dang injector
 

so I recently replaced my nozzles with monarks, at first three were leaking from the top of injector to the lower of the injector threads, not the injector to head threads. I removed them recleaned and replaced two kept leaking I pulled them cleaned and swapped lower fittings on them but kept the lowers relative to thier place in the head. One still leaked, pulled a not leaker and the leaker again swapped the lowers keeping them relative. The same one continues to leak through the threads. I plan on going to the junk yard to find an injector that doesn't leak, good plan? Input? Critique?

You are supposed to "lap" the two halves if they dont fit tight enough to seal.

Pretty simple, get very fine wet/dry paper and a perfectly flat stone or glass work surface. Sand the mating surfaces. Clean them SUPER good before resembling, pop test, adj, test again and install with new heat sheild.

Say what!? which surfaces? Not the threads... Right? Also I didn't pop test them.. Don't have a tester.. I'll buy or make one soon.. But please describe to me again in more detail the procedure you suggest?

Take the inj body apart. Set the guts aside. Sand each half of the inj body in circular motion to make the seam between each perfectly flat again so that when you put the two halves back together they will seal.

Or look up "lapped surfaces", "lapping" on google, etc.

PS: your plywood workbench top or the concrete garage floor is NOT a flat enough surface to work upon.

Exactly.
By fine wet/dry paper I would think 600grit or less.
I have been using a plate of glass with 600 grit lapping compound that rock shops (Lapidry?) folks use to lap/tumble/smooth rocks. You can lap a whole set of injectors with 1/4 teaspoon or less and some light oil like sewing machine/gun oil/3 in one oil. Water is OK to.

The flat surfaces. One flat surface on each side of the of that center plate and the flat surface on the bottom of the upper 1/2 of the injector.

Don't even THINK about touching these faces with even 1200 abrasive paper let alone 600! These are lapped to a Ra 0.5µm flat and flawless mirror finish on special grooved cast iron lapping plate with a 2 micron diamond lapping paste. The faces must 'Wring' together to hold 140 bar without internal or external leaks. Dirt can be removed by rubbing on paper soaked in silver polish on plate glass.

Ah, At last! The voice of reason!

I was wondering when someone was going to put this 'Sand-paper' rubbish to bed!:rolleyes:

Yup, Those are Precision ground/lapped parts. Sand them with wet/dry 600 or even 1200 grit, and they are Scrap!:eek:--

--IF you have done this and 'got-away' with it, You're bloody lucky!:D

When doing nozzle-changes, just clean these mating-faces well with cloth soaked in solvents. Nothing more--Finish up by washing Everything in FILTERED Diesel Before assembling -WET- with the filtered fuel....

When everything is Spotless clean, re-assemble and tighten by hand. Then slacken half a turn, and re-tighten. Do this slackening/tightening by hand three or four times Before finally tightening to the right tightness....

IF everything is Properly clean, and you have no damage to any sealing-surfaces (and why should you, as they have always been tight inside the injector until you took them out...)--

--Then you'll have no leaks either internally to the leak-off OR through the threads....:D

In the Fuel Injection shop I worked in (5 years) when used 500 grit lapping compound for our hand lapping plates and our Automatic Lapping Plate machine 99.9% of our lapping of Fuel Injection Pump Parts and Injector part was done with 500 grit.

We used 1200 grit for our nozzle re-regrinding operation to lap the Injector Pintel seats and on sticky Injector Pintels and Plunger and Barrels (IP Elements).

That shop was in business for 30 years until the owner died. I can't imagine that in all that time he was using the wrong grit lapping compound!

I would prefer not to use the plate of Glass as a Lapping Plate but so far I have always been out bid on Ebay for a real lapping plate.
Also the lapping plates do not have to be grooved and some plates have a grooved side and a flat side; both can be used.

I have lapped 3 (10 Mercedes injectors and 6 Volvo injectors) sets of injectors on the Glass Plate and none of them have leaked.

If I'm not mistaken
 

Didn't you have a diagram of this a few months ago?

Rubbish!:D :D :D

Rubbish=standard procedure.
Nozzle regrinding- Both nozzle and Pintle seating area were touched lightly with a (Nozzles with a spinning mandrel with a grinding stone on the end and Pintels with a machine similar to a Valve Face Grinder) followed by lapping. (by the way these were direct injection type nozzles not the type in Mercedes. Mostly Detroit Diesel nozzles.)
You take a tooth pick and only put tiny amount of the 1200 compound on the Pintle seat; do not get it on anything else. We had small chuck that grabbed the opposite end of the Pintle; you inserted the nozzle over the Pintle taking care not to wipe any of the compound. Turn the switch on and spin the Pintle putting a slight pressure on the on the nozzle.
Clean the compound out of everything and test the nozzle.
Polishing a sticky Plunger was done by chucking up the Plunger by it self. you put some of the 1200 compound on some sturdy Toilet Paper. Turn the machine on and spin the plunger while at the same time working the stroking the Toilet Paper with the compound up and down the plunger. This polishes it well.
If 1200 grit sounds too rough remember you Spin On Fuel Filter is a 10 nominal micron filter. This means that on the first pass it will filter out 50% of the 10 micron or larger particles.

Maybe some one out there can compare 1200 grit size and convert it to Microns.

I am quoting myself as I found a site that has the Micron size of 1200 grit lapping compound. 1200 girt = 5 microns.
5 micron particles are small enough that they can pass through your stock fuel filter and into your Fuel Injection Pump and injectors.
Here is the site:
http://stellafane.org/atm/atm_mirror_ref/atm_grit.htm

500 Mesh is 42µm! It is the maximum grit size that counts.

All flat lapping plates have flat and grooved sides. The flat side is for holding on Surface Grinder to resurface and is never used for lapping!

I’m just speechless!:eek: Hmmmmmm…......:confused:

You said it!

Seriously the only lapping we do these days is on the older inline pumps (eg MW) and KCA type injectors. No Fuel Injection Service shop use automatic lapping machines (nor toothpicks and sturdy toilet paper for that matter):D. After over 50 yrs in this business I’m sure I would have heard about it:o. Faulty injector nozzles are replaced – period. Diamond lapping pastes are used. 7µm – roughing, 2µm – semi-finish and 0,5µm to restore mirror finish when rebuilding.

Example:
http://i508.photobucket.com/albums/s...peedpolish.jpg

By the way the time peroiod I am talking about is aprox. 1975-1980.

The company bought the Nozzle regrinding equipment ready made so this tells me that at the time there must have been a market for that type of equipment. Meaning that someone besides the shop I worked in was re-grinding Nozzles.

Also, if the way we did things at that shop did not work we would have had a lot of warranties and lost business and that did not happen.

If 500 mesh is = to 500 grit; we used that only on flat surfaces. When you spoke of the Max size range of grit of the lapping compound; you can pay more and get 500grit or other sized compound that is not contaminated with other size grits.

If your shop has a better equipment and dose a better job; thats all to the good.