injector leaking at the halves

[92EcoDiesel Jetta]

Side question : what was the value of almost tripling the internal pressure @ idle? What did you gain?

FYI, 20 psi @ 1000 rpm is 3x lower than spec. All I did was to bring it back to spec. Result was more power.

i thought you were supposed to have like 42psi @ idle (internal pressure)

It depends on the pump. I called up a diesel injection shop and asked them what pressure my pump should be. It's a test spec parameter from Bosch.

[92EcoDiesel Jetta]

This is all speculation and conjecture on my part since I do not have that much experience with it yet. I think if there is a heat shield leak, the fuel from the injector is all burned and will not show up as a leak via the injector threads. What happens is soot will escape via the leaky heat shield and pack any cavity solid with carbon making the injector very difficult to remove. I had one injector like that on my Ecodiesel when I first acquired it, the injector just didn't want to come out. I was really afraid of breaking the head. It took an hour of back and forth, 1/16" at a timeand lots of penetrating oil to finally get it out and it was packed solid with carbon. You really don't know if a heat shield (re-used or new) is leaking or not till you pull it. The best you can do is make sure the sealing surfaces are clean and not damaged and lessen the chance of a leak by the use of a new heat shield. They cost a dollar each here and is not a great expense. I re-used them temporarily because I had to pull the injectors many times and ran out of new ones, which I had 10 on hand.

It was not a burnt heat shield but rather a burnt nozzle face. I'll try to remember to shoot a pic next time I get the injectors out to put new heat shields in.

Good grief man It's not definitive because my leak might be bigger than your leak , yet if as you say there might be a leak past the seals but not past the threads then that is not possible. The threads are not tight enough to be a seal. If there is a continuous leak, it will push past the threads and bubble up. How do you tell if your brand new just installed shield isn't leaking? Are you the only one who never has a new shield leak

Put up a picture of your burnt shield please. If it is burnt, then how do you know the fault isn't doing the same to your replacement shield? If I were as cautious as some here, I'd want to find out the cause before risking burning a hole in the head...

 If you want an immediate test just spill a little diesel onto the top of the thread. Doing the air release on the fuel lines is enough to drop a small amount of diesel down in the neccessary place. I bleed my lines every time I put injectors in, which is the only time I look at my heat shields, unless there is a leak.

The heatshields saved amount to over £3 each, so 15 x 4 x 3.00 x 1.50 =$270.

Are you going to be the first to pick the 4 old shields in my little game [/color]

[ORCoaster]

A little less based on graphic he posted on average pump psi. I dropped my idle pressure to 38 psi and am watching my MPG get back the the 50 mark as I continue to tweak it.


Mark is the top row the used shields and the bottom the new?  I see some wear marks on them and thus figured they must have been in place once already. 

[Mark(The Miser)UK]

A little less based on graphic he posted on average pump psi. I dropped my idle pressure to 38 psi and am watching my MPG get back the the 50 mark as I continue to tweak it.


Mark is the top row the used shields and the bottom the new?  I see some wear marks on them and thus figured they must have been in place once already. 

Important to remember the figure from the average graph and Bosch was for 1000rpm crank and not most idle settings, which on a half decently running engine should be lower [Q basic setting are higher than Golf types for some reason, but I run at about 850rpm or less]. I haave a new graph to offer up and will do so soon.

With the heat shields, none were new but one set had been used once The engine I removed them from took a breakerbar to undo them initially, so I assume they had been in situ for quite a while.

You are indeed correct otherwise. Good to see someone with a backbone .
The upper ones were reused another 7 times, two of which are still in the car, but I will replace them, either with the ones you thought were new, or with some truely new ones to match the others...

[ORCoaster]

Man I am just going to have to buy a Tiny Tach for my car!  Then I can get data to you for one more set of data points to average in with the others.  I already have the pressure gauge on the IP.  I generally try to set the idle near what I think is 850 RPM as that is the number on the yellow sticker over on the passenger strut.  So I set the pressure lower because it comes up in a good hurry on my pump and perhaps I should watch it again now that I put of tank of ULSD without my additives of wax and ATF in there.  Might be interesting to see how it acts.  Kicked out 48 MPG last tank.  Still struggling to get to a consistent 50 with the way I drive.  It may not be possible.  But I will not accept that just yet. 

You mean none of those heat shields were new.  I thought that was the comparison.  Some old the others new, the game/challenge was to figure them out.  Do I get a cookie?  I really like cookies.

If I ever get a tach set up I will be sure to send data your way.  I think you have the best set going that I know of.