IP Destroying Injectors, GP, and Prechamber? [long]
 

A few weeks ago my brother tells me that the white SD is having some bad problems starting. Okay, glow plug is dead, no big deal. A few days later it starts idling rougher and an occasional, but very loud clank/clink noise is heard. Did the wonderful 'loosen the injector line' trick and found that cylinder #4 wasn't running. Took the injector out and saw that there was no more pintle!!! Well that would explain a bad idle. Also noticed that the prechamber ball was not in the right place. Didn't have the idea to actually poke it with anything though... so only ordered a new set of injectors (the rest didn't look too hot either).

Put in the new injectors, and actually thought to poke around at the prechamber ball and it was loose. The clank/clink noise was that ball bouncing around in the prechamber... Wanted to see if it would run decent enough for my brother to drive while we waited for the prechamber and tools to come in. Fired it up and it ran just a little bit better. Thought that it wouldn't be great for the engine, but would be alright for a few days. He drove it for about a week, after which I had second thoughts and parked it.

About another week later (this Tuesday) prechamber tools finally came in. I replaced the prechamber, GP, etc. I noted that the injector's pintle was still intact (was worried the bouncing ball would have damaged it). Fired it up with new prechamber and it ran WORSE!!! It knocked really really bad, smoked like crazy, and rocked really bad as well. I thought that it was just all the built up crap from that cylinder not being run for a week. So off to the italian tune up! The knock slowly went away, but the car never really got any power back. floored, it could maintain 65. Its never been that slow before...

Got back to the house and it was still idling really rough. Did the injector crack test again and found that it was really only running on 3.5 cylinders. WTF?!?!? Took out the injector for #4 and THE PINTLE WAS GONE (see pic). The prechamber ball is still intact. Okay... replaced that nice new injector (is that a warranty defect ;) ), and put one of the better ones from the old set back in #4. No change in idle. Swapped #4 #5 injector. Injector line cracking behavior did not follow the injector.

I took a video of how the engine runs during the line cracking test:
http://video.google.com/videoplay?docid=6927372785548115014&hl=en

Something that I didn't mention earlier is that the bad prechamber has two large extra holes on the side. These holes appear to have been caused by the injector spray pattern being fubar. The head even has some *slight* indentations in the same location.

Especially with that last observation, this is my theory. This whole series of events started with the IP not functioning properly on #4. Something along the lines of badly out of time or longer lower pressure delivery, etc. This is what probably resulted in the rough starting. The IP problem caused the pintle to get damaged on the injector, which would make the injector spray a stream in some random direction. This is when the idle went to crap, and also caused the destruction of the glowplug and prechamber. With the new injector and prechamber the problem started all over again. It destroyed the pintle on that injector within 5 miles of the new prechamber being installed. Not sure about the not running with new injector and old prechamber (there was a lot of that prechamber missing, lower compression so it didn't fire often?)

I've got a big school project due this Friday at midnight, so I won't be able to do much till Saturday. I don't know anything else to do besides pull the IP from my blue car, and put it on the white car and see what happens. Anybody else have any ideas?

A chronological summary:

• Cold starts are difficult
• Idle gets rough, and clinking/clanking noise appear
• Find injector with no pintel
• Replace injector (notice that pre-chamber ball is loose)
• Runs/idles/starts about the same
• Car driven for a ~week (50-70 miles) with new injector bad prechamber
• Replace prechamber
• Destroy pintle on injector within 5 miles (the test drive)
• Engine runs on 3.5 cylinders
• Swapped in used injector (with pintle), no change
• Swapped #4 and #5 injectors, behavior didn't follow injectors
• ?????

Pictures should follow in next post...

Thanks in advance for all the help!!!!!

Prechamber pictures....

Remaining pictures...

Seems to me as if you were asking for it...
 

Whatintheheck made you think that it would be ok to run the engine with a piece of metal loose in the prechamber? Jeez.

ouch
 

No pintle. Prechamber disintegrated. Where'd all that metal go? What damage did it do on the way out?

What's the compression on that cylinder now? How does that piston and cylinder wall look? Is it chipped or scored?

The damage was probably done shortly after that ball came loose and started beating everything to smithereens.

from the closeup pictures of the old PC, it looks like you or someone pulled or tried to pull the PC with the GP still installed. my guess is the pc pintle ball fell into the cylinder and destroyed a valve or piston crown, and you will mostlikely need another engine.
John

I don't have a compression tester, nor a boroscope. So I can't really tell just yet. All I can do is my best to get it running again and hope for the best :(

for what you have put into it so far, I would go to the nearest Harbor freight and get a compression tester. at least pull the PC back out, and look around in the motor for debris, and see if you can find a broken piston crown or something.
I bet your motor is a goner.
John

Was in the middle of typing a reply to this and the computer died... bleh.

I did actually pull that PC out with the glow plug installed, but the glow plug was damaged earlier, and was already at that short length before the prechamber was pulled. I didn't feel any resistance from the glow plug when pulling the PC (to be fair I don't know if I would have with a good GP in there!)

Either way, the PC ball was removed with the old PC. Hopefully all the rest of the metal that is missing exited the engine in very very very small pieces. I will pull the PC again tomorrow and look around. During the first PC replacement the only abnormality I noticed was the indentations in the head where there were the undesired holes in the prechamber. I wonder if I can get one of those little 'dentist mirrors' to fit in the cylinder with the prechamber removed?

Nearest harbor freight is about 2+ hours away unfortunately. I don't imagine Autozone's has the right adapter, pressure scale, etc?


Thanks!!

AZ will charge over 150 for a diesel CT, if they even can get one.
HF's website should ship it to your door...
John

I have seen injectors look like that with contaminated fuel (Someone dumped some unleaded in one where I worked. About 50% mix). And I agree on the GP still being in the PC when removed.

All I can say is http://mika.kfib.org/wordpress/wp-co...s/GT/smack.gif

Went and pulled the new prechamber and found that it had a nice big round dimple in it. Noticed a hole in the same spot looking down onto the piston. At that point I wrote the engine off... and decided to at least learn something from this big screw-up of mine and pulled the head. Didn't swap the IPs like I said I was going to...

Almost. ;) As I fessed up in post #9, I did pull that prechamber with the GP still in :twak: , but I didn't think anything of it since the GP when I put it in was short (see the picture with the quarter, I bent off that flaky end piece). Apparantly it was just long enough for the PC to shear off and drop a 1 cm or so chunk of metal into the cylinder (it was NOT the prechamber pintle ball... see the pics, its on the concrete, the ball never left the PC). It actually didn't "break" anything, but for all intents and purposes it might as well have. I think the pics speak well enough for themselves...

I think its amazing the valve didn't break... and that the metal chunk is still embedded in the piston!! :eek:

Okay, so why that cylinder wasn't running is solved, but why did the new injector nozzle tip burn up in the 5-10 miles that the pictured damage was done? That chunk of metal was bouncing around in the cylinder proper... not the prechamber, so I don't see what that would have done to cause the injector to go FUBAR. Any ideas on that? IMO, something is still fishy with the IP. Unless you guys can convince me otherwise, I think that IP is trash/disassemble experiment.

As far as my options for this engine.... head could be rebuilt I think? Which from searching seems to be about $1100-1200. Do I have any options for the long block? That seems to be super expensive ($4-5k)... Can you get an individual piston (or is that a bad idea, they seem to only come as a set, and I imagine that is for a reason)? Basically, do I have any options that aren't less than a full rebuild? I'm not keeping my hopes up, just trying to gather all my options so I can figure out what to do with the car.

As I imagine everyone is going to say toasted engine... I guess I'll be parting it out for use on my other SD. If the interior of the white car was nicer, I would go about finding another engine... as it is.... I'm out my first MB, and my brother isn't too happy now that he has to buy a car... :(

I will always have the glowplug out whenever I pull a prechamber again!!! :o

Little bit cleaner...

Close up and the cylinder wall damage, the metal bit stuck into the piston, etc.

The departed...

I would have to say, yes. :eek:

Can you explain how this occurs? The holes in the end of the prechamber are very small........1mm or so..........so I'm not grasping how these large chunks of glow plug (or pintle ball) got inside the cylinder? Wouldn't they just sit on the bottom of the prechamber?

That SD looks to be in excellent shape from the photo. Another engine for it would not be all that expensive, especially if the body is as good as it looks.

It shouldn't go to the boneyard.........too nice for that.

IANAM, but out of sheer curiosity, why does it look like there are valve indentations in the tops of all the pistons???

Normally, I would think that a belt/chain broke and this was interference engine and the two hit. Are those round indentations normal? Intentional? Have some sort of mechanical function?

The pistons are manufactured with recesses for the valves. The clearance is apparently too small to take the risk without the recesses.

........good to see you around the forum again......

Very interesting! It's probably just a lack of knowledge, but I've never heard of this being done. Good to know.

.......I'm always around :D Just not as active as I used to be since I got most of the work done of the SD a while back. Nowdays, it's just the regular long-term work that pops up on occasion. But, I still peek around routinely looking for interesting threads like this one. :dizzy2:

Chris
'85 300SD

those prechamber shots look familiar infact identical to several i pulled out of my 300sd about 10 years ago.damage is almost identical.never did figure out why this happened but it was suggested that use of starting ether could have led to this:confused:

You would be suprised, they are actually pretty big...

The 3 holes on the front are 4mm, the one pointing down is 2mm, and the two on the back are 3mm.

Here is a pic of nice shiny new ones... courtesy of Worldpac.

http://img.eautopartscatalog.com/live/A204021316MAH.JPG

Cool! Transparent background :)

I'm curious about that too... the ball never left the PC on mine. I guess if it is in there long enough it could break up into pieces that are small enough to fit through the PC holes?

trouble
 

just read about your experience, you just saved my butt. i was going to do the smae thing to my engine

The body is in decent shape... but the jack points are starting to get rusty. Also, the seats are in pretty sad shape. To me... its a borderline thing. If there was just one less thing wrong with it I would slowly bring it back, but as it is I'm on the fence.

Glad that my mistake can help prevent others... :)

Yeah........I hear you. If it needs bodywork.......and another engine........you've really got to have the time and the dedication.........just very sad to see a W116 get terminated........there's so few of them left that are above hopeless.

The head still looks OK in the photos. I've seen worse that were reused. Go look for a junk engine. Pull both the piston and liner and swap them. If the head looks better, then swap it as well. The interior only looks like it needs to be restuffed. Give it a chance.

Go for it.
 

Nothing wrong in just replacing the damaged parts. At least that's my experience from replacing a bent connecting rod in my S350. Cylinder walls do not look too bad. Do remember to compare the connecting rod lengths to see if the force from the ball bent it. You could go crazy replacing every little wear part and spend thousands in a rebuild, but that's overkill IMHO. Use Hylomar on the head gasket when you reassemble. Worst case is that it dies after another 20 kmi. Could go another 100. If the head's not cracked, I'd use it as-is. the indents will lower compression a bit, but it will still run. Your potential loss is about $400 in parts and some time that will be a good learning experience. I had a blast when I did mine.

-Dave Walton
87SDL, 94S350, 99E300

Glad I followed up on this post. Too bad about your engine, I wonder if the Dents were caused by the original pc chunks, the GP end, or parts of the PC? can you tell what the piece of embedded metal is? the large hole in the pc let the gp end drop in? hard to belive. maybe something fell into the open GP hole before you got the new one in... those dents are from something SOLID, I can't believe the gp end is that sturdy. pull it out of the piston and find out what it is.
it may be a berring from something else like a turbo gone south and finding it's way into the intake and be completely unrelated to the GP booboo.
John

Interesting, verrrrrryyyyy interesting....
 

Is that li'l metal ball, the metal embedded in the piston crown...solid??

It almost looks as if it is a ball bearing from somewhere......

I looked at all of the photos......I don't think that little metal ball is from anywhere within the Injection system/prechamber......

could you post a photo of the intake valve port, for that cylinder??

So far, my train of thought seems to lead to a "foreign" object passing from the air cleaner, thru the turbo....and then kicked up into the engine.....it just happened to land in that particular cylinder......

SB

the pictures in this thread are stunning, but...What is the ball for? does it serve a purpose like the marble in a spray can?

Answer
 

The ball improves aerosolization = better combustion.

Precombustion chamber
http://en.wikipedia.org/wiki/Indirect_injection#Precombustion_chamber

diesel injector prechamber aerosolization
http://www.google.com/search?hl=en&rls=com.microsoft:en-us&ei=oH49S7nRKY7mnAfO1ciBCQ&sa=X&oi=spell&resnum=0&ct=result&cd=1&ved=0CA0QBSgA&q=diesel+injector+p rechamber+aerosolization&spell=1

I'll second that sentiment. W116's were a giant leap forward in their day. Sad to see them dropping off the roles of daily drivers....

And, what's the theory behind the huge holes in the sides of the prechamber? As I recall the little ball is attached to a thin rod with a wider flange at the end that "fills" the hole it is inserted through. What caused it to come off? Maybe I have been lucky, but I have never seen one come loose. I have seen them pitted and eaten away, but never loose. And looking like such a ball. I see no evidence of the rod it is mounted on in the photos.

Oh well, sorry to see this end so dismally.

Jim

The shaft that the ball rides on is pressed into the side wall of the prechamber. Over time, this connection loosens. On the SD at 180K, the shafts were all a bit loose. They were not in danger of disengaging from the wall of the prechamber, but the guess from Metric was that they wouldn't go another 100K. I replaced them all.

I believe it's quite common for these shafts to get loose once the engine gets over 200K. Whether they disengage is anyone's guess. I suppose it is related to the manufacturing process of the prechamber. The thin outer wall of the prechamber is not ideal for holding the shaft for an indefinite period of time.

I have never dissected a prechamber so I am not clear on how the ball is mounted on the shaft, but I thought it was actually one piece from peering at it through the opening the injector screws into. I also thought it was anchored on both sides, not cantilevered from one side. Again, based on gross observations. The ball in his photo in one of the earlier posts with pictures shows what looks like a pretty intact ball. Just seemed peculiar to me - the shaft it was mounted on is gone, and the ball is intact, without any evidence of a shaft having been attached or a through hole for the shaft to go through. Just seemed odd.

Jim
Jim

Yes, the ball and shaft are one piece and the shaft is anchored on both sides in the wall of the prechamber.

I can't explain the presence of an intact ball unless the "shafts" have disintegrated. They are quite thin near the prechamber wall.

And it seems the holes the little "flanges" at each end of the shaft are shrink fitted into have also departed, leaving a large hole. The one side shown in the photo shows the damage from shearing the glow plug shaft off. I wonder what the other side looks like?

The photo of the bore in the head the prechamber fits into looks like the entry into the main combustion chamber above the piston and under the valves seems intact - other than where one of those "flanges" appears to have pounded an indentation, but at a diameter that would be closed off by the inner tip of the prechamber once installed. Which, in the photos does not seem particularly damaged . The observations would lead one to conclude the design, intended to preclude the shaft ends or ball from dropping into the combustion chamber, was still capable of achieving its design intent. All very mysterious.

Jim