Injector pintle caps

[disco stu]

So I'm cleaning up the injectors to install on new engine.

Rubber seal part on the bottom are hard, real hard. Just did one injector and it didn't crack like the others, and it cracked the pintle cap on removing. Pintle caps I don't have replacements of

So my question-what is the point of pintle caps? They appear to just be nice looking little covers for the metal at the end-the shape doesn't do anything on these it would seem, and it doesn't appear to really shield anything effectively like they do on other injectors. I'm tempted to just not replace, but with such a component that is hidden away I can't see the manufacturer going to the effort of putting something on there just so it looks good

While I'm at it-anyone ever dismantled an injector? I thought it's a much better way of cleaning them out if we could get them apart and clean each piece

Anyway, keen to hear thoughts
Cheers

Stuart

[erad]

The blue cap on the injectors serves only to keep water and flies out of the system. It doesn't do any sealing of the fuel side of things at all. Way back in 1971 or 72, I had a Citroen DS21 Injection. It was the first of the Bosch KJet??? Injection systems. After a while, the injector bodies developed a leak. Dripping petrol onto a hot engine is not really recommended, so I looked into buying new injectors. $55 each! At the time, $55 was an enormous amount of money. Instead of buying 4 new injectors, I only bought one because the others were not leaking too badly at the time. I was about to throw the old leaking injector into the bin and then decided to strip it and see what was inside.

I got hold of a sectional drawing of the injector and looked closely to see how it was made. I machined away the blue plastic cap from the top of the injector, and found a metal body which had been nicely crimped over to form a mechanical barrier to stop the guts flying out. I carefully prised the metal open and then removed the guts of the injector. The injector had a plastic core which formed the frame for the electrical solenoid. There were 2 O rings visible. Actually they were no longer O shape - rather they were a squashed D shape. I went downtown to the local parts shop and bought 2 new O rings which fitted (with a bit of a squeeze) in to the body (cost 60 cents for the 2 of them). I cleaned up the inside of the injectors. They were fitted to the engine at an angle about 45 Degrees above horizontal, and there was rust on the body up to the level of the injector nozzle. Naturally, I cleaned it all out, but I suspect that over the years, more rust would develop there. There was no evidence of gumming up or other contamination.

I reassembled the lot, then bent the deformed metal casing over to hold all this in place, and put some plastibond epoxy over the cap to replace the blue cap. I fitted that injector in to replace the next severely leaking one, and it worked perfectly. Subsequently, all injectors were rebuilt this way. As far as I know, those repaired injectors are still in that car, although it is not used very much these days. This repair method was documented and published in the Citroen Car club newsletter, and I know of quite a few people who repaired their injectors rather than replace them. A friend who had (still has) a Volvo 123GT had the same problem at the time, and he repaired his injectors the same way. He also found an extra O ring near the injector needle, and he replaced those as well.

Do not test the injectors with 12 volts to see if they work, I believe they are only 5 Volts.

[disco stu]

Hey-I read that story on Aussie frogs while googling about injectors! Either you or someone had pinched your story

I started low on voltage and went up from there. It opened with 5 so I stuck with that

Not sure which one is the blue cap, but the cap I mean is around the nozzle part, but only covers metal

[disco stu]

Black part furthest from camera in this image for those that don't know. Doesn't stick out offer the end at all

https://images.app.goo.gl/JkmsjhE6kpyVW1QU7

[RUGGA]

Hey-I read that story on Aussie frogs while googling about injectors! Either you or someone had pinched your story

Could you link it?, I would be very interested.

[disco stu]

The version he told here is more thorough, but I'll see if I can find it

[erad]

These injectors are different from the ones I overhauled. The cap I machined away is at the top where the fuel enters the injector. They had a metal body, with a plastic cap at the top. Not sure how you would get into the Mitsubishi injectors - these days they are much cheaper, so I probably wouldn't bother. Interesting about the frog story - I hadn't heard or seen anything about overhauling injectors.

[disco stu]

Can't find the story now for the life of me...typical!

[tomwithannl]

Mr Google says the pintle cap is usually there to keep the lower seal in place on the injector.

Tom

[disco stu]

Thanks Tom. That's the best I could find as well, and it seems I thought similar to you. I'll just run it without cap-that seal isn't going to fall off once it's mounted

And I just realised I didn't note which seal goes where for when I install them!! I think the grooved one was at the top, but I'm sure I'll find a picture somewhere