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  #16  
Old 04-11-2020, 01:04 AM
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That sucks.

Maybe as suggested, try setting up an external tank, prime it, and see what happens.

It may be easier to see any abnormal flow at the lift pump check valve and the valve going out of the IP, and to narrow down where any air is entering the system.

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  #17  
Old 04-11-2020, 10:45 AM
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Ok, this will be a tad long, but please bear with me. As we know, the basics for combustion in a diesel engine are Fuel, air, compression, and timing, add glow plug heat for starting to that. That said, here is what I would do, and I know some will disagree with me, but this method has worked for me several times in the past.

First and foremost, make SURE all the glow plugs are working. Do a complete test. A good method that has worked for me can be found here Mercedes Diesel Glow Plug Repair.

Once you know you have good glow plugs, move on to a valve adjustment. Just because compression "feels" ok, does not mean the valves are adjusted correctly. Again, a good valve adjustment method can be found here. Mercedes Diesel Valve Adjustment Procedure While you are in there you can check the timing chain stretch, and basic timing setting.

Once that is done, change both fuel filters (prefill the spin on filter!), AND check the filter/strainer in the tank for gunk. You can blow some air from a compressor thru the fuel lines to be sure they are clear, then tighten all fuel lines. Lastly replace the hand primer if it is not one of the newer black knob ones.

Unless there is a significant mechanical issue (Burned/broken valve, stuck rings, bad Injection pump, stuck vacuum shut off) it should try to fire. Check the oil level in it, and try cranking it.

One other thing you could do to isolate the fuel system is try to run it off of a separate 5 gallon can of diesel (basically an external tank)

Bottom line is until you know for sure the glow system is working, the valves are adjusted correctly and you have a good fuel supply with clean filters, you will end up spinning your wheels.

Good luck
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  #18  
Old 04-11-2020, 12:55 PM
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Simple test. Use the primer pump. Effort to do so should steadily increase until you feel more resistance. If you do not there is a good chance the relief valve is open. Or the lift pumps valves are open as they act as the return check valve for the lift pump.


To separate the two close off the return line from the lift pump. If this does not increase pumping pressure the lift pump valves are open. If pressure increases the return valve is open or very weak.


A very simple approach when there are indications the injector pump is not delivering fuel. Mention your results of this test if you do.


Also it is typical with a good relief valve you hear a slight squeal type of noise as the lift pump increases the pressure beyond the calibration of the relief valve. It is the fuel going through it as the pressure opens it.


I can not accurately describe the relief valve opening sound but it is loud enough to hear it.
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  #19  
Old 04-11-2020, 01:11 PM
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I just Incidentally did a quick read of some of your posts. There was mention of a banjo bolt somewhere on the system that you were pumping fuel but no fuel was showing there. With it disconnected. May or may not be important but try the test I just posted first anyways.


Also do you know about how long this car sat before you got it?
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  #20  
Old 04-11-2020, 01:14 PM
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Quote:
Originally Posted by barry12345 View Post
Simple test. Use the primer pump. Effort to do so should steadily increase until you feel more resistance. If you do not there is a good chance the relief valve is open. Or the lift pumps valves are open as they act as the return check valve for the lift pump.


To separate the two close off the return line from the lift pump. If this does not increase pumping pressure the lift pump valves are open. If pressure increases the return valve is open or very weak.


A very simple approach when there are indications the injector pump is not delivering fuel. Mention your results of this test if you do.


Also it is typical with a good relief valve you hear a slight squeal type of noise as the lift pump increases the pressure beyond the calibration of the relief valve. It is the fuel going through it as the pressure opens it.


I can not accurately describe the relief valve opening sound but it is loud enough to hear it.

This thread has gotten too long and folks not reading what I have done. Glow plugs are working , lift pump check valve is working , relief valve is not stuck open as I confirmed it’s spring measurement and ball is seating.

The primer pump does pump fuel and becomes hard. I have bypassed the entire filter housing with an electric boost too the injector inlet but air is still showing up at the hardlines at injectors and verified no injector spray when injector is connected to hard line but not screwed into engine head.
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  #21  
Old 04-11-2020, 01:17 PM
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Quote:
Originally Posted by barry12345 View Post
I just Incidentally did a quick read of some of your posts. There was mention of a banjo bolt somewhere on the system that you were pumping fuel but no fuel was showing there. With it disconnected. May or may not be important but try the test I just posted first anyways.


Also do you know about how long this car sat before you got it?
Thanks yeah had to mention that on reply sorry... anyways car only sat for two years and was totally full of fresh diesel. Banjo bolt washers have been polished with 1000 grit sand paper and replaced. Something appears to be wrong internally on injection pump allowing air in?!
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  #22  
Old 04-11-2020, 02:38 PM
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Quote:
Originally Posted by barry12345 View Post
With air in the system it could be very hard for the hard lines to bleed. It is the first thing to find out where from and rectify it. Sanding the banjo bolt seals is one possible suspect. When they are aluminium replace them. When copper anneal them with heat. Getting them red hot softens the work hardening.


There should be a constant small bubble in the pre filter. If you see a small stream of bubbles traveling in there when pumping . The problem is right there or before it. No small bubbles going through after it of course.


Why with very little fuel is in the hard lines. Instead of the injection pumps elements adding more fuel. They just compress the air in those lines if the injector does not open. To get the pressure required to open the injectors requires the lines to be fairly full of pretty air free fuel. There are many approaches to finding where the air is getting in.


You sound able enough to locate the source.
Submerged in diesel should the primer pump cause aeration tested like this?
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W123 no start condition-06d1dfae-1ec6-41d7-8a30-c5bcd5d411f1.jpeg  
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  #23  
Old 04-11-2020, 02:57 PM
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That is the old style primer pump and they are notorious for your types of issues. The one you want has a black cap and you do not unscrew the top to use it. I am not suggesting it is all your problem. It could be though just as well. It is a piston in a bore basically . It uses the check valves in the lift pump to function as a pump. If exercising it with the nose submerged and bubbles are appearing. It is leaking by the internal seal of course. My quick test in place when suspect was to stretch a small balloon over it. Squeeze as much air out as possible. On engines that were still running but had some apparent air issues. In a short period the air left in there was consumed if it was bad and the engine smoothed out.

After twenty thirty or forty years I just suspected the seal in some of them has gotten tired. Or compromised by the diesel fuel.

Last edited by barry12345; 04-11-2020 at 03:25 PM.
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  #24  
Old 04-11-2020, 04:00 PM
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Quote:
Originally Posted by barry12345 View Post
That is the old style primer pump and they are notorious for your types of issues. The one you want has a black cap and you do not unscrew the top to use it. I am not suggesting it is all your problem. It could be though just as well. It is a piston in a bore basically . It uses the check valves in the lift pump to function as a pump. If exercising it with the nose submerged and bubbles are appearing. It is leaking by the internal seal of course. My quick test in place when suspect was to stretch a small balloon over it. Squeeze as much air out as possible. On engines that were still running but had some apparent air issues. In a short period the air left in there was consumed if it was bad and the engine smoothed out.

After twenty thirty or forty years I just suspected the seal in some of them has gotten tired. Or compromised by the diesel fuel.
This one does not use a cap to unscrew it that is currently installed. Are you indicating the old style is what you THINK you saw in pic?
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  #25  
Old 04-11-2020, 07:42 PM
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Yes I was. Yours could be the first failure I have seen if it is the newer design. If you are pumping it slowly I cannot see it creating bubbles in the test oil. After it gets rid of any initial air that was present in it. I did not identify it properly as I am used to the newer replacement versions being black.

Last edited by barry12345; 04-11-2020 at 07:54 PM.
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  #26  
Old 04-12-2020, 10:25 AM
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Ok, just to confirm that I have READ the thread......

If like you said, you bypassed the vehicle fuel system by plumbing an independent fuel line and boost pump directly to the Injector pump input and you are still getting air and no fuel coming from the injector tips, it is starting to sound like a bad injector pump......
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1994 Ford F150 4WD 249K (firewood hauler)
1983 Mercedes 300D 376K (diesel commuter)
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  #27  
Old 04-12-2020, 03:54 PM
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Quote:
Originally Posted by psaboic View Post
Ok, just to confirm that I have READ the thread......

If like you said, you bypassed the vehicle fuel system by plumbing an independent fuel line and boost pump directly to the Injector pump input and you are still getting air and no fuel coming from the injector tips, it is starting to sound like a bad injector pump......
Big update:
https://www.youtube.com/watch?v=cakY4sCRuyg

So with a tow start this morning I got to here!!!!!!!!!

I have some sort of fine tuning to do to hopefully have it produce real power!
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  #28  
Old 04-12-2020, 05:57 PM
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Great!! It has a way to go, but at least it is alive! Will it now restart when warm by just turning the key? How about when the engine is cold? I'm wondering if the starter and battery was not turning it over fast enough to fire, or is the compression too low requiring a tow start?

Once it is where it will start without a tow, I would definitely plan on the very least a valve adjustment, new oil and filter, change both fuel filters, clean the tank strainer, and a fresh tank of diesel. Then I would plan on getting new injector nozzles and having them installed and pop-tested. Forum member Greazzer does a fantastic job and his info can be found here https://dieselfuelinjector.guru/

Plus in the video it looked like it was puffing out a bit of blue smoke....hopefully that is just un-burned fuel and possibly residual oil in the cylinders that needs to burn off, otherwise you may have a couple of stuck rings (which could cause low compression).

Either way, you are making some good headway, great job, keep it up, and keep us posted!
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2012 Mercedes ML350 Bluetec 91K (hers)
2005 Corvette 55K (fun car)
2002 VW Jetta TDI 231K (mine)
1998 Volvo S70 T5 Turbo 196K (kids)
1994 Ford F150 4WD 249K (firewood hauler)
1983 Mercedes 300D 376K (diesel commuter)
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  #29  
Old 04-12-2020, 06:37 PM
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Quote:
Originally Posted by psaboic View Post
Great!! It has a way to go, but at least it is alive! Will it now restart when warm by just turning the key? How about when the engine is cold? I'm wondering if the starter and battery was not turning it over fast enough to fire, or is the compression too low requiring a tow start?

Once it is where it will start without a tow, I would definitely plan on the very least a valve adjustment, new oil and filter, change both fuel filters, clean the tank strainer, and a fresh tank of diesel. Then I would plan on getting new injector nozzles and having them installed and pop-tested. Forum member Greazzer does a fantastic job and his info can be found here https://dieselfuelinjector.guru/

Plus in the video it looked like it was puffing out a bit of blue smoke....hopefully that is just un-burned fuel and possibly residual oil in the cylinders that needs to burn off, otherwise you may have a couple of stuck rings (which could cause low compression).

Either way, you are making some good headway, great job, keep it up, and keep us posted!
Thank you , yes it actually did start on it’s own twice but that was due to the “on the farm” advancement I did on the injector case rotation, not just because it was warm as it would’nt self start (battery/starter only) until I made the change while parked!

Thanks very much for the link!
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  #30  
Old 04-14-2020, 05:36 PM
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Car is running

After another injection pump pull and tedious IP spline placement , valve adjustment, fuel lines, IP over pressure spring adjustment , the started this am on a crap battery on the first crank with a temperature of 42 degrees and an IP which still has not been drip timed.

Thanks to those who helped.

Video:

https://www.youtube.com/watch?v=1bnvrhS9oqQ&app=desktop

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