What!? You sayin’ I can’t sweat copper pipes that don’t leak?

Okay, I’ll start designing a digital retrofit. Best would be a Switec X27 motor mounted in place of the original bourdon tube. Standard electric transducer. Microcontroller and stepper electronics to linearize the sender output and drive the needle according to the OE (backwards) scale. I think I can hack this together.

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79 300TD “Old Smokey” AKA “The Mistake” (SOLD)
82 240D stick shift 335k miles (SOLD)
82 300SD 300k miles
85 300D Turbodiesel 170k miles
97 C280 147k miles

There is an underlying reason for the leak. Metal fatigue. Coating it with solder does not fix that. Which is why I personally would not expect it to be a permeant fix.

Or you could just buy a digital oil pressure gauge and sending unit and find a way to fit it to the oil filter housing.

The Engines on the SD's of the same years use a different plate on the rear bottom of the same oil filter housing and use an Eletric sending unit. However, I don't know other gauges the sending unit can be used on.

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84 300D, 82 Volvo 244Gl Diesel

Permanent fix? What a dumb proposition. No fix is permanent, this is what a mechanic is for. How permanent is permanent? The copper pipe ( sweat joints ) in your home also will fail due to whatever reasons. Personally I would not re-sweat all of them as a preventative measure.

I found JB weld very effective. You remove the gauge from the dash, clean it up and reattach to the line, start the engine without the dash and you can pin point the exact leak. Clean it up real good, roughen up the area and apply the glue. Retest when dry, it gives you 100% confidence that the leak is fixed.

JB weld is rated at 2500+ psi. It will fix a pinhole leak with no issues. Personally it is less messy, less chance to go wrong and as good, if not better than resoldering it. Good luck.

BTW: I have used JB weld to repair evaporator of my 190D. The part is no longer available. I cut off the leaky tube, inserted new tube and JB weld it. Evaporator is running at 250psi in liquid form, much higher than oil pressure. I pressure tested the fix with compress air, dipped into a big trash can with water. It was 2 years ago and it is as good as new.

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Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry.