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replaced injector, now won't start...

5.3K views 13 replies 5 participants last post by  DieselDave  
#1 ·
I replaced my visibly leaking #4 injector on my 81 300d. Took a little tinkering to figure out but not hard really. (except: is there a washer that I should have replaced? I saw such noted on a previous thread, but didnt see any evidence of one on my car or with the new injector...)

I completed the job (and replaced main fuel filter while I was at it), but it wouldn't start. It turns over but no combustion. Previous to injector replacement, starting hard and idling rough, also diesel run-on when cold.

I thought I would check my work, so I took it all apart again, and noted that the new injector had a layer of sooty diesel (oil?) on it... bad sign? Put all back together and still no start.

ANy help appreciated!
 
#2 ·
You must prime the system before it will start.
1st take the filter off and fill it with fuel all the way to the top and reinstall it. Then loosen to the injector line of your replaced injecter and pump the manual pump till fuel comes out, then tighten. Then lossen the back injector line and pump the pump till you get air out of it and then start getting fuel again. You should be good to go then.[:(] Replacing one injector would not keep it from starting UNLESS there was air in the system. Diesels HATE air.
 
#3 ·
I’ll make fiddlefoots words mine. That’s got to be air in those lines. The car would work even without one injector.
The injector has a small washer that is lodged inside the injector cavity. It is an axial seat washer, not a radial one like on the oil drain plugs.
 
#4 ·
Good advice - but I havent gotten it to work...
a couple questions:
1) by the "back" I presume you mean teh injector end of the pipe, not the injection pump end?
2) since I took off all the pipes, do I need to bleed them one at a time, or all at once...?
3)I couldn't seem to get fuel to the ends of the pipes no matter how much I pumped. would being low on fuel in teh tank make this procedure more difficult? I have less than 1/4 tank.

Thanks!
 
#5 ·
1. Yes> You bleed at the end of the line at the injector.
2. Yes. If you took off all the injector lines you will have to bleed all of them.
3. No. If you have enough fuel to run the car you have enough to prime it. Your pump may be broken. If you HAVE TO you can use the starter to prime it. You do all the things I mentioned before, but use the starter to push the fuel. Yoiu'll need a jumper cables to another RUNNING car to keep the battery from going dead and NEVER spin the the starter for more than a few seconds at a time.

Did you fill the filter with fuel? This is very important since you can work your arm off trying to fill the filter with fuel with the pump.
 
#6 ·
First try bleeding system by un-tightening a little the tube that runs out of the filter holder to the injector pump and then by priming the manual diesel pump. Pump until the diesel that overflows from that loose connection stops bubbling. Tighten the connection again and then try to start the car. You might have to insist a bit on that starter though… After the job, wash the parts that got soaked in diesel principally the engine mounts. The anti-freeze additives are terrible to rubber. The 1/4 tank is ok.
 
#7 ·
I did refill the filter case, and there is fuel leaving the filter with no bubbles,

but when I pump the manual diesel pump, there is no fuel coming from the end of the first (#1) line. Eventually, fuel squirts out of diesel pump. Sound like a broken pump?

Tried turning it over 15 times to no avail. Do I need to try more times? Will this destroy my starter?

thanks
 
#8 ·
Dave-
Yes, there are 'washers' that need replacing EVERY TIME YOU REMOVE THE INJECTOR, regardless whether you are replacing it or not. These 'washers' are called heat shields, and they protect the injector nozzle from the heat of the combustion chamber. You MUST replace these every single darn time you pull an injector, no ifs ands or butts. If there was no heat shield evident when you pulled the injector, look closer. You may have missed it. You should pull it back out and replace the heat shield before proceeding.
Purge the lines of air. Crack each metal injector line at the injector body and crank the engine till you get fuel coming out(have a buddy in there crankin while you watch and tighten the lines as fuel seeps out). Tighten down, pump primer till you hear a hiss with each stroke. Do two or three glow cycles and start the car. If it were me I'd go ahead and change the fuel filters at this juncture just to be safe.
This ought to do it.

edit: You have a faulty primer pump. These are easy as pie to replace, and the updated part is easier to use. Just a 24mm crowfoot to uninstall the original pump and a 17mm crowfoot to install the new one. This will keep you from running if it's really bad. Watch that you don't wear out the starter.
 
#9 ·
replaced primer pump. fuel delivered to filter, and to injection pump. I took off all lines to see if fuel was being delivered to lines through pump. When I manually pumped, no fuel came out the top of the injection pump.

Does this mean my injection pump is shot?

Also heard high pitched sound coming from fuel filter area when manual pumping, but no fuel escaping.

thanks
 
#10 ·
When you prime no fuel will come from the injector lines, only when the motor is operating. Unloose something prior to the injector pump and the prime ‘til fuel starts to flow with no air bubbles. Then re-tighten everything. That high pitch sound could be air still in the system or some obstruction. Is it possible that the filter is not well placed and letting is air get in? I guess your problem could only be air related because the problem appeared when you replaced the filter? Or could you have disconnected something.....?
 
#12 ·
As I said, 1 dead cylinder won’t keep the motor from running. The motor will run but with an unhealthy and clunky sound. However checking the plugs won’t do any harm. I would give the car a rest, charge/jump cable the battery and insist some more. Remember don’t use the starter continuously (no more than 15secs) and let it cool down once in a while.
 
#14 ·
I checked the glow plug relay and the plugs - all okay. Finally towed 'er to my local mechanic, who diagnosed her with a failed vacuum pump, which has contaminated the brake booster. Oil in the vac lines prevented it from starting

Does $517 ($330 parts, 187 labor) sound reasonable for rebuilding the vac pump? The fact that there is oil in the lines seems to indicate that its just the diaphragm...

Thanks!