Injection pump timing- squirts...no drips at 24BTC
 

1974 240D, auto.

Hey, folks.

It's been a while since I've posted. Frankly, my 240D has been running great the past few thousand miles.

Anyway, 4 years and 12,000 miles ago, I had my injection pump rebuilt. At the same time, I had a new timing chain and tensioner installed.

Today, I thought it would be time to check valve clearance and injection pump timing.

1. With the valve cover still off from the valve adjustment I rotated the crank to 24 degrees.
2. I measured timing chain stretch while turning the crank. 2 degrees out. I figure this is due to the new chain getting worn in.
3. I removed #1 fuel line, delivery valve carrier and then removed the spring and delivery valve. Replaced carrier and added drip line.
4. Opened throttle.
5. Removed vacuum line.
6. When I started pressing the hand pump, fuel squirted out. No drips.
7. I realized that I was 24 degrees *past* TDC. Doh! I rotated the crank around to 24 BTC on the compression stroke (both of #1 cam lobes facing up).
8. Started pumping again and still squirting.
9. I loosened the IP nuts and advanced and retarded the IP (towards and away from engine block) and it was still squirting. The only dripping was after the pressure bled off. I could never get the IP to shut off.


Anyway, I installed the IP myself when it came back from the shop. I even posted a "how to" around here somewhere. It was centered midway between full retard and full advance and was pretty much dialed in with hardly any initial adjustment needed and there definitely wasn't any squirting.

What gives? Has the timing chain stretch created a situation where I need to remove and re index the pump?

Thanks!

Best course of action is to determine when injection is happening in relation to the crank.

-turn the crank indicator to 30 BTDC. check the IP flow.
-go 3 degrees or so, check IP flow again.

repeat until you find the spot where the flow just about stops completely.

then the next step will be dialing it in, or re-indexing the IP

If you can't find it easily, I find that it is worth taking off the fan and clutch and using a long bar to spin the crank from above with a good view.

and, don't hesitate to pull the IP and do it all over if you cant find the spot. If its not happening within 8 degrees of where you need it to, its got to come out anyway.

How did you measure the chain stretch exactly ?

Maybe measure isn't the correct word.

I aligned the cam tower mark and chain pulley groove and then checked the degree marks on the balancer.

Try again using the approved method of the 2mm movement of the specified valve.. might be referred to in the threads listed in my signature... the cam method is not recommended by the FSM....except when putting the engine together ... and only for correct quadrant finding...

Are you not mentioning some things?

When you check the Timing you need to unscrew the #1 Delivery Valve Hoder and remove the Delivery Valve Spring and the small part/valve of the Delivery Valve Assembly put them in a Zip-lock bag and then re-install and torque the Delivery Valve Holder.

Also unless there is already a mark a cross the Fuel Injection Pump Flange to the Block it is a good idea to put one so that if you need to you can return the Fuel Injection Pump back to the same position.

When you rotate the Fuel Injection Pump you need to move it like 1/32 of an inch other wise you blip right on past the sweat spot.

Repair Links
http://www.peachparts.com/shopforum/diesel-discussion/197093-drip-timing-threads.html

Fast navigation http://www.peachparts.com/shopforum/diy-links-parts-category/146034-fast-navigation-do-yourself-links.html

Yes, I removed the delivery valve carrier, spring, and "chip" as it's called by the folks at Mercedes Classic Center. I then replaced the carrier and torqued. I also returned the IP to the previous etches when I couldn't find the sweet spot.

Speaking of sweet spots, what is the range of degrees that an IP adjustment can compensate for? Also, how many of those degrees are full delivery as opposed to being closed?

I was under the assumption, perhaps mistakenly, that all the way towards the engine block should have shut off IP delivery.

Regardless, at full stop on either side of the adjustment range and many points in between, it was a gusher and not a drip. I was trying to find a spot where there was at least diminished flow and start micro adjusting from there. However, it was effectively the same stream everywhere I tried.

Anyway, further troubleshooting will have to wait. My clumsy self lost the delivery valve carrier and spring to The Void. I was reassembling the #1 delivery valve when it slipped out of my hands and disappeared somewhere below. An hour of searching and I didn't find either. Oh well. A call to the Classic Center (and our sponsor) didn't yield results. The carrier (and why I know that to be name) is unobtanium from Ma Mercedes. Fortunately, they steered be to a fuel injection shop that was able to provide me with a new one.

Try again using the approved method of the 2mm movement of the specified valve.. might be referred to in the threads listed in my signature... the cam method is not recommended by the FSM....except when putting the engine together ... and only for correct quadrant finding...

After more research, I've discovered that the full range of IP adjustment should cover 8-9 degrees of timing and the IP should stop delivery entirely at 23BTC.

If the degree wheel indicates 24 degrees and I've fully advanced the pump (towards engine), it should normally be well within the cutout range.

Either:

1. I'm overlooking something incredibly simple.
2. I have timing chain issues (installed incorrectly by the mechanic)
3. I indexed the IP incorrectly when I installed it.
4. I have internal IP issues.

Either way, I can't do anything until the replacement carrier arrives which can take up to a few weeks.

Once it arrives, I'll advance the harmonic balancer in 1 degree increments as suggested above to determine where the fuel is no longer being delivered and take it from there.

I'm inclined to button everything back up and return it to the specialty European garage and let him take a look at it. If he installed the the timing chain incorrectly, he should make it right. Also, the fuel injection shop who rebuilt the IP is not far from his garage in case it has be looked at.

I'll be sure to write a follow up post, even it causes myself some embarrassment due to a simple goof.

Unfotunately Mercedes seems use a lot of different words for the same parts. The same part in a 240D might be labled the same campared to a 1984 300D and I have not read the listings in a Parts Book to know if that is also different from the other 2.

Even within the same Mercedes Service Manual the name of the same part sometimes differes from each other. Must be a lot lost in the translation from German to English.

And then what the maker of the Fuel Injection Pump names the parts may be different.

See the thumbnail pic. When I worked in a Fuel Injection Shop parts 4 and 5 together were called the Delivery Valve Assembly and part 4 was the Delivery Valve and 5 was just the Body of the Delivery Valve Asembly.

Part 3 was called the Delivery Valve Spring.

Part 1 was called the Delivery Valve Holder.

Also I have had to adapt to what the Forum Members call stuff. The Tubing that goes from the Fuel injection Pump to the Injectors forum members call the Fuel Injection Hard Lines and where I worked they were just called Fuel Injection Lines.

A Lift Pump on the Foum where I worked was called a Fuel Supply Pump. When I write on the fourm I will often write Lift Pump/Fuel Supply Pump letting folks know there is other names for stuff.

Notice that in the 2nd pic a few of the parts are labled differently.

Difference of names between the two pictures of the same type of parts from the Mercedes Service Manual but different year and model.

Pic one #4 Pressure valve, Pic two Delivery Valve

Pic one #6 Pressure Valve Carrier, Pic two Delivery Valve Carrier

As mentioned, keep pumping the hand pump as you rotate the crank. It will be squirting as you approach TDC until some point (factory spec is 24 BTDC) where the fill port closes and it stops squirting thru. You goal is to find exactly where that port closes, +/-1 degree.

In my two 300D's, it is a sharp change from squirting to not squirting. I don't really get the "1 drop/sec" deal, but you can fuss with that if you want. I also don't need the "drip tube" attachment. I just watch it "fountain up" from the #1 IP port. I set my 2 engines to 27 deg BTDC, since supposedly gives better economy & power (didn't notice a change).

Ok. I found the darned delivery valve carrier/holder thingie lodged beneath the oil pan and subframe. You can't see it and you can't get your hand in there far enough...but a good 'ol stick poked it right out.

Anyway, my OCD was still in high gear and I followed some of the advice above.

It still squirts, but less, at 22 degrees but is dry as a bone at 20. I'm thinking that perhaps I didn't have the bottom nut loosened enough and it was creating a "stop" to prevent me from advancing the IP. Another 1/4" might have been all that I needed.

Now I can breath easier knowing my timing chain and IP are holding up.

It still doesn't rule out that I incorrectly indexed it during install, however.

I'll probably run it into the classic MB specialist here regardless. I'm too frustrated with that bottom nut to keep trying. I need new rear subframe bushings installed, anyway.

Thanks for the "crank and pump" tip, ya'll!

'''Try again using the approved method of the 2mm movement of the specified valve.. might be referred to in the threads listed in my signature... the cam method is not recommended by the FSM....except when putting the engine together ... and only for correct quadrant finding... ''''

Bosch is not the only company that uses that method. The resoning is that one drop/sec gives and exact positon where is if you just turned it till the flow stops you don't know how far you have gone past.

What I do is I rotate the Fuel Injection Pump a tiny amount lock down one of the Nuts enough so that when I pump on the Hand Primer the IP will not mover.
By tightening one Nut a keeping the IP from rotating it is easy to bring the pressure up to the max with the Hand Primer because I only have to worry about pumping on the Hand Primer; not rotating and pumping.

The other thing is that if you do not loosen the Fuel Injection Hard Lines it can be a struggle to rotate the IP just a tiny fraction. I loosen mine at the Injectors before attempting to rotate.