IP timed to TDC rather than 24 degrees? - PeachParts Mercedes-Benz Forum

240dddd · #1 12-15-2016, 02:26 AM

I'm trying to drip time the IP on my 1984 300TD. This is my first time trying this procedure and I'm seeing some weird results that I'm hoping someone can help me decipher.

Before embarking on the timing I checked my chain stretch using the 2mm lift method. Both that method and cam mark method showed about 3 degrees of stretch (I did not check to see if the PO installed a woodruff key).

When drip timing with the timing mark at 24 degrees the fuel just pours out of the fitting and no amount of rotating the IP changes that. The only spot where the fuel begins to visibly drip is when I am near TDC, i.e. when the cam marks are lined up and the timing mark is close to 0. Even at that point the drip is faster than 1/sec and rotating the IP doesn't seem to have an affect.

Does this make any sense? Is it possible a PO mistakenly timed the IP to TDC instead of 24 degrees. What else could be going on here? Or what could I doing incorrectly that would show these results?

I should add that the car is relatively new to me and the PO I bought it from said that her ex-boyfriend had replaced the engine a few years back. That said, the engine was running decently, started and idled well and ran at freeway speeds fine. It did seem to lack low end power more than other OM617's I've driven, but once the turbo spooled it seemed normal. the compression on the engine was decent too, at about 390 across the board.

Diesel911 · #2 12-15-2016, 11:14 AM

The below is to find some more infomation on your situation.

On the side of your Fuel Injection Pump do you have the area circled in yellow with the 17mm Plug with the X on it?

If so you can remove that plug (Oil is going to come out when the plug is removed). You rotate the Engine clockwise past TDC on the compression stroke and stop at 15 degrees after top dead center.

When you do that when you look into that port you should see a blde like projection lined up across the middle of the port. If that is what you seen then your Fuel Injection Pump is at least close to being timed.
Note that the port and blade inside are used in another type of tming method then the drip diming.

If you don't have that Port with the 17mm Plug (17mm the size of the wrench you need to remove the Plug) you likely have an older than 1984 Fuel Injection Pump.

240dddd · #3 12-15-2016, 01:39 PM

Yep, my IP has that port on the side. I haven't had time to open it and check for the 'blade' at 15 degrees after TDC.

Does this mean the IP could be timed correctly even if it doesn't drip @ ~24BTC? I've been reading and prepping to do this timing job using the drip method but am unfamiliar with other ways to time the pump.

spock505 · #4 12-15-2016, 03:04 PM

I had problems using the drip method on my OM605, this is what I did which worked very well.

Another way is to put tipex on the crank peg and belt, take out injector from number one pot and crank with both injector and mark in vision.

Edit, if you do opt for this approach take care with the diesel injector, you are probably aware of the risks but no harm in mentioning just in case.

Diesel911 · #5 12-15-2016, 07:41 PM

Quote:

Originally Posted by 240dddd

Yep, my IP has that port on the side. I haven't had time to open it and check for the 'blade' at 15 degrees after TDC.

Does this mean the IP could be timed correctly even if it doesn't drip @ ~24BTC? I've been reading and prepping to do this timing job using the drip method but am unfamiliar with other ways to time the pump.

A lot of people over the years have struggled with the drip timing. By using the 15 degrees after top dead center just past the compressin stroke and viewing that blade it sort of eliminates a lot of the errors that can can happen with the drip timing method. In this case it is for trouble shooting.
If the blade is not near the center then the Pump was stuck back in the Engine wrong.

Note there is a timing locking tool for that goes in that port to hold the pump in time as it is inserted and there is another timing method that uses what is called an A&B Light that references on that blade.

Any way I thought it was better to check that first and be sure that the IP was at least timed close to what it is supposed to be before more comment on what to do.

jay_bob · #6 12-15-2016, 08:51 PM

Check out this video, Dieselmeken explains how it works...there are 2 ways to time the pump, either matching a notch on the main shaft to a mark on the front end, or removing the timing plug and looking for the tab.
When you use the front mark it is 24 deg before TDC, when you use the tab, it is 15 deg after TDC.

https://youtu.be/WpAxhJDrYC4

240dddd · #7 01-24-2017, 01:51 AM

I finally got back to working on this after the holidays and other business. Tonight I pulled the 17mm plug out of the IP and lots of oil ran out all over my garage floor. Diesel911 said that would happen but of course I forgot

After turning the engine to 15 degrees ATDC I could indeed see the blade in the port hole (I had to use a mirror to see it so it took a few rotations before I was sure of what I was seeing). I twisted the IP slightly to get the blade as close to dead center of the hole as I could and tightened the IP back down.

So it's encouraging to see that method of timing seem to be at least close to correct. After all this I tried drip timing it again and got the same result; at -24 degrees before TDC the fuel comes out as a steady stream not even close to a drip. I'm going to triple check how I'm doing the drip method and see if I'm doing something wrong.

Maxbumpo · #8 01-24-2017, 09:07 PM

If the problem you are trying to fix is a lack of low end torque, I would suggest that you research adjusting the ALDA. They tend to lean out with age, and turning the shaft clockwise a half turn or so can restore lost performance. Also make sure the throttle linkage is properly adjusted to reach the wide-open-throttle stop on the IP.

ROLLGUY · #9 01-24-2017, 10:00 PM

The engine in question is a 617, which has different timing specs than 60X engines. 24 degrees before TDC is a little retarded, so you might want to set it at 25 or 26 degrees for drip timing. I personally like them a little advanced, so I usually set them at 26. Even one degree either way on the crank makes a big difference in drip timing. If you have not removed the pump, and just want to see where it is timed, you may have to set the crank at a different spot (24, 25, 26) to find out where it was timed. If you remove the pump, you can start over and time it where you want.

240dddd · #10 01-25-2017, 02:49 PM

Advancing the timing a bit is part of the reason I want to get the drip method to work. I'd like to set it using 25 or 26. The other reason is that I just want to see it work. I also wanted to check my timing chain stretch and timing before I started adjusting the alda.

Hopefully i'll have some time this evening to try again.

ROLLGUY · #11 01-25-2017, 03:14 PM

Quote:

Originally Posted by 240dddd

Advancing the timing a bit is part of the reason I want to get the drip method to work. I'd like to set it using 25 or 26. The other reason is that I just want to see it work. I also wanted to check my timing chain stretch and timing before I started adjusting the alda.

Hopefully i'll have some time this evening to try again.

You may have to set up for the drip timing, and ever so slowly advance the crank while pumping the primer pump until you get the drip you are looking for. Then you will be able to see exactly where it was set at. Worst case is that you can remove the pump and start over (you probably don't want to do that).

240dddd · #12 01-26-2017, 01:41 AM

Tried to drip time it again. When I pump the fuel pressure diesel just pours out of the drip tube in a steady stream regardless of where the crank is, i.e. I can turn the crank a full rotation and the flow never stops and hardly even changes, even around the -24 degrees. I would expect that at certain points in the rotation the flow would stop altogether, correct?

BillGrissom · #13 01-26-2017, 11:02 AM

Been a while since I did it, so I might be FOS. You do know that a diesel is a 4-stroke, so think like a gas engine. Instead of a spark, it shoots a pulse of fuel. This happens every other stroke. You need to look for the squirt on the compression stroke. Sounds like you have the valve cover off, so watch the #1 cam lobes to see when they are rotating away from the head, i.e. both valves closed, starting the compression stroke.

Don't get hung-up on counting drips. You are looking for the point where the #1 IP cylinder closes off (to start squirting fuel, i.e. "start of delivery"). Before that, fuel will flow thru freely as you work the primer pump. As the port closes, the flow will suddenly stop (within ~1 deg crank). I don't fool w/ the drip tube, but just watch the fuel flow up out of the #1 delivery port (putput check valve guts removed). I set both my OM617 to 27 deg BTDC for supposedly better power and mileage, though can't say I noticed a difference.

Regardless, 27 deg gives you leeway for future chain stretch. By the same token, I also measured 2-3 deg delay in the camshaft so installed a ~4 deg offset key. It is easy to do while in there. Just stuff rags so you don't drop anything down the chain opening, and bungee-cord the sprocket to the hood to keep the chain tight. I don't think it can jump a tooth if you let it loosen, but no sense tempting fate. Good time to change the tensioner rail, especially the chain has worn grooves in yours. They aren't expensive. But, I recall you must pull out the lower pivot-pin, which I probably did w/ radiator out, and maybe crank damper off (then change front crank seal). So pick your battles wisely.

Rogviler · #14 01-26-2017, 11:37 AM

You may have better luck using pressure rather than the primer pump, which can be finicky on some cars I've noticed. I used a brake bleeder. You just connect it to the supply line, clamp off or plug your return lines (from the injectors and to the tank) and keep it under 5 psi.

-Rog

240dddd · #15 01-26-2017, 12:42 PM

turns out it really helps to wire the throttle full open correctly :$

Once i did that i got the expected results. Still planning on fiddling with the timing, but i know the procedure is working as it should.

Sorry for the noise. thanks for all the helpful feedback.