PRECHAMBER COLLAR bad/cross threads- now what?

[blankenship]

did a compression test on my 617 today, and when removing the injector from #3, i noticed it felt funky compared to the rest.
the compression tester fitting went in poorly, and came back out with scarred threads.
i can only get the injector back in about 1/2 a turn by hand, as opposed to multiple turns on all the others.

long story short: i need to EITHER:

TAP the existing collar while it's in place, with a 24mmx2 tap, with some kind of stuff underneath to keep shavings from falling in

or

REMOVE the prechamber collar and replace it. looks like mercedes says you need a special tool (615 589 00 07 00 (available online for $85!)) to remove it. (if i remove the collar, do i also need to do a total removal of the prechamber and replace its sealing ring, or can i do the collar only?)

anybody have experience w/ this?

[winmutt]

Originally Posted by blankenship

did a compression test on my 617 today, and when removing the injector from #3, i noticed it felt funky compared to the rest.
the compression tester fitting went in poorly, and came back out with scarred threads.
i can only get the injector back in about 1/2 a turn by hand, as opposed to multiple turns on all the others.

long story short: i need to EITHER:

TAP the existing collar while it's in place, with a 24mmx2 tap, with some kind of stuff underneath to keep shavings from falling in

or

REMOVE the prechamber collar and replace it. looks like mercedes says you need a special tool (615 589 00 07 00 (available online for $85!)) to remove it. (if i remove the collar, do i also need to do a total removal of the prechamber and replace its sealing ring, or can i do the collar only?)

anybody have experience w/ this?

Where did you find it for $85? Best price I have found is $118. The injector screws into the ring so I would expect that to be it.

[lietuviai]

You could try looking for a chisel about the size of the collar or you could grind one to about the size and width of the slot. Look for one that has a hexagonal shaft. That way you can grasp it with a wrench or if you're lucky enough, fit a socket on it.
I have some extra collars if you need one. BTW, where in the NW are you?

[alamostation]

May I offer another solution.

Use a cutoff tool, or with lots of time and discs, a Dremel tool. Trim down the opposite sides of a one inch socket (half inch drive works best) until you are left with two ears about 3/8 inch wide and 1/4 inch high sticking up on each side. Attach your socket to a breaker bar and an extention. Fit it in the grooves in the collar and twist.

Sometimes you will need a cheater pipe on the breaker bar. A second pair of hands to keep the socket aligned while you are pulling is a good idea.

[vstech]

whoa whoa, wait a sec. look at the ring first. Does it have carbon all over it? on several of mine, there was a LOT of carbon that leaked past the shields and covered the threads. even some that ate a bit of the injector threads. before you remove the ring, try a dental pic and clean out the threads and the heat shield pocket area. get all carbon off first, then decide if you still need to remove it. I bet you don't.

[winmutt]

Originally Posted by alamostation

May I offer another solution.

Use a cutoff tool, or with lots of time and discs, a Dremel tool. Trim down the opposite sides of a one inch socket (half inch drive works best) until you are left with two ears about 3/8 inch wide and 1/4 inch high sticking up on each side. Attach your socket to a breaker bar and an extention. Fit it in the grooves in the collar and twist.

Sometimes you will need a cheater pipe on the breaker bar. A second pair of hands to keep the socket aligned while you are pulling is a good idea.

I have tried this to no avail. 1" is to wide. I found the proper tool for $68 at pelican tools. Blankenship, if you buy the tool let me know I will rent it from you for a reasonable sum. Otherwise I will be buying this when I get back from germany (mid sept).

[blankenship]

well, it definitely isn't carbon.
it's the threads.

alamostation + lietuviai: have you successfully made and used the tools you're talking about making? sounds like a good speculation, but are we, indeed, speculating, or will it WORK?

is it unanimous that i shouldn't try a Tap? seems like putting a magnet down inside the prechamber would catch the shavings, but i don't know if there's enough room for the tap to go down in there without harming the prechamber, or whether it's worth the risk.

also: do i also need to do a total removal of the prechamber and replace its sealing ring, or can i do the collar only?)

[vstech]

you should be able to just replace the ring.
I have ground down the sides of a socket and successfully used it to torque a ring, it is REALLY hard to grind the socket. you have to PERFECTLY align the ground out parts, and holding the socket in place is very trickey. it may be simpler to just weld a piece of tool steel to the face of a socket. that way you have a perfect level tool, that you just need to grind down to fit.

[winmutt]

Originally Posted by blankenship

also: do i also need to do a total removal of the prechamber and replace its sealing ring, or can i do the collar only?)

I think you should replace the ring. its a $3 part or so. So is the sealing ring. The sealing ring is a crush washer afaik.

[blankenship]

yikes!
so you're saying the prechamber sealing ring needs to be replaced at the same time? meaning you think it will change position if the collar is removed?

manual says theres ANOTHER special tool (prechamber puller) required for THAT!

true? false? unnecessary? easy? painful?

man, sure which i could just twist a little tap in there with a magnet under it, and be done...

[vstech]

I would not worry about pulling the prechamber or it's seal ring. as long as you don't turn the motor over while the PC ring is out, it should not move. what do you have to lose?

[pdrayton]

My prechamber issues are with a 60X engine, which is quite different. Did you look in the manual for how it all goes together in your engine? I don't really know much about the 61X prechambers. It looks like they're the same principle - prechamber held in place with a ring/collar. The ring is splined on the 60X and grooved on the 61x. I posted a thread on a cheap 60x prechamber puller -
http://www.peachparts.com/shopforum/diesel-discussion/196905-%2415-redneck-slide-hammer-prechamber-adapter-pics-post1598250.html#post1598250
And gwxr posted on the 61x version using a bike crank.

If the threads are gone, I think you should pull the prechamber and replace it. I did that on my 60x and it wasn't as bad as I thought it would be. I put it off for months, but when I did it it wasn't bad at all. A couple of hours. The only hairy part was yanking on the slide hammer. The threads on my pc were screwed from putting the injector in skew. And the injector heat shield/sealing ring was lodged in there so tight it wouldn't come out. So I bit the bullet and coughed $89 for a new pc.

To get the pc out, you remove the injector and glow plug. Then remove the grooved ring collar. Screw in the injector as much as possible, mount the slide hammer and bang away. It's not too bad. Easy if you have the tools.

[lietuviai]

Originally Posted by blankenship

well, it definitely isn't carbon.
it's the threads.

alamostation + lietuviai: have you successfully made and used the tools you're talking about making? sounds like a good speculation, but are we, indeed, speculating, or will it WORK?

I have the actual tools designed for the job. I was looking at a chisel in my tool box that actually fits the groove in the ring and has a hexagonal shaft that a wrench or socket can fit. I have not tested it on by trying to remove one from a head. In theory it should work but it worries me to read that you may need a breaker bar to loosen the ring.

[winmutt]

You will need to grind the corners of the chisel to 45'.