reamed glow plugs, now won't start in warm weather! - Page 6 - PeachParts Mercedes-Benz Forum

whunter · #76 12-20-2009, 04:55 PM

Quote:

Originally Posted by Biotour

i tried both methods. the carriage bolt doesn't work, it just slips out, there's not enough of an edge because the hole is too small. the lag bolt didn't work either. the 5/16 was too loose and 3/8 was too tight.

is it really that big of a deal to just replace the prechamber? Ive built the tools to do it. should i use a new part or a junkyard prechamber?

Be sure to remove that glow plug before attempting removal..

Yes, this is a major operation.
* Make a mistake and the piston can hit the pre-chamber = junk engine.
* Have it jam half way out, and the head may need to come off.
* Break the pre-chamber (rare but does happen), and the head must come off.

The pre-chamber is NOT going to come out easy.
Plan a full day for this DIY, and count your blessings if it pops right out...

P.E.Haiges · #77 12-20-2009, 05:59 PM

Thanks Jim.

I now remember seeing a heat shield a long time ago when I had an injector out.

Seems to me its more of a seal than a heat shield. So it probably would be a good idea to replace the heat shield every time an injector is R&R.

P E H

Biotour · #78 12-20-2009, 09:12 PM

i removed the glow plug to attempt using the lag bolt as i didn't want it to damage the glow plug. after failing with the lag bolt i went to the local auto parts store and picked up a set of bolt extraction tools, they look similar to lag bolts except the threads are reverse, much more coarse, and the tool is tapered. its meant to cut into a hole (usually drilled in the stuck bolt) and then it will eventually stop screwing in and the bolt will start to unscrew. i screwed it into the hole as tight as i could get it, and tried pulling on it with vice grips but it wouldnt budge. i hooked up a slidehammer to the vice grips (and they were on there really tight) but it just pulled the vice grips off the bolt extraction tool.

i wanted to further explore using this bolt extraction tool, but unfortunately it has a square end and is really just meant to spin, not be pulled. after the slide hammer method failed i decided to try tightening it in with a torque wrench. it started digging into the metal and eventually the bottom of the tool touched the atomizer ball and refused to go in any further. it just reamed out the hole and the atomizer ball now has a slight flat spot on the top.

i'm starting to think this is a different prechamber than the rest, and not simply just a heat shield stuck in the prechamber. shouldn't it have come out by now if it were just a heat shield?? i can't see any seam or edge and it really looks like the heat shield is actually part of the bottom of the prechamber.

i'll probably go to the junkyard at some point this week and test out my prechamber extraction tools so i know what i'm doing and dont screw anything up if it comes to that. what do i need to know about installing a replacement prechamber? i obviously don't know what size crush washer i will need, as everything's still in the engine.

whunter · #79 12-21-2009, 12:28 AM

Quote:

Originally Posted by whunter

It is possible, but not a good sign.
The next logical question = what other alterations where done to the car.

The pre-chamber is MB# 617 010 03 52

The Seal Ring under the pre-chamber is used to set the correct depth.

Standard MB# 615 017 00 60

2.3MM MB# 615 017 01 60

2.6MM MB# 615 017 02 60

2.9MM MB# 615 017 03 60

Links to the parts

Fastlane: pre-chamber
http://catalog.peachparts.com/item.wws?sku=6170100352

Fastlane: Prechamber Seal Ring, Standard MB# 615 017 00 60
http://catalog.peachparts.com/item.wws?sku=W0133-1643608

Fastlane: Prechamber Seal Ring, 2.3MM MB# 615 017 01 60
http://catalog.peachparts.com/item.wws?sku=W0133-1715215

Fastlane: Prechamber Seal Ring, 2.6MM MB# 615 017 02 60
http://catalog.peachparts.com/item.wws?sku=6150170260

Fastlane: Prechamber Seal Ring, 2.9MM MB# 615 017 03 60
http://catalog.peachparts.com/item.wws?sku=6150170360

whunter · #80 12-21-2009, 12:45 AM

Quote:

Originally Posted by Biotour

i removed the glow plug to attempt using the lag bolt as i didn't want it to damage the glow plug. after failing with the lag bolt i went to the local auto parts store and picked up a set of bolt extraction tools, they look similar to lag bolts except the threads are reverse, much more coarse, and the tool is tapered. its meant to cut into a hole (usually drilled in the stuck bolt) and then it will eventually stop screwing in and the bolt will start to unscrew. i screwed it into the hole as tight as i could get it, and tried pulling on it with vice grips but it wouldn't budge. i hooked up a slide hammer to the vice grips (and they were on there really tight) but it just pulled the vice grips off the bolt extraction tool.

i wanted to further explore using this bolt extraction tool, but unfortunately it has a square end and is really just meant to spin, not be pulled. after the slide hammer method failed i decided to try tightening it in with a torque wrench. it started digging into the metal and eventually the bottom of the tool touched the atomizer ball and refused to go in any further. it just reamed out the hole and the atomizer ball now has a slight flat spot on the top.

I'm starting to think this is a different prechamber than the rest, and not simply just a heat shield stuck in the prechamber. shouldn't it have come out by now if it were just a heat shield?? i can't see any seam or edge and it really looks like the heat shield is actually part of the bottom of the prechamber.

I'll probably go to the junkyard at some point this week and test out my prechamber extraction tools so i know what I'm doing and didn't screw anything up if it comes to that. what do i need to know about installing a replacement prechamber? i obviously don't know what size crush washer i will need, as every thing's still in the engine.

If you can find/extract a good used pre-chamber, it can be re-used on your engine, MB service data confirms this.
The ball and sealing surfaces must not be damaged.

In theory, you use the same dimension seal ring as the one removed.

* If the wrong pre-chamber was installed, it may have made contact with the piston = unknown damage.
* The seal ring may have been replaced with a part from the unknown donor engine.

IMO: you are better off extracting the odd pre-chamber from your engine, confirming no piston damage, then finding a replacement pre-chamber + seal ring.

Diesel911 · #81 12-21-2009, 12:51 PM

Quote:

Originally Posted by Biotour

well its definitely NOT carbon in cylinder 5's prechamber. i got that paste type paint stripper, put that in there and used a rag to wipe it off, then a scratch awl to try and poke out the carbon. turns out it's metal. and now its all scratched and has little dents from the scratch awl.

did someone put a prechamber from another engine in here?? i don't really know what to do.. i'm thinking about building a prechamber puller tool..

Maybe someone put one Heat Shield on top of another?

Also, did you make a tool to remove the Slotted Ring that holds the Prechamber in place? If so how about a pic.

This is what mine looks like: http://www.peachparts.com/shopforum/showthread.php?t=265870

Biotour · #82 12-22-2009, 12:42 AM

there's definitely 2 revisions of the prechambers. the first pic is my engine (81 300sd). my buddy's 82 has the same prechambers. in a previous post on this thread i showed closeups of them. the second picture is the prechambers i pulled today. two were from an 83 and one from an 84. they all look exactly the same as the 3rd pic, my 5th prechamber. apparently it wasn't just a stuck heat shield as i had first assumed! the last picture is of some of the collars i removed today as well as the prechambers. i pulled the injectors from both engines and every prechamber i saw looked like this "newer" style. i figured i'd just pull and replace the one i had, but wanted a couple extras just in case. the removal process was FAR easier than everyone on here makes it out to be.

now the question of course is why are there two different styles? and which one should i be using?? or does it even matter?

Biotour · #83 12-22-2009, 01:08 AM

heres what i used to pull the prechambers:

first, a 7/8" regular impact socket, 1/2" drive, made by husky, sold at home depot.

second, a $40 harbor freight 5 lb slide hammer, and a Avenir brand crank puller. it was the cheapie they had at my local bike shop.

third, a 1/2" drive cordless impact wrench, and a 4 1/2" grinder from home depot.

4th is how you turn the slide hammer and bike tool into a prechamber puller. the object on the left is whats left of the bike tool after you unscrew the black part and screw it onto the part on the right, one of the harbor freight slide hammer attachments. the threads obviously dont match but who cares? harbor freight tools are cheap soft metal, and the bike tool is high quality hardened steel. it will make threads for you in the harbor freight attachment and although i thought it would surely strip, i removed the above 3 prechambers with no issue. just put the slide hammer attachment in a vice and use a wrench to tighten the crank tool onto it. make sure you get it screwed in all the way so no threads in the bike tool are showing.

note: most crank pullers have the same 22x1 thread pattern, and i believe the park tool has the same inside diameter as this one. support your local bike shop and just bring the harbor freight attachment in and see what will work. they should have something that you'll be able to get to work.

obviously use the grinder to make the socket look like picture #1 and #5. i just guessed and went out to the car and back a couple times test fitting to see how much more metal i need to remove. you want it to be a pretty tight fit. i had to tap them in with a socket wrench, but if it fits in there just right you shouldnt have to worry about it wobbling out. i believe the impact wrench is crucial as well to getting the collar removed. you'll try for hours and end up with bloody hands if you try a torque wrench. this $300 tool gets them off in less than 2 seconds. just make sure you put some weight behind the wrench and that it remains perfectly perpendicular to the retaining ring. i had one of those wimpy 1200 in. lbs. impact wrenches but it couldn't do much. the tool i used is rated at 300 ft. lbs.

Biotour · #84 12-22-2009, 01:13 AM

note the very slight taper i put into one of the ears. it barely fits by hand but if you give it a tap it will sit in the groove tightly and not wiggle out.

Olivier · #85 12-22-2009, 07:13 PM

Very nice writting Biotour. Thank you.
How were the chambers inside? A lot of carbon or free of it?
Hope the car will start now.
Olivier

Biotour · #86 12-22-2009, 09:52 PM

after pulling those prechambers from the junkyard cars, i thought it'd be easy to do on mine. turns out the collar was torqued way too tight; the 300 ft. lbs. impact wrench couldnt get it out! oh well. yeah i screwed up the hole and the atomizer ball has a flat spot, but one odd prechamber won't keep the engine from starting anyways. and after i did the compression test, the adapter i screwed into the 5th prechamber seemed to "fix" the burrs caused by trying to remove what i thought was a stuck heat shield. i decided to put it all back together with new heat shields and my rebuilt and balanced injectors. and its still not starting.

i didn't think the injectors would solve this problem; only improve on cold starting. there is something else going on here that's preventing me from starting the engine.

i did a compression test before putting the injectors back in. now keep in mind, this car has been sitting in the cold for the past week and a half at least. i don't remember the last time i drove it. but about 5 days ago i put a quart of marvel mystery oil in the prechambers to try and soak the rings and give me a better compression reading. i pulled the glow plugs and cranked to get the oil out before this test. this car has been my daily driver for the past 6 months and the only issue i had with it was it wouldnt start in single digit temps, so all this work ive been doing was in an attempt to help it start in colder weather. i would assume that if compression were an issue, i wouldnt have been able to use it as my daily driver.

#1 190 psi
#2 80 psi
#3 70 psi
#4 150 psi
#5 80 psi

i believe there is a significant amount of blowby as cranking with the oil cap loose blows it off the valve cover.

i havent done anything to this engine besides ream the glow plug holes, which resulted in it now not starting at all, even in mild 40 degree temps. recently i replaced all the glow plugs and put in 5 new monark nozzles which all popped at between 2050 and 2100psi.

ive made a video of the engine attempting to start. does it sound like its cranking too slow and just not building up enough pressure to start? would a new or rebuilt starter help this issue at all? i tried a new known working battery from another 300SD and it didn't make a difference in the cranking speed.

i also inspected the air intake and there are no blockages. the turbo spins freely when turned by hand. while cranking, i can feel the engine sucking in air, but its not a super strong vacuum. should it be?

the hard lines were tightened at the IP and left a little loose at the injectors, and tightened after i saw fuel coming out. they were bled properly. i also pumped the primer pump about a hundred times, for fun.

GregMN · #87 12-22-2009, 11:01 PM

Adjust your valves, unless you know for a fact they are in spec.

Those compression values are so far from min. acceptable that it's a wonder it ever started.

kerry · #88 12-22-2009, 11:27 PM

Those compression numbers are terrible. Was there enough carbon around the glowplugs prior to reaming to push up those compression numbers into the startable range? Reaming out the carbon, lowered the compression enough to cause the no-start condition/

Biotour · #89 12-23-2009, 12:17 AM

Prior to reaming, all of the glow plugs were pretty hard to remove. This is why i thought it'd help my cold start issue to ream them out. When actually reaming them, however, there didn't seem to be a whole lot of carbon on the reaming tool. But now the glow plugs can be screwed all the way in or out by hand, once loosened with a wrench. Maybe i haven't been torquing them down enough, and i'm losing compression through the glow plug holes? I really can't imagine the carbon around the glow plugs helping with compression that much. I mean, it started perfectly (in moderate weather) before reaming.

what is the minimum acceptable compression for a COLD engine? i know the min. specs for a hot engine are somewhere above 200 psi.

i did the valves about a month ago so i know they are in spec.

whunter · #90 12-23-2009, 01:07 AM

Quote:

Originally Posted by Biotour

#1 190 psi
#2 80 psi
#3 70 psi
#4 150 psi
#5 80 psi

I see three possible answers to compression this low:
* Valve adjustment is bad = the adjusting nuts are weak/damaged = slipping/becoming loose.
* The head gasket is blown.
* The compression rings are gone.

A fast slipping valve adjustment is in the factory service manual, the recommended cure is new nuts.

Upper nut, valve adjustment
MB# 615 053 00 72

Lower nut, valve adjustment
MB# 153 990 02 51

Valve adjustment OM617 FYI.
Valve adjustment OM615, 616, 617 FYI.