-
AAZ injector torque # with anti-seize?
by
Otis2
on 06 Mar, 2021 20:16
-
Hi all, long time no post, but I'm back again to ask about the torque number for the fuel injectors on an AAZ cylinder head.
Bentley manual says 51 foot pounds, which I believe is to be measured dry.
I have not found a thread here where there is a clear and accepted torque number to use if you are using antiseize on the threads.
There are a few hints in some very old threads here, but no clear answer. One guy said he uses 30 foot pounds, and others said they just do it dry and go to the full Bentley spec. Going further afield with general Google searching yields random people saying to use 25% or 30% less torque for their random applications.
Ideally I would like to know the received wisdom about this torque number from experienced IDI people, for this specific application!
Thanks.
The reason I pulled these injectors was that one was leaking, although I am not sure whether it leaked at the injector body seam, or right at the cylinder head. I figured I would just pull them all for servicing now.
These injectors had been installed with copper antiseize, and all came out like a knife through butter. It seemed like way less than 51 foot pounds torque to unscrew them, which makes me wonder whether there was a cause & effect relationship between the use of antiseize, too-low torque, and the leak...
A couple of notes from my experience with this job so far, that may be useful for other people doing it for the first time:
After reading the threads here recommending various sockets for this job, I took a chance on the expensive Snap-On S6104B socket. I bet it works fine for 1.6 TD injectors, but initially it did not fit down over the AAZ injector's hose nipples. So I hit it with a Dremmel and grinding stone for several minutes, and wallowed out the inside of the socket above the 12 point pawl area. After that, it dropped over the nipples, but it was blocked where the threaded top of the injector is supposed to fit through the socket hole at the top. The hole in the socket was slightly too small, so the 12 points of the socket would only get down to about half the height of the hex on the injector body. SO I grabbed the Dremmel again and wallowed out the hole in the top of the socket, and now it drops down completely over the hex on the injector body. Expensive and a hassle, but now I have the right tool for the job in future.
Also of note, Injector #2 looked absolutely impossible for me to get the socket into position over it because of the position of the LDA. It almost looked like I would need to pull the injection pump off to get it. But after fiddling with it by about half a millimeter at a time, there was *just* enough room that the socket eventually slid down onto the injector. So don't give up! After the socket slid into place, no wobble extension was necessary for me, which one of the threads here recommended. YMMV.
-
#1
by
libbydiesel
on 06 Mar, 2021 23:19
-
I use zinc based nuclear grade anti-seize and always torque to 52 ft-lbs. I do not use copper in contact with aluminum as any electrolytic corrosion will cause the aluminum to be sacrificed rather than the copper. Zinc is a better choice in contact with aluminum. I have done that with more than 100 (probably more than 200) IDI injectors and have never had one come loose on its own. Doing that I also have never caused damage to a head although I am always cautious to orient the bar the correct way (parallel to the head and pushing toward the head) for tightening and loosening.
-
#2
by
Otis2
on 07 Mar, 2021 00:33
-
Excellent, thank you very much for your clear answer.
So effectively you torque the injectors to the same spec as the Bentley manual, even though you also use antiseize on the threads.
Obviously that's going to be tighter than a dry fit, but I like your evidence of 100 - 200 injectors and never any damage to any IDI cylinder heads prepared according to that method.
Good enough for me.
I will follow your lead here, or at least very close (accounting for the likely inaccuracies of my retail-grade torque wrench, so maybe shooting for 45 to 50 pound feet just to be a little on the safe side).
These injectors that I just removed from my AAZ head felt suspiciously loose.
I'm not sure that is what caused the leak in the #1 injector necessarily, but I don't like the idea of using only 30 foot pounds "just because antiseize". If there is good evidence that it's possible to go higher and not strip out the aluminum threads, then that is what I would prefer.
The other three injectors were perfectly dry, FWIW.
I'm going to have a local Bosch shop service them all, so maybe they can tell me whether they think the leak in #1 was in the injector body, or at the head seal.
-
#3
by
sgnimj96
on 07 Mar, 2021 18:54
-
Fuel leaking is the injector itself.
Any leaks from where it screws into the head would be compression getting past the heat shield - soapy water there would make air bubbles with the engine running.
-
#4
by
libbydiesel
on 08 Mar, 2021 02:10
-
I do not believe that diesel will ever leak up the threads from below. Any diesel leaks that occur to allow diesel at the threads of the injector will occur from the seam of the two halves of the injector or from above at the little nipples or the metal line union.
Soapy water at the injectors making bubbles when the engine is running is *not* an indication of a compression leak. Soapy water sprayed into the threads of the injector will ALWAYS make bubbles when the engine runs without any compression leak. Diesel spilled down into the injector threads will also make bubbles as the heat at the heat shield causes it to boil away. Compression leaks at the injectors will *not* typically form bubbles with either soapy water or with spilled diesel as the pressure and velocity of the escaping gases will simply blow away faster than a bubble can form.
-
#5
by
Otis2
on 09 Mar, 2021 01:19
-
Thanks to you both for your insight.
I did not do a soapy water test before removing the injectors, so that evidentiary ship has sailed.
I will follow up again here when the injector shop gets back to me. It's this place, FWIW:
https://nwfuel.ca/I'm pretty sure the leak was in the joint between the two injector halves. It was wet with fuel in that seam, and below it, but totally dry above it. So it is unlikely to be a problem with the return nipples or the hard line feed. And I can't imagine how the fuel could leak up from the cylinder head to the injector seam, then do a 180* drop into the seam, all without leaving any wet traces above that seam. So I'm pretty sure that's the issue.
While dealing with this injector leak, I found a nice air bubble in the clear fuel feed line going to the injection pump, and I saw that the copper washers on the top & bottom of the banjo bolt there are wet.
So there is a second leak in the system, joy.
I cranked the banjo bolt a little tighter, maybe a twelfth of a turn, but without using a torque wrench I am reluctant to be too enthusiastic. Once the injectors are back in, I will see if there are still air bubbles in that feed line.
Anyone have the torque spec for that banjo bolt handy?
Am I best advised to replace the copper washers there, anyway?
One step at a time. Vehicles eat themselves. Entropy comes to us all.
Also, on removal of the hard lines, I noticed that all the vibration clamps were missing. God knows how long it ran that way. I see it's no picnic to find replacement AAZ hard lines these days, either. Joy.
NW Fuel Injection will do a hard line test at 300 bar, so that's double what the injectors are rated. I would rather the lines break on a shop bench than in the back of beyond.
-
#6
by
libbydiesel
on 09 Mar, 2021 11:20
-
In lieu of the correct anti-vibration clamps, it is possible to cut short sections of rubber hose with ID of hose matching the OD of the metal lines. Make a slice in each those short sections the long way so you can slip them over the lines. Then add a hose clamp around them similar to how the stock clamps are positioned.
-
#7
by
sgnimj96
on 09 Mar, 2021 13:10
-
-
#8
by
libbydiesel
on 09 Mar, 2021 13:24
-
Many of the listings of parts at Hans auto parts are wrong or misleading.
Metal lines that fit the 1.6 will not fit the AAZ. The block is taller and the injector bodies are taller making a significant combined difference. All of the lines in the link are 1.6 lines and would need significant contortion to fit an AAZ.
-
#9
by
ORCoaster
on 09 Mar, 2021 13:41
-
sgnimj96,
I can't believe that you have been on this forum since Aug of 2012 and would offer Hans as a place to go for anything. I thought the overwhelming opinion here was to stay away from him.
Maybe your experiences with him have been favorable but most are not.
I don't think the OP needed new lines, He is looking to deal with leaking injectors and by the sound of it he may have it figured out.
And yes he will likely want new heatshields unless he follows the advice of some here that reform them and reuse them until they get cracks.
-
#10
by
sgnimj96
on 09 Mar, 2021 15:31
-
I'm just glad there is any vender out there stocking hard to find pieces for older vw diesels AND using vw part numbers for reference.
Local part stores sell a lot of low-end products at ripoff prices, but won't even stock most of parts we use,
makes people think early vw diesels aren't worth owning if you can't find the parts.
-
#11
by
Otis2
on 09 Mar, 2021 15:50
-
Yes, I am not yet in the market for AAZ hard lines. Hopefully these ones are still fine, as they did not seem to be leaking yet. My concern is that they have become work hardened with the lack of clamps, and somewhere down the road, even after replacing the clamps, I will need to source replacement hard lines. That is currently not easy with an AAZ engine, although anything is possible with enough time/money I suppose. Just not very convenient.
NW Injection called and told me they did not find a leak in Injector 1, when they tested it. I find that very surprising. So the leak source is still a mystery.
I am having them do a full injector service anyway, and they guarantee their work.
Before disassembling it, they are going to test Injector 1 a second time for leaks, by hitting it with a little more pressure.
So after they do all that work, then if a leak still exists after reinstallation of the injector, I must rule out that injector seam as being the source of the leak.
Hope to have the engine all buttoned up again on the weekend, and will report results.
-
#12
by
ORCoaster
on 09 Mar, 2021 18:46
-
Otis2, I will send you a PM with a Craigslist attached. Just look to see if there are any parts you might need. Unfortunately no lines. I thought there were. IF I come across some I will shoot you another PM to follow-up on.
-
#13
by
Otis2
on 20 Mar, 2021 20:18
-
Follow up, as promised.
NW Fuel Injection did a nice job cleaning and testing the AAZ hard lines, and they are all good, so hopefully I'm ok for a long time to come.
On reinstall, the #2 line seemed a little tweaked from neatly lining up with the pump & injector, but I pushed it into position before tightening the nut, and it does not leak. I have read that's the one most likely to crack, so I will have to keep an eye on it.
I sprung for rebuilt AAZ injectors from Giles in the end, because they were about the same price as NW Fuel Injection charged ($115 vs $110 CDN per injector currently), and I know Giles does a lot more VW (and specifically AAZ) stuff. For the extra $20 plus shipping, it's better peace of mind for me. YMMV.
I couldn't find any zinc based antiseize at any FLAPS near me, so I used Permatex Silver, which is an aluminum/copper/graphite mix. It's rated to 1600* F, as compared with 1800* F for the copper stuff, so either way the cylinder head should not be seeing those temps. Hopefully I will not have to put its efficacy to the test for a very long time to come...
Engine runs great again, no leaks.
Thanks again for all the help.