Project Smokey Wagon 2014! - Mostly just noob questions inside. W123 1985 300TD - Page 2 - PeachParts Mercedes-Benz Forum

uberwasser · #1 12-04-2014, 01:17 PM

You can look at the iFixit guide link in my signature to find a step by step on accessing and replacing the OVP relay fuse. It was the cause of my dead tach on my '85. The 1985 model year has a unique setup for the tach vs. 1984 and earlier cars.

WarTowels · #2 12-04-2014, 02:11 PM

I'll keep that in mind, thanks. If they can match or beat others I will use them.

WarTowels · #3 12-04-2014, 03:51 PM

This will be my charging issue post. I will update this post as it develops.

Symptoms:

1. Car is not charging the battery
2. Battery Idiot light is on (As are the brake and brake wear lights)

Info:

1. Brand new Napa battery (1 week or so old)
2. Trickle charged battery to full, reads 12.7 volts
3. With car ON engine RUNNING, battery reads 12.25 volts
4. Voltage drops the more accessories you turn on

Resolution Ideas:

Based on my research and the above info, I'm fairly confident it is a Voltage Regulator or Alternator issue.

I am not aware of a way to definitively test either of those at home so my plan is to pull the Alternator w/ Regulator and have it bench tested at Napa. Will that give me the data required to determine which is at fault?

WarTowels · #4 12-04-2014, 04:02 PM

Anyone have a go to place for looking up parts/part numbers?

WarTowels · #5 12-04-2014, 01:43 PM

Bosch pads, Bendix rotors, new rack damper bolt (and o-ring), wiper blades all around, front brake wear sensors, air filter all ordered up. Will also pick up new brake fluid for a FULL flush.

Coolant in the car looks new and it just had an oil change so should be good there.

SLS hydraulic system may need a flush/fill though. That's best to get from Merc?

Need to order tires too. Decided to go with Goodyear Winter Grip's (195/70/14) as they are very affordable and should give decent winter performance while not being too loud.

Also, going to try this pencil test on the accumulators and report back and then may order those up.

ROLLGUY · #6 12-04-2014, 02:09 PM

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fahrvergnugen · #7 12-05-2014, 01:15 AM

Quote:

Originally Posted by WarTowels

SLS hydraulic system may need a flush/fill though. That's best to get from Merc?

You want Pentosin CHF 7.1 fluid; I got five bottles on sale from ********AZ. I don't know if the sale is going on still or not... Do NOT use CHF 14, not the same.

uberwasser · #8 12-04-2014, 04:03 PM

Not sure what the bench test at NAPA will reveal or not. However, you can certainly consider pulling the voltage regulator (held in by two screws) to do a visual inspection. If the brushes are obviously worn, that's an easy diagnosis.

Partscarver · #9 12-04-2014, 04:03 PM

grab short #2 phillips crawl under securely lifted front end, find alternator,
unscrew voltage regulator reinstall with new, test voltage

uberwasser · #10 12-04-2014, 04:04 PM

Quote:

Originally Posted by WarTowels

Anyone have a go to place for looking up parts/part numbers?

If you live in the US, sign up for the EPC at epc.startekinfo.com

When you create an account you will be required to provide a valid US credit card but it will not be charged. It's only to verify US residency.

The EPC is the parts system used by the dealer part counters. It's the best source you'll find for that.

WarTowels · #11 12-04-2014, 04:04 PM

Good deal, I'll do that first. It's probably the original!

WarTowels · #12 12-05-2014, 12:22 AM

Well, perhaps oddly the voltage regulator had flat head bolts instead of Philips. One came out nice and easy, the other however did not. Couldn't get it out and was afraid it would strip so I'm mid way taking the alternator off- one bolt out and belt off. Will finish that tomorrow.

I also took the wheels off in prep for a brake job this weekend and found the passenger front side brake wear wire was cut. Luckily there is just enough left to rewire it.

However, since these activate the light by grounding the sensor, I suspect a cut wire would not trigger the light I currently have.

toomany MBZ · #13 12-05-2014, 07:28 AM

Quote:

Originally Posted by WarTowels

Well, perhaps oddly the voltage regulator had flat head bolts instead of Philips. One came out nice and easy, the other however did not. Couldn't get it out and was afraid it would strip so I'm mid way taking the alternator off- one bolt out and belt off. Will finish that tomorrow.

I also took the wheels off in prep for a brake job this weekend and found the passenger front side brake wear wire was cut. Luckily there is just enough left to rewire it.

However, since these activate the light by grounding the sensor, I suspect a cut wire would not trigger the light I currently have.

Removing the alt can be problematic, but is doable.

You may just want to replace that brake pad wear sensor wire, get a pair while you're at it. Correct, you shouldn't have a light now, or ever with the wire cut.

Click on the Mercedes-Benz button at the top of the page.

uberwasser · #14 12-05-2014, 10:56 AM

Which brake light is it? The pad wear indicator is the circle with little dashes all around it. It lights up yellow, I believe. Then there is the light that says BRAKE, which lights up red.

If it's the red one that is unrelated to the brake wear wire, and instead is tied to the parking brake and the low-fluid sensors in the brake fluid reservoir.

WarTowels · #15 12-05-2014, 03:25 PM

BOTH of the brake lights are on: "BRAKE" and the Pad Wearing sensor light.

In other news, you'll all have to forgive my ignorance but I'm not seeing how to clearly take the alternator off. I have the lower bolt out, no problem.

It then seemed to me that the second bolt is shared with the tensioner adjustment that is connected via the rod. However, I've loosened the adjuster all the way out but the way the adjustment holder is designed I don't see how you can take the bolt out. (Seems like the large nut not the adjuster might have to come off, but it just spins.)

Something obvious I'm missing?

In other news, I removed the passenger footwell panel to inspect the OVP relay fuse- IT WAS BLOWN! So I replaced it with a fresh fuse of the same size. Would be sweet if that fixed the dead tach and it didn't blow again. Can't test until the alternator is done though!

EDIT: Need to get me that service manual!

Cheers