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1984 300TD
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Discussion Starter #1
I've had my 1984 300 TD Turbo for about 2 months has been great until today... well a couple of days ago. Starting a couple of days ago it would not start every 2-3 times. I would just keep trying and then, voila, it'd start right up. I posted about this and a couple of people mentioned the starter. I've changed starter in 2 of my previous cars (65 Mustang and 90 Volvo 740). When starter problems began with those cars it began with that awful grinding noise. I could tap on the starter to get it going until I had a chance to change it on the weekend. In my 300TD there has been no grinding metal noise or clicking. Just nothing like when your battery is dead. Any ideas? Does this still sound like a starter? Maybe this is what it's like with a merc diesel. I'm new to these great cars and also have limited experience working on cars.

Another problem I had driving to work today. The car fired up great, drove about 20 miles fine and just before I got to work I was driving up hill and the rpm's slowly began to drop until the car "stalled." I tried to start again and I had the same start up issue. I had the gas pedal fully depressed when I started to lose power if that helps. After the tow truck driver dropped off my car at work, I tried to start up the car and voila! It fired and revved right up.

I'm not sure if these two issues are related. I suspect they are not. Also, the car has weak-ish power to begin with but I figured I would address it when I had a chance. It would drive gutless up hills even when flooring the pedal. Not to the point where I was concerned though.

This is my daily driver and I have little repair experience so feel free to respond as such without offending me. for now, I have trouble finding actual parts in the engine but once found I can usually do the job. The problem I find with many pics is that they are close ups so I don't even know where it is.

I will get a ride to and from work tomorrow and try to deal with it over the weekend.

Thanks,
Don
Los Angeles (South Bay)
 

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2013 MINI Copper S Clubman, '84 300CD-weekend car
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Fuel filters.

Check the ALDA for unclogged pressure lines.

Check the glow plugs for resistance.

I had a no start issue once, difficult with a jump as well.

Turned out to be the starter, no grinding noises.
 

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1984 300D
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I am not sure from you description if your Starter is Cranking the Engine but it is not Starting or the Starter is not turning at all some times.

If the Starter is not turning at all some times and you have an Automatic Transmission that can be Neutral Safety Switch or the Shfter Bushings going out.
The Wire Terminal/Junction Block in the pic below is in front of the Battery. If you Starter is not turning connecting a Remote Starter Switch (the safest way also in Park) or using a Jumper Wire on the Terminals shown at the Arrows will make the Starter Crank.

If you Starter Will not crank like that you have a problem with the Starter.

If the Starter does crank there is a good chance you have a Neutral Safety Switch or Shifter Bushing issue.
Another symptom is that the Starter will crank in Neutral but not in park.
 

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Look at the Plastic Fuel Filter and see if there is anything inside of it. If there is grayish black stuff in that Filter there is a good chance you have an organism growing inside of your Fuel tank that is starting to plug up your Fuel System.
 

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1984 300TD
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Discussion Starter #6
Ok, that makes sense about the start issue. There is definitely a bushing issue with the automatic transmission. I had thought maybe it wasn't fully in Park so I've shifted back to neutral then back up but I hadn't thought that might be it because it didn't work every time. I guess I didn't fully engage it in Park.

In theory, if that's the start issue, should I be able to replace the bushings of shifter/transmission linkage to fix it? Or do I need to change the neutral safety? Both? Now I just need to find out where this Neutral Safety Switch is located.

I did a quick look at the fuel filter before heading into work. It's the translucent one that's a little bigger than an old school film canister? Located towards the rear, right -side of the engine at the top? I saw some black chunks/particulate. I thought there were 2 fuel filters though. Would I inspect/change both? I'm not sure if you're joking about an organism growing though. Should I check the fuel screen on the bottom of my tank? Unfortunately, I still 3/4 tank.
 

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Brown 83 300SD I have a few other projects before I get to her!
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I would also get the tank cleaned too. I would bet your tank screen is clogged. The fuel pump sucked the dirt to the screen not allowing enough fuel to the line. After you towed it & it's been off for awhile, whatever that was on the screen was not being held on by suction any longer.

You can keep changing the primary & secondary filters or start fresh from the tank & I believe your stalling issue will be over. At least rule that out first. Think about it, your fuel tank has been holding fuel for over 28 years. I know mine was never out of mine before I did it. It was still being held by the original factory glue. It's amazing mine even ran w/ how dirty my screen was.

Good Luck,
Dave
 

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Ok, that makes sense about the start issue. There is definitely a bushing issue with the automatic transmission. I had thought maybe it wasn't fully in Park so I've shifted back to neutral then back up but I hadn't thought that might be it because it didn't work every time. I guess I didn't fully engage it in Park.

In theory, if that's the start issue, should I be able to replace the bushings of shifter/transmission linkage to fix it? Or do I need to change the neutral safety? Both? Now I just need to find out where this Neutral Safety Switch is located.

I did a quick look at the fuel filter before heading into work. It's the translucent one that's a little bigger than an old school film canister? Located towards the rear, right -side of the engine at the top? I saw some black chunks/particulate. I thought there were 2 fuel filters though. Would I inspect/change both? I'm not sure if you're joking about an organism growing though. Should I check the fuel screen on the bottom of my tank? Unfortunately, I still 3/4 tank.
You can bypass the Neutral Safety Switch; but after that you need to besure it is in Park when you start the Car.

“First make sure the selector is in P or N. Cycle through all the gear positions and try in N.

Above the accelerator pedal is a 4-wire plug with a harness that runs down to under the accelerator pedal and to the transmission tunnel. Unplug it, jumper across the two purple wires in the female plug and try to start again. If it starts, you need a NSS.”

I copied the above from another Forum. He did not say this but it still could be the Shifter Bushings. However, it is more often the Switch itself that is the cause. You won't know until you look at the Bushings.

I do not know if your cars wiring is the same but I got part of this quote from another Forum concerning a no cranking problem with an 84 300D.

For more details
Repair Links
DIY Links by Parts Category - PeachParts Mercedes ShopForum

PeachPartsWiki: Do It Yourself Articles - Mercedes Vehicles

There is the Translucent Plastic Filter (the Primary Filter) and there is a Spin-on Fuel Filter (The Secondary Filter. in front of and slighly to the left of the Fuel Injection Pump.)
 

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1984 300TD
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Discussion Starter #9
The more I research on the different sites, it sounds like changing the fuel filters should be changed and hopefully do the trick. I think I will also clean or change the fuel tank screen.

Any stuff I need to do to prepare the car, fuel system... For a tank cleaning? Before and after.

Does anyone know of a reputable place in the L.A. area (Westside or South bay) to get the tank cleaned?

Thanks,
Don
 

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1984 300TD
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Discussion Starter #10
HELP!!!

Earlier today I replaced both fuel filters. As I was doing that, I noticed that the clear nylon hose that comes out of the ALDA to the back of the intake manifold (?) was not connected. It was still connected to the ALDA but not at the other end. I had broken off at the intake end and was flopping around.

I got a new hose from the auto parts store. I removed and clean out the banjo bolt with brake cleaner, put everything back and connected the new hose.

I started the car and it sounded and felt great. No unusual vibration or roughness. I did notice some white smoke at idle and more when I pressed on the pedal while in Park. I drove it around to test it and it was much more powerful and smoother driving. I was feeling like I had really fixed the situation.

...then, after driving for about 4 miles it happened again. The rpms dropped until it stalled. I was able to start it right back up but when I tried to rev it up it was unresponsive and then died again. I waited about 10 minutes and it fired up again right away and I drove off. Again, it drove nice until 2 miles later when it died again. I happened to be near a Home Depot so I window shopped for about 30 minutes and came out then drove home. It started right up and drove well for about 3 miles when the rpms dropped again. This time I pulled over before it stalled. I left the car running and periodically revved up the engine to about 4000 rpms until it felt normal. meaning it didn't feel like it wanted to stall. It felt like I was "clearing" out the fuel lines. I drove home and it felt good again.

Does this sound like the fuel tank strainer is getting clogged and then the sediment "swooshes" around or settles and allows the normal flow of fuel to continue? A cycle of clearing and clogging?

I have no clue and I'm feeling desperate now because this is my daily driver.

A couple of things that may or may not help figure this out. I emailed the former owner and asked if this had happened. He said no, but for all i know he was lying. He did say he hadn't done it for a few months prior to me buying it, but had previously run it on some veggie oil cocktail. he listed off the ingredients but I don't remember any of it except veggie oil and kerosene. :-((((( I can only guess that this could be a major culprit. Also, I noticed that the middle injector (#3?) seemed to be leaking fuel from around the midpoint of the exposed housing. It didn't seem like a lot but it was moist.

thanks,
Don
 

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Discussion Starter #11
I did prime the fuel with the pump until it felt more difficult to pump. I didn't want to create too much pressure and break something. Should I have pumped longer and got more air out. I still saw a little air pocket in the clear fuel filter.
 

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Sorry I sent that before finishing...as I said loosen up the spin on housing and pump until no more air comes out then tighten back up.
 

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This will bypass the Fuel Tank Screen but you need to have a minimum of 1/2 Tank of Fuel and you need to remember that you are going to be drawing Fuel from a higher position in the Fuel Tank and that means if you are not careful to keep the Tank 1/2 full you can run out of Fuel earlier than the Gauge shows.

Where the 2 Fuel Tubings come off of the Fender Well. Swap the positions of the Fuel Inlet Hose with the Fat "Cigar" Fuel Return Hose. That will draw Fuel from a Higher spot of of the Bottom in the Fuel Tank; bypassing the Fuel Tank Screen.

If your Plastic Fuel Fuel Filter is showing gray blackish colored stuff inside you have something growing inside of your Fuel Tank.

You will need to treat the Fuel with a Chemical to kill of the Organisms growing in the Fuel ; you still need to do that even if you were to pull out your Fuel Tank and clean it out to kill the Infection that is still in the Fuel Lines/Tubings.

After Cleaning an Fuel Treatment you may end up changing Filter several time untill all of the Dead Bodies have passed through the system.
Using the Startron product that is made for dealing with the organisms you may not need to change the Filters as often.
 

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I did prime the fuel with the pump until it felt more difficult to pump. I didn't want to create too much pressure and break something. Should I have pumped longer and got more air out. I still saw a little air pocket in the clear fuel filter.
Actually even if you put the Spin-on Filter empty you can pump the Hand Primer until you hear the squishing or buzzing sound of the Air passing through the Fuel Pressure Relief/Over Vlow Valve. After that pump somemore just to be sure.
That beeeds the Air out of the Fuel Supply System.

The High Pressure Fuel injection System happens between the Fuel Injection Pump and the Injectors.
If Air gets trapped in there it can keep you from starting because the Air compresses and does not easily move on down the line.
To bleed the Air from the High Pressure part of the System you simply loosen the Fuel Injection LIne Nuts at the Injectors to allow a way for the Air to escape and crank the Engine untill Fuel is coming out.

Is the Injector Leaking between the upper and lower 1/2 of the Injector?

Or is the Injector leaking where the Injector screws into the Cylinder Head?
 

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Discussion Starter #16
Thanks for the responses. I couldn't get back to the computer yesterday. I think what you mentioned might be the case. When I first changed the 2 fuel filters the tank was 40% full. That's when I still had stalling issues. The next day (Sunday) I went to run some errands but went to the gas station right away. I've driven about 50 miles since filling up without any issues. Now that I think about it, it stalled right around the tank being 1/2 full. I guess I'll keep it safely above 1/2 full until I have time to address it more thoroughly. The clear, inline filter definitely has quite a bit of black stuff after a day and a half. I'm assuming now that is algae. I have a week off from work coming up soon. Let me know what everyone thinks about the following course of action.

-use some sort of algae killer (bio-cide, Startron, ...)
-Continue to change inline fuel filter as necessary
-diesel purge
-empty and clean fuel tank. Since this is a wagon, from what I've read I think I can get away with this without pulling the tank. Hmmm, I wonder if I can pull the fuel sending unit out without pulling the tank too.
-clean or change fuel strainer as necessary.

Regarding the leaky injector. I can't really tell but I think it's leaking near the middle because the bottom half has "residue.". I'm wondering how urgent this is to keeping the car running. For now, I'm not worried about loss of power but of destroying the engine.

I do not notice any smoke at idle anymore and can't tell when I'm driving.

My final concern for now is that the ALDA bypasses the switchover valve and goes directing to the back of the intake. I've read that some people do this but have read mixed responses about whether or not this is bad for the engine. Thoughts? I would just hook it back up to the switchover valve but I don't see anything on the firewall that resembles the pictures I've seen. I will try to get a picture posted of the area.

Thanks,
Don
 

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Inspect the injector jumper lines, a leak there will run down onto the injector itself.

The switchover valve is close to the brake booster.

Mine has been bypassed by a previous owner.

My other car has the ALDA adjusted, I've driven with it completely disconnected, no issues other than using more fuel.
 

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Thanks for the responses. I couldn't get back to the computer yesterday. I think what you mentioned might be the case. When I first changed the 2 fuel filters the tank was 40% full. That's when I still had stalling issues. The next day (Sunday) I went to run some errands but went to the gas station right away. I've driven about 50 miles since filling up without any issues. Now that I think about it, it stalled right around the tank being 1/2 full. I guess I'll keep it safely above 1/2 full until I have time to address it more thoroughly. The clear, inline filter definitely has quite a bit of black stuff after a day and a half. I'm assuming now that is algae. I have a week off from work coming up soon. Let me know what everyone thinks about the following course of action.

-use some sort of algae killer (bio-cide, Startron, ...)
-Continue to change inline fuel filter as necessary
-diesel purge
-empty and clean fuel tank. Since this is a wagon, from what I've read I think I can get away with this without pulling the tank. Hmmm, I wonder if I can pull the fuel sending unit out without pulling the tank too.
-clean or change fuel strainer as necessary.

Regarding the leaky injector. I can't really tell but I think it's leaking near the middle because the bottom half has "residue.". I'm wondering how urgent this is to keeping the car running. For now, I'm not worried about loss of power but of destroying the engine.

I do not notice any smoke at idle anymore and can't tell when I'm driving.

My final concern for now is that the ALDA bypasses the switchover valve and goes directing to the back of the intake. I've read that some people do this but have read mixed responses about whether or not this is bad for the engine. Thoughts? I would just hook it back up to the switchover valve but I don't see anything on the firewall that resembles the pictures I've seen. I will try to get a picture posted of the area.

Thanks,
Don

To the best of my knowledge with normal use of your Car the Switchover Valve will never activate. I believe you have to have an abnormal amount of Manifold Pressure for that.

The leaking Injector will cause no Engine Damage; just a mess.

You might just as well get some Injector Return Fuel Line and replace it on the leaking Injector if only to rule out the Return Line as a source of the problem. NAPA sells it as does the local VW Dealer (used on the Older VW Rabbit Diesel from the 1980s). From the Dealer it comes in a 1 Meter length.

If it turns out the Injector is leaking between the upper and lower halves remove the Injector and try torquing it to the proper torque and install it and see if it leaks.
If it does not leak remove the Injector again and replace the Injector Heat Shield.

If it still leaks in the thread below there is instructions on taking the Injector apart and how to lap the precision surfaces

How to Rebuild Injectors
vincewaldon.com - HOW-TO: Rebuild Diesel IDI Injectors
 
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