Injectors Rebuilt Twice....Still Leak...I'm stumped

[Doakster]

I've had my injectors rebuilt twice now in the last few weeks, first time the injectors leaked between the body and boss.

Pulled them out again and sent them back to the shop I'm going to, they relaped the nozzle and all four still leak.

What are they missing here...they are a bosch dealer and have rebuilt these type of injectors before.

[burn_your_money]

It sounds like they are not properly lapping the surfaces or there is a nick in one of them and it is causing the leak.

[Doakster]

It sounds like they are not properly lapping the surfaces or there is a nick in one of them and it is causing the leak.

That's what I thought...but these guys are pretty good. It's simply a lapped surface that seals it correct?

They said they were going to make certain they lapped them well, the second time they rebuilt them.

[Doakster]

Sometimes fuel will leak into the injector threads when you are bleeding air from the injectors and will take a while to boil away giving the impression that fuel is bubbling out for a while.  Have you gone through several heat cycles with the engine?

I'd say at least one cycle....I ran it up to full temp on a good drive and observed no air in the lines. The first time I had them rebuild only a couple leaked at first, drove the car for awhile, and they all eventually leaked.

This time they just started to leak as soon as a lit it idle for about 3 minutes, and they of course leak worst after a good drive.

[burn_your_money]

Yes it is just 2 smooth metal surfaces making the seal.

Do you have access to compressed air? It's a lot easier to blow everything dry and then look for leaks. It could be the return lines, or even the hard lines feeding the injectors that are leaking and giving the impression that it is the injector halves.

[Doakster]

Yes it is just 2 smooth metal surfaces making the seal.

Do you have access to compressed air? It's a lot easier to blow everything dry and then look for leaks. It could be the return lines, or even the hard lines feeding the injectors that are leaking and giving the impression that it is the injector halves.

I've checked the hard lines, and the return lines, no leaks, the tops of the injectors are completely dry, I've been spraying down with brake part cleaner so every thing is good and dry, and the fuel always develops around the body.

[Rabbit TD]

Man that is strange, especialy from a place that {supposedly} knows what they are doing.  I've taken them apart  before just to clean them and put them back together without even lapping them and they didn't leak.  You could always take them out and put them in a vise and retorque them just a little tighter and see what happens.  The bottom line is that a business is no better than it's employees no matter how big the name on the door is

[jtanguay]

i've bought prothe injectors just to check them out.  they work okay but they were wet where the bodies meet as well.  after about 1500km or so they never really leaked much... just seemed wet.  but ya they shouldn't be wet like that...

[Quantum TD]

Torque the bodies up to 55-60 lbs. I think bentley says 52lbs?

I had the same problem on some rebuilts I bought. I toqued them a bit more and the leaking went away.

It will affect breaking pressures a touch, but you can "hillbilly" tune you pump to compensate if it bothers you.

[camboscams]

I went through this very same thing a few months ago when i finished my rebuild. What the deal was, was that the torque on the injector bodies and the torque of the injectors in the head was close enough to reduce the net torque on the bodys themselves, because the torque affect is in the exact oppisite directions, to the point to were they start to leak. So what i did was have the injector shop put a little more on the bodies and i went a little less on the torque in the head! NO more problem.

hope this helps, Cambo

[Doakster]

Alright, what is the torque suppose to be when you install the complete injector into the head?? Just got off the phone with them and they are telling me bosch recommends 31 or 35 i believe.

I was going to 51ft-lbs off my bentley manual, but I could be an idiot and not read it right. I assume the 51 ft-lbs is when you are resembling the injector halves themselve.

What they are getting at is that I'm tweeking the injector too much.

[jtanguay]

if you can get the feel of the injector heat shield 'crushing' you can do it without the torque wrench.  don't forget your anti seize on the threads too that will reduce the torque required, and lessen the chance of the injector body loosening.

[burn_your_money]

Alright, what is the torque suppose to be when you install the complete injector into the head?? Just got off the phone with them and they are telling me bosch recommends 31 or 35 i believe.

I was going to 51ft-lbs off my bentley manual, but I could be an idiot and not read it right. I assume the 51 ft-lbs is when you are resembling the injector halves themselve.

What they are getting at is that I'm tweeking the injector too much.

31 or 35 is way too low.

I'm going by memory but the injectors as a whole going into the head is 55 ft-lbs. I've heard 51 a lot as well so that might be right. Possibly a variance in the bentleys.


If they are only torquing the injectors to 31-35 at the shop then that'll be more prone to leaks. Do it to 58 ft-lbs

[Doakster]

Alright, what is the torque suppose to be when you install the complete injector into the head?? Just got off the phone with them and they are telling me bosch recommends 31 or 35 i believe.

I was going to 51ft-lbs off my bentley manual, but I could be an idiot and not read it right. I assume the 51 ft-lbs is when you are resembling the injector halves themselve.

What they are getting at is that I'm tweeking the injector too much.

31 or 35 is way too low.


I'm going by memory but the injectors as a whole going into the head is 55 ft-lbs. I've heard 51 a lot as well so that might be right. Possibly a variance in the bentleys.


If they are only torquing the injectors to 31-35 at the shop then that'll be more prone to leaks. Do it to 58 ft-lbs

At the shop when they are assembling the injectors they are torquing the halves together at around 50-55ftlbs, i don't remember the exact number they stated, but they went off the bosch spec.

When I install them in the car, on the head I am torqueing them to 51ft-lbs

I just looked at my bently manual again. The specs are:

Injector halves: 51ftlbs
Injector into heads: 51ftlbs

The shop is saying that they contacted bosch directly and bosch stated they are to be torqued to 31ftlbs into the head. They are thinking that the 51ftlbs may have tweeked the halves a little bit to cause the leaking, they also agree that retorqueing to 31ftlbs may not fix it.

I was simply going off my bently manual, but I'm going to try loosening and retorquing to 31ftlbs and see what happens.

[rabbitman]

Seems strange that you did the torque correct and then they say that could be the problem......everyone else installs them like the bentley says and doesn't have a problem. I'd try a different shop