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Engine Specific Info and Questions => IDI Engine => Topic started by: Turbinepowered on September 06, 2008, 04:51:07 am
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Soooooooo... lapping these injector nozzle seats blows.
The car the engine came out of had 150k+ miles on it... and I think these were the original nozzles. If they were ever replaced, I don't think these sealing surfaces were lapped.
I've taken a shim increment's height off one of these! .06mm, and the gouges in the nozzle sealing surface still aren't gone! I'm still on 200 grit sandpaper and light oil, working on a glass tabletop.
One of them is looking nice, though. 200, 400, and 660 grit sandpaper, and she's nice and clean and shiny as a mirror. :D
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Oh, and, as a question for Vince and others who have done this... how long does it usually take for you guys to do the lapping per injector?
It's really only the nozzle sealing surface that's giving me crap. The injector halves lap nicely, and their respective seat sealing surface is a piece of cake too. Just that nozzle seat... :x
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You are not alone, I did a set and it took a long time to get rid of the grooves. Longer then I thought it would. Be careful you dont loose patience and start giving it some to get it done quicker. I did and ended up with 2 that were not perfectly flat. Ie.. leaking. I suggest setting up infront of the tv with a six pack, throw in a movie and away you go.
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Oh, and, as a question for Vince and others who have done this... how long does it usually take for you guys to do the lapping per injector?
It's really only the nozzle sealing surface that's giving me crap. The injector halves lap nicely, and their respective seat sealing surface is a piece of cake too. Just that nozzle seat... :x
My recommendation would be "easy does it"... a quick pass with the rougher sandpaper and then most of the time (maybe a minute ?) on the 600 (or even finer if you can get it.). I found a supplier of 1000 and 2000 and that's what I'm using these days. I also tend to skip the rough paper if there are no visible wear marks on the sealing surfaces, and head straight to polish.
I actually found a 4000 abrasive bar that I use as a final polish.. as I understand the official Bosch procedure that's about the grade they use to do their polish as well. No doubt the entire thought of using sandpaper makes Bosch-trained folks shudder... but it seems to work.. again, easy does it !!
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Just been experimenting with some injectors. Cleaning the carbon off I've found an oven cleaner foam softens quickly and can be wiped off.
On one I decided to lap the pintle. Under an eyeglass the trailing edge of the seal was pitted.
I used some ancient valve lapping paste [fine paste side] I dabbed some on the tip, reinserted carefully into nozzle and used a small hand drill to rotate oiled pintle removed /cleaned etc and reassembled. It did seem to work. Inspecting seating area it did look a little grooved, but that may disappear after use.
When increasing break pressure, I'm unclear why there is talk of lapping several different parts. The only part that needs lapping is the top half of the injector. this is easily done with one of those cheap diamond impregnated wood chisel sharpening stones.
The more faces you try to lap, the more chance of loosing parallel mating and then forcing to mate the surfaces, binds up the pintle IMO
If things are mating properly then injector body shouldn't leak with maybe 15lb ft torque. [Increase when happy with setup.]
If there is a leak then disassemble and use permanant black felt tip to find leak
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Ha Ha Turbinepowered! it's not as easy as it seems! my finger's ach just thinking about it!
i actually hate doing them now! buying this poptester i realize was not such a great idea after all !
you still sending them to me to poptest or did you make up your own rig?
Duane
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My recommendation would be "easy does it"... a quick pass with the rougher sandpaper and then most of the time (maybe a minute ?) on the 600 (or even finer if you can get it.). I found a supplier of 1000 and 2000 and that's what I'm using these days. I also tend to skip the rough paper if there are no visible wear marks on the sealing surfaces, and head straight to polish.
I'm not bearing down on it at all, just the weight of my finger in a circular motion; I don't want to cut more grooves in the thing. The problem is all my "wear marks" are quite deep, concentric circles that match up with the top of the nozzle. They aren't uniformly deep, they're almost gone directly under the fuel ports, but the arcs between those ports are still visible, and I still hang up when I draw a fingernail lightly across them.
I actually found a 4000 abrasive bar that I use as a final polish.. as I understand the official Bosch procedure that's about the grade they use to do their polish as well. No doubt the entire thought of using sandpaper makes Bosch-trained folks shudder... but it seems to work.. again, easy does it !!
So reaching for the 3k grit stone wouldn't be a bad idea for the final? :D I imagine using a bottle-jack based pop tester makes them shudder, too, but I am clean with this process.
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Ha Ha Turbinepowered! it's not as easy as it seems! my finger's ach just thinking about it!
i actually hate doing them now! buying this poptester i realize was not such a great idea after all !
you still sending them to me to poptest or did you make up your own rig?
Duane
I finally found the leak, so I've got them covered. Missed an entire bleeder port, eeesh. :roll:
I keep coming home from work (12.5 mile bike trip at 3AM, nice ride), having a sandwich, then sitting down at my glass table with the radio on to lap a seat.
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what are you guy's talking about? are there any pic's or vid's in the archive's? on what your really doing?
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Yeah, it's a bit obtuse, isn't it.
We're talking about "lapping", one of the steps needed when rebuilding injectors:
http://vincewaldon.com/index.php?option=com_content&task=view&id=20&Itemid=28
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Hey Vince, you're famous!
I had a set of newish nozzles swapped into the 1.9 bodies from the 1.6 ones that came with the umwelt AAZ Passats and the Bosch guy mentioned that he had an increasing amount of injectors show up at his shop "because some guy put a DIY page up in the internet and now all these people are screwing up their injectors and showing up at my shop with "rebuilt" injectors that need to get cleaned, re-done, shimmed and pop tested to work properly."
He wanted to thank you for all the extra work you're sending his way :D
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LOL
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That's actually my secret evil plan to keep the remaining diesel shops in business.
You're welcome, Giles !!! ;-)
Vince
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He! He! thats funny! and that means mine that i have done are good even the one's i did for my self! so either that means i know how to read? or i'm just brilliant and luckey ? but i could not have done it with out Vinces site!
they are a lot of work ! but well worth the effort compared to buying new?
AAZ are a different breed even i know that i can not do those with the equipment i got! but some day?
as it stands now i've done 4 sets and have not heard anything being wrong!
but i am sure they would tell me if they were!
Duane
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True, some people can break a crowbar in a sandbox.
Having said that, based on all the email I get:
- there's a healthy appetite out there on the Interweb for working on these beauties ourselves
- many people are hundreds or thousands of miles from a shop that even knows what an IDI diesel injector is
- there are still things I can do to make my particular instructions clearer... and I will.
Might even add in a story about a little shop in Burnaby... :wink:
All in all... I'm just happy to see people going ole skool and actually getting greasy... becoming less and less common these days sadly. And if you break something... well, you tried and you learned. Perhaps you learned to read the instructions ??!!!
AFAIK there are exactly two 1-man shops in Edmonton, a city of nearly 1 million people, that will still happily work on air-cooled VWs. :cry:
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Yeah, it's a bit obtuse, isn't it.
We're talking about "lapping", one of the steps needed when rebuilding injectors:
http://vincewaldon.com/index.php?option=com_content&task=view&id=20&Itemid=28
Vince I have some questions re lapping:
1) Why do you have to lap the centre spacer? More-so why the top grooved side; especially as it will be mating back up with the injector top that it was mated to in the first place. Surely every face individually lapped runs the risk of tilting the plane of its mating face leading to uneven pressures, and at best distortion/leaks at worst?
2) Why are you taking off so much flesh that it amounts to a decrease of 5 thou, or an increase of 15 bar on original spec (probably more in reality, as it seems to me, with the 20 [TD] injectors I've looked at, so far; most operate at nearer 140 -145 bar). Thats more akin to grinding than lapping.
3) As I stated earlier in this thread why are people clamping down with such force in an attempt to avert leaks? Aren't the grooves a sign of distorting everything as warned against in all good books to avoid nozzle distortion; especially as the pintle can float on an oil film, and a good matched pair barely leak to the returns at all [when cold at least] I guess mating pressure is of the order of 60,000 psi.
'Newly into injector repairs'
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Mark(The Miser)UK
I am going out on a limb to one suggestion and would work for me in that it would save me some money rather than buying all new injectors.
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Vince I have some questions re lapping:
1) Why do you have to lap the centre spacer? More-so why the top grooved side; especially as it will be mating back up with the injector top that it was mated to in the first place. Surely every face individually lapped runs the risk of tilting the plane of its mating face leading to uneven pressures, and at best distortion/leaks at worst?
2) Why are you taking off so much flesh that it amounts to a decrease of 5 thou, or an increase of 15 bar on original spec (probably more in reality, as it seems to me, with the 20 [TD] injectors I've looked at, so far; most operate at nearer 140 -145 bar). Thats more akin to grinding than lapping.
3) As I stated earlier in this thread why are people clamping down with such force in an attempt to avert leaks? Aren't the grooves a sign of distorting everything as warned against in all good books to avoid nozzle distortion; especially as the pintle can float on an oil film, and a good matched pair barely leak to the returns at all [when cold at least] I guess mating pressure is of the order of 60,000 psi.
'Newly into injector repairs'[/color]
Hi Mark... keeping in mind what my posted instructions say:
"This is how I do things… it is not necessarily the right way nor the best way !"
.... some thoughts:
1) In my mind when you rebuild an injector there are 3 "old" sealing surfaces (the top of the injector housing and both sides of the centre spacer) and one "new" sealing surface... the top of the new nozzle. There are often visible grooves worn in at least two of the three... to me a quick pass on the third side is cheap insurance that *all* sealing surfaces are fresh. I assume that the new nozzle has a fresh sealing surface... besides, I don't like to handle them anymore that I have to... insanely close tolerances within the nozzle !
2) Dunno what you mean here mate... nowhere do I specify 5 thou... or any other thou for that matter. I gently lap with successively finer grit until I have a nice polished surface... and then adjust the breaking pressure to compensate as required. If there are no grooves there is very little lapping required... if there are deep grooves then there's more lapping and more material removed. I've never been scientific enough to record before and after popping pressure per injector so can't comment on how many bar mine specifically... more a general feeling that they go up some.. and as I say, it's gonna be dependent on how much grooving I'm faced with.
3) Can't comment on what "people" do... I specify the factory torque (70 Nm or 51 ft-lbs) and that's what I personally use. I'd agree with you that overtorquing is a good way to distort the nozzle and risk pintle misalignment or binding.
So far I've only had two leak that I can remember.. and in both cases I re-lapped rather than torquing harder... a bigger hammer is rarely the answer imho. ;-)
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Vince I have some questions re lapping:
2) Why are you taking off so much flesh that it amounts to a decrease of 5 thou, or an increase of 15 bar on original spec (probably more in reality, as it seems to me, with the 20 [TD] injectors I've looked at, so far; most operate at nearer 140 -145 bar). Thats more akin to grinding than lapping.
'Newly into injector repairs'[/color]
Hi Mark... keeping in mind what my posted instructions say:
"This is how I do things… it is not necessarily the right way nor the best way !"
.... some thoughts:
2) Dunno what you mean here mate... nowhere do I specify 5 thou... or any other thou for that matter. I gently lap with successively finer grit until I have a nice polished surface... and then adjust the breaking pressure to compensate as required. If there are no grooves there is very little lapping required... if there are deep grooves then there's more lapping and more material removed. I've never been scientific enough to record before and after popping pressure so can't comment on how many bar mine usually change by.. and as I say, it's gonna be dependent on how much grooving I'm faced with.
So far I've only had two leak that I can remember.. and in both cases I re-lapped rather than torquing harder... a bigger hammer is rarely the answer imho. ;-)
Thanks for responding.
My second point was based on your mention of sometimes resulting in a 170bar break pressure.... 170 -155 =15 bar. Each shim increment is 0.05 mm, for approximately 5bar pressure raise. Thus .15mm = .15/25.4 = 6thou. All my so far checked [gauge could be duff, thinking about it] TD injectors are between 135 and 145 bar
Do you think grooves are neccessarily a cause of a leak, or if the injector is not leaking not particularly a bad thing.
Hmm not sure if that's clear,,, Basically is it worth trying an injector with a new nozzle without lapping even if it is grooved, if it wasn''t leaking before and therefore the marks are possibly just cosmetic, seeing as lapping is somewhat time consuming?
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I'm beginning to feel that a quick pass with 1,000 grit to freshen the sealing surface might be the best initial approach. Then, if any leak, address those specific ones with additional lapping.
Andrew
I'd concur... given that they are fine tolerance surfaces the less done the better. I have a 4000 grit lapping bar that is perfect for touchups.
My only caveat might be that if I see visible grooves I'm likely to lap 'em rather than go to all the trouble of dialing them in first since I know that lapping away grooves is likely to invalidate the initial dial-in.
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Well there's my problem right there.... every diesel I own has had a cylinder stolen from it, since I only use *4* injectors. :wink:
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Could you give some details on the
"4000 grit bar"?
Is this the stuff used for polishing
stainless steel?
Do you just spread the stuff on a
piece of plate glass, or what?
I've been wondering about that
stuff and any information you'd
be willing to share would be much
appreciated.
Thanks, in advance.
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It's an actual lapping bar sold originally to hone woodworking tools.
Got mine from Lee Valley Tools:
http://www.leevalley.com/wood/page.aspx?c=1&p=33009&cat=1,43072,43071&ap=1
I lube it with diesel rather than water... works a treat and the price is pretty reasonable.
The only downside is that it's pretty soft... I find I need to true it fairly often. Lee Valley also sells the tool to keep it true !
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Hmmm, interestingly enough, the Dasher Bentley manual that I have (which gives "instructions" for rebuilding an injector, or at least taking it apart) makes no mention of lapping, grooves, or sealing surfaces.
I've dug out four more matching injectors, they're less "groovy" on the sealing surfaces, so I'm going to do the "just polish them up a tad" and test them out.
[edit] Forgot to mention I can't find the 3k water stone we have around the shop somewhere, it hasn't honed a wood tool in ages and is "expendable" in my father's words, so... 1700 grit sandpaper and light oil it is. I'll go extra easy on the finger pressure.
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It's an actual lapping bar sold originally to hone woodworking tools.
Got mine from Lee Valley Tools:
http://www.leevalley.com/wood/page.aspx?c=1&p=33009&cat=1,43072,43071&ap=1
I lube it with diesel rather than water... works a treat and the price is pretty reasonable.
The only downside is that it's pretty soft... I find I need to true it fairly often. Lee Valley also sells the tool to keep it true !
Thank you for that link.
I'll go down to Lee Valley and
check it out.
Thanks again
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Hmmm, interestingly enough, the Dasher Bentley manual that I have (which gives "instructions" for rebuilding an injector, or at least taking it apart) makes no mention of lapping, grooves, or sealing surfaces.
I've dug out four more matching injectors, they're less "groovy" on the sealing surfaces, so I'm going to do the "just polish them up a tad" and test them out.
[edit] Forgot to mention I can't find the 3k water stone we have around the shop somewhere, it hasn't honed a wood tool in ages and is "expendable" in my father's words, so... 1700 grit sandpaper and light oil it is. I'll go extra easy on the finger pressure.
Turb.
I wouldn't bother with ultrafine grades.
If you make a mirror surface, and there is some mismatch, then higher torque pressures are needed to 'take up the slack' Using something like 600 grit, then the 'matt' surfaces will bond better and the microscopic peaks and troughs will plateau, only as required.
I would also leave water-stones behind. Use a Norton's type carborundum or Al Oxide. Why? Well waterstones are excellent for sharpening blades knives etc; but at what point do you create an acceptable convex lap, before the stone needs periodic dressing.
The references to a lapping block in the Bosch manual refer to an impregnated steel block. A diamond one works well with a light pressure.
All disagreements welcome; after all, thrashing it out not only gets a result, it also tends towards the correct answer :twisted:
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The references to a lapping block in the Bosch manual refer to an impregnated steel block. A diamond one works well with a light pressure.
And to me, at the risk of thrashing this thread to death... that's the point of all this. :wink:
There *is* an official way: a precision diamond-impregnated steel lapping block.... I hear they're green in colour ! I also know that they are spendy little creatures. I've read that there's a really really expensive microtome lapping machine for this task as well... takes off molecularly-fine layers of material in perfect alignment.
Given that I only do a couple of sets of injectors a year... I look for less spendy alternatives that approach the same results, particularly when safety is not compromised. Fine sandpaper on glass, inexpensive water stones that need to be dressed now and then... stuff like that. It isn't the recommended method or the recommended tools... but based on the scale of my operation I'm OK with the results. :wink:
I also substitute muffler clamps, impact wrenches, pieces of string, pieces of angle iron, fingernail polish, plastic putty knives, and various screwdrivers ground in all kinds of weird ways for the official tools... tools that I'd own if I ran a business but substitutions that make sense given the scale I operate at.
Actually, I do own the official exhaust clamp removal tool... it works well, but I sure wish I'd discovered this forum before I shelled out the hundred bucks !!! :lol:
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score=
Vince= 6
miser=0
L.O.L. :wink:
Duane
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Nah.... no score.... we're all learning here.
For starters, I'm keeping my eyes open for an carborundum or aluminum oxide stone because, yes, those water stones are pretty soft.
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The references to a lapping block in the Bosch manual refer to an impregnated steel block. A diamond one works well with a light pressure.
And to me, at the risk of thrashing this thread to death... that's the point of all this. :wink:
There *is* an official way: a precision diamond-impregnated steel lapping block.... I hear they're green in colour ! I also know that they are spendy little creatures. I've read that there's a really really expensive microtome lapping machine for this task as well... takes off molecularly-fine layers of material in perfect alignment.
Owch... I take your point. I don't even know where you'd get a lapping plate the size of the Bosch one. I've seen a small one through a 'Google'. My old man has the waterstones. I happen to have collected the harder types, some are natural and some the Norton type. Frustrated by why the hell you rarely see them bigger than 6" x 2" or a 'giant' 8" x 3" I took to finding more than one of the same grit and imbedding them together into a block of wood.
I even made one out of a large piece of deglazed ceramic from the back plate of a toilet cistern [er John :?: :?: flush box?] Its about 8" x 1ft
Given that I only do a couple of sets of injectors a year... I look for less spendy alternatives that approach the same results, particularly when safety is not compromised. Fine sandpaper on glass, inexpensive water stones that need to be dressed now and then... stuff like that. It isn't the recommended method or the recommended tools... but based on the scale of my operation I'm OK with the results. :wink:
I totally agree on the less spendy routes. Every time I buy something for the car, I think well I only paid $60 for the whole thing! ... I regularly have to refocus :mrgreen: ...
New water stones or hard types of any quality cost the earth over here, but we have something over here on weekends called 'carboot' sales [trunk :roll:]; where modern man gets rid of granddads rusty old [extremely high quality] tools to make room for shiney new stuff from Indochina :roll: If I'm lucky one turns up for a $1 :lol:
Those cheap diamond impregnated plastic ones on Ebay for a few $ work well. I used an old 600 grit one on an injector last week to raise the b/p by 10 bar.
I also substitute muffler clamps, impact wrenches, pieces of string, pieces of angle iron, fingernail polish, plastic putty knives, and various screwdrivers ground in all kinds of weird ways for the official tools... tools that I'd own if I ran a business but substitutions that make sense given the scale I operate at.
Actually, I do own the official exhaust clamp removal tool... it works well, but I sure wish I'd discovered this forum before I shelled out the hundred bucks !!! :lol:
12mm socket and extension on a 'Q'... But granny [turned 83 last week] does have that dreaded GTD, so I may have that to come :wink:
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It's an actual lapping bar sold originally to hone woodworking tools.
Got mine from Lee Valley Tools:
http://www.leevalley.com/wood/page.aspx?c=1&p=33009&cat=1,43072,43071&ap=1
I lube it with diesel rather than water... works a treat and the price is pretty reasonable.
The only downside is that it's pretty soft... I find I need to true it fairly often. Lee Valley also sells the tool to keep it true !
Actually, if you want to go that fine,
www.rockler.com sells "Micro Mesh"
ranging from about 2400 grit up to
12,000 grit for $3.59 per 3"X6" sheet.
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Actually, if you want to go that fine,
www.rockler.com sells "Micro Mesh"
ranging from about 2400 grit up to
12,000 grit for $3.59 per 3"X6" sheet.
Crikey 12000 grit, what the heck is that like? A mirror?
A CCD out of a small camera has bigger dots :lol:
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Actually, if you want to go that fine,
www.rockler.com sells "Micro Mesh"
ranging from about 2400 grit up to
12,000 grit for $3.59 per 3"X6" sheet.
Crikey 12000 grit, what the heck is that like? A mirror?
A CCD out of a small camera has bigger dots :lol:
No doubt!
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Actually, if you want to go that fine,
www.rockler.com sells "Micro Mesh"
ranging from about 2400 grit up to
12,000 grit for $3.59 per 3"X6" sheet.
Crikey 12000 grit, what the heck is that like? A mirror?
A CCD out of a small camera has bigger dots :lol:
No doubt!
Hang on I've just caught on.... that's snake oil [Its just a sheet of brown paper with writing on] :mrgreen: