Does anyone know of an "upgraded" M103 belt tensioner that is a bolt-on using a steel torsion spring rather than the Mickey Mouse "rubber donut".

Elastomers like rubber exhibit a phenomenon called "creep" if under load for a long period causing them to "relax," and if unloaded will not return to their original shape. For this reason only a moron would use rubber as a tensioning device.

Most metals like iron (and its steel alloys) and aluminum alloys have insignificant creep characteristics if loaded below their yield limits. That's why the Brooklyn Bridge is still standing. If it was made of rubber its would have collapsed at least a hundred or more years ago.

Duke

There is no "upgraded" tensioner for the M103 nor will there ever be one unless you are able to build one yourself. I thought about it when I took the one I had apart, but then I just scrapped the idea. The sad reality is that we are the last of a dying breed. I don't know of anyone that was born in 2000 or after that would bother with half the stuff anyone on this forum does. I was at a gas station about 6 months ago with a coolant leak and asked the guy (maybe in his mid 20s) if he could turn on the water. He had zero idea that the air machine also has a water feature nor did he understand why I would put water in my car. He also asked several of the other workers and one girl said she didn't know and thought it was "weird" that a car needed water. Funny thing is, I'm probably not even old enough to be their parents (well some of them I could be) and they all had ZERO idea! Interesting enough I see articles like the one I attached of a 2014 Tesla reaching 1.2 million miles after going through 14 motors and 3 battery packs and seems like everyone is amazed lol. And Here I am in my W201 with 580,000 miles and only 1 engine upgrade to the 3.0L at 531,000 miles.

Attached Thumbnails

 

__________________

1990 190E 3.0L

Here's how I did mine:

94-95 E320 ac compressor/power steering bracket, part number is A1042300142

W124 AC compressor to fit that bracket (most M103 and any M104 W124s used it). Denso part number is 471-1224, though it has been discontinued.

Belt tensioner part number A1042000870 and three attachment bolts N910143008003

Pulley I used was A1192001470 but there's also A1042001070. Attachment nut is A1119900053.

Belt is dependent on a ton of factors, I'd just measure for fitment.

The 190E AC lines will still work but they are pushed back slightly. You have to remove the front intake support bracket. I used some random bracket I had laying around to add extra support to the fuel cooler assembly on the hose.

Not an easy or fun job but gives you the modern belt tensioner.

__________________
Current: 1975 450SEL, 83 300D, 88 Yugo GVX, 90 300D OM603 swap, 91 F150 4.6 4v swap, 93 190E Sportline LE 3.0L M104 swap, 93 190E Sportline LE Megasquirt, 03 Sprinter, 06 E500 4Matic wagon.

Wow, only about 87K miles per motor. Where I live Teslas are the "yuppie staff car", and they all look the same. Did you read about the Swedish guy who blew up his Tesla with several pounds of dynamic when he found out how much a battery replacement job cost? I really liked that story!

BTW, if you got 531K miles out of the original 2.6L I-6 how many times did you refresh the head or do a complete engine rebuild and have to replace the cam belt tensioner, water pump, and center driveshaft bearing or other significant parts you can recall?

If you outlive me maybe you should buy my 190E 2.6 from my estate. I assume you're old enough to know how to drive a "stick shift".

Duke

I keep a log of what was replaced, when it was replaced, and how many miles is on the odometer when it was replaced. I've owned the car since '05 so nearly 20 years, so I have done pretty much only normal wear items. I did have the transmission replaced in 2013 with a used one and also in 2021 with another used one, both times the reverse was gone. That is the only major repair/replacement I had to do. A/C compressor, water pump, alternator, tensioner were replaced a few times. PS pump was resealed twice, steering gear box resealed twice. Center bearing on driveshaft replaced a few times (Uro parts premature failure). Replaced a rear axle with a good used one, courtesy of W123fanman, because I ended up stripping the end threads on the axle nut end. Pretty much all rubber has been replaced at some point or another, but other than the valve stem seals, I never had to open up the engine at all. The only reason I had to replace it was because a connecting rod bearing was worn due to low oil from a failed dash light. By the time I did the troubleshooting, the oil pressure had already been declining. So instead of fixing it, which would require the engine removal anyways, I just let it go and drove it until it gave up on me.....long stretch of highway doing about 75 in a rural area. I heard the rod knocking sound change and then I decelerated because I knew something bad had happened and then car temp started going up as I was pulling over and I saw steam. When I popped up the hood I could see coolant pouring out of a hole in the freeze plug. Something had went through it and made a small hole in it. That was it. I already had the 3.0L on standby at home. I have 1 other 3.0L and two 2.6L as well. So I can resurrect this car another 2-3 times if I need to.

__________________

1990 190E 3.0L

Your dedication to your car is inspiring, I'm glad to have been able to get you that axle, though I found a few months back I needed to do both on my 260k mile Sportline haha. I'm currently swapping in a M104.981 into that car and doing a bunch of maintenance at the same time. The 3.0L that was in it was fine but I had to pull it to do some transmission work and found that engine for cheap at an old rural yard that didn't ever have anyone looking at the Mercedes in their acreage.

__________________
Current: 1975 450SEL, 83 300D, 88 Yugo GVX, 90 300D OM603 swap, 91 F150 4.6 4v swap, 93 190E Sportline LE 3.0L M104 swap, 93 190E Sportline LE Megasquirt, 03 Sprinter, 06 E500 4Matic wagon.