Problems getting it started. My love/hate relationship with my 1970 220D "project."

[The220D]

I'm working on returning a 1970 220D to its former glory. In the past year I've replaced its fuel lines, rear brakes (everything), fuel filters, etc., and rebuilt the vacuum pump. I thought we had smooth sailing ahead when I completed the vacuum pump rebuild last month, but I was wrong.

I've been struggling for the last few days with a new problem. 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 fuel 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 across 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 tune-up" 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 oil bath air filter. Cleaned the air filter housing out (it was quite dirty), drained the old oil, refilled it, replaced the air filter. 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?

[Mike D]

The outside temperature and barometric pressure makes a difference. Started fine for you all summer? Started after work one day on a nice warm afternoon? Won't start in the cool mornings or evenings? ( the one time at 10PM shouldn't be considered because you had been piddling about with it and it was hooked to the charger).

Either glowplugs or the compression finally slipped below the minimum. I'd guess on glow plugs. Are you getting a good glow from the "salt shaker" grill?

[The220D]

I don't think the temperature is a factor, but I can't definitively rule it out. Last Friday it was HOT in the morning and I had a beast of a time starting it. Saturday was warm, and it was just as hard to start. Last night it started - and I'm not sure how my fiddling with the car for a couple of hours would influence / compensate for a lack of glow plug action.

I replaced all of the glow plugs a month or two ago, too.

Can you tell me more about the compression slipping below the minimum? There is definitely some blowback with this car, but why would it start some times and not others? And why would it run fine (like it did last night) after it was started if the compression was too low? I'll be the first to admit that I know (virtually) nothing about how this car actually works (e.g., what exactly a compression test measures [besides "compression"], why its important, etc.).

[pch2021]

you are most certainly losing your prime on your injection pump.

this is probably not a compression issue, as a diesel with poor compression tends to not start all!

for starters, lets make sure you used OEM rubber hoses and hose clamps. Mercedes stipulates that a non biting, BINDING hose clamp be used.

lines should fit perfectly.

check the primer pump, delivery valve seals and formed platic fuel liens by the pump for leaks.

Look in the primary [small] fuel fitkler, while the car is running, and look for bubbles.

have you replaced the primer pump handle?

once the car starts, how does it run?

[The220D]

pch2021- There is a bubble in the small primary fuel filter. I've pumped and pumped the primer to try to get all the bubbles out, but I've not been able to get the bubble out of the primary filter. I pump the primer pump to the point that diesel comes out from the edges of the pump. Even when I crack the bleeder nut on the top of the secondary filter very little air comes out. Interestingly, very little fuel comes out either.

I haven't looked to see whether there are other bubbles in the primary filter when its running.

I have not replaced the primer pump handle. When I got the car started last night, it ran rough at idle at first, then would run smoothly, then rough, then smoothly. I was / am guessing that it was bad diesel, but perhaps it is air (???) bubbles. When I drove the car around the neighborhood last night for 30 mins or so it ran very smoothly, even sitting & idling at stop lights.

When I pump the primer pump there is a hissing sound of sorts (that's probably not the best description for the sound). I've looked around at the lines, etc., at don't see any obvious crack / hole, nor do I see diesel leaking out.

[Mike D]

The hissing sound is fuel going back down the return line. There is a pressure relief valve of sorts connecting the return line to the engine block side of the injection pump. The injection pump requires volume not pressure. The valve releases the excess pressure and is making the hissing (rapid clicking or buzzing) sound. Normal. Think of letting air escape from a ballon while holding the fill inlet taut.

If you are talking about a small plastic/glass "filter" in the fuel line between the tank and the primer pump, this is a "baffle" designed to smooth out the supply of fuel. Sometimes it has been replaced with a in-line filter but the air bubble is common.

[meltedpanda]

sounds like you are sucking in air somewhere or fuel delivery is being altered or below specs
Could be low compression but unlikely, burning oil?
I would not rule out IP either, how many miles on the car?

[The220D]

The air bubble I am talking about is in the primary fuel filter. This car has two. The primary is right there in the fuel delivery line, while the secondary is much larger (looks kind of like an oil filter) and sits enclosed in its own housing.

Its not burning a whole lot of oil. I might add a quart every month or 3.

I'm not entirely sure how many miles the car has on it. My father inherited the car from my godfather, drove it for a year or so, had the engine rebuilt ~2000 (yr), drove it for a year or so, and then parked it under his barn for ~5+ years. I rescued it in 2007 and have been working with it ever since. The odometer reads ~47,000 miles. I don't know whether they replaced the IP when they rebuilt the engine, but I seriously doubt it.

[The220D]

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.

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?

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.

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?

[t walgamuth]

I think you have bacteria in your tank. I would try another biocide treatment.

Tom W

[pch2021]

the "bubble" is not a permanent "bubble"- it is air coming from a leak. DID YOU CHANGE YOUR PRIMER PUMP ?

[vox_incognita]

Hi,there might be more than one thing that`s problematic...
1.Clean the tank strainer.While there,check the fuel hoses for cracks(metal lines also).Renew whatever needs to be renewed.
2.Remove the lift pump on IP.Clean the internals,check the 2 disk valves for proper operation.Dirt and rust clogs in there ,preventing the plates to seat properly.The kit is cheap,the material used is altered to comply with the new diesel fuel.Observe the correct orientation of the disk valves and the position of cylindrical metal ring over the outlet valve.Do not overtighten the nipples.
3.Renew the hand primer pump with the new type one,tighten well ...
4.While there,renew the oil in IP.Rotate the crank so that the IP camshaft doesn`t engage the lift pump follower for your ease of reinst.
5.Change the rubber hoses if cracked or old and use the recommended hose clamps.
The correct bleeding procedure-when you feel the cannister and IP are full ,while still priming the new type hand pump,loosen the bleed screw on top of the cannister,keep on priming and tighten (while still pumping)when only free of air fuel flows out. Keep on priming and loosen the bleed screw on IP between the 4-th delivery valve and the oil filler hole.Don`t stop pumping until you tighten the bleed screw.Now you`ll feel quite a resistance in the hand pump.If everything is allright and the system is air-tight ,very little amount of fuel will flow back to the tank if you leave the car not used for ,say,a year.Need not to worry about the small bubble in the pre-filter...you may tap it to make the air sneak thru the plastic mesh,but it will form soon...it`s not a 100% valid indication of a problematic fuel system.

There is a by-pass valve on the other side of the IP,you may want to open it and clean(a ball and a spring inside).If it refuses to attain the recommended pressure-1-1,5 bar @ idle and over 2,2 Bar @ high revs,you shim the spring.A new one is 25$$.(capsulated).
There should be a reducer bolt on the lid of the cannister,which holds the excess fuel union,check whether it`s not been swapped for a regular hollow bolt by someone(not very probable,but check )...
All of the above is easy to do and should be done at some point.The hand primer and rep.kit are cheap,so are the hoses and clamps.Some points mighjt be an overkill,but will make you feel better.

Good luck!

[nhdoc]

You will NEVER get all of the air out of the prefilter, there is always some in there and it is perfectly normal.

I agree with Vox that you may very well have a problem with the lift pump (the mechnical fuel pump driven off the side of the injector pump).

When was the last time the valves were adjusted????

[The220D]

I didn't change the primer pump. I'm trying to locate one locally so I can swap it out tonight.

I added some oil to the IP pump last night too - just forgot to mention it. I'll check my manual tonight to see if it shows me where the lift pump on the IP is and how to remove / service it.

The rubber hoses look fine to me.

I notice some fuel at / coming from the bottom of the secondary fuel filter canister. I tighted the bolt at the bottom of the canister, but wonder if I also need to replace the brass washers that fit between all of the canister bolts (there are at least 4 different ones) and the fuel lines. Could that be the source of the air leak?

I'm not sure where the bypass valve on the IP pump is either, but once I locate it can I clean it out without having to pull the IP pump out of the car?

And finally, I don't know the last time the valves were adjusted. I haven't had them adjusted in the year (15 months) that I've been working on the car, and they certainly weren't adjusted in the 5 years or so that it was sitting under my father's barn. I assume this is something I need a shop to do for me??

[meltedpanda]

no way you should pump the primer that long, the diaphram in your pump may be gone and that is where air is coming in. Does it have a white screw on top? or all black one piece ( new version) As mentioned the lift as well may be toast, but my money is on the primer pump and severe alge in the tank/lines If you have a way of blowing smoke into the engine area whilst running you may be able to see where the air is sucking in. Perhaps an incense stick, just dont blow yourself up. you are not working with gas so it is just a bit safer. BUT PLEASE be careful if you choose this route.
Valves on these gals are easy with the right tools, you will need a new valve cover gasket. valve adjustment should be done every 15-20K, providing it was done correctly the last time, I doubt that many miles have been put on it according to your posts. Are you getting a lot of blow by?
When running take off oil filter cap, oil spray out???
we will figure this out, keep feeding us information.
Good Luck