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  #16  
Old 01-28-2016, 04:28 AM
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If the valves haven't been adjusted on schedule, that is part of the issue. If any of the following are marginal, cold weather starting is compromised: valve adjustment, glow plug system, battery, wrong (thick) engine oil, strong starter, fuel system losing prime (air leaking in), water in fuel.

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  #17  
Old 01-28-2016, 07:00 AM
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one plug was bad... now the light flickers when glowing... I'd change all 4 to bosch... just my opinion.
and make sure you have the resister wires and washers in the correct positions...
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  #18  
Old 01-28-2016, 07:44 AM
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Quote:
Originally Posted by vstech View Post
one plug was bad... now the light flickers when glowing... I'd change all 4 to bosch... just my opinion.
and make sure you have the resister wires and washers in the correct positions...
That is rapidly becoming my opinion as well. Clearly, the glow circuit is not working 100%. I am a bit tempted to convert to a parallel system if I'm going to the effort/expense of changing all four plugs.

To address a few other questions raised:
-It's a 1978 model with plugs wired in series. (just edited my signature so that shows up)
-Tank is full. After the non-start in the cold a few weeks ago, I filled up and added anti-gel. Temps have warmed to the point that the fuel shouldn't be gelling.
-Regarding "cold" issues, the weather that originally left it stranded in a parking lot was around 15F. The outside air is now 30 or better and it's probably in the 40s in my garage and has been for a couple days. It's more than just a cold issue.

I'll be working on it more after work tonight and will report back.
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Last edited by Redpeople; 01-28-2016 at 08:27 AM.
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  #19  
Old 01-28-2016, 09:09 AM
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Scott,

I'll bet that the maintenance manual for your 240D says that the valves should be adjusted every 12500 miles or annually, which ever comes first. A good strategy is to adjust the valves in the fall to ensure best engine compression during the most challenging starting conditions (cold weather).

Even though this problem suddenly appeared, coincident with a failed glow plug, if your valves are due for an adjustment, the engine can go from "starting" to "not starting" seemingly overnight, due to valves going out of adjustment (tight, less compression).

In my experience, the block heater only needs about 30 - 60 minutes to do its thing, so you may want to measure the resistance between the flat blades of the plug. Should be around 28.8 ohms, assuming your block heater is 500 watts.
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  #20  
Old 01-28-2016, 09:19 AM
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My 77 240D had no issue starting up in the midst of the coldest Chicago winter, usually after one glow cycle. Never used a block heater, I did treat the fuel during the winter with Power Service Cetane Boost ( Robot Check )

That made a noticeable difference in cold running smoothness. I would also always turn the idle adjustment knob to the furtherest most left (fastest idle) when it was that cold. I would run it really fast for a few minutes then adjust it back down to a normal idle. That seemed to help in very cold temp starts.
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  #21  
Old 01-28-2016, 09:41 AM
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Super advice, guys. I do have the wrenches for a valve adjustment, but haven't actually done it yet.

BTW, my idle adjustment cable is broken, so no adjustability there. I have the idle speed set with a zip tie, which is why I have to give it a little fuel for the first minute or so before the idle smooths out.
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  #22  
Old 01-28-2016, 01:29 PM
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Also, four new Bosch plugs and a reamer are on the way.
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  #23  
Old 01-28-2016, 01:33 PM
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Watching the interior light for the length of dimming with the key in the glow position should give some indication of what is going on. The action of the dash glow plug indicator bulb acting as you describe does tend to indicate something Is going on.

For example if the interior light does not dim at all there is no heavy current flowing through those plugs. Or only dims for too short a time is also an issue.

For many reasons it is important to give the 616s especially at some point a kind of overall tuneup. The cars are really old and many if not most have not been maintained. The tune up is more labor intensive than dollar cost.
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  #24  
Old 01-28-2016, 01:39 PM
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Barry, when you say "interior light" I assume you mean the dome light? I honestly had never noticed dimming, but only because the door switch only works very intermittently. I'll make it a point to turn on the dome light manually, then watch for dimming.
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  #25  
Old 01-28-2016, 01:44 PM
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Quote:
Originally Posted by Redpeople View Post
Also, four new Bosch plugs and a reamer are on the way.
Going to spend some money you should convert to parallel plugs. They should still be available with the larger base threads for your car. For a 616 used all year round especially in places where it gets cold they are superior.

They where actually a substantial improvement over the series plugs.
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  #26  
Old 01-28-2016, 01:57 PM
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Quote:
Originally Posted by Redpeople View Post
Barry, when you say "interior light" I assume you mean the dome light? I honestly had never noticed dimming, but only because the door switch only works very intermittently. I'll make it a point to turn on the dome light manually, then watch for dimming.
Yes the dome light. Personally I would cancel the four new series plugs as well if possible. If you are going to spend more than a few dollars the upgrade is far better value.

I think your current system can be troubleshot and made workable until you get the newer plugs. They may or may not be a little harder to find.

I believe without being absolutly certain there is also a strip fuse on the firewall in the system you have. I have one car with your setup but have had no issues with the glow plug circuit so am unsure. Keep that in mind as well.

Your glow plug relay is above the floor pedals incidentally. Auto wreckers or some of the guys on site can save you decent dollars if you ever need one. I wish we had a pick and pull operation anywhere near me.

Last edited by barry12345; 01-28-2016 at 02:12 PM.
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  #27  
Old 01-28-2016, 02:24 PM
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Quote:
Originally Posted by barry12345 View Post
Yes the dome light. Personally I would cancel the four new series plugs as well if possible. If you are going to spend more than a few dollars the upgrade is far better value.

I think your current system can be troubleshot and made workable until you get the newer plugs. They may or may not be a little harder to find.

I believe without being absolutly certain there is also a strip fuse on the firewall in the system you have. I have one car with your setup but have had no issues with the glow plug circuit so am unsure. Keep that in mind as well.

Your glow plug relay is above the floor pedals incidentally. Auto wreckers or some of the guys on site can save you decent dollars if you ever need one. I wish we had a pick and pull operation anywhere near me.
Yeah, there is a strip fuse. It seems intact and I am getting 12V at the first plug in line, so I don't think the problem is there, but I did add a $.75 fuse to my order. I originally thought it was the relay, but I wasn't reading my voltmeter correctly. While I thought I had a bad relay, I picked up a spare at the pull-a-part. I was pretty amazed that they actually had a 78 240D. I have another thread discussing that process.

I'll probably follow through with the conversion eventually, but I'll think I'll press on with replacing the standard plugs now. Wanting to try to get this back on the road ASAP. Its' my sons' daily driver and I'm about ready to put them back in their summer car, an MG Midget, because it's more reliable (ironically).
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  #28  
Old 01-29-2016, 08:59 PM
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If your Injector Nozzles are worn out and the pop/opening pressure is not good the Fuel will not atomize as well.

As the Timing Chain and Gears wear your Valve Timing and Fuel Injection Pump Timing become late/retarded.

Retiming the Fuel Injection Pump will take care of that but does not change the Valve Timing.
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  #29  
Old 01-31-2016, 01:55 PM
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Argh. Four new Bosch plugs and a reamer arrived yesterday. Reamed and installed but no difference. I did check the dome light when operating the preglow and it dims. I also used an IR thermometer to determine that all four seem to be heating up.

I also tried to bleed out any air in the injector lines. No difference. Just checking, should that be done by cracking and closing one injector at a time? I'll probably go back and do that again.

After that, I guess it's on to valve adjustment. I'm a little apprehensive about that; just don't want to screw anything up.

Is there anything else I'm missing?
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  #30  
Old 02-01-2016, 01:08 AM
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I think it is more common to loosen all of the Fuel Injection Line Nuts at the Injectors and crank till you get Fuel out of all of them.

Some people only loosen a one of more and hope to get one cylinder or more cylinders going in hopes that the Fuel Injection Pump running faster will pump the air through the Injectors that they did not bleed.
But, that means that the Engine has to be able to start on the one or more Cylinders and in your case you are having trouble starting on any Cylinders.

Since apparently no one has been adjusting the Valves since you owned it how many miles do you think it has on it since the last valve adjustment or since you have owned it?

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