How long should I have to crank after injector replacement (OM616)? - Page 6 - PeachParts Mercedes-Benz Forum

funola · #76 07-10-2012, 10:44 AM

Quote:

Originally Posted by BodhiBenz1987

Unencouraging update: I changed and tightened the lines on the primary filter, with factory brand lines, and checked with a mitivac to make sure air wasn't getting past the primary filter connections. I also changed the return lines with new factory line. I'm just getting froth in the line from the lift pump to the spin-on now, and I can see little bubbles coming into the primary filter, but from the lift pump side (i.e., against the fuel flow). One end of the hose is submerged, it is tight on both barbs of the filter (and the filter looks unobstructed). The fitting is as tight as I could reasonably get it on the intake to the lift pump, and I cleaned that fitting before putting the hose on it. I'm considering replacing the primer pump and see if that helps. I don't know if or how they break, but it sounds like an air pump when I'm pumping it ... granted that sound could be coming from somewhere else down there. Is there a way to test which part of the lift pump is leaking? I don't have the money to just buy parts I hope fix the problem.

Lift pumps do not usually fail. Have you replaced the primer pump on the lift pump at some point? If so, that is the most likely place for air to leak in if you did not keep everything surgically clean when you replaced the primer pump. Before replacing the lift pump, I would remove the primer pump, take out the copper washer and either replace it with a new washer (very hard to find a new one the correct size), or take the old copper washer and heat it up red hot with a propane torch to soften it, clean it with 600 grit wet dry paper and surgically clean it. Also surgically clean the washer mating surfaces on the primer pump and lift pump before re-assembly.

layback40 · #77 07-10-2012, 10:14 PM

Quote:

Originally Posted by funola

Lift pumps do not usually fail. Have you replaced the primer pump on the lift pump at some point? If so, that is the most likely place for air to leak in if you did not keep everything surgically clean when you replaced the primer pump. Before replacing the lift pump, I would remove the primer pump, take out the copper washer and either replace it with a new washer (very hard to find a new one the correct size), or take the old copper washer and heat it up red hot with a propane torch to soften it, clean it with 600 grit wet dry paper and surgically clean it. Also surgically clean the washer mating surfaces on the primer pump and lift pump before re-assembly.

X2
This is good advice.

If you wash everything around the lift & primer pumps so it is all oil / fuel free (may need brake cleaner or acetone), you could smear some non hardening gasket cement, or be rough like me & use spray glue (I suggested this many posts ago). If the air leak stops, you have found your problem.
I am not sure how the updated primer pumps work. Maybe some one could tune in with a cross section diagram. Just in case they can fail & leak air in.

I agree it is not a good idea to just keep on replacing parts till the problem is gone. ~That is the mentality of some of the dealer service departments over here.

Take pride in that you resisted the temptation to just blame the injectors. You have focused in on the problem & found where it is.

funola · #78 07-11-2012, 10:38 PM

Using a non hardening sealant on suspected leaking joints to find leaks is a good idea. It may be hard to do in tight quarters such as the primer pump seal.

Don't forget the trick of cracking the fuel pressure relief valve banjo bolt on the back side of the IP during bleeding. It will really speed up the process. Instead of 150 strokes you only need 20 strokes. I use a 1 inch diameter 3 foot long tree branch with one end pointed to fit the primer a pump depression. Much easier than pushing with your fingers.

BodhiBenz1987 · #79 07-12-2012, 06:24 PM

Thanks guys. I bought a new crush washer as they had one at the dealer. I will try cleaning the surface and using gasket maker on it to see if it makes any difference. Layback, when you say spray glue, do you mean the stuff you buy at an office store? I have some of that.
Here is a picture from Bosch that shows a cross section of the hand pump. Bosch Hand Primers I have to confess when I first went to prime the car, out of old habit (or just brain hiccup) I grabbed the pump and turned it ... maybe I damaged the spring inside or twisted the gasket inside of it. First I'll see if it's just the connection between the primer pump and lift pump though.

BodhiBenz1987 · #80 07-12-2012, 08:44 PM

Tried replacing the copper gasket, and found two in there (I'd complain about the idiot who put a second one in there but I was the last to change it ...). Wiped it super clean and put the new gasket it in. No help. I took it back out and will try either the gasket maker or glue. Would this gasket be OK? http://www.permatex.com/products/automotive/automotive_gasketing/gasket_sealants/auto_Permatex_Form-A-Gasket_No_2_Sealant.htm. I can probably get that at Walmart.
Just to make sure my logic is right ... if there are bubbles in the line from the lift pump to the spin-on, can I narrow it down to: primer pump, fitting for line on line from primary to lift pump, line from primary to lift pump, primary itself, line from tank to primary? There isn't any other way air can get in to that line, is there? I also see bubbles in the primary filter, which makes no sense to me, because I tested that part of the system with the MitiVac and it held vaccuum. Maybe I didn't put enough vaccuum on it. I will try sealing all of it with gasket sealer anyway.
I did also try sticking the primer pump into a jar of diesel and pumping to see if air comes out. It does on the first couple pumps, but then stops. So I would assume the pump itself is not sucking in air.
I wish I could so this without getting so much fuel everywhere, it's making me sick, I think.

layback40 · #81 07-12-2012, 09:40 PM

Quote:

Originally Posted by BodhiBenz1987

Thanks guys. I bought a new crush washer as they had one at the dealer. I will try cleaning the surface and using gasket maker on it to see if it makes any difference. Layback, when you say spray glue, do you mean the stuff you buy at an office store? I have some of that.
Here is a picture from Bosch that shows a cross section of the hand pump. Bosch Hand Primers I have to confess when I first went to prime the car, out of old habit (or just brain hiccup) I grabbed the pump and turned it ... maybe I damaged the spring inside or twisted the gasket inside of it. First I'll see if it's just the connection between the primer pump and lift pump though.
......................................

Just to make sure my logic is right ... if there are bubbles in the line from the lift pump to the spin-on, can I narrow it down to: primer pump, fitting for line on line from primary to lift pump, line from primary to lift pump, primary itself, line from tank to primary? There isn't any other way air can get in to that line, is there? I also see bubbles in the primary filter, which makes no sense to me, because I tested that part of the system with the MitiVac and it held vaccuum. Maybe I didn't put enough vaccuum on it. I will try sealing all of it with gasket sealer anyway.
I did also try sticking the primer pump into a jar of diesel and pumping to see if air comes out. It does on the first couple pumps, but then stops. So I would assume the pump itself is not sucking in air.
I wish I could so this without getting so much fuel everywhere, it's making me sick, I think.

Yes thats the stuff I used. Rough but did the job. It may not be fuel proof but you are only using it as a diagnostic.
looking at that link, as I suspected the primer has a seal that could be bad. Pressurizing the fuel system through the return line with air is the way I prime most diesels now as there is no chance of air leaking in if its all under pressure. I resisted the idea of changing out my old original primer as I was concerned the new style could leak as well.
it does not look like rotating the plunger will damage anything.

You logic is good !
I hope you are doing this with good ventilation !! Like outside in the open air.
You have a nasty air leak there some place.
Sometimes I had to pump 1/2 a gallon of fuel through the system to get rid of all the air. The surprising thing in your case is that the air is not clearing once the car has started. @ 1500 rpm you are getting 750 pumps a minute of the lift pump. Are there any cracks in the hose fittings?

Good luck !!

funola · #82 07-13-2012, 11:45 AM

Quote:

Originally Posted by BodhiBenz1987

Tried replacing the copper gasket, and found two in there (I'd complain about the idiot who put a second one in there but I was the last to change it ...). Wiped it super clean and put the new gasket it in. No help. I took it back out and will try either the gasket maker or glue. Would this gasket be OK? http://www.permatex.com/products/automotive/automotive_gasketing/gasket_sealants/auto_Permatex_Form-A-Gasket_No_2_Sealant.htm. I can probably get that at Walmart.
Just to make sure my logic is right ... if there are bubbles in the line from the lift pump to the spin-on, can I narrow it down to: primer pump, fitting for line on line from primary to lift pump, line from primary to lift pump, primary itself, line from tank to primary? There isn't any other way air can get in to that line, is there? I also see bubbles in the primary filter, which makes no sense to me, because I tested that part of the system with the MitiVac and it held vaccuum. Maybe I didn't put enough vaccuum on it. I will try sealing all of it with gasket sealer anyway.
I did also try sticking the primer pump into a jar of diesel and pumping to see if air comes out. It does on the first couple pumps, but then stops. So I would assume the pump itself is not sucking in air.
I wish I could so this without getting so much fuel everywhere, it's making me sick, I think.

1 item you did not mention where air leaks can get in is the lift pump. Rare but possible.
Only way to know for sure is test it or replace with a good unit.

FSM does not call for sealant on copper washers. Beware it will make removal and cleaning more difficult, especially in tight quarters such as the primer pump. I would recommend against it.

BodhiBenz1987 · #83 07-13-2012, 05:06 PM

Quote:

Originally Posted by funola

1 item you did not mention where air leaks can get in is the lift pump. Rare but possible.
Only way to know for sure is test it or replace with a good unit.

FSM does not call for sealant on copper washers. Beware it will make removal and cleaning more difficult, especially in tight quarters such as the primer pump. I would recommend against it.

Where does the air enter the lift pump (other than the two fittings and the primer)? Unfortunately I don't really have the kind of money now to buy a new lift pump, unless I knew it was the problem. I'll keep playing with the hose fitment for now and hopefully find something. I'll leave the sealant off the copper washer.

funola · #84 07-13-2012, 05:28 PM

Quote:

Originally Posted by BodhiBenz1987

Where does the air enter the lift pump (other than the two fittings and the primer)? Unfortunately I don't really have the kind of money now to buy a new lift pump, unless I knew it was the problem. I'll keep playing with the hose fitment for now and hopefully find something. I'll leave the sealant off the copper washer.

Internally, the lift pump has a piston and a seal (an o-ring?) which is a potential area for air leaks if the seal/piston/cylinder wall is compromised. I agree you should not throw money at it.

I have a good used lift pump from a 83 240D if you want to borrow it. Just pay for shipping. Another thing you can try is bypass the lift pump altogether and supply fuel to the secondary filter with an elec pump, which you will have to acquire.

funola · #85 07-13-2012, 05:36 PM

Just a thought, can you post a pix of your current setup? I'd like to see how the plumbing is hooked up, including the 2 quart fuel tank, the clear lines (to look for bubbles) etc. Maybe I can spot something unusual.

BodhiBenz1987 · #86 07-13-2012, 09:39 PM

Thanks for the offer on the lift pump ... that would be a huge help if I can't find any leak in the lines. I will let you know.

Pictures ... it's hard to see in the photo but the supply line is thoroughly submerged in the diesel. I did wonder if maybe the line being routed up and over the bottle might be too hard for the pump to pull the diesel out, but I wouldn't think it would be any harder than getting it from the tank ... though the tank's hose is in the bottom of the tank so it has help from gravity.

If you look closely in this photo you can see where the fuel sits in the hose to the pressure valve ... all the way down near the first glow plug ... the rest is air.

funola · #87 07-14-2012, 07:18 AM

I can't tell from the pic but the return line also needs to be submerged. You have no hose clamp on the return line, it needs one there to make sure it does not leak. Is there a hose clamp at the black supply line to the pre-filter? You must have one there for the same reason. I see you have rags all over to soak up diesel, in places that should be dry. During priming, the only place that should wet is the return banjo bolt that you loosened to bleed air. Any place else should be dry! If not dry, those are leaks and needs to be corrected first!

The fuel level in the brown line (pressure valve line) should be full to the top, all the way to the clear line, which must be full with fuel all the way down to the bottle.

The fact that the level of the fuel in the brown line is down to the glow plug suggests:

1. Priming was insufficient.

or

2. The pressure valve banjo aluminum seals are leaking and/or the pressure valve (ball) is not sealing.

or

3. The IP may have a leak somewhere.

I'd suggest wash off the diesel with Simple Green and water then let it dry. Stuff a rag tight under the pressure valve while bleeding, which is the only area that should be wet. Anywhere else that gets wet is leaking and needs to be fixed.

funola · #88 07-14-2012, 07:29 AM

If you are going to wash it, cover up the opening of the bottle and be careful you don't get water in there. Stuff a towel in the opening and a plastic bag placed over it should do.

BodhiBenz1987 · #89 07-14-2012, 01:18 PM

The red rag is there because that's where I was trying to bleed it ... the other rags are just there because I took this picture after I had removed the primer pump and I tried to cover up the engine mount.

The one under the return line was from when I swapped those lines out ... not sure why I forgot a hose clamp, I'll add that. The return line is not submerged in the diesel ... I did not know it had to be. There are hose clamps where the supply hose connects to the filter on both ends and the fitting at the lift pump.
I don't see any fuel leaking other than when I take something apart, but it's getting pretty generally messy so a clean-up would be a good idea so I can see better. I will try that and also get a longer return hose so it can be submerged.

funola · #90 07-14-2012, 09:37 PM

The return is 1 inch above the bottom of the tank so it is submerged until the tank is almost on empty.

Note that you may not be able to see tiny amounts of fuel leaks. A trick you can use is take white tissue paper and press it against the area you want to check for leaks and look for signs of wetting.