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  #1  
Old 03-21-2018, 01:40 AM
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W115 240D slow, and eating glow plugs

So, long story. A guy at work had this car for years. He finally sold it to me after sitting in a storage unit for two years. He never had to work on the car because it never gave him any problems. The primer handle started leaking and he pulled the whole pump off. Needless to say, it wouldn’t start anymore. My indy got it installed and timed, but it took 45 seconds to get to 30 mph. I bought a used injection pump and it ran faster, but crazy black smoke. Tried two more pumps before having the first one rebuilt for $1400. Still some smoke and we’re thinking it’s the stem seals. My mechanic says the engine is very good, but the car is still half as fast as my W123 240D.

0-60 in ~40 seconds. I had read that it should be around 22 seconds. I can barely drive it to work because of a rise in the freeway. My other 240D and my 300D maintain their speed on this hill, but this 115 drops down to 50mph.

About every couple trips to work, I lost the cylinder 2 glow plug. I installed the mercedes source fast glow parallel wiring kit and lost the #2 glow plug twice, then the #3 glow plug twice. My indy had me get one new prechamber to see what happens because he’s out of ideas. Now I lost the #1 glowplug. I ordered three more prechambers to see if that fixes it.

I’ve had the tank out, new screen, new filters, all new lines, new injection pump, new injectors, and soon new prechambers. Valve adjustment was done two weeks ago. A/C was done last summer and blows super cold, but doesn’t slow down the engine at all when it’s on. The car feels slowest in 3rd gear, no matter what rpm, even when downhill.

Any ideas for the poor performance? Or the glow plugs?

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  #2  
Old 03-21-2018, 07:07 AM
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Make sure the ground strap that was used when the glow plugs were wired in series is not attached to any part of the glow plug system now that you have the fast glow plugs.

Did you ream out the glow plugs holes to remove any carbon that may be present?

Check your throttle linkages for any play.
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  #3  
Old 03-21-2018, 08:52 AM
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Quote:
Originally Posted by Hawk8789 View Post
So, long story. A guy at work had this car for years. He finally sold it to me after sitting in a storage unit for two years. He never had to work on the car because it never gave him any problems. The primer handle started leaking and he pulled the whole pump off. Needless to say, it wouldn’t start anymore. My indy got it installed and timed, but it took 45 seconds to get to 30 mph. I bought a used injection pump and it ran faster, but crazy black smoke. Tried two more pumps before having the first one rebuilt for $1400. Still some smoke and we’re thinking it’s the stem seals. My mechanic says the engine is very good, but the car is still half as fast as my W123 240D.

0-60 in ~40 seconds. I had read that it should be around 22 seconds. I can barely drive it to work because of a rise in the freeway. My other 240D and my 300D maintain their speed on this hill, but this 115 drops down to 50mph.

About every couple trips to work, I lost the cylinder 2 glow plug. I installed the mercedes source fast glow parallel wiring kit and lost the #2 glow plug twice, then the #3 glow plug twice. My indy had me get one new prechamber to see what happens because he’s out of ideas. Now I lost the #1 glowplug. I ordered three more prechambers to see if that fixes it.

I’ve had the tank out, new screen, new filters, all new lines, new injection pump, new injectors, and soon new prechambers. Valve adjustment was done two weeks ago. A/C was done last summer and blows super cold, but doesn’t slow down the engine at all when it’s on. The car feels slowest in 3rd gear, no matter what rpm, even when downhill.

Any ideas for the poor performance? Or the glow plugs?

Is this an AT or MT? I didn't see any mention.


With an AT, there is the need to check your shift linkages using the procedure in the manual. Have they been changed?


How does the car shift? Do you feel any difference if you accelerate slowly or faster?Does it ever sound like it's overspeeding in a gear, waiting to shift??


If AT, when was the fluid changed? Filter changed?


These are cars where multiple simple things impact the diesel's ability to accelerate. Ya gotta check them all. That's why I went to 240D MT models which are simplicity themselves.


Good luck!
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  #4  
Old 03-21-2018, 09:08 AM
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The glow plugs are not grounded. I double checked all the wiring last night after I posted and it looks good. It is a manual transmission and first thing I did when I got it was replace all the bushings in the linkage. Everything feels good.
Basically, the car accelerates rather quickly at first, but the pedal doesn’t really do anything the farther you push it. The throttle linkages have been checked many times. It also feels slower every time I drive it.
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  #5  
Old 03-21-2018, 09:28 AM
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Eating glow plugs, in what way? Do you mean the end of the plug is eaten away, or the plug just died? What brand plugs are you using?
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  #6  
Old 03-21-2018, 09:31 AM
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Lack of power / speed: check the brakes to make sure none are dragging.

The most important throttle linkage test or check is to make sure that the injection pump linkage is at full stroke (against the external stop) when the accelerator pedal is held to the floor.

I believe this model has a butterfly valve in the intake somewhere? Is that operating correctly?

Another possibility is that the exhaust is plugged up and preventing the engine from breathing in fresh air.
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'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
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  #7  
Old 03-21-2018, 10:15 AM
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There was a local 115 diesel. The owner contacted me. Slow and top speed was about 50 mph he claimed. Found the previous owner or owners had installed an electric fuel pump for a gas carb engine. Was too low of a fuel pressure. A four to six pound pump. I suggested rebuilding his lift pump but he did not. Since the injection pump was rebuilt the lift pump is assumed good for now on yours. The lift pump must be functioning properly to calibrate the injection pump when rebuilt.

You may have rebuilt the linkages that being a good thing. The injection pump is rebuilt as well. Another good thing as the earlier injection pumps can have certain issues. It also is such a simple thing but from my experience far too many owners miss it.

Observe if the linkage is enabling the lever on the injection pump to reach all the way. Takes two people with one pressing the fuel pedal. At this point only spend money where there are solid indications. Pull the number two injector and have it tested. Tested not rebuilt if not needed. A bad injector can take out glow plugs. Also by this time I assume you know that for all practical purposes only one brand of glow plugs should be used. I doubt this is your problem as even the bad brands last longer and would not have failed more than once that quick in the number two location.


There is another simple test. To eliminate something like a bad tank fuel strainer. Your rebuilt injection pump should be creating a constant overflow out the relief valve. This valve also is an operational fuel pressure regulator. If no flow there is a possibility of a fuel starvation issue. It is very frustrating to have a problem like this. At the same time it does not really mean it is serious.

Also the smoke you see should be identified. If it stings the eyes the injectors are suspect. Where they ever tested? This based on the assumption the mechanic really knows the basic engine is sound. Plus he has the injection pump timed properly.

I am not familiar with the butterfly issue on these earlier engines. The poster that mentioned it probably is. Your mechanic has suggested a new pre chamber for the second cylinder. Is the ball dislogged? Or is it only speculation? Has the injector even been removed and the pre chamber inspected? There are quite a few things you can check out yourself on these engines.

Last edited by barry12345; 03-21-2018 at 12:01 PM.
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Old 03-21-2018, 10:34 AM
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The glow plug holes were reamed. He said my prechambers were dirty, but the bearing was still there and the holes were clear. We’ve been putting that off till last, but now there’s not much to do except replace them and see what happens.

The pump goes to full stroke. The butterfly valve works. I have the oil bath filter in now, but the previous owner made a housing for a ‘regular’ air filter. I’ve gone back and forth between them and haven’t noticed any change other than the car running a little warmer in the afternoon with the oil bath.

My indy says the engine itself is like new. He didn’t think the prechambers were that bad, but since I was losing the same glow plug he wanted to install one new prechamber to see what happened. Since I lost a different plug this time, I went ahead and ordered 3 more.

The loop style plugs were breaking off. I switched to Monark pencils with the new wiring kit. I’m not sure what brand they were giving me at the shop, but they told me I used them all...

Before the kit was installed, my indy found the start knob was shorting in the glow plug position. He thought that was the cause and I opted for the kit rather than trying to find a new knob. It still seems to engage the starter correctly and I don’t see how that could affect the glow plugs now that they’re on their own circuit.
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  #9  
Old 03-21-2018, 11:58 AM
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Quote:
Originally Posted by Hawk8789 View Post
He never had to work on the car because it never gave him any problems.
How unfortunate. Sounds like a vehicle that has been grossly neglected. These cars require significantly more maintenance than a modern car does. Driving it into the ground until something breaks is not a recipe for longevity. It's like saying you don't need to worry about your health, because you haven't been hospitalized yet.
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  #10  
Old 03-21-2018, 12:27 PM
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Eating glow plugs is NOT NORMAL (too much iron in the diet). Seriously though, if you were consistently losing a glow plug in one cylinder consistently, it would make sense to check injector pattern and look at prechamber condition.

However, you've lost a plug in nearly every cylinder now, and in VERY short time. I'd be looking at your glow plug system somehow remaining energized.
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  #11  
Old 03-21-2018, 12:30 PM
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Monarch glow plugs if they really are. Not a good choice. Injectors need testing if not already done. No particular positive indication. Yet at the same time a general maintenance item. Probably long overdue. Could also be some of the issue in your case.

I assume the valve clearances where checked on this engine as well. It sounds like the last owner never bothered. Ask your mechanic. If not familiar with this type of engine. He might have just assumed they are hydraulic.

Once again a standard maintenance item that is probably not creating a real problem. At the same time a lack of valve clearance can cause some. It is likely that you do have a problem. Plus a substantial amount of deffered Maintenance as well.

Personally I would fixate on the relief valve having overflow first of all. Partially because it is easy to do. Also that the fuel coming out does not have a lot of air mixed in with it.

You have no power or top end. A classic case of fuel starvation has to be considered high on the list.. Just my opinion though. This car is also a candidate for dragging brakes. Hand push it on a flat surface for a foot or two.

The glow plug issue may or may not be related. So I would leave that for later at this time. They in themselves do not control power or the ability to have top end. That is the first problem to chase.

Last edited by barry12345; 03-21-2018 at 12:47 PM.
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  #12  
Old 03-21-2018, 01:00 PM
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I must clarify that the previous owner maintained the vehicle. What I meant was that nothing ever needed replaced or repaired until he removed the injection pump and he lost interest when he realized he was out of his element. I re did the entire fuel system before I realized the pump was bad. The injector or Bosch reman and all checked. The first thing I did was adjust the valves and they were all in spec.

If the brakes are sticking, would it be the calipers or something else? The pads and rotors looked good when I did the shocks and there are no leaks so I haven done any brake work. Wouldn’t sticking brakes slow the vehicle down more at low speeds than it would at 70 on the freeway?
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  #13  
Old 03-21-2018, 04:00 PM
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are any of the wheels hot after you go for a drive?
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  #14  
Old 03-21-2018, 04:24 PM
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Check the air intake and exhaust for restrictions. Run it BRIEFLY with the air cleaner disconnected and same for the exhaust.

Good luck!!!
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Old 03-22-2018, 10:25 AM
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I had run it without the intake with no difference. I haven’t tried the exhaust. I’ve put several hundred miles on the car, hoping it would clear up but it hasn’t. I’ve been waiting for a chance to replace the valve stem seals and part of me thinks I shouldn’t spend time or money until I do that. Most of what I read are smoke issues, but would the seals affect performance? My indy doesn’t think they’re responsible for the glow plugs, but could they be messing with my fuel/air mixture?

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