Hello folks, I need some advice. I've had my 123 since May of 09. It's a beater but I've put maybe 5000 miles on it and like the car. The battery has always been weak but in the summer if I drove it every few days it would start. This winter, BURRRRR cold in Tucson, barely made 70 degrees today, I have to start it every day or jump, trickle charge it.

I had the local Checker auto do a check with there little hand held charger machine. It showed diode fluctuation out of spec, battery over charging, and of course bad battery.

I pulled the voltage regulator thinking it was the brushes, but the look almost new. I cleaned everything with electrical monkey juice and put it back together. I had it retested and we got the same results. The battery light on the dash works as it should. So........

Do I need a new regulator or do I need to do some additional trouble shooting? Thanks

__________________
83 300D 227,xxx miles, sold
86 300 SDL 130,000 miles, sold

Other than the brushes wearing down, regulators do not fail often. However, a spare is always nice to have. I suggest buying and installing a replacement regulator. If that solves the problem, well and good. If it does not solve the problem, leave the new regulator in place and put the old one away in the trunk as a spare.

An old, weak battery can also be the cause of the problem you are seeing. If you don't want to buy a new battery (on top of your new regulator), maybe you can borrow a good one to see if that helps.

Other things to check are the battery cables and their clamps on the battery terminals, the wires at the alternator, and the big ground wire (flexible strap) between the engine block and the car's chassis (usually underneath and not too far from the starter motor).

Jeremy

__________________

"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

Yes I plan on getting a new battery, no question in my mind this one is damaged and hanging by a thread but.......I don't want to overcharge another battery. I'm just wondering why the machine says overcharge and if it is correct. I don't mind buying parts IF I am 99% plus sure I need them. Thanks

__________________
83 300D 227,xxx miles, sold
86 300 SDL 130,000 miles, sold

they have failed at least once on all mine. really nice to get to work and find out your battery has 9 volts.

If you are showing diode fluctuation, a new regulator and battery will soon fail as the problem is with the internal diode pack. Your best option is to find a local automotive electrical rebuilder or second best find a replacement new/rebuilt.

__________________
Sam

84 300SD 350K+ miles ( Blue Belle )

Yep, it showed diode fluctuation out of spec. So if it is internal I have no problem pulling it and getting it repaired. It's a Bosch so I would like to keep it. I have no history of the car before May so it may be as old as the car. Thanks

__________________
83 300D 227,xxx miles, sold
86 300 SDL 130,000 miles, sold

I'm not sure they sell to normal humans...but,they'll tell you when you call.
(You might have to have your "Electrician" order it for you.)

New Bearings might be a wise investment at that mileage ,Too.

http://search.waiglobal.com/vehiclelookup/bomsearch.aspx?search=bom&part=0-120-489-918

http://search.waiglobal.com/partsearch/partnum.aspx?part=IBR303-1

Attached Thumbnails

   

__________________
'84 300SD sold
124.128

You may wish to consider a rebuilt alt, or a high amperage replacement. If you are going to the trouble of pulling the thing to bits & replacing the diode pack as well as the regulator, you should do the bearings & have the slip rings turned. by the time you do all that, it may have been cheaper and easier just to get a good quality re-manufactured one. Best you contact Phil at fastlane

__________________
Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving

All very good advice. I don't run anything electrical so, although nice, I really don't need any high output than stock. If I had a winch on the front and some lights and an amp I would but I'm good. Looks like a rebuilt from Phil is around $160 so....I just don't feel like rebuilding at this time but I appreciate the parts link. My local rebuilder will take a look see and depending on the diode its 35-45 bucks. If he finds something else we'll have to talk. Unless the bearings show wear I'm running it. Thanks for advice and I'll let you know in a day or so the outcome. I don't think I'll pull it today but who knows. Thanks

__________________
83 300D 227,xxx miles, sold
86 300 SDL 130,000 miles, sold

An update on what I found. I pulled the alternator and took it to the rebuild shop and explained what I knew. They hooked it up to their machine and ran it. It put out 14.5 volts and every meter they had on it showed steady. So we pronounced it good and I put it back on the car and purchased a good battery and walla everything seems fine. No idea why the parts house little hand held said it was bad but no big deal, the money I saved went to a good battery which I needed anyway.

While I was under the car I changed the oil pan gasket that was leaking. Well I should say installed a gasket. When I pulled the pan neither pan nor drain plug had a gasket. Set my valves- they were all 2-.003 inch tight. The butterknive wrenches worked well. It could be done without but it was more fun with.

I pulled the EGR and black box on the valve cover. Lubed every throttle linkage connection and set the linkage to go to the full IP stop. It was about 1/8 inch away before adjustment.

Measured timing chain stretch with a dial indicator and found it to be 9 degrees so my guess is someone installed an offset key not too long ago.

I'm installing a boost gauge and have a question. Someone has been into the ALDA as the cap is gone. It seems almost like 3 pieces coming out of the cover. Black rubber and some aluminum, the screw, then the lock nut on the screw touching the black rubber...If I turn the screw the black washer wants to turn too. Is the OK or should it stay still or does it matter? this is an AZ car so everything is free to move. Thanks

__________________
83 300D 227,xxx miles, sold
86 300 SDL 130,000 miles, sold

i diode can be intermitant as temp is the issue at times, when hot it will fail and over charge the battery, hope the battery has a warr and dont tell them if it goes bad you suspect a diode, they do sell a cheap plug into the cig lighter Volt meter you can keep an eye on. My guess the issue is not over as i think the diode has burned out the first battery and time will tell the story -- jz

Sounds like you have everything under control. One extra thing I did was to replace both cables and re-route the negative so that it went directly from the (-) terminal to a spot on the engine, lack of good ground has been the only issue with the current car, once the defective glow plugs were replaced. But the dual ground cables on the Benz threw me for a loop at first.

__________________
Strelnik
Invest in America: Buy a Congressman!

1950 170SD
1951 Citroen 11BN
1953 Citroen 11BNF limo
1953 220a project
1959 180D
1960 190D
1960 Borgward Isabella TS 2dr
1983 240D daily driver
1983 380SL
1990 350SDL daily driver alt
3 x Citroen DS21M, down from 5
3 x Citroen 2CV, down from 6

John, I guess we will see. I got the car last May with the bad battery and drove it until I just fixed it. As long as I started it every other day or so it would start. The battery was several years old and I think it would have completely melted down if it was truling over charging. My thinking is the Chain parts house hand held didn't like the 14.5 volts and freaked out. Not the first time we've all had conflicting test results. Have to go with the best guess and time will tell. Thanks

__________________
83 300D 227,xxx miles, sold
86 300 SDL 130,000 miles, sold

Those store hand held wiss bang detect all things are not all they are cracked up to be. The next time you go to the Doctor and he asks you whats wrong, tell him he's the Dr & he should know!!
Charging problems are often blamed on the alt, its seldom the problem. You need the car running at a good work shop for them to find the real problem. You cant just point some magic black box at it & expect the answer.

__________________
Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving

The belt tensioner on my 103 engine went weak so unknowingly i had a marginal battery charge ,eventually the alternator broke a carbon bush caused by slipping and jerky operation under load .Fault was rectified : suspected Battery was good so was the alternator
a few points ;In addition to a bad ground or old poorly conducting leads we can also have
A rectifier diode malfunction when hot . simply test using a DMM set on AC voltage Any measurement above 0.5V AC is diode problem
Worn out slip rings will give a erratic voltage and regulator failure .
mak