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  #1  
Old 05-10-2013, 12:35 AM
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It's running, so I have new questions - w108

A couple of quick issues I discovered now that I've driven the car.

1. Speedometer works, odometers do not. I assume it's something inside the speedometer - has anyone tackled this?

2. Shift indicator does not work. I had asked this before and someone said there is a cable somewhere, but after taking off the lower column cover all I see is a tube that the shifter shaft runs in. Where is the cable?

3. I know these cars like to upshift very late (compared to new cars). Is this adjustable at all?

4. Turn signal stalk does not stay on. I saw a repair procedure somewhere, but now I can't find it... anyone know where it is?

5. Turn signals flash very fast. Where is the flasher? IS there a guide to which relay does what on the car? Or the fuses in the engine compartment?

6. On the fuel filler lid it says the rear tire pressures should be higher than the fronts. Really? Why?

Thanks,

Csaba
72 280SEL 4.5
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  #2  
Old 05-10-2013, 12:54 AM
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Quote:
Originally Posted by vandor View Post
A couple of quick issues I discovered now that I've driven the car.

1. Speedometer works, odometers do not. I assume it's something inside the speedometer - has anyone tackled this?

2. Shift indicator does not work. I had asked this before and someone said there is a cable somewhere, but after taking off the lower column cover all I see is a tube that the shifter shaft runs in. Where is the cable?

3. I know these cars like to upshift very late (compared to new cars). Is this adjustable at all?

4. Turn signal stalk does not stay on. I saw a repair procedure somewhere, but now I can't find it... anyone know where it is?

5. Turn signals flash very fast. Where is the flasher? IS there a guide to which relay does what on the car? Or the fuses in the engine compartment?

6. On the fuel filler lid it says the rear tire pressures should be higher than the fronts. Really? Why?

Thanks,

Csaba
72 280SEL 4.5
1.- How to Repair Your Broken Odometer


4.- PeachPartsWiki: Self-Canceling Turn Signal Indicator Fix

5.- did you check you don't have a blown light bulb?

6.- rear wheel drive, to compensate oversteer.
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  #3  
Old 05-10-2013, 10:01 AM
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Hi,

Thanks for the info!
All of the turn signal lights work, front and back. It does this on both sides, flashes about twice as fast as normal. I've used electronic flashers on other cars with good success, but I do not know if it is adaptable to the MB.

Csaba
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  #4  
Old 05-10-2013, 10:26 AM
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5. Wrong voltage bulbs in the signals, perhaps.
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  #5  
Old 05-10-2013, 10:50 AM
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2) Yep, pull the cluster and you'll see the cable from the indicate to the shifter on a column shift car.

6) Probably because the engine is heavier
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With best regards

Al

Check out the W114, W115 enthusiast website.
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http://www.w108.org

Join the Mercedes W108 group
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My 280SL restoration

http://www.w108.org/gallery/albums/a...0959.thumb.jpg
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  #6  
Old 05-10-2013, 12:03 PM
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Quote:
Originally Posted by vandor View Post
3. I know these cars like to upshift very late (compared to new cars). Is this adjustable at all?
5. Turn signals flash very fast. Where is the flasher? IS there a guide to which relay does what on the car? Or the fuses in the engine compartment?
6. On the fuel filler lid it says the rear tire pressures should be higher than the fronts. Really? Why?
Csaba, I'll try my shot at some that either aren't answered or you indicated the wrong answer:
3 - There is a rod from the transmission to the throttle linkage. Making the rod shorter makes shifts occur later and longer makes them occur sooner. Base adjustment is to take the rod off, and adjust it so it's neither being pulled nor pushed and put it back on, then adjust from there to your preference.

5 - This likely is a burnt out bulb, loose connection or improper wattage bulb. We've all been there and even if your turn signals look fine this can be an issue. For example, if one of your front amber bulbs isn't in tight or is in backwards it can either cross between the (+) for parking lights, or if reversed the lower-wattage park is used as turn and either could cause the issue. You'd be surprised how many people put these bulbs in backwards (anyone whose tail lights are blinding, or has one super-bright tail light, has put this bulb in backwards).

6 - Keep in mind these cars originally had bias-ply tires. The rear pressure was probably higher for better rear traction. I found that the best pressure for front AND rear performance and handling and ride-quality wise was about 33-35 PSI. These are very tall sidewall tires and lower pressures will result in way lower MPG and a "Washy" feeling on the highways but will help cushion bumps better.
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  #7  
Old 05-11-2013, 01:56 AM
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Thanks for all the responses!

My other RWD cars always specified higher pressures in the front, so I suspect it has something to do
with rear suspension setup/geometry.
BTW, maybe 108s had bias-ply tires in '65 when they first came out, but I'd think a '72 came with radials.
My Fiats had radials since '68, so I'm sure an MB costing 3 times as much did too. I had set pressures at
33 front/36 rear, must have read your mind :-)

I will experiment adjusting the rod to the tranny, but now a more imediate need crept up: the left rear
caliper is sometimes dragging. I think it's a recent rebuilt, so I will remove the pads and excersise the
pistons some, hopefully that will cure it.

The turn signals do this in both directions, but I will double check everything anyways. Heck, I'm getting
used to it.

Tried charging the AC (has been converted to r134a and has all new hoses) and the compressor clutch started slipping.
I wonder if it's adjustable?
Also the condenser fan never came on, anyone know where it's relay is? I'd like to wire it so it's always on when the compressor is on.
Thanks,

Csaba
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  #8  
Old 05-11-2013, 02:06 AM
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Quote:
Originally Posted by vandor View Post
Tried charging the AC (has been converted to r134a and has all new hoses) and the compressor clutch started slipping.
I wonder if it's adjustable. It's a GM compressor, right? Was this the R4?
Also the condenser fan never came on, anyone know where it's relay is? I'd like to wire it so it's always on when the compressor is on.
Thanks,

Csaba
You probably overcharged it. R134 runs at a higher pressure then R12 so less volume is required. Did you use gauges or just shot a couple of cans into it?

The compressor is a Frigidaire / GM A6 compressor and is common to many GM cars from the 60's and 70's. You can get rebuilt ones for under $120 at the local parts places.

There should be two wires going into a pressure switch on the dryer. If you connect them together using a GM style fuse, it should engage the fan. I'm not sure if you can set the fan to fire up every time the compressor starts, but you can probably rig it to run all the time which is just fine for the summer.
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With best regards

Al

Check out the W114, W115 enthusiast website.
http://www.stroke8.org

http://www.w108.org

Join the Mercedes W108 group
http://autos.groups.yahoo.com/group/mercedesw108/

My 280SL restoration

http://www.w108.org/gallery/albums/a...0959.thumb.jpg
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  #9  
Old 05-11-2013, 09:04 AM
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Quote:
Originally Posted by vandor View Post
Tried charging the AC (has been converted to r134a and has all new hoses) and the compressor clutch started slipping.
I wonder if it's adjustable?
Clutch isn't adjustable on it... you have 2 possible issues. Either like Al says it's overcharged, or you have a common issue with backyard / novice R134a conversions...

If the system was not COMPLETELY flushed of R12 and oil and even a small amount of oil was left, AND if the system was not vacuumed VERY low prior to filling, the R12 oil & R134a oil and/or R134a oil and moisture in air mixed, producing an acid that eats through the compressor's mechanicals and can cause it to seize. When I did my Jeep's R12 > R134a conversion I replaced everything but the evaporator (didn't want to take apart the dash to do it). I flushed it fully.
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  #10  
Old 05-11-2013, 10:41 AM
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Hm, ok, so I am likely looking at a new compressor. Yes, the conversion could be sketchy, there are no stickers indicating it has been done...
I have definitely not overfilled it, as it was nearly empty and I only put one can in. I do have a set of gauges and even when the compressor was working at first the high side never went much above 100 psi.
Thank for the info!

I will be tackling the dragging rear brake this afternoon after our Fiat club's lunch meeting :-)

Csaba
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  #11  
Old 05-11-2013, 10:54 AM
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I'd pull a vac for a very long time and then charge it before replacing the compressor. The weather is pretty cool right now so you wont see too high a reading from the high side.
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With best regards

Al

Check out the W114, W115 enthusiast website.
http://www.stroke8.org

http://www.w108.org

Join the Mercedes W108 group
http://autos.groups.yahoo.com/group/mercedesw108/

My 280SL restoration

http://www.w108.org/gallery/albums/a...0959.thumb.jpg
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  #12  
Old 05-11-2013, 01:48 PM
Pooka
 
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I am not sure if there is a low pressure cut-off on this system or not, but if you only put in one can then it could be your don't have enough in there to build up the proper pressure.

Before you spend a ton of cash on this you might try just taking it to a shop for charging. They will have the correct equipment and know how even on a system as old as this one, and the cost will likely be far less than if you start replacing everything.
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  #13  
Old 05-11-2013, 04:51 PM
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To do the AC correctly you need a heated charging cylinder(otherwise it takes a LONG time to get all the charge into the system), gauges and a vacuum pump at the very least. You need to know what the system capacity is so you can put the correct charge in. I remember in my high school days just dumping a couple of cans of R12 into it till it got cold and off I went and it seemed to work just fine.
If there is ANY air in the system it will not last long.
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  #14  
Old 05-12-2013, 01:48 AM
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Hi Al,

>I'm not sure if you can set the fan to fire up every time the compressor starts

It's easy, just use the +12V compressor power to turn on a fan relay. With 134a the fan is supposed to run all the time when the compressor is on.

>I'd pull a vac for a very long time and then charge it before replacing the compressor

That won't fix a bad clutch :-( It worked fine when I first started charging and the system was empty, but then it would
turn slower and slower, eventually barely turning. NO bad noises, so I don't think the compressor is locking up.
The system was charged and working when the engine blew, that is why I was hoping I could just fill it.


Pooka,

>Before you spend a ton of cash on this you might try just taking it to a shop for charging.

My motto is that I won't pay someone to screw it up when I can do that myself :-) Seriously, I do know about A/C
systems, I built two custom system for other vehicles. I also worked as a mechanic when I was in college and know
that it's hard to find someone that does a good job and gives a *****. I would not pay someone I do not know to do
any work. I don't do my own oil changes because it's cheaper, I do it because I do not want anyone else working on
my cars.


Tony,

The system capacity info is available (I think I saw it in the owner's manual or on a sticker?), but that was for r12.
R134a will be different, so one has to get close and then experiment, see what charge gets it the coolest.


Today I checked the 'sticking' rear caliper, I took out the pads and pushed the pistons in and out. Everything looked good,
not sure if the caliper was the problem. Can the handbrake shoes stick?

I also took out the heater lever assembly and replaced the heater levers. It took me forever to figure out that the heater cables have to be undone by positioning the levers in a certain place and then turning a phillips screw from the top.

Oh, I found that the shifter indicator cable is broken and Pelikan does not seem to have them. Is this a dealer item?
bye,

Csaba
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  #15  
Old 05-12-2013, 01:38 PM
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Sticking rear calipers: I would change out the rubber flex lines on both sides (and fronts as well, why not, they're not that expensive).

Even if the outsides look ok, the insides are likely separated or collapsed and the fluid only moves one way, not back towards the master cylinder. BTDT.

The rear hoses may have different ends (male/female) depending on s/n, so be sure to have it on hand when you order them. My local import car parts place had them in stock or within a day.

Sounds like you're on a roll. Post pics.
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