Sorry guys, being on forums at work is frowned upon for some reason. Just looked under the truck and now im not sure if this thing is splined or not, the front mercedes section that runs into the center split mount is obviously not splined but the yoke coming out is hard to tell. I dont see visible splines... Grease fitting indicates movement/sliding though..



Thanks for the info on the tachs guys, I will do some more research and post questions here.

Rollguy- Okay so that is a drain tube, at first I thought I was missing the dipstick but quickly found the actual dipstick. I will make sure i plug it off. The valvecover breather looking at my photo kind of looks like its going just down to the frame as drain, thats not good, i didnt even notice that haha. I'll be sure to hook that up pre-turbo. Good catch!


Dan- Cool build! If I had the funds, I would love to attempt a more in depth build such as yours, it looks like its turning out well. Regarding the stack, im completely aware of the stack yielding no performance gains (possibly decreasing although a negligible amount), its just there for cosmetics and to confuse people haha. Regarding the no smoke with the alda cranked all the way out. What I was referring to is it doesnt even have a hazy colored smoke or anything, im not trying to roll coal, I just think it could use more fuel as there is no visible smoke. Everything I have read says a hazy colored smoke is a rough indicator of an ideal a/f. I was wondering if maybe that meant ip timing was off, clogged fuel filters or something thats all.

Thanks everyone for the responses so far!

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1986 Chevy S10 - om617 swap

Yep, those are splines. That rear shaft is a tad long so the splines are all the way engaged while ideally they would at about the half-way point. The good news is that on an S-10 the rear doesn't move fore and aft much as it goes up and down (mine measured 1/16" from full droop to full up) so what you have should be fine. The only bad thing is that it'll be harder to pull the driveshaft - you'll probably have to drop that midship bearing.

Dan

Well thats good and bad, thanks for the information. I guess I will have a heavy friend of mine jump in the bed while I check to make sure it atleast has some room to move. If not I guess i'll have it shortened.

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1986 Chevy S10 - om617 swap

The Monarch is a lab-quality instrument and therefore costs a bit more - but worth it. Accuracy, serviceability, and durability are unequaled. Auber probably has a photo tach but I didn't check - after decades of using the Monarch on our dyno set-ups I knew what I wanted.

An analog gage would be nice but not essential. I can program the Monarch to flash at any set speed reading so it can be a shift light (I'll need to dig out the instruction sheet for that function!). It'll also data log and download but I don't know how long it can record or if I need a computer to activate that function. But the point is - it has all sorts of capabilities.

The less expensive tachs might do the job depending on what you want it to do for you.

Dan

Your tach although awesome and I would love to have, is more than id like to spend and more precise and accurate than i would probably need. Im just looking for the simplest option to make sure im not cruising at too high of an rpm. I can completely understand your reasoning for getting it due to your intentions for the truck and caliber of the build.

I went ahead and checked the lash on my valves because I was bored after work. It had sat for about 2-3 hours before I adjusted/checked any so I went off of the "cold" specs. The exhaust were all decent, a couple were just a hair loose so I tightened them to .350mm. I admittedly didnt have a .100mm feeler for the intake valves so I just made sure my smallest size feeler, a .152 wouldnt fit under any and it did not. I typically dont like to assume things but considering the exhaust lash values I got I will for now.

Next thing I would like to do is check injection pump timing via the drip test which seems pretty popular. I was wondering, do I have to cut up a line or can I use an injector line for the drip count part of the process. I assume not because of its shape but figured id ask before I run to the shop. If I do need to get a line, can I use a similar sized brake line cut to replicate the pics I see online of the Drip line?

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1986 Chevy S10 - om617 swap

If you're not overly familiar with MB diesels, then you will think your are over-revving "by ear" without a tach. These old diesels are designed to rev high.

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You can't always get what you want, but if you try sometime you just might find you get what you need.

IIRC, the stock tach in the 300SD was redlined at 4,500 (I think those were metric RPMs). I plan to shift at 5,000 which is supposed to be safe. That's a REALLY high RPM for a Diesel - my Dodge/Cummins is all in at 3,200 which is pretty typical for a Diesel.

Dan

These 4spd auto'a have a 1:1 4th gear correct? Judging by my gps and an online calculator, 70mph is like 3000rpm which is lower than I expected.

I ordered fuel filters and the drip tool to do the up timing. Can you guys think of any other maintenance I should perform? Trans fluid is fresh as well as oil. Already adjusted valve lash.

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1986 Chevy S10 - om617 swap

Okay, new fuel filters installed. Im having some trouble with the drip timing. I installed the drip tube with spring and delivery valve removed. Turned the engine to 20,24,25,27 and 30 degrees btdc (rotating clockwise on the crank, the first set of numbers that appear). WIth the throttle wide open and the vacuum hose disconnected, all i get is consistent fuel flow when press the primer pump thing. I at no degree locations get only drips or no fuel at all. any thoughts? This is all with the first cam lobe sticking straight up.

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1986 Chevy S10 - om617 swap

You're correct: 4th gear is 1:1, and it looks like you've calculated RPMs correctly also.

In my '84 300SD, 3000 RPM is just above 70 MPH. 85 MPH puts me at ~3600 RPM. There is no "redline" (red-colored section) on the tachometer. Basically, the max RPM is governed by the injection pump. I've personally seen the tach on my friend's 300D at 4300 RPM while cruising.

For what it's worth, my car loves running between 3000 and 3500 RPM. Fuel economy drops a measurable amount when cruising above 3000 RPM (~70-75 MPH).

It sounds like you've already done some good basic maintenance. The biggest noticeable improvements on my car came from new glow plugs (only 2 worked when I bought it), valve adjustment (you've already done), and rebuilding and balancing the injector pop pressures. Monark injector nozzles are still German-made (Bosch nozzles are now made in India).

You might benefit from finding a good independent Mercedes mechanic to do the timing. I believe the manual says the correct timing is at 24 degrees, but some say the drip timing can be a bit tricky. The only service I haven't performed on my MB myself was the timing. The mechanic I took it to says he has some sort of a "bubble" timing method that is better than the drip test. Either way, he got it timed perfectly.

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1984 300SD
351,000 miles

Revolutions per minute are revolutions per minute. How can they be metric or imperial ?
While there is no redline on the tach the governed speed is 5150 +-50 RPM
You are confusing industrial/truck grade cummins with a light duty automotive diesels.
The cummins has almost a liter per cylinder displacement and it is quite an oversquare engine.
The OM617 has around 600CCs per cylinder and is only slightly oversquare.
Practically all automotive diesels redline at 4500-5500 Rpm

"rebuilding and balancing the injector pop pressures. Monark injector nozzles are still German-made (Bosch nozzles are now made in India)."

Thanks for the suggestion, does this require removal of the injection pump?

Next couple questions. First, I still have not been able to figure out why my injection pump has a steady stream of fuel when hand priming at various different timing marks at and near 24* btdc. I mentioned this in my above comment. Anybody have any thoughts?

Second, I tried to reroute my pcv so that it wasnt an open dump. I drilled a hole in my intake tube just big enough to fit a pcv valve I had laying around off a 350 engine. I then ran the valvecover vent hose to this pcv valve that is popped into my intake tube. The engine will not run for more than 20 seconds before sputtering and stalling out with this setup. The pcv is slightly restrictive but is in the correct position to pull vacuum into the intake. I assume it needs almost zero restriction to operate correctly. Also, is a oil catch can highly advised for the pcv setup?

Thanks in advance?

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1986 Chevy S10 - om617 swap

Remember, a PCV is designed to pull a vacuum at a controlled rate (essentially a calibrated vacuum leak) and your Diesel has NO vacuum - hence the vacuum pump. There's no throttle in the intake stream so there's nothing to make vacuum and it's one of the reasons a Diesel has such good FE - lower pumping losses. If you tied into a vacuum line you probably compromised your brakes and anything else that uses the output of the vacuum pump.

I'm not sure of the circuit for the PCV that M-B uses. You might want to

A) look at a working system on another M-B and
B) check a manual (my Haynes is pretty weak on this).

Dan

No need to remove the injector pump. Rebuilding the injectors in my 300SD really made a difference. I chose to go all out and build an injector pop-tester and to shim them to where they're all within 2.5 bars or each other. I also lapped all the mating metal surfaces and now, they're all leak-free and produce a nice atomized spray of fuel.

Just replacing the nozzles will help engine performance and economy. It's not absolutely necessary to get them all pop-balanced. Out of the box, my new nozzles were all within 5 bars of eachother, but the injectors were just a little low of the 135 bar rated pop pressure. I shimmed all of mine with .1mm shims, and one of them needed an extra .05mm shim.

Just pulling the injectors, replacing the nozzles, and reinstalling the injectors along with new heat shield washers and injector return lines can easily be done in less than an hour (I can pull 5 injectors from a junkyard in 10 minutes). To get the injectors out, you just need a 19mm (or is it 17mm?) wrench for the injector lines and a 27mm (or 1 1/16") deep socket to get out the injectors. I use one with a 1/2" drive and an extension driven by a 1/2" breaker bar.

Below are links to where you can buy all the parts (less than $150 total).

EDIT: Links are being blocked. Anyway, there is a very good "mercedes source (.com)" website where all the parts can be found.

Search for these part numbers:
DSL-5MON120
DSL-COMIRL
DSL-COMIEPAD

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1984 300SD
351,000 miles

Dan- Sorry I shouldve mention, the pcv was mounted between my air filter and turbo not in the manifold. From what i've seen (rough photos on google) it looks like most just mount a line going from valvecover to preturbo intake pipe similar to what i did...

seebeexee- Thanks alot for the in depth response, I will follow what you mentioned once I get all of this minor stuff sorted and it is running top notch, although it does start and run great as is. I think i'll probably start with replacing the nozzles and see how that effects it. Thanks again.

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1986 Chevy S10 - om617 swap