads on that.

However, even if the Threads on the W123 Oil Filter matched the Electric Sending unit the location of the port is such that there is likely not enough room for the fat diameter of the Electric Sending Unit.

I attached a picture of the end of the W123 Oil Pressure Gauge line that screws into the Oil Filter. The Center part remains stationary and the thread par rotates around it.

Diesel911 · #14 11-17-2018, 03:11 PM

http://www.peachparts.com/shopforum/diesel-discussion/363905-oil-pressure-line-leak.html

Post number #5 has a pick of the oil filter end Oil Pressure Gauge Line metal fittings removed form the plastic tubing.

Diesel911 · #15 11-17-2018, 03:56 PM

OK the threads on the Oil Filter end of the W123 (on the 5 cylinder engine) Oil Pressure Gauge Line is also M12X1.5mm