the oil line for the vacum pump vent goes into the intake manifold,, right near number 1 cylinder. Thats y it smokes so bad, like someone else said,, your burning engine oil. Very common failure, been there done that.

Tackled the project today. Let me start by saying that the only conceivable way that this is a 1 hour project is if you are a MB-trained tech who has done dozens of these.

Started by disconnecting the vacuum lines. Easy enough. Removed the radiator hose so I could get into the area. Next I attempted to unscrew the 'top' of the vacuum pump to pull it and replace the diaphragm. No luck there. The radiator / fan / housing were in the way, so I couldn't get in there with a ratchet or screw driver. Might in theory have been able to take the top ½ off of with some bent arm (or whatever they're called - they look like an elongated S) screwdriver. Had I succeeded in doing so, however, there still would have been a zero percent chance of being able to replace the diaphragm at that point. Just too hard to get up into the space where the pump is located, even working from underneath the car.

I decided that rather than pulling out the radiator, etc., I should just take the entire vacuum pump off and work on it separated from the car. Cleaned the heads of the Allen screws off, sprayed a shot of penetrating oil on them, and eventually was able to unscrew the pump from the engine. That was only the beginning of the challenge. At that point I tried to slide the pump out past the fuel filter housing. No luck. So I reversed course and tried to take the pump out through the bottom. No dice there either. The opening of each space was too small to squeeze the pump through. I resorted to disconnecting all of the lines going to / from the fuel filter housing, unscrewed the house from its mount, and pulled the entire filter housing (w/ filter inside) off the car. Success! I could finally remove the vacuum pump from the engine compartment and work on it over to the side.

Sprayed the vacuum lines out with brake cleaner to flush all the nasty oil out of them. Worked well. Lots of oil up in them.

Took the top half of the pump off, and then opened the housing where the valves are located. Cleaned the housing out well (lots of oil in there - used brake cleaner and shop towels), and put in new O rings and new valves. Reused the springs, but I did clean them well first. Put that all back together without any problem.

Next I disassembled the bottom ½ of the vacuum pump. Removed the old diaphragm which had a decent size tear in it (don’t think I put it there when I used a screwdriver to pry the 2 halves open – the diaphragm had them stuck together, and it looked like a touch of silicone sealant might have been used). The bottom half was a mess. Cleaned it well (same drill) and then checked out the roller and ball bearings. The all looked good and rolled around nicely. Gave the bearings a small shot of WD40 to keep them lubed. Cleaned the disks that go in there too (one below and one on top of the diaphragm). Then I started to put the thing back together with the new diaphragm.

That is easier said than done. The roller assembly is spring loaded, and you have to push it up into the pump body to align the built in ‘nut’ (though its not really a nut, more like a nut-tube-whatever) with the center screw that keeps the diaphragm in place. I struggled mightily with that for about 30 minutes. I was ready to give up entirely when I decide to compare the new center bolt that came with the rebuild kit (diaphragm, bolt, washers, 4 of the 8 bolts that go around the edges of the diaphragm) to the old one that I removed when I replaced the diaphragm. Sure enough, the new bolt was at least a quarter inch shorter than the old one. @#$%^. Why can’t they send the right bolt! Cleaned off the old one and tried again to screw the diaphragm in place. It finally worked. Placed the top half of the pump on top of the diaphragm, aligned the holes, and started screwing in the 8 bolts that keep the 2 halves together. Tightened them in a star pattern, as others have instructed.

I did not, however, remount the vacuum pump and hook everything back up as I do not have a gasket for the pump. The old one stuck partially to the pump and partially to the engine. Had to scrape it off with a razor blade. Obviously can’t reuse it. Contemplated using gasket sealant instead of waiting to get a new gasket, but decided against that for now. I plan to order a new gasket tomorrow and have it overnighted, so I can try to work on it Tuesday evening after work. I feel like a fool for not having ordered it when I bought the repair kits and had them overnighted to me. It’s a $2 part!! What was I thinking?

I took a couple of pictures, which I’ll try to post. Start to finish I spent about 5 hours on this. It would have gone much faster had I known in advance which roadblocks I was going to hit, of course. But this is still at least a 2+ hour job IMO.

In the meantime, did I miss any important steps along the way? I assume waiting to get the gasket is the right choice – does anyone disagree? Once I hook everything back up, reprime the fuel filter, etc., is there anything else I need to do prior to trying to start her up?

Many thanks for the advice you all have offered so far. Please keep it coming! As I mentioned, I’m a complete novice and am just learning as I go.

The220D, five hours on the first try without the factory instructions ain't bad in my book. You won't know if you did it right until you run the engine. Good call about waiting for the gasket, and I would somehow find out if you remount it correctly when that time comes.

One red flag, though. You said you cleaned both vacuum lines. Does this mean there was oil in the pump inlet line (from the brake master cylinder)? If so then you have another job to do: the brake master cylinder. Take a look and see if the paint is peeling off it, especially where it connects to the vacuum reservoir (the big pancake between the master cylinder and the firewall). If the paint is peeling and you have oil in the pump inlet line then you probably have a leaking master cylinder and brake fluid in the reservoir.

Regarding the fuel system: connect all the lines, put in a new fuel filter, then crack open the cannister vent (small plug on top lid) and the injection pump vent (small plug on top, just in front of the oil fill cap). Do not mess with the injection pump injector line clamp nuts. Hand pump until fuel comes out the injection pump vent (then close it) then hand pump until fuel comes out the filter vent (then close it) then hand pump a few minutes more until the bubbles in the injection pump overflow (to top of filter) mostly go away. You may have to replace the washers to stop the leaks, but that's normal. The little filter is the primary and the big filter is the secondary, by the way.

__________________
daBenz - 1970 220D

dabenz- I'm not 100% sure it was oil, brake fluid, or just 38 years worth of crud in the inlet line. There was definitely something dark and nasty in it. The 'big pancake' where the vacuum inlet line attaches is old and rusty. Not sure that there's any paint left to speak of. If my master brake cylinder is leaking, how high a priority is fixing it? Any way to tell whether its a slow leak that I don't need to fix now (in the next month, etc.)?

The220D, a quick check for fluid in the brake vacuum reservoir is to pull the brake master cylinder away from the vacuum reservoir and look: 1) is the rear of the master cylinder wet? and 2) make a dipstick out of an old coat hanger and stick it into the vacuum reservoir. Should come out dry in a perfect world. Brake fluid is a good paint stripper so use lots of rags/paper towels. If both checks come out dry then perhaps you have a pinhole in the vacuum reservoir. A hand-operated vacuum pump is a handy tool: you can connect to the vacuum pump inlet hose (after reconnecting the brake master cylinder) then pull a vacuum on the hose and vacuum reservoir. A small leak is OK - that's what the car's vacuum pump is for - you should be able (with the engine off) to push the brake pedal, push the car to release the brakes, and repeat at least two times before losing vacuum.

When to fix a leaky brake master cylinder? Ask the fellow in the mirror:
1) can he stop WHEN the kid chases the ball into the street?
2) how often does he want to dive into the vacuum pump?

I'm "away" for a few days, but I'll check back to read of your success.

__________________
daBenz - 1970 220D

Sorry I misled you on the job time. The vacuum pump on a 615 engine must be quite different than the one on the early 617's because I was able to remove the front face and replace the diaphragm and check valves in short order without removing anything but the fan shroud on the 617.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

kerry - I didn't feel misled (esp. as that word has a rather pejorative connotation). Just can't imagine anyone knocking the job out in under 2 hours if you have to remove the parts I had to remove, clean them, reassemble, etc. I knew it would take me longer than most, so I allowed myself all afternoon!

Sounds like I'll be checking the system per your instructions ASAP!

Well?? Are we happily whistling that "on the road again" tune?

__________________
daBenz - 1970 220D

The vacuum pump rebuild appears to have been a success (knock wood).

I also tried the dip stick / vacuum reservior test and it came out clean. I'm not 100% sure that the master cylinder isn't on its way out though, as its rusty and the brakes do shudder on occassion. Stopping power is as good or actually better than its ever been.

I've been struggling for the last few days with a new problem, though. Wed / Thurs of last week the car was hard to start. Took 10-30 minutes for it to finally start. Cranked and cranked and finally caught. I figured I might need to change the fuel filters again, as they were both pretty nasty when I replaced them about 2 months ago. So I went ahead and changed them out. The small, primary mainline filter had a fair amount of crud in it (black specs / particles). The large, secondary filter that is enclosed in the fule filter housing wasn't noticeably dirty, but I changed it anyway.

Drove it around Thursday night to make sure everything was good to go. No issues to report. Went out Friday morning to drive to work and the car wouldn't start. It would turn over, catch / start for a second, and then die. Checked to make sure I had bled all the air out of the fuel filter housing, etc. Kept trying for 30+ mins before it finally caught and stayed running. Drove a block, stopped at a stop sign and then hit the gas to pull out. It died.

By this time I had run the battery down, so I walked to the service station accross the street and borrowed their booster box. I actually pulled the big secondary fuel filter out, looked it over, refilled the canister (put Diesel Kleen in there to mix with the diesel that was there), rebled it, and tried starting it again. After 10 mins or so she finally started. I let it sit there and idle (rough then even, rough then even, etc.) for 10 mins. Returned the booster box and drove away. Got it up to almost 70mph on my way to work to give it an "Italian tuneup" in case carbon was blocking an injector or something. Drove fine. Came out after work (~9 hours later) and she started on the second try. No issues driving home.

Saturday morning I went out to try to start her again, with no success. Just wouldn't start. Worked on it for about 3 hours yesterday (Sun.). Checked all the fuses, etc., to make sure the glow plugs were heating up. Couldn't find the 8 amp strip fuse that I'm told goes to the glow plugs. Did find other fuses where the strip fuse was "supposed" to be, so I replaced them. Pulled and inspected the secondary fuel filter again. Removed and cleaned w/ diesel the oilbath air filter. Cleaned the air filter housing out (it was quite dirty), drained the old oil, refilled it, replaced the air fliter. Couldn't get it to start. Tried and tried and eventually ran the battery down. Hooked a charger up to the battery and went inside.

Came out to give it one last try at about 10pm. After about 10 minutes it finally started. I let it idle for 10mins or so and then drove it all around for about 30 mins. Parked it and went to bed.

This morning I came out to start it to drive to work. You guessed it - she wouldn't start. Tried for 30 mins., with the assistance of the battery charger boost function. Turned over, even started for a second but immediately died.

What the heck is going on? It has 3/4 of a tank of gas. I filled it up on either Tues or Wed. Do I have a tank of bad diesel (if there is such a thing)? Are the new filters preventing enough diesel to get to the engine when I'm trying to start it? But if its a filter / bad diesel problem, why does it run fine once it starts? If there's a problem with the glowplugs, why does it start some times and not others?

I'm a bit at wits end. Just when I think I'm making progress and getting things fixed, I hit a new wall. What am I missing here?

The220D, as close as to the order you asked:

1) rusty master cylinder exterior could be from a leak from reservoir-to-master cylinder seals or even from sloppy filling (you've ruled out a leak into the vacuum reservoir). Brake fluid is a good paint stripper if it isn't washed off - most just wipe it dry and take paint off over a few years. I'd just clean and paint it, then keep an eye out for leaks.

2) shuddering brakes could be anything from a warped brake disk to sticky caliper pistons to the master cylinder. Kind of depends on where in the braking process the shuddering starts and stops. Try, when the vehicle is moving, pushing the pedal just until you feel the pads hit then hold the pedal still then release the pedal. What happens? Try it again with a bit more foot pressure. Working brakes are more important than a working engine, in my opinion.

3) Black specks in the primary filter could be rubber bits from aging fuel hose segments or it could be dead diesel bugs. Diesel bugs love water in fuel. I'd biocide the tank before doing the Diesel Kleen in the secondary filter hooey.

4) if you have the stock glow system then be aware that it's not fused - the electrical power comes from the side of the headlight switch, of all places. 50amps behind the dash and through the firewall twice without a fuse was the dumb part of the design. If those "coat hangers" between the plugs get hot then so are the plugs between the hangers - the best part of this series system. How long are you glowing and at what outside temperature? I glow about 40sec after the salt shaker turns color when the outside temperature is 65F or warmer.

5) if you pull the secondary filter then change it. Otherwise open the drain at the bottom corner and let some run into a small can - I do this at a minimum the day after I get fuel, even though I have a water separator installed. Two or three ounces is enough, more and you run the risk of pushing an air bubble into the injection pump. Transfer that "fuel" to a glass jar and let it settle for a day or so - you'll see the water if it's there. One of my guesses is you got a bad batch of fuel (it happens), maybe with a bunch of water. Button it up and pump the snot out of it with the hand pump. I usually give the hand pump a few whacks every time I check the oil, which is every day I run the engine.

6) my other guess is you've got a battery on its way out, or you aren't driving it enough to fully charge up, or you aren't glowing enough. A handy tool is one of those floating ball battery testers. I'll let a battery sit overnight after a long, slow charge (one or two amps for a day) then check again in the morning - all balls should still be floating. Could be you're getting a bit of corrosion at the cable connectors and it's always been slowing the starter down - the cooler fall weather means the lubricant in the starter is getting "stickier." The starter needs to spin pretty fast, but if glowed properly then the engine should fire quickly - the first cylinder that gets a full compression stroke.

7) my biggest guess is if the hard start really became an issue after the vacuum pump fix, and not when you put new fuel in, then you pushed a big air bubble into the injection pump which can be a pain to get rid of. There is a vent on the top of these injection pumps you can open, just like the vent at the top of the secondary filter. The bolt just forward of the oil fill - don't mess with the barrel clamp nuts. Tip the car nose down a bit, open the vent then slowly hand pump while tapping the side of the pump. Use your third hand to wipe up fuel as it runs out the vent. Won't get it all but every bit helps.

Hang in there. You've got a car that needs very little tinkering once you get it running properly. Most can't say that.

__________________
daBenz - 1970 220D

3) I added some Star Tron Enzyme tonight. Its supposed to kill the algae, etc., but not result in huge masses of slime that clog the filters. We'll see how it goes.

4) Can't find the power connection for the glow plugs that connects to the headlight switch, but it may not be necessary for me to do so at this point. I tested the system tonight (see more below) and they eventually got hot. Took a while, but they definitely work.

5) I pulled the secondary canister fuel filter and replaced it (even though it was only a week old) with one that had been in the trunk for, well, years. It was still in the box and fit right it. A bit smaller in diameter than the one I pulled and tossed, but perhaps that is a good thing?

6) I didn't test the battery today (need to get a tester) but I charged it last night for about 7 hours and it was good to go today. And I just bought the battery back in January.

7) Wasn't able to positively identify the bleeder bolt on the IP. There is a little screw that sticks up on the top of the IP, but I didn't back it out as I wasn't sure I was looking at the right thing.

Here's what I did tonight:

I pulled the primary, inline fuel filter to make sure it was hooked up properly and not defective. The thing already, after being run for 2 hours total driving time since I installed it new last week, had a serious amount of crud in it. I didn't have another one to pop in, so I washed this one out and then gave it several good long shots of WD-40 to expel any water that might be in there. Changed out the secondary filter too, just to be safe (see above).

I pumped the primer for, literally, just over an hour. Even after all of that time I could not get a very large air bubble out of the primary inline filter. The filter fills about 2/3 of the way up with diesel, but the top third is just a big air pocket. I pulled the bleeder bolt from the top of the secondary canister and pumped and pumped and pumped. Eventually diesel came out, but the first two times I did this after I stopped pumping, paused and started pumping again it took another 30+ pumps to get diesel to come out of the top of the bleeder hole again. It seems to me that once diesel has been forced up into the filter and through the bleeder hole the diesel should remain there, and squirt out immediately once you start pumping again. Am I wrong? If I'm right, that means that air is getting into the system somewhere, right?

In any event, I continued pumping and eventually I could stop, pause and start again and immediately get diesel to squirt out. But even after all of this, approaching the hour and 45 minute mark, I still couldn't get the huge air bubble out of the primary filter. Also, when I pump diesel comes up out of the pump itself. And it makes the hissing sound I mentioned earlier. I can't tell if the sound is air being pushed out of some hole, diesel coming out of the pump, or air being expelled from the pump.

At that point I figured it couldn't hurt to try to get her started. Cranked her several times and she eventually caught. Died quickly, cranked some more, and caught again. I let it idle for about 10 minutes until it abruptly died. Scratched my head and tried starting it again. Once again I got it running and let it sit and idle. This time it sat it idle, sometimes rough and sometimes smooth, for about 40 minutes. I eventually turned her off and said goodnight.

So, tell me if I am wrong but I'm pretty sure (1) I have algae in the fuel and perhaps a clogged tank filter as well as (2) an air leak somewhere which is preventing (a) me from getting the bubble out of the primary filter and (b) the car from starting / running smoothly. Assuming all or part of that is correct, how can I fix the air leak? Am I doing something wrong viz. pumping the primer? Am I not bleeding it correctly? What is the correct method? Do I need to take it to a shop and have them replace all of the fuel lines, as I looked them all over and can't spot the leak?

The220D,

1) I backflush the primary fuel filter with gasoline then stick it back in. A spare in the trunk is a good idea, as well as a couple spare secondary filters. You have more searching and reading to do: you'll never get the air bubble out of the primary filter. You can, with the vents, get most of the air out of the secondary filter and injection pump. Let me know if you have the owner's manual - should have a photo of the injection pump. Good call in not messing with the injection pump top bolts if you aren't absolutely sure. If you have a clear injection pump return line (to top of secondary filter) then you should have very few bubbles going through it when the engine is running.

2) With your comments about additional black specks in the primary filter, I'd say it's time to pull the fuel from the tank and clean the tank. You need a new o-ring for the tank drain plug at a minimum. Before siphoning the fuel out into clean fuel jugs I would try to blow back the tank supply line from just upstream of the fuel pump, with an air compressor set at about 20psi. This should clear the tank strainer. Pull the tank drain plug after the siphon job then clean out that "dent." Put the plug and old o-ring back and put a couple gallons of gasoline in the tank. Grab a buddy and make the car do the hula: nose up and nose down a few times. Drain the gas out the bottom, then put the drain plug in with the new o-ring.

3) You're close enough to the ocean to find biocide - pure biocide without the magic potion. Check a marina or ask at a truck dealer or a parts store. It's expensive but worth every penny.

4) Before you put the fuel from the jugs into your clean tank you need to biocide and filter out the crud and water. Let the jugs sit a day or so after biociding, maybe shake the jugs once or twice. I use a furnace oil filter rigged to a 55gal barrel to do the final polishing. You do what works for you, except put contaminated fuel into your clean tank.

5) If you can fix a vacuum pump then you can change out the rubber fuel line bits at the ends of the metal fuel lines. Use bulk fuel hose - you buy it by the foot, remembering to tell the fella that it's for diesel. It's probably time and you have the opportunity with an empty fuel tank (the clean job).

6) Don't trust an automatic battery charger. The floating ball tester will tell you if you're "good to go."

Keep us posted....

__________________
daBenz - 1970 220D

Bled the IP. Didn't seem to have much air in it as fuel came spurting out as soon as I cracked the bleed screw and pumped the primer.

Gave her another dose of Star Tron on the theory that more is better than less, especially as the bottle says there is no danger to overdosing.

Plan to swing by the hardware store for a couple of 5 gallon containers today so I can siphon out the fuel, drain the tank, clear the tank filter, wash it all out with some gas and see if that helps.

Pulled one piece of fuel line - 5/16 ID i believe - to take with me to get some new hose. But I didn't pull a piece of the hose running from the injectors (drat) so I'm not sure what ID they are. Smaller than the othe fuel hose, but that does me no good of course.