'86 300 SDL - Mystery - Please Help - PeachParts Mercedes-Benz Forum

Cowboy · #1 02-11-2006, 02:26 PM

Hello Everyone,

Although this is my 1st post, I have been reading thru this forum
for a number of weeks now. What a tremendous amount of
information.

However, I have yet to find the answers to my problems!

I could write a book about this entire adventure and I am sure
some of you would find it quite entertaining...I'll not bore you
with all of the details.

This all starts with...I purchased this car on eBay. It is an '86
300 SDL with 187K miles. When I picked this car up, it started
really fast but, it did not sound smooth. We trailered the car
to home and she would not start to unload. We jumped her
off, unloaded her and parked her in the driveway.

She ain't started since!

I am in rural central Texas...no Mercedes mechanics around
here. Every trusted mechanic and diesel mechanic I know in
these parts has looked at this car...to no avail. The only
diagnosis is that the car is not turning over fast enough to start.

I took her to a recommended mechanic in Abilene and he had
this to say: The battery is good, the starter is good, it is getting
fuel, and the starter is pulling way too many amps while trying
to crank her. He suggested a 'stacked' bearing might be the
culprit.

Here is what has been done to the car:
Replaced the battery
Replaced the starter
Check all the grounds
Checked the glow plug relay
Made sure fuel was getting past the injector pump
Pulled valve cover off
Took out the timing chain tensioner-it seems to be ok-I lost one
of the 5mm steel balls and am trying to locate one then I will
reinstall it.

FYI- she does not have a 'trap oxidizer'.

A couple of things are real puzzling...how fast it started at
first and how fast it decided never to start again.

I am not a mechanic. However I can do have some mechanical
experience. And I am not 100% familiar with all of the
abbreviations you guys use in this form. So, please be very
descriptive with your responses.

In a nutshell: Please Help!

Thanks a million.

Hatterasguy · #2 02-11-2006, 06:38 PM

Hmm this is a perplexing one. Has the IP and/or head been off recently? I say this beacuse I am wondering if it may be way out of time. Timing a 603 is easy you just need to rent the tool from a forum member.

Other then that I assume you cracked the injector lines and made sure they all have fuel getting to them?

Also make sure the engine "stop" lever is not down. I know it may sound stupid, but it is the simple stuff that usually gets you.

Brian Carlton · #3 02-11-2006, 06:41 PM

The information provided is not sufficient to determine why it started once when you picked it up but won't start again. Is it possible that it was not completely cold when you picked it up? Is it possible that the ambient temperature was 10-15°F. warmer when you picked it up?

Without a clear picture of the events, it's necessary to verify that the glow plugs are working properly. You need to verify that there is 12V at each of the plugs and that the glow plug relay is working properly.

Most starting problems that happen suddenly will typically lead to some issue with the lack of one or more glow plugs. The causes can be bad plugs, a bad relay, or a simple cracked fuse within the relay. All these possibilities need to be investigated. There is a multitude of posts on the forum with these procedures.

For the mechanic to state that the starter is drawing too much current would require a mechanic very knowledgeable regarding these vehicles. I can't state flatly that he is mistaken, because I don't have the number for the current draw or the cranking speed, but, given your description of the type of mechanic available in your area, I have some suspicions regarding the accuracy of his statements.

bhatt · #4 02-11-2006, 07:25 PM

I have the same car.. give this a shot:

1. ENSURE your glow plug light is working. If not, check the fuse (do a search on how.. or email me)
2. Turn the key till the glow light comes on, then it should go out in about 3sec or so.
3. Keep waiting with the key in the same position. After about 10-15sec longer, you should hear a 'click' from under the hood (easier heard if the hood is open). This means the glow relay has shut off. Another way to tell is by watching the overhead light with the door open.. it will get a bit brighter when the relay shuts off.
4. Repeat step #3 again
5. Crank and keep cranking the engine for 10 seconds or so.

My car (in Canadian winters) will start at 0 degrees Fahrenheit by doing the above, and it starts in about 5 seconds after glowing twice. If you glow twice and it doesn't start (in Texas weather!) something is DEFINATELY wrong.

Let us know what happens after you follow the above. It will give us some clues to move on to the next troubleshooting step.

Neal

Palangi · #5 02-11-2006, 07:27 PM

This is a long shot, but I recall 2 or 3 cases with similar symptoms where the problem turned out to be a siezed alternator. You might want to let the belt tension off and spin the alternator, water pump, compressor, pulleys, etc, by hand.

#6 02-11-2006, 07:53 PM

I think from the information giving that you have solved it I cannot think of any other cause for low cranking speed under these circumstances. Loosen the belts try to start it even if it fails to start is the cranking speed greatly improved if so find the belt driven part that is frozen then check glow plugs.
Dave S

Cowboy · #7 02-11-2006, 07:53 PM

Quote:

Originally Posted by Hatterasguy

Hmm this is a perplexing one. Has the IP and/or head been off recently? I say this beacuse I am wondering if it may be way out of time. Timing a 603 is easy you just need to rent the tool from a forum member.

Other then that I assume you cracked the injector lines and made sure they all have fuel getting to them?

Also make sure the engine "stop" lever is not down. I know it may sound stupid, but it is the simple stuff that usually gets you.

I do not know if the ip or the head has been off recently. I have deducted
the ip has been off sometime in the past, as it has yellow steel paint across
selected bolt heads...which is generally how they mark one to make sure
you don't take it apart then cry warranty.

Yep, cracked all the lines...this was done more than once and by two
different mechanics and it resulted in a small amount of fuel coming out.
The diesel mechanic said it was not turning over fast enough to check if
the ip was working properly.

Stop lever is working properly.

Nothing has been done to the ip or the head under my ownership.

Thanks a bunch.

t walgamuth · #8 02-11-2006, 08:05 PM

is loos be sure to check the tensioner. (is this a serpentine belt?) i am assuming it is.

other than that the glows would seem the most likely suspect.

tom w

Cowboy · #9 02-11-2006, 08:18 PM

Quote:

Originally Posted by Brian Carlton

The information provided is not sufficient to determine why it started once when you picked it up but won't start again. Is it possible that it was not completely cold when you picked it up? Is it possible that the ambient temperature was 10-15°F. warmer when you picked it up?

Without a clear picture of the events, it's necessary to verify that the glow plugs are working properly. You need to verify that there is 12V at each of the plugs and that the glow plug relay is working properly.

Most starting problems that happen suddenly will typically lead to some issue with the lack of one or more glow plugs. The causes can be bad plugs, a bad relay, or a simple cracked fuse within the relay. All these possibilities need to be investigated. There is a multitude of posts on the forum with these procedures.

For the mechanic to state that the starter is drawing too much current would require a mechanic very knowledgeable regarding these vehicles. I can't state flatly that he is mistaken, because I don't have the number for the current draw or the cranking speed, but, given your description of the type of mechanic available in your area, I have some suspicions regarding the accuracy of his statements.

This car had been sitting for about 2 weeks and had not been started. It
was pouring down rain and about 50 degrees. She fired up on the 1st try.

The very next morning, about day break, temperature in the mid 30's and
still raining I decided to see if she would fire up and sure enough she fired
on the first try. The block heater was not pluged up.

The glow plug relay has been checked and is working properly. I did discover
a hair line crack in the 80 amp fuse and replaced it. I do not know the exact
voltage being delivered to each glow plug. I can check tomorrow.

This vehicle came under scrutiny of eBay's Vehicle Protection Program and
the related insurance agency which handles each case for eBay.

I took the vehicle to a recommended mechanic in Abilene who knew all the
details on the car before I took it to him. It's about 100 miles from here. It
was agreed the 1st thing he would do is check the amount of (damn I don't
remember whether it is amp or volts...I think it is amps) the starter was
pulling while trying to crank the vehicle. In other words, while it was still on
the vehicle.

He reported back the next morning the car was pulling way too many amps
while trying to start the car. Whether or not he knows what he was doing I
can't say for sure, however I felt he did.

Thanks for your input.

Cowboy · #10 02-11-2006, 08:23 PM

Quote:

Originally Posted by bhatt

I have the same car.. give this a shot:

1. ENSURE your glow plug light is working. If not, check the fuse (do a search on how.. or email me)
2. Turn the key till the glow light comes on, then it should go out in about 3sec or so.
3. Keep waiting with the key in the same position. After about 10-15sec longer, you should hear a 'click' from under the hood (easier heard if the hood is open). This means the glow relay has shut off. Another way to tell is by watching the overhead light with the door open.. it will get a bit brighter when the relay shuts off.
4. Repeat step #3 again
5. Crank and keep cranking the engine for 10 seconds or so.

My car (in Canadian winters) will start at 0 degrees Fahrenheit by doing the above, and it starts in about 5 seconds after glowing twice. If you glow twice and it doesn't start (in Texas weather!) something is DEFINATELY wrong.

Let us know what happens after you follow the above. It will give us some clues to move on to the next troubleshooting step.

Neal

Yep the glow plug light does come on for a very short period of time.

I will follow your directions as soon as I find a 5mm steel ball and put the
timing chain tensioner back on and the valve cover.

I'll let you know.

Thanks.

Brian Carlton · #11 02-11-2006, 08:28 PM

Quote:

Originally Posted by Cowboy

He reported back the next morning the car was pulling way too many amps
while trying to start the car. Whether or not he knows what he was doing I
can't say for sure, however I felt he did.

Thanks for your input.

It does sound like you are close to ruling out the glow plugs. And, if the cranking speed is insufficient, then it won't start, even if the glow plugs are functional.

So, if it won't start due to low crank speed, there are a couple of items to check:

1) Get a 27mm socket and try to rotate the engine via the crankshaft bolt. It's not easy to rotate a diesel but with a 12" lever (1/2" socket wrench) you should be able to budge it with all of your arm strength. With an 18" lever you will certainly move it.......not easily but more than sufficient to rotate it 30 degrees or so.

If this happens, then the engine and it's accessories are eliminated as the cause of the problem.

With the engine and it's accessories eliminated, the cause of the excessive current draw is a bad starter or bad cables to or from the starter. Since cables are the cheaper option, disconnect and clean the positive terminal and the wires to the starter. Do the same thing with the ground cable and it's attachment to the body. Make sure the grounding strap from the engine to the body is solid and clean.

See if the engine now turns faster.

2) If the battery is definitely the proper size and fully charged, the engine rotates freely with the socket wrench, and both supply side and ground cables are properly attached and clean, and the cranking speed remains too slow, then consider pulling the starter and having it tested and/or replaced.

Cowboy · #12 02-11-2006, 08:29 PM

Quote:

Originally Posted by Palangi

This is a long shot, but I recall 2 or 3 cases with similar symptoms where the problem turned out to be a siezed alternator. You might want to let the belt tension off and spin the alternator, water pump, compressor, pulleys, etc, by hand.

Now there is an idea. I'll check them tomorrow.

There seems to be something no allowing the motor to spin fast enough
to crank. And after the first few seconds of trying it will drain the battery
and cranking speed is further reduced.

It even does this with my diesel pickup hooked up to the jumper cables...and
the battery is brand new on the car. I think it is an 850 or 900 cca.

Thanks.

Cowboy · #13 02-11-2006, 08:32 PM

Quote:

Originally Posted by mattdave

I think from the information giving that you have solved it I cannot think of any other cause for low cranking speed under these circumstances. Loosen the belts try to start it even if it fails to start is the cranking speed greatly improved if so find the belt driven part that is frozen then check glow plugs.
Dave S

I'll get 'er done tomorrow.

Thanks.

Cowboy · #14 02-11-2006, 08:33 PM

Quote:

Originally Posted by t walgamuth

is loos be sure to check the tensioner. (is this a serpentine belt?) i am assuming it is.

other than that the glows would seem the most likely suspect.

tom w

Yep it is a serpentine. We shall see.

Thanks.