Ashtray gauges for the W124 - Page 3 - PeachParts Mercedes-Benz Forum

Jeremy5848 · #31 07-26-2009, 07:13 PM

Quote:

Originally Posted by sixto

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

When I get the brazing done you may come see for yourself.

I'd rather not drill holes in the turbo feed pipe since that is not a reversible operation. If the metal is not thick enough to support several threads, I'd have to weld on a piece of threaded steel, which I did get as part of the EGT gauge kit. That would require the car to be down for the length of time it takes to get the welding done. But it would be an ideal location, no question.

Jeremy

Jeremy5848 · #32 08-05-2009, 09:41 PM

Here are three pictures of the EGT gauge sensor in its final location. The adapter allows the sensor to stick well into the flow of exhaust gases as they pass on their way to the turbo. I'll try out the installation as soon as the RTV cures -- probably tomorrow sometime. The parts for the adapter were from my scrap box but the machine shop charged me $40 to braze them together.

The third picture shows an image of the sensor in its probe overlaid upon the image of the exhaust system, via the magic of Photoshop. The scale is probably off a little but it gives you an idea of where the probe is compared to where it would be without the adapter.

One nice thing about using this location is that it makes the missing EGR valve less obvious since the stub exhaust pipe now seems to have a purpose. It wouldn't get past someone who knew what they were looking for but it might fool a novice.

In the meantime, I'm still learning to finish Zebrawood but hope to have the panel for the gauges finished later this month.

Jeremy

Jeremy5848 · #33 08-07-2009, 02:27 AM

First chance tonight to drive the car since installing the EGT sensor with the adapter so it sticks well into the exhaust stream.

Vehicle: '87 300D (W124, OM603)
Speed: 65 mph
Engine: 2500 rpm
Outside air: 61F
Coolant: 80C
Boost: 5 psi
EGT: 650F (340C)

It will be interesting to see what happens on a long hill and/or in hot weather.

Jeremy

Jeremy5848 · #34 10-10-2009, 10:23 PM

OK, so I'm not a woodworker. The wood panel took forever to finish but it is finally done and in the car. The panel is such a tight fit in the ashtray space that the gauge brackets cannot be used. Instead, the gauges are held in place with hot-melt glue. The glue provides a firm hold but can be pried off if a gauge ever needs to come out. The panel is held in the console with friction at the top while the bottom is trapped by the lower console panel.

The wood portion is made of Zebrano veneer glued to 1/8 inch birch plywood with contact cement, stained with Red Mahogany to match the existing wood and finished with multiple coats of tabletop (hard) varnish. Backing up the wood is a sheet of 1/16 inch aluminum, also glued to the birch with contact cement. The curve at the bottom of the aluminum protrudes below the wood and allows the finished panel to be trapped in place by the lower console wood panel.

The holes in the aluminum were made with a 2-1/8 inch Greenlee chassis punch while the wood was drilled with a 2 inch Forstner bit and enlarged to 2-1/16 inch with a Dremel-mounted sanding wheel. I finished the wood before drilling the holes and got away with it but the experts tell me it's better to cut the holes first and then finish the wood.

The wiring of the gauges was made easier by the existing switched 12 volt, console illumination, and ground wires. I added a pair of wires for the EGT gauge and hard plastic tubing for the boost gauge.

The position of the gauges means that the driver must take his eyes off of the road to view them, so I don't actually look at the gauges a lot. The voltmeter and boost gauges are really for diagnostic purposes anyway. Only the EGT gauge serves a critical function and that only in special circumstances such as high-speed hill climbs.

The JVC stereo above the gauges in the last picture will go away as soon as I have time to install the factory Becker 1492 radio that Sixto and I pulled out of a '94 E320 in North San Jose Pick and Pull. The matching trunk-mounted amplifier and complete wiring harness came with the radio while the companion 3196 CD changer was an eBay purchase. Since I don't want to install late-124 door panels, I'm searching for a pair of thin speakers for the front doors; they should fit in the space behind the map pockets.

Jeremy

pmari · #35 10-11-2009, 11:59 AM

Really nice work and great write up! Only one comment and not a criticism

It's looks like the stain "blushed" a little. In the future (or anyone else doing this mod) try using a sanding sealer before staining. The old timers used to use a spit coat
to keep the stain even.

Jeremy5848 · #36 10-11-2009, 12:18 PM

Thank you. The Wood Crafter store recommended shellac as a sealer. I bought some and used it in experimenting with the veneer but don't remember whether it was used on the final piece. Clearly, your eyes can see something I am missing. My main concern was in filling the grain in the zebrano, which I finally was able to do with another Wood Crafter purchase.

OTOH, the photo hides the hard time I had with the varnish. It's really difficult to do a clean job in a garage but that is all the work space I have. Fortunately, the panel is down where it's hard to see so I can get away with my mistakes.

Jeremy

Quote:

Originally Posted by pmari

Really nice work and great write up! Only one comment and not a criticism

It's looks like the stain "blushed" a little. In the future (or anyone else doing this mod) try using a sanding sealer before staining. The old timers used to use a spit coat
to keep the stain even.

BodhiBenz1987 · #37 10-11-2009, 01:17 PM

Quote:

Originally Posted by Jeremy5848

It's really difficult to do a clean job in a garage but that is all the work space I have.

I hear you on that one! Ugh! I've done 6 coats of marine varnish on my panels, and just cannot escape dust. With the high gloss varnish, the dust looks like boulders. The last coat I put on looks stunning ... except a few tiny dust spots on one big dust spot on the boost panel I made. I'm going to try building a dust booth in the garage, but even then, getting each panel into the basement to dry without getting dust on it is another impossible mission.

Still, your panel looks really nice! Very cool! Also, I actually kind of like how the stain blushes a bit ... it adds variance to the wood that looks sort of natural, and also enhances the woods natural patina in the lighter spots. Mine has a few light streaks where I just sanded too deep .... refinished twice so the veneer got very, very thin in the end. But I kind of like the nature-like imperfections in mine.

Jeremy5848 · #38 10-11-2009, 01:57 PM

I finally got a fairly good finish by letting the varnish dry for a week or so and then using the leftover bits of my 3M headlight polishing kit (bought for the '96 E300D) to lightly sand and then polish the varnish. It actually worked out fairly well. You need to have several coats of varnish on the wood so you don't sand through to bare wood -- a bit of a balancing act. The varnish takes a polish just like the plastic headlights (I was desperate but it worked).

pmari · #39 10-11-2009, 05:00 PM

Small pieces can be covered with cardboard boxes (like a shoe box etc...) to keep dust from settling on the finish.

BodhiBenz1987 · #40 10-11-2009, 06:33 PM

Quote:

Originally Posted by pmari

Small pieces can be covered with cardboard boxes (like a shoe box etc...) to keep dust from settling on the finish.

I actually built a little drying booth with a table base and a shower curtain, but I think I need to redesign it with a front flap that closes completely to protect the pieces. I'm living at my parents' house right now, which is so dusty and dirty that I've developed asthma ... adds to the challenge. I spray the pieces in the garage, dry them in the basement ... and hope I don't pick up a lot of dust getting them from A to B ...

babymog · #41 10-11-2009, 07:12 PM

I'm thinking about a panel also, considering West System to build the finish, any comments?

pmari · #42 10-11-2009, 07:50 PM

Quote:

Originally Posted by babymog

I'm thinking about a panel also, considering West System to build the finish, any comments?

You may want to consider building coats with spar varnish to get the UV protection. Good article here

Quote:

I actually built a little drying booth with a table base and a shower curtain, hope I don't pick up a lot of dust getting them from A to B

The smaller the area used for drying the eaiser to keep it dust free. Cardboard works great becuse it absorbs the moisture given off during the cure. It's also easier to transport the pieces.

babymog · #43 10-11-2009, 07:52 PM

The West System hardener with the UV protection in it was what I plan to start with, then a couple of coats of Captains clear.

pmari · #44 10-11-2009, 07:57 PM

Quote:

Originally Posted by babymog

The West System hardener with the UV protection in it was what I plan to start with, then a couple of coats of Captains clear.

Should be awesome!

Battling the forces of nature

When varnish is used alone as a coating, it is constantly fighting two distinct battles. One is to stay attached to a substrate that is expanding and shrinking as the moisture content of the wood changes. Seasonal changes in moisture content occur because varnish is not a particularly effective moisture barrier. When the wood changes dimensions, it forces the varnish to stretch and shrink in order to stay attached. Given enough stretch/shrink cycles, the coating will eventually crack.

The other battle is oxidation from exposure to the sun's UV light, a phenomenon that contributes to loss of gloss and cracking.

Good varnishes are designed to address both stretch/shrink cycles and UV degradation, but eventually the two forces in combination will break down varnish and cause it to fail.

The benefits of epoxy

Another method to achieve "the look" is gaining popularity and cuts labor time. Professional yacht refinishers now use WEST SYSTEM® 105 Resin/207 Special Clear Hardener as a clear base over wood trim before applying coats of varnish.

Three coats of epoxy followed by three coats of varnish can achieve the same depth and look of twelve or more coats of varnish. Because there are no solvents evaporating away from the epoxy, it builds thickness faster per layer than varnish and it doesn't shrink when it cures. In addition, three or more coats of 105/207 can be applied per day.

More importantly, sealing wood with an epoxy moisture barrier dramatically lessens its stretching and shrinking. Varnish benefits from being applied over a stable substrate. High-quality marine varnish is formulated with UV filters. So, the epoxy coating benefits by getting the protection from UV radiation that it needs. WEST SYSTEM 105 Resin/207 Special Clear Hardener and varnish complement each other synergistically. The two in combination last longer than each coating by itself.

Excerpt from:
Varnish over epoxy
BY Tom Pawlak

babymog · #45 10-11-2009, 08:17 PM

Yes, this summer I learned a bit about marine wood finishes, ...