617 weird behavior diagnoses - Page 2 - PeachParts Mercedes-Benz Forum

leathermang · #16 10-30-2014, 11:54 AM

Quote:

Originally Posted by barry12345

...... What disturbed me was the idle getting better with glow plugs turned on although you have good compression. .....

Once again the idle quieting down with glow plugs applied may not quite fit in with my thoughts at the same time.....

That is why I went with the messed up holes in the precombustion chamber guess...
perhaps just that little help from glow plugs eases the lack of proper dispersion due to clogged holes...
The number and size of the holes was changed several times in upgrading the head over the years... by MB....

Stretch · #17 10-31-2014, 03:26 AM

As I don't have the tools to remove the pre-chambers and because of the likelihood of valve stem wear I'd be removing the head. Pre-chambers can be inspected this way too and then the sometimes difficult job of getting them out without breaking stuff can be done more safely on a work bench. (This is the point where I'd be off down to the machine shop with 6 cans of beer)

leathermang · #18 10-31-2014, 07:00 AM

Stretch totally skips over the amount of work created by the fact that the timing chain is attached to the head... and the potentials of breaking things or messing up relationships like the IP timing.... in the process or putting it back together... lots of people get it off a sprocket JUST rolling in a new chain attached to the old one...
I say do the least dangerous and less work items first ... only go to major take apart if forced to.
There are about three of our members who advise against taking the precombustion chambers out no matter what the situation being described.... cleaning and inspection of the precombustion chamber pintle and holes is in the maintenance manual ... and of the people who have taken them out.... no one that I remember has broken anything...
The shape of the pintle ball was patented.... and the shape , size , and direction of holes was changed several times... indicating the MB engineers thought it ' might' be important that they functioned correctly....
It is the EXACT point where the fuel, compression and timing come together to make a diesel engine work correctly...

Simpler=Better · #19 10-31-2014, 09:34 AM

Mark your current timing, and then retard it a little. Say, 2mm. That will tell if it's a timing issue. It sounds like detonation too early-my rig made those noises when my alcohol mix was too rich.

Prechamber pulling isn't too bad. Clean the threads with a wire brush & kroil first. You need the lockring tool-rent or buy one. I've pulled a couple sets, the scary part is unscrewing the 30yr old 2-prong lockring.

funola · #20 10-31-2014, 10:14 AM

Quote:

Originally Posted by leathermang

............................. cleaning and inspection of the precombustion chamber pintle and holes is in the maintenance manual ... and of the people who have taken them out.... no one that I remember has broken anything...
.......

Please post the FSM chapter. You advise taking out the pre- chambers as routine maintenance. Do you practice what you preach? If so, please provide pictures of the pre-chambers and what they look like. The only experience I have with pre chambers was pulling the head on my 83 240D to save it before junking the car (good running engine in a rusted out body). I did and do not have tools to pull the prechambers but externally I do not remember any of the holes being clogged. I have a pic of the head somewhere. My thoughts on the pre chamber is that they cannot clog from normal carbon that is in there, Only by FOD that came in externally or from pieces of disintegrated prechamber ball (if that could even be possible). Carbon build up in the pre chambers (from short trips, not getting engine up to temp) I'd think is similar to carbon build up around the valves, they can be cleaned up from Italian tuneups over a perieod of time. Taking the pre-chambers out to inspect on a regular basis is crazy IMO.

If the OP is up to it, I'd love to have him pull his pre chambers and to see pics them.

I think what he should do next (instead) is to mount all 5 injectors on a set of hard lines on the IP spraying into the air with video and see what the spray patterns look like. That will tell if there is an IP (or injector) problem.

leathermang · #21 10-31-2014, 12:52 PM

Quote:

Originally Posted by funola

..... You advise taking out the pre- chambers as routine maintenance.......

Yes, I have suggested that people with problems with power they can not figure out .... once every****** 20 years*******....pull and clean their precombustion chambers...

I have a lot of running vehicles... most of which have AC.... I live in the middle of Texas.... My 240 gets driven once a week up to the mailbox... about 800 feet...and to town to get it inspected....8 miles total per year.... and I drove it to Houston twice in one week... so I have put about two thousand miles on it in the ten years I have owned it... so I have not pulled the precombustion chambers on it.... and it starts every time... even the
32 degree morning a few winters ago that I got up and went out to test it... normal glow.. started right up... no block heater or anything..

OM617YOTA · #22 10-31-2014, 11:45 PM

Thank you for the suggestions and help, everyone. You've all helped me so much with this project, I hope I get the opportunity to return the help to the community.

Edit: Holy cow I typed a lot. Sorry folks!

To answer questions:

I test drove the truck again this afternoon after work. Turning on the glow plugs removes the miss when cold entirely and greatly reduces the pinging, though it does not eliminate it entirely. It only misses when cold, once it's warmed up there's just the pinging. When warm, turning on the glow plugs again reduces the pinging considerably but does not eliminate it entirely, both when idling and when cruising down the road. Generally it does not ping when warm and idling.

The miss when cold started when I set the timing with the drip method. Originally the #1 delivery valve wouldn't seal again, I had to install a new crush washer. Once I got the new crush installed and sealed, it started and has had a miss when cold ever since. Killing individual cylinders makes no difference other than the skipped cylinder, the miss is still there.

The pinging originally started very slowly, just a little tick here and there and eventually got worse. From what I read, it was following exactly the symptoms of faulty injectors. I sent them off and had them checked + rebuilt. They were SHOT, peeing before and after the pop, wildly varying pop pressure, etc. After rebuild, symptoms went away for a while. When the pinging started coming back, Greazzer was kind and gracious enough to recheck them for me for only the cost of freight.

(Quick plug here, Greazzer went above and beyond. He would have been more than justified in pop testing them, saying nope they're fine, and being done with it. Instead he repeated the entire cleaning and balancing cycle AGAIN, balanced them VERY precisely - well in excess of FSM recommendations, and reset the pressures to low end of factory spec, but still within factory spec, for my possibly compromised IP.)

A bit smoother, but still pinging. Something else was up.

The pinging is VERY related to throttle position, in fact when warm I'd say entirely so. Near idle or heavy throttle is fine, part throttle sounds like there's rocks in the cylinders, with no relation to RPM. When at part throttle and pinging, I can give it some more throttle and the pinging disappears immediately, even though the engine hasn't had time to change RPMs.

I have the tools and the time this weekend to double(quintuple?) check the timing, yank the injectors, and see if I can rotate one of the lines and get the injectors hooked up outside the engine for testing. I'll get video, though I expect the injectors themselves will be fine. While they're out, I'll see if I can push a pipe cleaner or similar past the pintle ball to the holes in the bottom of the prechamber.

Depending on what I find, I'll decide whether to get prechamber parts on order, or just take it to the MBZ guru in the area. Maybe both.

I have a headache. Bedtime for me. Good night all, and thanks again.

leathermang · #23 10-31-2014, 11:55 PM

Quote:

Originally Posted by OM617YOTA

..... While they're out, I'll see if I can push a pipe cleaner or similar past the pintle ball to the holes in the bottom of the prechamber.......

Don't do that...
Read the instructions...
or just leave them alone...

and for the record.. you can't because they are radially drilled...

epowers777 · #24 11-01-2014, 02:14 AM

Can you please tell me how you killed each cylinder. I'm guessing you make the nozzle not fire diesel? This will help my diagnosis on my om617. Thanks

OM617YOTA · #25 11-01-2014, 09:48 AM

Loosen one injector hard line at a time, so fuel escapes instead of building pressure and getting fired through the injector. It can make a mess and spray diesel around, eye protection is HIGHLY recommended.

funola · #26 11-01-2014, 12:12 PM

Quote:

Originally Posted by OM617YOTA

.............................................................................
I have the tools and the time this weekend to double(quintuple?) check the timing, yank the injectors, and see if I can rotate one of the lines and get the injectors hooked up outside the engine for testing. I'll get video, though I expect the injectors themselves will be fine. While they're out, I'll see if I can push a pipe cleaner or similar past the pintle ball to the holes in the bottom of the prechamber.

Depending on what I find, I'll decide whether to get prechamber parts on order, or just take it to the MBZ guru in the area. Maybe both.
..............................................

One only? That will only check one of 5. I'd suggest doing all 5. Checking the timing again never hurts. How sure are you of doing drip timing correctly? I have never done drip timing, can't help there. I have built a tool though that is much easier than drip timing- checks dynamic advance too.

Click to play

Do not poke anything in the pre chamber to clean the holes. You can't! The ball is in the way and you may knock it loose.

epowers777 · #27 11-01-2014, 03:56 PM

Thank you for your help. I'm going to try today. Hope it's a nozzle not a valve.

On the pre chamber this is what I did to the om603 I have been building. Buy contact cleaner (no residue). Pull the nozzles and spray each chamber with ALOT of fluid. I used probably a few cans. Then fill each cylinder with atf. This will clean the Chambers and re set the Rings. Let soak for a few days. Bar engine over to shoot out all atf. Re install nozzles fire her up.

I miss diagnoste my spare motor and ended up pulling the head. The Chambers were super clean. And the top of the head was cleaner. Had a bad head gasket thought it was a bad turbo.

leathermang · #28 11-01-2014, 07:27 PM

Quote:

Originally Posted by epowers777

...... Then fill each cylinder with atf. This will clean the Chambers and re set the Rings.....

' Re set the Rings '..... it is ok if you believe that... as your procedure will not do any harm..
but it will not ' re set the rings ' ..... so we have to speak up when statements which do not represent mechanical reality appear...

OM617YOTA · #29 11-01-2014, 09:45 PM

Funola, I was going to test all five injectors, just connected in turn to one delivery pipe that I could swivel out of the way. Otherwise some major bending of the hard lines would be necessary to do all five at once, and I wasn't in a huge hurry to do that.

As it turned out, I need to eat some crow. I apparently was pretty unsuccessful at drip timing, as it was way off. I retimed it using a different method and it sure runs better. The miss when first started is gone - in fact it restarted without glow plugs with the temperature gauge under 100F. I didn't have time to test drive it, but the rattle at idle when cold was gone. I suspect I still have it fairly advanced, it sounds a lot more like a Cummins than I think it should. At least the rare 617 powered vehicle I come across doesn't sound like that. Mach4's 617 powered SL sure didn't. I may have it timed by a pro, and ask him how much more he'd charge me to teach me how to do it.

Kind of an anticlimactic end, but one I'm thankful for. Nothing special after all.

leathermang · #30 11-01-2014, 09:53 PM

Well that is nice you found out what was wrong..

I have often wondered why someone has not built a mechanism which would move the ip while driving... with a fuel flow gauge and an exhaust gas temperature gauge... one could set it at speed for best performance....