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  #1  
Old 10-29-2016, 08:22 PM
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1995 E300

Greetings, I just purchased a bucket list vehicle. I've never owned a Merc but love diesels. The 95' E300 is in fantastic condition and was a one-owner (fully documented) from new. It currently has 243k on the odometer. I replaced the battery and it starts beautifully, even in balmy weather. However, the headlamps dim when you release the accelerator pedal and the radio antenna retracts when you press the accelerator. I combed through the 21 year old maintenance records and did not see an alternator. Could this be my solution? Literally, everything on the vehicle has been serviced at some point. Unrelated, the owner also had the original window sticker! Thanks in advance for you help!

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  #2  
Old 10-29-2016, 08:36 PM
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Location: Oberlin, OH
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Has the engine wiring harness been replaced? These are notorious for degrading especially once you are past 20 years
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'95 E300, 216k miles, Silver Surfer
'05 E320 CDI, 138k miles
'07 S550 4matic, 69k miles

Gone but not forgotten:

'76 300D, 350k miles?, SOLD in 1995
'75 240D, 300k miles, SOLD in 1991
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  #3  
Old 10-29-2016, 10:10 PM
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It sounds like system voltage is very low. Begin by measuring the voltage across the battery terminals. It should be between 13.5 and 14.2 most of the time. It can drop as low as 12.5 at idle with everything turned on.

I would be careful about driving the car until you have this sorted. You may have failure to start if the battery drains out.
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  #4  
Old 10-30-2016, 04:14 AM
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Replacing the voltage regulator might not be a bad idea.
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14 E250 Bluetec "Sinclair", Palladium Silver on Black, 153k miles
06 E320 CDI "Rutherford", Black on Tan, 171k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver, 142k mi, wastegate conversion

19 Honda CR-V EX 61k mi
Fourteen other MB's owned and sold
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  #5  
Old 10-30-2016, 11:01 PM
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The voltage regulator is a separably-replaceable part of the alternator. THe regulator includes brushes, which wear out over the years and miles. You can replace the regulator yourself or pay someone to do it. Regulators are about $50.

BTW, does your monovalve leak?

Jeremy
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"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
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  #6  
Old 10-31-2016, 12:48 PM
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Thanks, I have not replaced the engine wiring harness. Will look into finding one. Is this a DIY project?
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  #7  
Old 10-31-2016, 12:54 PM
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Quote:
Originally Posted by Jeremy5848 View Post
The voltage regulator is a separably-replaceable part of the alternator. THe regulator includes brushes, which wear out over the years and miles. You can replace the regulator yourself or pay someone to do it. Regulators are about $50.

BTW, does your monovalve leak?

Jeremy
Thanks, I think I am going to replace the entire alternator since I cannot find any record of it ever being replaced or serviced. Hoping this solves the issue. I do not know if my monovalve leaks; I'm going to look when I get home. This valve is a part of the Heat/AC system? Could a leak here have something to do with the electrical issue I'm having? Also, the Merc is extremely slow to accelerate, any ideas? Thanks in advance!
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  #8  
Old 10-31-2016, 12:57 PM
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Quote:
Originally Posted by Mxfrank View Post
It sounds like system voltage is very low. Begin by measuring the voltage across the battery terminals. It should be between 13.5 and 14.2 most of the time. It can drop as low as 12.5 at idle with everything turned on.

I would be careful about driving the car until you have this sorted. You may have failure to start if the battery drains out.
Thank you, I am going to measure the voltage when I get home. If the voltage is within the specs you provided, what would be your guess on what's causing the "Christine" -like behavior?
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  #9  
Old 10-31-2016, 01:10 PM
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Replacing harness is DYI but finding replacement part is difficult and expensive.
__________________
-- Chris

'95 E300, 216k miles, Silver Surfer
'05 E320 CDI, 138k miles
'07 S550 4matic, 69k miles

Gone but not forgotten:

'76 300D, 350k miles?, SOLD in 1995
'75 240D, 300k miles, SOLD in 1991
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  #10  
Old 11-01-2016, 07:56 AM
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Quote:
Originally Posted by Mxfrank View Post
It sounds like system voltage is very low. Begin by measuring the voltage across the battery terminals. It should be between 13.5 and 14.2 most of the time. It can drop as low as 12.5 at idle with everything turned on.

I would be careful about driving the car until you have this sorted. You may have failure to start if the battery drains out.
The volts came in at 16.1 at idle....... any thoughts?
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  #11  
Old 11-02-2016, 02:18 AM
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That sounds high, especially at idle with a stock 90 Amp alternator. Should be about 13 Volts. Voltage regulator failure is possible; this could damage other circuits in the car and could eventually fry the battery through over-charging.

A monovalve leak probably would not affect electrical circuits. Look for drips or squirts from the monovalve after driving (warm engine). Typically doesn't leak big time, just enough to have to add a bit of coolant occasionally. For more information search this forum with "monovalve" and "jeremy5848" as keys. Repair is fairly easy; replacement is beyond merely "expensive" and won't fix the problem since MB's spares are defective.

Slow acceleration is usually due to not getting air or fuel. Check:
1. Primary and secondary fuel filters (easy)
2. Strainer in fuel tank (not so easy)
3. Air filter (easy)
4. EGR valve (consider blocking it for testing purposes)
5. Throttle flap (intake just before EGR valve)
6. Tuning flaps (crossover pipe and intake manifold)
7. Intake ports in head (often crudded up by EGR soot and crankcase breather oil)

Report results.

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
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  #12  
Old 11-05-2016, 09:16 PM
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New Alternator

Update: this afternoon I replaced the alternator and most of the electronic gremlins have gone away. Today marked the first time I've driven any distance and I love it. The only interior item not working is the tachometer, so I'm planning to pull out the gauge cluster and see what's going on. Replacing the alternator was straight forward with the help of a few YouTube videos lol. I post pictures as soon as I figure out how. Thanks for everyone's help!
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  #13  
Old 11-05-2016, 11:35 PM
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Location: Oberlin, OH
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Overvoltage relay failure can make the tachometer not work and can cause all sorts of electrical gremlins. Your might want to replace it before taking the gauges out.
__________________
-- Chris

'95 E300, 216k miles, Silver Surfer
'05 E320 CDI, 138k miles
'07 S550 4matic, 69k miles

Gone but not forgotten:

'76 300D, 350k miles?, SOLD in 1995
'75 240D, 300k miles, SOLD in 1991
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  #14  
Old 11-06-2016, 01:11 AM
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Location: Vancouver, BC
Posts: 1,493
Check the fuse on the ovp relay first, might have blown when the voltage went wonkey
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2007 Volvo XC70 -Wife's Daily
1998 Ford F150 -Rear ended
1989 J-spec 420SEL -passed onto its new keeper
1982 BMW 733i -fixed and traded for the 420SEL
2003 Volvo V70 5 Speed -scrapped
1997 E290 Turbo Diesel Wagon -traded for above
1992 BMW 525i -traded in
1990 Silver 300TE -hated the M103
1985 Grey 380SE Diesel Conversion, 2.47 rear end, ABS -Sold, really should have kept this one
1979 Silver 300D "The Silver Slug" -Sold
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  #15  
Old 11-06-2016, 03:52 PM
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Join Date: Nov 2010
Location: TX
Posts: 3,978
most probably the overvoltage relay fuses are open and the ELR relay is not working anymore (which drives the tach)

buy 2 10A blade fuses and replace them, the OVP relay is behind the curtain which is behind the battery. You can remove it with battery installed but its a bit of "small hands" job.

as preventive maintenance you should get a set of cabin filters for your car and a 30A strip fuse for the blower motor. The 30A fuse is quite tricky to buy so best order it from this site. NAPA have it but its quite a unicorn horn in their database.

The cabin filters are also almost never changed on these cars because they only showed up in 1995 and require some finagling to change out. They are under the wiper system. and are accessed by removing the driver side wiper tray/drain piece and lifting up the weatherstripping.

you have to simply peel up the rubber strip from the lower edge of the glass and you will see some screws, take them out, now look near the brake booster and heater pipes, you will see a white clip, it pulls straight out (dont drop it) - now remove the wiper trays.

you then reach in and unclip the filter cover and remove the filters one by one.

reverse the process for packup.

critical point when packing up, clean the weatherstripping channel with brush and soap, and use liquid soap in the channel to aid in install

make sure to install the wiper trays in their drains correctly otherwise water will collect where it shouldnt.

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1995 E300D - The original humming machine (consumed by Flood 2017)
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