Ashtray gauges for the W124 - Page 2 - PeachParts Mercedes-Benz Forum

winmutt · #16 07-03-2009, 02:25 PM

Someone sell me a W123 one!

Jeremy5848 · #17 07-03-2009, 03:39 PM

PM reply sent.

Jeremy5848 · #18 07-03-2009, 03:56 PM

Quote:

Originally Posted by babymog

Find a couple of nice ones, make a spare and sell it. Finding good zebrano is always the trick.

Which reminds me, I have some Zebrano left over from building my 123 panel. It's in perfect condition, as-purchased, uncut, and unfinished. I have two pieces, each enough to make a panel for the ashtray area of a 123. $10 each and I'll pay for mailing in the US of A. PM if interested.

For a picture of the final result, see post #24 in this thread:

Where's the best place to mount gauges?

Caveat: not tall enough for the W124 ashtray area, sorry.

I can also provide a template for cutting the Zebrano to hold 3 gauges, each 2-1/16 inch in diameter, the standard size. If you want to hold something else, you'll have to make your own template.

If you need the holes drilled, I have the proper size drill. We'll have to talk about the price but I could do this if someone is interested. You will have to stain and finish the Zebrano yourself.

Jeremy

Jeremy5848 · #19 07-04-2009, 06:35 PM

Quote:

Originally Posted by KarTek

. . . It might be possible to create a "deep well" plug that will let the probe mount deeper into the tube or possibly a longer version is available. . .

I think I can build that from copper tubing. Does anyone happen to know if solder (the kind you use for plumbing with a torch and separate flux, sometimes called "hard solder" as opposed to electronic "soft solder") will stand up to the exhaust heat as it enters the turbocharger? My gauge reads up to 1650 degrees F which I know is too hot for the engine--I think you're not supposed to go over 1000 or 1200 degrees F, right?

From some quick Internet research, it looks like soldering will not work--solder melts at 840F or below. I'll have to pay someone to braze the joints for me.

Jeremy

Jeremy5848 · #20 07-06-2009, 08:52 PM

Quote:

Originally Posted by babymog

A blank zebrano wood panel is available from the '86-'90 190E/190D center console. Perfect match, just needs to be cut down to size and drilled for the gauges.

Thanks for the idea. I got two of them at Pick and Pull today. I'll list them for sale in the Parts section.

ashedd · #21 07-06-2009, 09:20 PM

I have been looking at doing this too.

My problem right now is finding a boost gauge that isn't cheesy/cheap looking. Seems like they all look cheap to me or they are expensive digital ones. Any ideas? Something that goes well with the Mercedes Benz interior.

Jeremy5848 · #22 07-06-2009, 10:58 PM

Quote:

Originally Posted by ashedd

I have been looking at doing this too.

My problem right now is finding a boost gauge that isn't cheesy/cheap looking. Seems like they all look cheap to me or they are expensive digital ones. Any ideas? Something that goes well with the Mercedes Benz interior.

VDO makes a nice one, goes good with Mercedes since VDO typically makes their speedometer and other gauges. Mine is shown in this thread:

Where's the boost???

The gauge is from egauges.com. Their number 150-101. See this link:

http://www.egauges.com/vdo_mult.asp?...Vision&Units=E

The 15 psi "Boost" gauge is $32.50, not including tubing, which is available in several kits or you can roll your own. The input to the gauge is 1.8 male pipe thread which easily connects to either 1/8 or 1/4 inch tubing.

This particular gauge family, the "Vision" series, has really good lighting, something that us old farts with our weak eyes especially appreciate. The Vision series is also a good appearance match for the factory gauges in the W123 cars.

Jeremy

SirNik84 · #23 07-07-2009, 12:09 PM

Great looking bezels there Jeremy. Fantastic work as usual

Jeremy5848 · #24 07-11-2009, 12:30 AM

Thanks, Nik. BTW, where ya been?

Here's an update. I discovered that 3/4 inch copper is too big for the EGR port on the exhaust and 1/2 inch is too small for the EGT probe, so the idea of building a "deep probe" has to be set aside until I figure out how. In the meantime, I built a replica of Brian's EGR block-off from copper scrap and drilled it for the probe. It doesn't stick in far enough (as KarTek pointed out several posts ago) but it will do for now. I'll try it in the morning after the sealer has had time to set up. [Photo #1]

The boost gauge gets its feed from a spare port on the intake manifold. I don't know what MB had in mind, maybe some kind of test port, but it's a great place to plug in a boost gauge. [Photo #2]

The gauges are temporarily mounted in the aluminum plate that will back up the Zebrano, when I get the Zebrano finished. Woodworking is not my thing so I have to go very slowly. The Zebrano, which is veneer, has been glued to a piece of 1/16 inch birch plywood. After I get the gauge holes cut, I'll stain and finish the Zebrano. Photo #3 shows the driver's view and photo #4 is a close-up. Photo #5 shows the panel with the Zebrano Photoshopped into place. Sure wish the real stuff was that easy!

The ashtray area turns out to be a great place for gauges -- it has 12 volts when the key is on and ground for any instruments that need it (EGT, voltmeter), and it has illumination, which I can chop off and run to the three gauges. (If you didn't know your ashtray was illuminated, maybe it just has a burned-out bulb.)

Jeremy

Jeremy5848 · #25 07-17-2009, 10:26 PM

Quote:

Originally Posted by KarTek

I would install the probe in the plug area where the EGR was but the tip really needs to extend at least 1/3 of the way into the exhaust stream for the most accurate reading.

It will create artificially low readings if it's stuck in the eddy currents in that little tube.

It might be possible to create a "deep well" plug that will let the probe mount deeper into the tube or possibly a longer version is available.

Failing that, it's really easy to drill and tap a hole in the right spot on the cast iron manifold.

OK, here are the test results:

With the EGT probe in the factory tapped hole at cylinder #1 (why they do that?) the gauge reads between 450-650F around town and on the local freeways (no hill climbing or extended accelerating, no high speed driving).

With the probe in the EGR outlet, the temperature ranges between 350-450F for the same conditions. I need to take some more data with the probe in this location. Clearly I would have to compensate if I left the probe in this position.

I designed a "deep well" for the probe and it was going along great until I discovered that 3/4 inch copper pipe is too big for the EGR outlet while 1/2 inch copper pipe is too small for the probe. I need to find a compromise size.

The pipe that gets installed when the football is replaced has an ideal spot to drill a hole for probe access. At the moment, I don't want to take a chance drilling with the pipe on the engine and don't want to pull it off the engine either. Maybe later.

Jeremy

babymog · #26 07-18-2009, 12:36 PM

Although you can get basic performance data from a single cylinder, getting collective information will indicate a problem in any cylinder.

Jeremy5848 · #27 07-23-2009, 09:55 PM

Quote:

Originally Posted by KarTek

. . . It might be possible to create a "deep well" plug that will let the probe mount deeper into the tube or possibly a longer version is available. . .

Here it is. The pieces go to my welder tomorrow for brazing. Since he is typically very busy, I have no idea how long it will be before he can get to it. I'll post results once the brazing is complete and I can get the thing in the car.

The tube material is 1/2 inch EMT (steel electrical conduit). The end that sticks into the exhaust stream is closed off by a steel washer that I ground down to just barely overlap the EMT. The other end is a home-made copy of the copper block-off plate that Brian sells as part of his EGR delete kit. I used a 3/4 inch punch to make the hole in the copper. It is a slightly sloppy fit on the 0.7 inch OD EMT.

Notice the slight bend in the EMT. The bend allows the EMT to follow the curve in the EGR takeoff that is part of the factory's "football" replacement. You have to be careful not to bend too much or the probe won't go through. I ruined my first attempt by bending it too much. I used a small tubing bender that I have had for ages. You have to leave the tubing a foot or more long or there isn't enough for the bender to grab. Once you have the curve bent in then you can cut the tubing to size.

It is also possible to use 5/8 inch copper water pipe but I didn't happen to have any in my plumbing box. If the EMT rusts or otherwise deteriorates badly in the exhaust I'll build another of copper.

I've been too busy to complete the Zebrano panel. It'll get done "one of these days."

Jeremy

KarTek · #28 07-23-2009, 11:23 PM

Very well done! That's what I was envisioning for the EGT sensor. Great idea on the gauges too. I plan on doing something similar with my car in the lower ashtray cubby area.

The metal will braze but how are you planning on attaching the top curved flange to the metal tube?

Jeremy5848 · #29 07-24-2009, 12:10 AM

Quote:

Originally Posted by KarTek

Very well done! That's what I was envisioning for the EGT sensor. Great idea on the gauges too. I plan on doing something similar with my car in the lower ashtray cubby area.

The metal will braze but how are you planning on attaching the top curved flange to the metal tube?

I'm not sure I understand your question . . . are you speaking of the copper piece when you write "top curved flange?" I had assumed that it could be brazed to the steel EMT. I know little of brazing and had assumed that steel and copper could be brazed together . . . OK, a little research says they can, but there may be expansion issues between the dissimilar metals. That could be especially true in something exposed to the temperature extremes of an exhaust system. Maybe I should change the copper piece to steel. A large washer might work.

If you mean attaching the assembly to the EGR exhaust port, the copper is attached to it by the clamp, same as in the EGR delete kit, and sealed with hi-temp silicone. See the first picture in post #24 of this thread.

Jeremy

sixto · #30 07-26-2009, 06:31 PM

IIRC the turbo feed pipe comes off easily. 2 nuts at the manifold, 4 nuts at the turbo.

I'd like to see how far the probe goes into the exhaust flow.

Sixto
87 300D