OM617 turbo out of ideas smokes and rough idle - PeachParts Mercedes-Benz Forum

jpelletier · #1 09-01-2023, 12:40 PM

So, I will try to keep this short. I have a 84 vintage OM617 turbo diesel, has about 135K on it, had the head done at a reputable machine shop, new guides, oil seals, valves lapped, oil and exhaust seals are correct and I have lashed the valves they are correct. New injectors pop test out at 1900 psi, new injector heat shields, engine compression is 300-310, looking inside cylinders after running engine they are dry ie no oil, primed and bled injector lines, rebuild fuel pump and it seems fine fuel is clean ie no oill leaking from IP into fuel pump, IP was installed at 24 degrees BTDC and I have done this 3 times to be sure it did not jump, chain stretch is just about zero, new glow plugs all heat up fine. No oil in intake or exhaust, exhaust has some soot but nothing unusual.

So, when I start the engine it is smoking and idles really rough, it will idle but rough and smokey, it seems like the JP timing is off, I did have the head off and replaced the front crank seal but I am sure as I can be that I put it back together correctly, verified TDC with the borascope and cam is dead on with cyl 1 exhaust lobe at 45 degrees to the right if looking from front of engine. I did hear the engine run before I bought it a few years ago.

At this point I am out of ideas, I have an original FSM as a reference.

I have followed the threads in this forum for years seems there is a lot of knowledge here so hoping someone has an idea on what may be happening here, thanks

dieselbenz1 · #2 09-01-2023, 07:06 PM

180 degrees out you are on the exhaust stroke not compression???

jpelletier · #3 09-03-2023, 12:09 PM

I had thought of that but would the motor even run that far out? Also the engine timing is set with both valves on cylinder one closed (crank and cam marks where they should be). At what I believe is TDC on the compression stroke the cylinder 1 exhaust valve is at about 45 degrees to the right if standing in front of the engine. I will certainly look at it again since at this point I believe the IP timing is too advanced (black smoke and a lot of it) and will try halving the degrees and try to get it closer that way.

Sugar Bear · #4 09-03-2023, 01:55 PM

With #1 on the compression stroke and the piston at TDC,
the crank should be on zero,
the mark on the cam gear should line up with the mark on the front cam tower; AND,
both cam lobes on #1 should have the base circles contacting the rocker arms.

The lift of the two cam lobes will point almost equally away from the rocker arm contact pads.

jpelletier · #5 09-03-2023, 07:47 PM

I will definitely check that again the am and if I can figure out how to do it post a pic as well. Although I believe I have triple checked everything clearly something is still not right. thanks

Moving this to diesel discussion sub-category, I think I mistakenly put it under the gas Mercedes tech help section

jpelletier · #6 09-14-2023, 08:58 PM

Ok so when I lock the injection pump I am at about 12 degrees ATDC, I just drip timed it and get 1 sec per drip at just about exactly 0 degrees, did a couple of times and still there. Very odd, so do I remove pump, lock it (using tool) and put it back in when the engine is at TDC and start it? I guess I can try that and see what I get

Sugar Bear · #7 09-14-2023, 10:48 PM

removing injector pump OM617

Read through this, see if it helps.

It's been a loooooong time since I've done this but IIRC #1 goes TDC compression, the pump index lines get aligned (assuming the front bearing plate alignment is correct), the crank next gets set to 24°??? BTDC and then the pump goes in. I don't have access to a manual to confirm at the moment.

jpelletier · #8 09-15-2023, 03:28 PM

thanks, I redid the drip timing when I could grab some help, looks like I am at 1 drip per second at 13 degrees atdc (using injector pump lock), it is starting and running better, still a bit of smoke, of course even given it is a diesel, I may give it another shot tomorrow afternoon.

Maxbumpo · #9 11-12-2023, 10:41 PM

Once you've sorted out the injection pump timing (making sure you are not 180 degrees out, and yes they will run with the pump 180 out but rough and smokey and no power to speak of) then you probably need to drive it for a bit and let the injectors and head / pre-chambers get acquainted and get comfortable with each other.

Other ideas: you did not mention the state of the turbo. If that is leaking oil into the intake, that will make some smoke and rough running. Also, if the EGR valve is failed in the open position, that will cause smoke and low power, but probably not rough running.