240D IP/Cam Timing Debacle

[wagneric]

For some background, I purchased this 4-speed manual 1981 240D (approx 202K now) in TX about a year ago ($700 on eBay, so expect some non-subtle problems), and drove it home to CO with no problems, getting a consistent 34-36MPG on the highway at 60mph [miles figured conservatively using mapquest - hadn't yet fixed odometer]. It has spent most of the past year sitting, as I rebuilt CV joints and replaced many clutch/driveshaft/brake/etc. parts that were worn, saving the engine problems for last. Lurking on this forum has been invaluable, but I can't find my current problem addressed anywhere.

After being driven at highway speeds, below about 2000rpm the engine always made horrible rattling and clanking noises toward the front/top of the engine. I recently replaced the timing chain, making absolutely sure nothing shifted, and now the noises are gone (the tensioner seems good, though it'll be replaced as funds allow, along with the worn cam gear). According to the marks on the crank-vs-cam, measured the same way before/after the swap, there was about 8-degrees of stretch.

After confirming with a very sensitive pressure meter via the glow plug hole, I learned that I've been looking at the wrong indicator to determine where TDC is [I was looking through a round hole that is about 18 degrees to the left of the normal flat indicator, which made me think my cam timing was okay]. I subsequently determined that the cam was ahead by 18-degrees [measured 18before at crank with cam mark aligned]. Yesterday I pulled the valve cover and cam gear and managed to slip the chain over one tooth, effectively rotating the cam 1-tooth ccw, so now the cam and crank agree [haven't driven it yet but I think it sounds quieter at the tail pipe].

Using both a "look for fuel accumulating in the #1 port" and a "look for a shift in fuel level at the top of the #1 port fuel element" IP timing determination method, I found that the start of fuel delivery is 6-degrees BTDC -- that is, BEHIND by 18-degrees. There's clearly no way to gain 18 degrees by adjusting the pump.

SO, it looks like the Injection Pump is 18-degrees late, and the Cam was 18-degrees early, which corresponds suspiciously to one tooth in either direction, based on what I've read here, and based on the fix I applied to the cam. Add to the mystery that there is a hole in the upper oil pan right below where the sprocket for the timing gear would be - it looks as though a small chunk of metal was forced out, and I've used JB Weld to patch it. Did the loose timing chain knock it out somehow in all its rattling? The old timing chain was pretty beat up, but it has a dark-blueish master link, which tells me it might not be original (I assume they'd use continuous chains originally), so I'm thinking maybe someone really botched an installation, or botched a head swap or something else, since I can't think of any way that the chain could have jumped both forward and backward on the cam/ip.

My big question is: Is there any way to change the IP timing by 18-degrees, without entirely tearing the engine apart? I haven't taken the vacuum pump off yet, but according to pictures I've seen it looks like maybe I could work the chain around that timing wheel somehow; or is there something that can be done with the wheel itself to adjust the timing? I assume the IP is splined such that there's no way to remove it, rotate it, and put it back in [I'd sure like to avoid removing it]?

I realize this is long -- thanks for reading, and thanks even more for any advice. I'm new to Mercedes, and Diesels, though I've really enjoyed working on this car, and have gone a little nuts with taking pictures and logging all the work I do. With the timing chain and cv joints I've managed to do things effectively without special tools, so I can't help but wonder if there's an innovative way to solve this problem too.

-Eric

[Mister Byrnzoil]

I don't have a freeking clue, but heres a bump for ya.

there was a member here called "beagle" maybe he could help you.

[FrankM]

Originally Posted by wagneric

My big question is: Is there any way to change the IP timing by 18-degrees, without entirely tearing the engine apart? I haven't taken the vacuum pump off yet, but according to pictures I've seen it looks like maybe I could work the chain around that timing wheel somehow; or is there something that can be done with the wheel itself to adjust the timing? I assume the IP is splined such that there's no way to remove it, rotate it, and put it back in [I'd sure like to avoid removing it]?
-Eric

I would just remove the pump and reset the pump, crank and cam timing. The 240 is easy, plenty of room..
there is a marked spline on the pump for TDC line up. then rotate it while you have a drip tube in the #1 line .

[Mustang_man298]

He is right. Firstly get your cam to crank timing squared. Set the engine on 24* BTDC & #1 cyl.(can check for #1 cyl by looking @ tower mark, it should be close to it but not on it when @ 24*.) by turning in the direction of rotation. Pull the pump, it is splined via a splined collar piece to the timing chain gear, no need to pull gear or open the front up. Pump pulls right out, take collar off of pump, there will be a "missing" spline on the IP shaft, which should be coordinated in line to a "nick" in the end of the IP shaft. Line that spline/mark up with the matching nick mark on the pump facing that bolts to the engine, it's usually toward the upper left when looking at the facing. Reinstall collar and pump carefully, trying not to rotate it or shaft, and try to get bolts close to center of slots. Snug bolts just enough to hold steady, remove the top only portion of the IP fitting on #1 (just the nut the line goes onto, not the bracket.) Remove the pop plunger and reinstall fitting, then attach a clear hose to it, loop the hose into a horseshoe and stick the end into a coffee can or the like. Now there are 2 ways to do this, one needs 2 people, the other uses 1 man, I did mine the 1 man way. Pump the hand primer and you should see fuel flowing, rotate the pump slowly in the direction of engine rotation (move top of pump toward the head) while still pumping the hand pump until it just slows to 1 drop/second. If it didnt flow to begin with or you couldn't achieve the drip, try starting from the other end of the slots. If still can't get it you might have to respline it again. Once you get the drip right, you will have set initial timing, and she ought to fire right off after you reassemble the IP valve and bleed the lines. I never touched a pump before I tried the "drip method" I found here and it worked very well with little hassle.
-Chris

[wagneric]

Thanks so much for the very intelligent and helpful replies. I got overenthusiastic and dove into it before I read them, so since I already had the vacuum pump off, I tried going at it that way and it worked. It was a little tricky, but I inserted 5mm hex allen wrenches, screwdrivers, etc., around the intermediate gear that drives the IP, in order to get the chain to slide over the gear. Start of delivery is now at 25-degrees before, and I'm not going to argue with that.

The car now has more power, though it is idling a little rougher for some reason. I'll get it out on the highway over the weekend and will see how it settles in to the notion of having the crank, cam, and IP all working together for a change. I can't imagine getting fuel mileage better than the mid-30's I've been getting, though I won't complain if I do.

I'm now a semi-expert in timing anomalies... Thanks again!
Eric (and his 240)