pre com removal

[abram]

could someone post a step by step guide to remove some pre coms in a 3J5559SP? So far i've gotten some of the allen screws out, a couple broke inside the hole... not sure if this is a two piece or one piece design....i'm a visual person so pictures would help alot

[ccjersey]

looks like a single piece PC chamber design in the J series D3400 engines.

Drain coolant!
Get the set screws out,
get the correct adapter tool to fit down the chamber (hex?).
Remove injector lines and injectors. You will need a socket for that purpose. One can be made up from the correct sized 3/4" drive 12 pt socket cut in two and extended with pipe, trimmed out for the injector nipple to allow it to make enough of a turn to move the retaining nut at least 1/12th of a turn each time.

If the head's off, spray the thread area with penetrating lube or heat chamber and melt candle wax into the thread area before allowing it to cool.

If not off, you just will have to have a go with a big pull handle and cheater or an impact wrench sometimes will rattle them out better, I would break them loose and then turn back in and repeat after every round to avoid as much as possible taking the threads out of the head. there are helicoil kits available to repair the thread if you do damage them badly.

[Mike Mahler]

looks like a single piece PC chamber design in the J series D3400 engines.

Drain coolant!
Get the set screws out,
get the correct adapter tool to fit down the chamber (hex?).
Remove injector lines and injectors. You will need a socket for that purpose. One can be made up from the correct sized 3/4" drive 12 pt socket cut in two and extended with pipe, trimmed out for the injector nipple to allow it to make enough of a turn to move the retaining nut at least 1/12th of a turn each time.

If the head's off, spray the thread area with penetrating lube or heat chamber and melt candle wax into the thread area before allowing it to cool.

If not off, you just will have to have a go with a big pull handle and cheater or an impact wrench sometimes will rattle them out better, I would break them loose and then turn back in and repeat after every round to avoid as much as possible taking the threads out of the head. there are helicoil kits available to repair the thread if you do damage them badly.

Where did you learn about the candle wax?!? You beat me to it!
Mike

[ccjersey]

probably from you, someone on these ACMOC/ACME boards at any rate.

[abram]

i don't understand how the whole hex tool thing works? won't it damage the threads???? and that BIG nut on the top, does that have to come off first? or is it part of the precom?

[Old Magnet]

The hex portion is below the threads.
Need to loosen the big nut (1-3/4 in.) to remove the injector.

The hex is 1-5/16 in and can be made by double nutting and welding to a bolt with 1-5/16 in head.

You can make your own wrench by cutting, notching and welding an extension between the cut sections.

[abram]

ok i understand now, the only thing is mine does not look like that...there is no hex...once you remove the big nut does it uncover the hex?? i'll see if i can get some pictures for you guys when i can....basically it looks like there is a small metal rod coming out from the bottom in the center with 3 very small holes around it....

[ccjersey]

oops!
Sounds like the innards of an injector to me.

The big retainer nut should come loose allowing the whole injector to be removed from the precombustion chamber and exposing the hex shaped cavity that your tool has to fit.

It's best not to disassemble the injector unless it needs repair, and then only if you know how/have the tools to do it. These have to be assembled and adjusted properly to function correctly.

[abram]

ack...great....okay, any trick to gettin that nut off? i dont have a socket a proper size and im tryin to use a big ol wrench with no luck because of the angle.

[Old Magnet]

That's why I included the instructions on making a socket

I hate to say it but that's why you commonly see those big ass chisel marks on the nuts.....that's all I'm going to say....I hate butcher work