Purging fuel line in 85 300TD wagon after primer pump & filter replacement not easy
 

Hi there, I just replaced the hand primer pump on our 1985 300TD wagon, and now it wont start again. I also replaced the diesel spin-on filter and the primary filter. Ive been told you just gotta keep cranking till the fuel eventually purges the air out of the lines. Ive run the battery dead 2 or 3 times doing this now (and its a honkin battery). When I pump the primer pump I see a few bubbles enter the primary filter and then stop and the I can see it happen again a minute or two later and stop if I keep pumping. Also I see the fuel climb up one of the transparent lines that leads into the secondary fuel filter as I pump, once it pumps up to the filter It bubbles down again as if it pured out into the filter. (it takes a long time to do that) Ive filled the filter with diesel before putting it back on, Ive kept the fuel cap off when cranking to prevent a vacuum in the tank. Ive also siphoned out all the fuel and removed the tank screen to see if it was clogged but it wasnt. Ive tried testing the suction of the fuel line between the fuel primer pump and (I guess eventually the line to the fuel tank?) simply by actualy sucking on the hose slightly to see if there was resistance. There did seem to be some and I was wondering if this would be an indication of plugged line or simply the natural resistance of pulling fuel out of the tank.? Also when I sucked (I know risking a mouth full of diesel but Im quite tool deprived) I could feel the resistance and then sometimes it would bring bubbles into the primary filter however I could still suck fuel and it wasnt like air was pouring in but a few bubbles when the pressure got high enough it seemed.
Its said its a pain to get the air out of the lines of diesels like this but I didnt expect it to be this bad. Ive been trying for a couple of days now to no avail. Any Ideas? It was also suggested to get a generic in-line fuel pump to put in after the primary filter to purge the line simply by connecting a couple aligator clips to the battery when needed. However when the pump isnt on it seems like it would generate a lot of resistance in the line is that not so?
Any help would be appreciated. Thanks in advance
Michael

Does your spin on filter housing have a little air weep hole at the top ?

If you emptied the Fuel Tank you had an awful lot of air volume to get rid of from the tank up to the IP.
To save your Battery I think it is best to use the Hand Primer no matter how long it takes.

Some Members loosen the Fuel Outlet Banjo Bolt on the Filter Housing so that the Air bleeds out fast. To find the outlet you can look at the Filter Housing and you will see a small Arrow cast into the housing pointing away from the Filter Housing.

Another way to locate it is to see that it is the the line that goes down to the IP at the Front of the IP. loosening the Banjo Bolt at that spot will also allow a fast fill when you change the Spin-on Filter.

After you get Fuel up to that point and have tightened the Banjo Bolt you are still not done.
You need to pump on the Hand Primer to clear the Air out of the IP housing. If you listen closely you will hear a buzzing or squeeling sound over by the Overflow Valve. When that sound changes or stops you are done pumping.

In you present situation sinc you already creanked the Engine you most likely pumped Air that is now trapped between your Injectors and the IP in side of the Hard Lines.
Loosen all of the Injedctor Nuts up by the Injectors and crank the Engine until you see fuel comming out; after that tighten the nuts and try to start.

So you are actually bleeding air out of 2 sections. The Fuel Supply section that includes the Spin-on Filter and the Fuel Injection Pump housing.
Next you are bleeding the air from the Hard Lines. (If you run out of Fuel it will also be necessary to bleed this area too).

If all you had done was change the Spin-on filter; pumping with the hand primer a lot until you hear that buzzing sound and the sound changes is most often enough by itself.

I have had to loosen the overflow valve bolt before. I think that if you have enough air in the IP it will take forever to get it out if you don't loosen this bolt. I'm not sure exactly why, but it just takes longer with that valve functioning. Think of the air inside acting like a spring. If your pumping against this spring is more difficult than without. So, I would recommend loosening it and pumping till you get fuel coming out, then you know the IP is full of fuel. Then you can loosen the injector lines at the injectors and crank it until fuel comes out there. It will start at this point.

You can buy a hand pump at Pep Boys or Car Quest that is normally used to pump something like gear oil from a container into the fill hole on the side of a transmission or differential. I used one of these to prime my completely empty fuel system after replacing the leaky fuel pipes underneath my TD.

All you need to do is to disconnect the intake hose from the primer/lift pump assembly and connect it to the input of the hand pump, then connect the other side of the hand pump to the nipple on the primer/lift pump assembly using one of the included transparent hoses. This pump can move a lot more diesel than the primer pump and will have you set up in no time.

For moving air from the line at the bottom of the tank to the engine compartment...
You can use compressed air put into the fuel tank... loosen the place it is going to ( perhaps put a catch can also )... then put an air gun wrapped with a rag into the opening... does not take much to get it going....I use this to siphon out old fuel also.. with a tube already inserted I just get it started with the air pressure..... once it starts you can leave it to run out..

When I wasn't able to use my primer pump I would use a mityvac to get the fuel up to the injection pump. I would use a clamp or something to pinch off the fuel line so the diesel couldn't go back in to the tank. It would take maybe 10 - 15 seconds of cranking before it would start to catch, but then another minute or two of trying before it would run enough to get all the air out. I HATED doing this to my car, so be happy you have a new pump now.

I'd say mityvac it (if you have one) to the injection pump, then use the primer pump to get it the rest of the way.

Great very good start anyways. So when I loosen the injectors do I simply loosen the first "nut" i come to when you follow the metal line or the one thats against the engine?
Thanks so much.
P.S. Sorry but just to be clear, what is the IP. (Im still unfamiliar with the lingo!)

You don't need to loosen any injectors!!! Put some fuel in the tank, make sure the hose connections are tight and use the primer pump. Loosen the return bolt on the top of the spin-on filter and pump until fuel comes out instead of air.

I disagree. If you loosen the injector lines, the air will evacuate much quicker. plus, you'll know when you've got fuel at the injector rather than guessing. IP=injection pump Just loosen the nut on each injector (the one that attaches the metal line to the injector) and crank with the peddle floored till you get fuel (after everything else is bled) re-tighten and go.

So your talking about the bolt with the arrow pointing AWAY from the filter housing as mentioned by Diesel911?

[I do not understand why someone would decide to pick on the "loosen the Injectors" comment when later in the sentance it is clear that your meaning was to Loosen the Injector Nuts not to Loosen the Injector itself from the Head. So I hope you guys are not going to argue over that.]

IP= Injection Pump or Fuel Injection Pump.
The Lift Pump/Fuel Supply Pump is bolted to the side of the IP and is the one that has the Hand Primer on it; at least on the older models.

If all you did was changed the Filter and after that used the Hand Primer to clear the air from the IP housing; loosening on the #1 Injector would be extra Insurance to get the air out.

However, ounce you have cranked the Engine and air has gotten into all of the Injector Hard Lines I would loosen all of the nuts up by the Injectors and make sure all fuel is getting to all of the Injectors.

Either bolt on the top of the filter housing will work. The smaller one with the hoses (return lines) attached is the better option.

I ment #2; this is the Fuel that is going into the IP.

Alternativly you could loosen the very top small Banjo Bolt; the one with the 2 hoses and 1 tubing going into it but you will have a slight resistance when using the Hand Primer as the line with the Plastic Tubing goes down the the back of the IP and attaches to the Overflow valve.
So there are several varations to choose from.

To be honest if just change the filter; I do not loosen anything and just Pump a lot on the Hand Primer; listen for that sound I mentioned to change and hope for the best. That way there is no mess.

If I was lazy and did not pump enough on the Hand Primer and I get some air in the Injector Hard Lines I loosen the Injector Nuts and bleed that air out (and scold myself for not pumping enough).

http://i242.photobucket.com/albums/f...zzMVC-045F.jpg

yup. since you have cranked with air in the lines, I'd do, in this order...
loosen the arrow out line nut on the side of the spin on housing.
pump the hand primer until it's seeping fuel bubble free then tighten the nut.
pump the hand primer until it is quiet when you pump, and you feel resistance in the fuel flowing with each pump...
loosen the 17mm injector line nuts from the top of the injectors, and pump some more, it's unlikely any fuel will come out during this step but it does not hurt to do it.
then while the lines are still loose, have someone crank the car while you watch the nuts for bubbles and fuel. as each line becomes bubble free, tighten them up while still cranking. if it starts while you are cranking it's ok, just keep watching the lines and tighten them up as you see them seeping bubble free fuel. when ALL lines are tight again, charge the battery well, then follow normal 30 second glow procedure, and give it a good crank and it should start right up!

Loosening the injector nuts does nothing to speed up starting. I've tried both ways and it purged/started just as fast either way. With vigorous pumping of the primer pump you can get the whole system bled in a few minutes.

Up to the IP, that's where the starter comes in handy.

Oh Ive pumped vigorously alright, Ive even traded off with my brother like a marathon. I'm also using a new Bosch primer pump and I dont know I would be able to feel any resistance as its spring loaded (as Diesel911 mentioned).

vstech thanks for the step by step.

One thing Im wondering about is when I pump the primer pump there seems to some resistance somewhere and by what Ive expiremented with (see my 1st post) it feels like its coming from somewhere before the primary filter as I see bubbles coming up in the translucent filter as Im pumping.

Not consistently but it seems like the pressure will build then a few bubbles will come.

Ive checked all the lined in the engine and all are new and tight. I havent checked the ones coming from and attached to the tank but would air bubbles show up in the primary filter all the way form there?

I havent mentioned I have a greasecar kit installed for WVO. However Ive bypassed it all to see if there would be a difference (perhaps a faulty switchover valve) and there wasnt.

I think Ill be trying the injector loosening nut techniqu as It one of the few things I havent tried.
vstech when you say to watch till there are no bubbles coming from the injectors will I be looking for foamy bubles or just bubles in the stream? I guess I should just try it to see what it looks like but I thought I would prepare myself to know what to expect when I go tomorrow to work on it again.

Thanks for all your input! this feels like I may be able to avoid the mechanic (I hope)
Michael

If I'm not mistaken, the FSM procedure says to pump the primer pump until you hear the bypass valve in the filter housing start working.

Purge line with pressure
 

I may get flamed, but here is how I got the air out of my fuel lines after cleaning the tank screen and replacing the hand pump and filter. On my 1982 240 there is a fuel tank vent line that terminates by the left back wheel. It has a little bell shaped device with a one way valve in it, (check valve) clamped at the end. I easily removed the check valve and inserted an old valve stem from an old inner tube into the rubber hose. I reused the clamp from the check valve. Next I removed the gas cap and placed a thick plastic bag over the fuel opening, (ziplock)and replaced the gas cap. Now the tank is sealed. With a hand operated bicycle pump I pumped several times adding a couple of pounds of air pressure to the tank. I then went up to the filter and cracked open the banjo bolt exiting the filter. After a minute or so clean fuel flowed from the filter. I closed the bolt, released the air pressure, and I was able to start my car very easily. Afterward I removed the valve stem and replaced the check valve. On my car the check valve is located by the rear jack point. Once I found the check valve it only took 5 minutes to pressurise the tank. Don't put in too much pressure, you might blow up your tank. It only takes a little bit, just enought to force the fuel through the lines. Good Luck Dave

I think you win the prize for the Most Origional Method Catagory for your application of pressurizing the Tank!

Also you can upgrade the process. In all of my Cars I have a 12 Volt Electric Tire Inflation pump in the trunk. Harbor Freight sells them and Big Lots sells them. I have bought them for as low as $8 each.

Since they put out a low volume of air you would not have to worry about overpresurizing the Fuel Tank as the pressure would build up very slowly.

Of course those Pumps are also handy for their intended Tire inflation purpose.

Sounds kind of fun, anyone know if theres one of these check valves on an 85 300TD wagon? Im not near the car right now. but will be there tomorrow.
Thanks again.
Ill let you all know how I manage.
Michael

I know my 84 300D has one. I would imagine all the W123 models would have it.

The question about air bubbles appearing in the primary fuel filter has not really been addressed. That sure sounds like one or more leak points in the flexible or hard lines between the tank and the filter. The hard lines can develop leaks from abrasion or corrosion, and of course the flexible ones can just deteriorate. Needs to be looked into!!

The bubbles are likely caused by too much air in the fuel tank. Some of that air needs to be displaced.

I suspect that most of the previously mentions "extreme' measures involving pressure and vacuum could be avoided if one thing was considered: fuel flows down hill. If the level of fuel in the tank is higher than the fuel pump, gravity will take care of the situation.

Especially in the TD since it's tank is mounted flat.

For this to work I would Imagine the return line would have to be blocked so that pressure wouldnt be also building there thus just creating a "loop" of pressure? or pushing possible air back in from the return line?

It would make more sense to pressurize the return line (in the direction of the tank) and leave the vent line alone. The valve on the vent line will allow a slight amount of positive pressure in the tank while protecting the tank from excess pressure at the same time.

So I loosened the injector nuts, after purging the line leading to banjo bolt exiting filter, and once it spat out fuel form the injectors and a couple tries after that It caught and started up.

I also took off the return line from the tank and pressurised the tank with a bicycle pump although I dont think the filler cap was totally sealed so presure would lose fairly quickly.

It ran for about 5 minutes idling and I was proud and ready to pull out of the driveway when it stalled again.

I tried the injector lines again and I never did see fuel comming out again as I did the first time. I rigged up a more constant flow of air to the tank with an air comprssor set to 3 or 4 psi.

I waited till fuel came out of the banjo bolt exiting the filter and tightened it. I primed the pump till one could prime no more.

Probably 5 minuted of fast pumping and turned the key and it would just crank sometimes without even a sign of catching any fuel.

Eventually when I bled the line to the bolt again and tried again with the injectors, sometimes seeing bubbles come out when I loosen them but never seeing any fuel comming out when cranking for several minutes, It started again. Probably after 6 or seven more tries with varying pressure, pumping and nut removing and retightening, and about 3 hours later.

It started for longer and it Idles well while I cleaned up and I even had the balls to switch it to Veggie fuel. It ran just as smoothe for about 15 or 20 min.

then some slight hickuping, I went and stepped on the pedal and purged the lines with the auto purge system that sends diesel through alkl the lines again but befroe the 30 second purge was over it had stalled. and as I tried and tried again it got less and less smooth and eventually was just the battery cranking the starter and nothing else.

I made a mess of the driveway with all the fuel spurting out of the return line and I managed to switch the two lines which were old and crumbling while I was at it. But I dont want to get under there again and get full of fuel to stick a comressor in the line. I dont seem to have a check valve as was mentioned.
Could the injector pump be malfunctioning? or is that belt driven?

Any Ideas that would save me from swimming in Diesel again?
Thanks so much for all of your suggestions. It got me very close but I had to call it a night. I dont know whats going on.

I myself applied pressure to the tank in the manner I sugested. It is not some theory. I did not clamp the return line. I know nothing about the system being a closed loop. Air in the fuel line is released when the banjo bolt on the fuel filter is cracked open. I tried this method when I had trouble getting fuel to the filter after a fuel tank screen cleaning, hand pump replacement, and filter change. I suggested this method when Azitizz said that he had had similar troubles, and that no amount of pumping seemed to prime his engine. Try it, as long as you don't go overboard with the air pressure, what harm have you done. If it's going to work you should know very soon after you crack open the banjo bolt. Good Luck, Dave

What about the air that might be trapped between the banjo bolt and the injectors? If you tighten the banjo bolt while fuel is seeping out from the tank pressure, would you not eventually see fuel coming out of the injectors as well?

I thought that might be the case but I waited quite a while and if the fuel traveled at the same speed as it did to get to the banjo bolt It would have come out of the injectors long ago. But nothing.

Does the injection pump have to be cranking in order for fuel to get to the injectors or could pressure ffrom the fuel tank do it?

I'm no expert on the injection pump, but I believe that with the method I described, no fuel would come out of the injection pump, unless the engine was being turned by the starter. It sounds to me that you have an air leak somewhere in your Greasecar system. From looking at the Greasecar web site it seems to be a common problem. I would suggest checking all of your clamps on the Greasecar valves. Isn't there also a problem if you loop your return line and returning it before or after the filter, something about getting air trapped in, and not being able to get it out. You might get some help on Greasecar.com Dave

Its unlikely its the greasecar system because theres only one GC valve that the diesel passes through before returning to its normal course and Ive checked that valve and both the hose and the valve are very new and there doesnt appear to be a problem in that area, unless its very difficult to see.

I did use the method of pressurizing the tank. I did it through the return line as it was the only option. I was just hoping for annother entry other than the return valve as it made such a mess and is difficult to get at.

I guess Ill keep trying and see if I get it a 3rd time. 3s a lucku number eh?

So After trying everything to no avail I brought it to a mechanic who finally determined the new primer pump was causing the problem but they didnt know why.

On two different occasions they put the old one back on and it started right up. I still feel like there is power loss due to air entering the primer pump, But I see no other option that to try and make it work with the new one.

I went to a MB dealership here and they showed me a diagram of the primer assembly and a picture of the original pump and they said they would could order it and they did. I went to pick it up and it was the same BOSCH primer pump that Ive been trying (except with a price tag twice as high) Thankfully they let me return it.

Any Ideas? Can you get the old screw off primer pumps new anywhere? or are we stuck with the newer BOSCH ones.?

http://www.peachparts.com/shopforum/...5&d=1241733459

do you see the difference in these 2 'updated' primers... is it possible that you tried the one that was NOT intended for your engine?

Very Interesting. I have the one on the right, the 126. That is what was sent to me and really the only option I had to choose to order. How would i know which is made for the car otherwise? Its such a simple piece of equipment it seems there can be little to go wrong with it.

I almost 100% sure that is the one you want. They are each rated for different lift pump pressures.

Did you replace the copper washer beneath it when you installed the new primer... its hard to tell its even there.

Yup, replaced the copper washer, and so did the mechanics when they did it. so i know its not an installation problem. Interrestingly enough, when I do a search on bimmerspecialist.com or.ca for the pump assembly or the base to which the small pump screws onto for my year and model of car, this is the picture that they show.
/home/mikepanc/Desktop/1243527996.gif.jpeg
http://www.peachparts.com/home/mikep...27996.gif.jpeg

Its the same as the one on the left (125) in the picture you posted of the two comparing. However every other source Ive contacted say its the other pump I need (126) Is there a big difference in the pump assembly (the base to which the hand pump screw into?)

I guess I dont know how to post a picture. any tips on that too?
Thanks
Michael

You can search on Ebay and also other Parts sellers on the internet. Both the older and newer style primer pumps are still on sale; with the older style selling for a few dollars less than the newer style.

There was a member who over 1 year ago had problems with the newer style primer pump. He exchanged it for another from the same place and still had a problem. He returned that one; got his money back and went to a store in a different location and bought another newer styly primer pump.
The last pump worked. He concluded that the 1st store he went to must have gotten a bad lot of primer pumps from the maker. By going to another store he got a new hand primer from a different lot.

No matter how you bleed the fuel supply section of the IP the delivery valve springs have enought tension on them that it would keep you from bleeding them all they way up to the Injectors; with the hard line nuts up by the injectors loose.

It might be possible to pump with the hand primer and overcome the spring pressure of the delivery valves if you wired the manual shutoff lever down and blocked of the fuel going out of the overflow valve.
This might allow you to pump fuel passed the delivery valves up to the loosend injector hard line nuts.

I guess you wouldnt happen to know how to find this person would you? It would be good to get more info about what happened and see if his situation was similar. Of course searching back a year isnt exactly easy or even possible. Just a shot.

Did I read correctly that you have bubbles? If your getting air out in bubbles then your getting air in. This is the first thing you need to trouble shoot. Try replacing a section of hose with clear pvc so you can SEE whether fuel/bubbles are present.

Ya the bubble problem was solved. I had a wrong size primary pump and even though it felt tight I guess it was cripmping the line enough to let air in. I may put some transparent line on just to make sure though. Thanks for the suggestion.
Now im almost sure the air is coming from the pump.

I do not remember who posted.
It is easy to search back several years the problem would be if you searched for "Primer Pump" or "Hand Primer" you would get a lot of threads and post that you would have to read through before you found what you wanted.
Sometimes it is better to pick a key word that is more specific to the post like the work "returned". It would still generate a of threads and posts to search through.
Another way to find who is was would be to start another thread and ask; and hope that that same person is a regular reader of the forum.

Anyone ever had problems with new BOSCH replacement primer pump?
 

Hi There, Im just looking for anyone who might also have had problems replacing their hand primer pump (in the models that have them) I have an 85 300TD on and the pump seems to be the source of power loss problems. (air leakage) However I went and bought a new one and when I put it in it wouldnt start at all.

I even had it taken to some pro mechanics and they eventually figured out that by putting back tho old primer pump the car would start again. It was installed properly as I did it and also the mechanics did it on separate occasions. Its pretty simple.

Also if anyone knows off hand the two part number differences between the new and old style pumps I would love to have them so I can refer them to the Mechanics or parts searches.

Thanks

In this thread you can partly see the Fuel Supply Pump number Plate (part of which is like the model number of the Fuel Supply Pump; look like FP/K 22 WW 22) and you can see the part number on the Handle of the New Bosch Replacement pump.
If your Fuel Supply Pump has the same Model number on the number plate the same New Bosch Hand Primer used in the Thread should work on yours.
http://www.peachparts.com/shopforum/diesel-discussion/

If your Fuel Supply Pump has a different model number on the Number Plate right it down and call some Bosch authorized Fuel Injection shops and see if you can find out what the correct part number of hand primer is for your Fuel Supply Pump number.

While doing an internet parts search for an 85 300TD (TD= Station Wagon) one of the companies said the Threads on the Diesel Primer Pump were 16mm. I referanced their part numbers to the same year 300D and the D and the TD used the same Hand Primer.
Unfortunatly they did not give the Bosch part number.