I am putting the top end back together after head gasket job and have gotten to injectors. I have read replace o-rings replace o-rings replace o-rings.. I ordered the head gasket kit from Atlantic British including headbolts. It appears that the kit came with new o-rings, however, when I looked at mine I noticed that the injectors have an o-ring and then some kind of smaller plastic o-ring shaped (maybe?) fastener? Two of those pieces are missing off of my injectors and I am not sure what they are to try and replace them!

If you know what this piece is I am talking about please help point me in the right direction of what to do!

I thought about possibly just putting a smaller o-ring on the of the replaced o-rings? Thoughts?

I haven't seem to find where anyone has talked about this before.

 

This is one injector with just the o-ring. The plastic securing type ring was gone off of this injector when I pulled it.
In this picture you can see the two securing type rings on top of the o-rings. (or technically under, I guess) What are these called? Seems like it would be an important part of the injector.

 

They're called injector pintle caps. They snap on. Any car parts store should have them. Bosch style injector.

 

While you have it apart....change the injectors.

 

This guy is a great injector cleaning shop. Fuel Injector Cleaning | Hurst Injector Service. Superfast turnaround, fair prices, and great attention to detail. I stuffed a set from my M5 in a box on Wednesday and sent them out, figuring he'd get them Friday, service them Tuesday (holiday weekend and all), and ship them out Wednesday. I called today to see if there were any issues and when he planned on returning them and he told me "No issues. They're already on their way and you'll have them tomorrow. And by the way, they were rusty inside, not dirty from use but rusty from sitting." He was spot on. I told him I took them out a few months ago and left them outside near my parts washer in the carport. He also told me whoever serviced them last used generic pintle caps and he replaced them with genuine BMW caps.

 

I went ahead and put everything back together last night before you all replied. I replace the pintle cap with another 0-ring about the same size as pintle cap. Is this going to cause firing issues? Once the injectors were in and fuel rail was bolted back in it seemed like all injectors were sitting evenly in the intake. I am not sure what roll the pintle cap plays (if anything really) other than holding the o-rings in place. Let me know what you guys think. Should finish up the job tonight and let you know what happens unless someone thinks what I have done is definitely not going to work.

 

you don't even need the pintle caps

 

I didnt think so. Seemed to serve no real purpose.

 

If engineers did their homework, and I doubt the Land Rover guys put their best feet forward in this department, the intact tract is tuned for maximum airflow into the cylinder with optimum atomization of the fuel that's being directed towards it. Pintle caps are in the airstream and therefore have an effect when such things are measured. In the case of our Discos I'm guessing you wouldn't notice if the pintle cap was a tuned airfoil, or an avocado. So relatively speaking, abran is correct, YOU don't even need them. This is not the same thing as saying ALL injectors do not need them.

 

FYI
When your buttoning everything back up and before you put your upper plenum back on.
Jump the fuel pump on at the relay under the hood and make sure the new injector o-rings aren't leaking at the fuel rail.
Don't ask me how I know.