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  #1  
Old 03-08-2009, 08:31 PM
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1978 240D won't start

Folks,

I'm in a lurch. After servicing the injectors (nozzles replaced and pop-tested at an injector shop), the engine will not start. I've been following the fuel-pressure-heat-air formula, but I'm running out of leads. Here's the list of what works:

Fuel:
# Bled air from the hard lines until fuel emerged at each injector
# IP reset to 24* BTDC

Pressure:
# Battery is new (Group 49-R, replaced last week; started at 12.75 V, discharged down to 12.43 V, going on slow charger tomorrow)
# Valves adjusted 3,000 miles ago; chain stretch of 5* ATDC by camshaft tower method
# Starter motor works (engages when key is turned far right)

Heat:
# Glow plugs engage (relay is shot, so I've been removing the relay wire from the last plug and jumping the plugs straight from the battery for 30 seconds; voltage input at the plug on cylinder four is 10.6 V; all four plugs were replaced last month, and I measure voltage all the way down to cylinder one)

Air:
# I'm assuming the engine is receiving air; haven't replaced filter because the engine seemed to be running well enough with the old one

Even though I bled the hard lines, it still seems as if no fuel is reaching the engine: after cranking for two minutes (fifteen-second intervals), it won't catch. I don't even see unburnt fuel coming out of the exhaust, which is surprising since this car has always smoked profusely when it fails to start. What should I check next?

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'Betsy the Getaway Car' : 1978 MB 240D, 582k
'The Mistress of the Sea' : 2001 Giant Boulder, 10.30k
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  #2  
Old 03-08-2009, 08:42 PM
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Did you change IP timing before or after the car would not start? Are you sure you bled all the air from the IP and secondary fuel filter and lines?
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  #3  
Old 03-08-2009, 08:59 PM
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Quote:
Originally Posted by kingdoc1 View Post
Did you change IP timing before or after the car would not start?
Yes and no. Some chronology:

# Reinstalled injectors after service
# Installed camshaft offset key, which reduced chain stretch to 5* ATDC
# Tried to start engine without adjusting IP; no go, and no sign that fuel was reaching the engine
# Reset IP (begin of delivery was set about 17* BTDC) and bled injector lines
# Tried to start engine; no go, and no sign that fuel was reaching the engine

Quote:
Originally Posted by kingdoc1 View Post
Are you sure you bled all the air from the IP and secondary fuel filter and lines?
I didn't break the fuel supply before the IP--I assume that there is no air in the IP, the secondary fuel filter, and soft lines. (Hand pump is the old style, but I replaced it six months ago, and it shows no signs of leaking.)

How can I be sure that I have completely bled the fuel hard lines? I figured it was enough to see diesel at the injectors.
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'Betsy the Getaway Car' : 1978 MB 240D, 582k
'The Mistress of the Sea' : 2001 Giant Boulder, 10.30k

Last edited by apsaulters; 03-08-2009 at 09:00 PM. Reason: added previous begin of delivery
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  #4  
Old 03-09-2009, 05:50 AM
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So, you did not try to start the engine until you had both changed nozzles and installed an offset cam key? I have never had any problems starting a previously running engine if I removed only the injectors, just bleeding the hard lines like you described has always been sufficient. However, you have done several operations at once, I would first go back and verify cam timing and IP timing, because those are the two items that you have disturbed. As you probably know, it is very easy for the IP shaft to turn as you install the IP and that can really throw things off. Do the drip test or fuel rise test. Make sure your cam lobes are pointing in the right direction. If you did not disconnect any fuel lines at the IP, air should not be the problem, but maybe you flexed one of the rubber hoses and it has a small crack in it that is hard to detect? I usually loosen the banjo bolt at the top of the secondary filter housing and pump the had pump until all liquid comes out around the bolt and then retighten it to bleed air out. I know this is going to sound really dumb, but are you sure you are not out of fuel? If you feel the need, you can spray WD40 into the intake as a starting aid, the car will run on it and it won't cause damage like ether.
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  #5  
Old 03-09-2009, 12:22 PM
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Kingdoc,

Thanks for your responses.

I did not try to start the engine until after reinstalling the injectors and the offset key. I'll recheck the IP timing and cam timing.

In your response you describe how the IP shaft can turn during reinstallation--I'm not sure what you mean. I didn't remove the IP; just loosened the four bolts, and bumped it toward the block until I got drops out of the drip tube. Should I still be concerned about the shaft turning unintentionally?

Didn't disconnect any lines before the IP. Before doing the drip tube adjustment I loosened the top banjo bolt on the main fuel filter bracket and pumped until only fuel came out--only one or two pumps required. I kept this connnection open while doing the drip tube test, and I can't recall whether I bled air from the main filter before retightening. I'll open it up and bleed it again if necessary.

As for the question of fuel, I started with about nine gallons. I've spilled a lot of fuel recently, but no more than a gallon. There should be enough in the tank.

An additional detail: after cranking in frustration for thirty seconds, I could only get the oil pressure up to 30 psi. The gauge tops out at 45 psi, and I have never been able to start the car without first bringing the oil to full pressure. Of course, at that point the battery was nearly 50% discharged, so it could have been the lack of power from the starter motor. What might be keeping the oil from reaching full pressure? And what role does the oil pressure play in starting the engine?
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  #6  
Old 03-09-2009, 05:49 PM
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From your previous description, I assumed incorrectly that you had removed the IP, so disregard my comment about the shaft turning. When you are absolutely sure that the cam and crankshaft are in the correct relationship, then do the drip test or the fuel rise test on the IP, I bet one or the other is out of whack. There are some very good step by step tutorials on the forum. Also, how is your valve adjustment? If the valves are too tight and they are staying open,the compression will be too low and it won't start. I don't think your oil pressure without the engine running has any bearing on the situation, its probably just coincidental that your engine takes long enough to start that it shows full pressure on the gage by the time it does. Also, I don't know cold it is where you are, but you might want to keep the block heater plugged in while you are working on it, any extra heat you can get will help. Also, will the engine run if you spay WD 40 into the intake?
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  #7  
Old 03-11-2009, 08:20 PM
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Folks,

Rechecked camshaft timing and IP timing this afternoon. Camshaft stretch is 6* ATDC, IP timing is set at 24* BTDC. Checked valve clearances, and it's as if I just adjusted them: exhaust at 0.3 mm, intake at 0.1 mm.

I would like to avoid spraying WD-40/ether/starting fluid until I'm absolutely hopeless, which I'm not yet. However, I am out of leads.

At this point, I think there is air in the fuel system because the car produces no visible exhaust when I crank it.

Some questions:

# Even though I didn't break the fuel lines before the IP, and the hand pump seems to be solid, could the IP have gotten air in it just because I removed the injectors? If so, how do it get it out?

# Assuming I am dealing with air outside of the IP--in the supply lines, the injectors themselves, and the return lines--will I be able to get the car to start by simply cranking the engine for as long as it takes, in 30-second intervals?

# Any other suggestions for getting this thing back on the road? I'm getting to the point where there's not much else I can try.
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'The Mistress of the Sea' : 2001 Giant Boulder, 10.30k
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  #8  
Old 03-11-2009, 08:32 PM
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Try cracking the supply lines at the injectors. Then crank it. Are they wet? If not, you are cranking air.
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  #9  
Old 03-11-2009, 08:34 PM
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They're wet. I've been doing a mixture of hand-pumping and cranking for a couple of days now.
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'The Mistress of the Sea' : 2001 Giant Boulder, 10.30k
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  #10  
Old 03-11-2009, 08:46 PM
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whats the compression like ? From what ive read here, wd-40 will not hurt, and will assure you that its a fuel/timing issue if it fires up.
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  #11  
Old 03-11-2009, 09:15 PM
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John: Tomorrow I will ask the injector shop to pop test the injectors again. Before I put them back in, I'll do a compression test. If the compression comes out well, then I'll know it isn't low compression. If the injectors come back well, I'll know there is some problem (air?) in the fuel system between the hand pump, which seems to be solid, and the injector nozzle.
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  #12  
Old 03-12-2009, 03:01 PM
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Injector shop says all of the injectors would pop, but one would not shut off. I'm about to pick that one up, and put everything back together.

Compression test results:

1: 203 psi
2. 200 psi
3. 232 psi
4. 270 psi

Now, the FSM says normal compression should be between 319 and 348 psi, when the engine has been warmed up to a coolant temperature of 80* C. Since the car would not run, I could not warm it up, and the test occurred at ambient temperature, 7* C. Does anyone have a reference for cold-crank compression testing?

When I removed the injectors this morning, I noticed that the heat shields were covered in dirty fuel: fuel has been making it to the engine. I compared the heat shields I had put in with the injectors to a heat shield that was in the car when I received it--the new heat shields had a larger aperture than the old one. Could this be the cause of the no-start condition I've been experiencing?

Thanks for the suggestions. More later folks.
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'Betsy the Getaway Car' : 1978 MB 240D, 582k
'The Mistress of the Sea' : 2001 Giant Boulder, 10.30k
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  #13  
Old 03-12-2009, 03:32 PM
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Those pressures are low, too low. My dead cold 79 300sd with 115k miles was showing 330 psi at an altitude of 5280'.
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  #14  
Old 03-12-2009, 05:29 PM
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They did seem low (shop manual says the lowest allowable is 217 psi), but it's a very old engine that has started down to 24* F before (of course, a lot has happened since then). I'm about to try to crank it, with fingers crossed.
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'Betsy the Getaway Car' : 1978 MB 240D, 582k
'The Mistress of the Sea' : 2001 Giant Boulder, 10.30k
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  #15  
Old 03-12-2009, 06:05 PM
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Get the injectors back and use the WD40 . If you get it running remember to throw in new heat shields for the longevity. If the injector that did not shut off was leaking, make sure you crank the snot out of the motor to blow out any extra possible fuel left from the leak in the chamber before you install the injectors again. Make sure the battery is 100%. Glow, and let her rip. If you have a remote starter button, it helps to hose the WD40 while cranking. Good luck and let us know what happens.

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