Can I replace the top part of an injector without needing to re-adjust breaking pressure? One of the leak-off nipples on one of my injectors started leaking (yes, I replaced the hose and checked for line obstructions). I have 4 spare junkyard injectors and I was going to have the shop put my good nozzle (almost new) into one of my JY bodies, but I got to thinking.... can I just replace the injector top myself without messing up the breaking pressure? The adjuster shim goes against the injector top so I'm thinking maybe a new top would throw it off, but I figured I'd ask and maybe save myself a few bucks and a trip to the injection shop.
So... whaddya think?
Injector guru needed
Moderator: Fatmobile
Injector guru needed
'82 Diesel Rabbit • '88 Fox (RIP) • '88 Jetta (work in progress)
I'd take one of the spare injectors you have and put a new nozzle into it, or the nozzle from the bad injector. I've broken a barb before and that's exactly what I did. I've never mixed/matched injector pieces, but keep them together as an assembly.
Everybody else lists their cars here - but not me.
I have too many to count
I have too many to count
YES.... changing any part of an injector, including replacing needle & nozzle will change the crack pressure.....
The question then becomes, how critical is it that "Crack Pressure or Breaking Pressure" be dead on......
My guess is that a lot of older bunnies and bunnys that havn't had injectors (properly) worked or have 100,000+ miles on them have crack pressures that are out of spec high and low, big differences in crack pressures when comparing readings for a set of 4, not to mention problems like poor spray pattern and atomization of fuel.... and yet they are all running pretty good!!!!!!!!
Ideally all crack pressures for a set of nozzles would be close to the same and (if I remember correctly) set to about 1850psi......
The reason for crack pressures to be the same for a set of noozles is that crack pressure affects timing..... If you have a noozle with a low crack pressure relative to your other injectors then that cylinder will run advanced relative to the other cylinders.... this can affect mileage and cause some vibration, although my guess is that the affects are minimal and maybe not even discernible....
My recommendation is change out the parts, put her together and see how she runs,,,,,, AND the Blond says most importantly, don't forget to replace the Heat Shield EVERY time you remove the injector, even if it has only been installed one minute,,,,, and also ,, be cautious removing injectors,,, to reduce strain on head, socket handle should be oriented so that you are pushing towards windshiels when removing injector, do not use impact wrench,,, if its tight coming out try running it in and out and apply plenty of PB blaster,,, doesn't hurt to let it soak for a day or too...
Richard
The question then becomes, how critical is it that "Crack Pressure or Breaking Pressure" be dead on......
My guess is that a lot of older bunnies and bunnys that havn't had injectors (properly) worked or have 100,000+ miles on them have crack pressures that are out of spec high and low, big differences in crack pressures when comparing readings for a set of 4, not to mention problems like poor spray pattern and atomization of fuel.... and yet they are all running pretty good!!!!!!!!
Ideally all crack pressures for a set of nozzles would be close to the same and (if I remember correctly) set to about 1850psi......
The reason for crack pressures to be the same for a set of noozles is that crack pressure affects timing..... If you have a noozle with a low crack pressure relative to your other injectors then that cylinder will run advanced relative to the other cylinders.... this can affect mileage and cause some vibration, although my guess is that the affects are minimal and maybe not even discernible....
My recommendation is change out the parts, put her together and see how she runs,,,,,, AND the Blond says most importantly, don't forget to replace the Heat Shield EVERY time you remove the injector, even if it has only been installed one minute,,,,, and also ,, be cautious removing injectors,,, to reduce strain on head, socket handle should be oriented so that you are pushing towards windshiels when removing injector, do not use impact wrench,,, if its tight coming out try running it in and out and apply plenty of PB blaster,,, doesn't hurt to let it soak for a day or too...
Richard
82 1.6 N/A
83 1.6 N/A
84 1.6 N/A
82 FORD 3610 Diesel Tractor
82 CASE 580D Loader/Backhoe w/Cummins
83 IH 274 Tractor w/Mitsubishi Diesel
88 Chevy C-70 w/Cat 3208
2000 Toro 223D Groundmaster w/Mitsubishi Diesel
2000 John Deere 4600
2003 MAGNUM Light Tower/6KW Generator w/Mitsubishi Diesel
2003 Mitsubishi Fuso Truck
83 1.6 N/A
84 1.6 N/A
82 FORD 3610 Diesel Tractor
82 CASE 580D Loader/Backhoe w/Cummins
83 IH 274 Tractor w/Mitsubishi Diesel
88 Chevy C-70 w/Cat 3208
2000 Toro 223D Groundmaster w/Mitsubishi Diesel
2000 John Deere 4600
2003 MAGNUM Light Tower/6KW Generator w/Mitsubishi Diesel
2003 Mitsubishi Fuso Truck
Yes, and they're eroding the piston tops and wearing the cylinder walls causing premature oil burning and low compression and requiring the need for a re-bore and new pistons where good nozzles would have allowed the engine to run fine for an extra 200,000 miles...3Bunnys wrote:My guess is that a lot of older bunnies and bunnys that havn't had injectors (properly) worked or have 100,000+ miles on them have crack pressures that are out of spec high and low, big differences in crack pressures when comparing readings for a set of 4, not to mention problems like poor spray pattern and atomization of fuel.... and yet they are all running pretty good!!!!!!!!
Andrew
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Fatmobile
- Global Moderator
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Ya know Hagar mentioned that when screwing the injector bodys together one turn of the bodys represents a distance.
You can feel when the springs first begin to compress, and you can feel when the injector bottoms.
If you turned the injector bodies the same amount, the breaking pressure should be the same. Each spring will be compressed the same distance.
You can feel when the springs first begin to compress, and you can feel when the injector bottoms.
If you turned the injector bodies the same amount, the breaking pressure should be the same. Each spring will be compressed the same distance.
'91 Golf gasser converted to a 12mm pump, M-TDI.
'84 1.6TD Rabbit with a VNT-15 turbo, still setup to run on vegetable oil.
'84 GTI with 1.7TD pistons and intercooled.
2003 TDI wagon
2000 TDI Jetta.
'84 1.6TD Rabbit with a VNT-15 turbo, still setup to run on vegetable oil.
'84 GTI with 1.7TD pistons and intercooled.
2003 TDI wagon
2000 TDI Jetta.
That's if the springs have the same spring rate to them and the shims and injector body's are all the same. If one spring is worn and the other three aren't, one injector will have a lower pop pressure, since the spring rate is not as high as the others.If you turned the injector bodies the same amount, the breaking pressure should be the same. Each spring will be compressed the same distance.
However, I agree with you that they should really be all similar. I've never pop tested any of my injectors and have had many miles of fine service.
Everybody else lists their cars here - but not me.
I have too many to count
I have too many to count
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Quantum-man
- Turbo Charger
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- Joined: Mon Apr 24, 2006 4:34 pm
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Here I am standing outside the can of worms again ... 
Rather than all that work why not block up the injector barb and run that injector return to a tee from windscreen washer and join up with the other injector returns. Pressure is only low and is mainly back pressure from the return banjo
Rather than all that work why not block up the injector barb and run that injector return to a tee from windscreen washer and join up with the other injector returns. Pressure is only low and is mainly back pressure from the return banjo
"I'm not here to help... I'm here to Pro-Volke"
Be like meeee...Drive a Quantum TD
...The best work-horse after the cart...
Quantae grow on you...but Rabbits are like roses...
... girls like em ;o)
Only one Darwin, Einstein, Poe and Verne.
That is why if you listen, you will learn:
From the one and only Quantum-man,
Who sees the worms from outside of the can.
7 Quantae in 20 years; 4 dead and 3 TD's still alive [2 wagons & 1 fastback] oh and a GTD
)
Be like meeee...Drive a Quantum TD
...The best work-horse after the cart...
Quantae grow on you...but Rabbits are like roses...
... girls like em ;o)
Only one Darwin, Einstein, Poe and Verne.
That is why if you listen, you will learn:
From the one and only Quantum-man,
Who sees the worms from outside of the can.
7 Quantae in 20 years; 4 dead and 3 TD's still alive [2 wagons & 1 fastback] oh and a GTD
)
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surfcam
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- Contact:
You don't expect him to cut his game of darts short.
99 TDI Jetta (Z1 engine code)
94 Grand Caravan
89 Dodge Gold Stream B class
http://www.antiquedollhouseofpatterns.ca/
94 Grand Caravan
89 Dodge Gold Stream B class
http://www.antiquedollhouseofpatterns.ca/
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hagar
- Hillbilly Tuner
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- Location: Near Lund B.C. Kanada.
Bosch Injectors for Rabbits.
I hagar (the Horrible) swear by mein Gott "Odin" ----and let "THOR"
strike me down ,by swinging his hammer. --if I am not telling the truth.
I the tinkerer hagar has fooled around with hundreds of injectors-----of
many , many types.
BUT I never laid eyes on a nicer , more perfect design for a DIY type
than the BOSCH Mk 1. and Mk 2 . -----
My guess is that a lot of older bunnies and bunnys that havn't had injectors (properly) worked or have 100,000+ miles on them have crack pressures that are out of spec high and low, big differences in crack pressures when comparing readings for a set of 4, not to mention problems like poor spray pattern and atomization of fuel.... and yet they are all running pretty good!!!!!!!!
IMHO and by first hand observation ----he is right.
hagar.
strike me down ,by swinging his hammer. --if I am not telling the truth.
I the tinkerer hagar has fooled around with hundreds of injectors-----of
many , many types.
BUT I never laid eyes on a nicer , more perfect design for a DIY type
than the BOSCH Mk 1. and Mk 2 . -----
My guess is that a lot of older bunnies and bunnys that havn't had injectors (properly) worked or have 100,000+ miles on them have crack pressures that are out of spec high and low, big differences in crack pressures when comparing readings for a set of 4, not to mention problems like poor spray pattern and atomization of fuel.... and yet they are all running pretty good!!!!!!!!
IMHO and by first hand observation ----he is right.
hagar.
Actually this got me to thinking. If I had been smart enough to mark which barb was leaking, I could have cut it off and soldered the opening closed... then used that injector on the #4 position that only has 1 leak-off anyway.Quantum-man wrote:Here I am standing outside the can of worms again ...
Rather than all that work why not block up the injector barb and run that injector return to a tee from windscreen washer and join up with the other injector returns. Pressure is only low and is mainly back pressure from the return banjo
'82 Diesel Rabbit • '88 Fox (RIP) • '88 Jetta (work in progress)
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Vincent Waldon
- Turbo Charger
- Posts: 1148
- Joined: Sat Dec 16, 2006 3:05 pm
- Location: Edmonton, Alberta, Canada
tylernt wrote:Actually this got me to thinking. If I had been smart enough to mark which barb was leaking, I could have cut it off and soldered the opening closed... then used that injector on the #4 position that only has 1 leak-off anyway.Quantum-man wrote:Here I am standing outside the can of worms again ...
Rather than all that work why not block up the injector barb and run that injector return to a tee from windscreen washer and join up with the other injector returns. Pressure is only low and is mainly back pressure from the return banjo
JB Weld works quite well for sealing broken injector barbs and can be done in place, and small plastic fuel line tees from a model airplane shop are just the ticket to plumb it back into the return system if you already have a blocked off #4 from a previous incident with a deep socket that evidently wasn't deep enough.
Vince
Edmonton, Alberta, Canada
2001 silver TDI Jetta Malone Stage 1.5 , 2001 blue TDI Jetta SBIII 216s Malone Stage 3
1970 Bay Window bus
Gone but not forgotten: 1969/1971 Beetles, 1969/1974 Westies, 1979 Rabbit, 1986 TD Jetta, 1992 gas Jetta, 1994 TD Jetta
Here's a small collection of HOW-TOs
Edmonton, Alberta, Canada
2001 silver TDI Jetta Malone Stage 1.5 , 2001 blue TDI Jetta SBIII 216s Malone Stage 3
1970 Bay Window bus
Gone but not forgotten: 1969/1971 Beetles, 1969/1974 Westies, 1979 Rabbit, 1986 TD Jetta, 1992 gas Jetta, 1994 TD Jetta
Here's a small collection of HOW-TOs
-
Quantum-man
- Turbo Charger
- Posts: 2085
- Joined: Mon Apr 24, 2006 4:34 pm
- Location: Gloucester; Limey-Land
One of my first leaks I encountered with these injectors when I was a novice [I still am 
] was very misleading.
I thought it was the body leaking. Then it was the rubber line[ it may have been] I replaced that only to find it still sweating away
I took off the dead end to see just how much diesel there was. It shot into the air and so I thought no wonder it leaks..
.
I then decided to remove the dead end and form a loop from #1 and #4 and using a 'T' link back to the drain.
My thoughts were that returning diesel from #1 wouldn't have to fight its way past the jets coming from 2 ,3 & 4.
It was upon testing my new 'circuit' that I discovered that the sum of the diesel returning from the injectors [at least at idle] was negligible as upon forgetting to link the 'T' to the final return to the banjo and then starting the engine barely a dribble was coming from the injectors but I had flooded the engine with the back pressure from the banjo.
I then convinced myself the the barb was leaking at its base. So I tried glueing it. Nothing seemed to work.
Eventually I realised that the new tubing was being distorted by the barb that had been bent previously when doing up/undoing the injector. Prying it back away from the body just slightly was enough to cure it.
] was very misleading. I thought it was the body leaking. Then it was the rubber line[ it may have been] I replaced that only to find it still sweating away
I took off the dead end to see just how much diesel there was. It shot into the air and so I thought no wonder it leaks..
.I then decided to remove the dead end and form a loop from #1 and #4 and using a 'T' link back to the drain.
My thoughts were that returning diesel from #1 wouldn't have to fight its way past the jets coming from 2 ,3 & 4.
It was upon testing my new 'circuit' that I discovered that the sum of the diesel returning from the injectors [at least at idle] was negligible as upon forgetting to link the 'T' to the final return to the banjo and then starting the engine barely a dribble was coming from the injectors but I had flooded the engine with the back pressure from the banjo.
I then convinced myself the the barb was leaking at its base. So I tried glueing it. Nothing seemed to work.
Eventually I realised that the new tubing was being distorted by the barb that had been bent previously when doing up/undoing the injector. Prying it back away from the body just slightly was enough to cure it.
"I'm not here to help... I'm here to Pro-Volke"
Be like meeee...Drive a Quantum TD
...The best work-horse after the cart...
Quantae grow on you...but Rabbits are like roses...
... girls like em ;o)
Only one Darwin, Einstein, Poe and Verne.
That is why if you listen, you will learn:
From the one and only Quantum-man,
Who sees the worms from outside of the can.
7 Quantae in 20 years; 4 dead and 3 TD's still alive [2 wagons & 1 fastback] oh and a GTD)
Be like meeee...Drive a Quantum TD
...The best work-horse after the cart...
Quantae grow on you...but Rabbits are like roses...
... girls like em ;o)
Only one Darwin, Einstein, Poe and Verne.
That is why if you listen, you will learn:
From the one and only Quantum-man,
Who sees the worms from outside of the can.
7 Quantae in 20 years; 4 dead and 3 TD's still alive [2 wagons & 1 fastback] oh and a GTD
)Well, I'm beginning to wonder whether it's really worthtylernt wrote:Well I played it safe and put my newish nozzle in the JY assembly (to avoid the mix'n'match) and had it pop tested. 130.5 bar and they didn't even charge me. I love a happy ending.
it to bother replacing nozzles.
I bought four new nozzles, from a U.S.source, for $26.64 each.
plus $23.25(u.s.) shipping.
I lapped the injectors with 400, 600, 800 and 1500 grit sandpaper.
I contacted a diesel shop, here in Ontario, highly touted on the GTD
Forum, to have the injectors pop tested.
He tells me that if the injectors need to be adjusted, it'll cost me
$35.00 per injector.
So, ($26.64 X 4)=$106.56 + $23.25 shipping (U.S.)= $129.81(U.S.)
And, now, an additional $35,00 X 4= $140.00 (Cdn)
Forgetting about the exchange rate...replacing the nozzles is going to
cost me $269.81
I'm pretty sure I can buy NEW injectors for far less than that.
All very discouraging
Blue 1986 Golf N/A Bought it in '94. Never been on the road since.
Green 1991 Jetta TD. Bought it 6 months ago.
Hasn't been on the road since.
Green 1991 Jetta TD. Bought it 6 months ago.
Hasn't been on the road since.