injector question

[FL911]

I have taken off my CIS intake system and noticed that where the injector lines attach to the actual injectors that he injectors spin. They are not in essence loose, but you can spin every one of them=is this normal. I suppose it is because I had a fine running engine at the time I disc. the head stud problem.
How do these inj. come out and is this something I should replace?

Thanks

[GaryR]

They are held in by a rubber O-Ring and simply pop out. I did mine following my shop's intricate instructions using special tools. "Take 2 12mm wrenches, put them between the injector and the intake and pry them against each other.. the injector will pop out".. and they did!

[DaddyGlenn]

You should be able to twist them. There is nothing to prevent that and it is not a bad thing. However, they should be pretty snug. It can't hurt to replace the injector o-rings. It is cheap insurance against developing a leak there. I did mine a year ago. The o-rings are inexpensive and it is an easy job.

[mhoffman]

if you do replace the o-rings, you might as well do the sleeves too- they get brittle with age. They are not expensive at all. Good chance to have the injectors cleaned or clean them yourself too. (That slippery slope you always hear about...)

To answer your base question though of if they should be tight, the o-ring just provides a seating surface for the injector- it is not designed to be airtight with a differential pressure. The CIS Primer has a good discussion of it. The injector is "upstream" of the combustion chamber and is only exposed to a vacuum as the intake valve is open during the fuel injection and air intake stroke, which tends to seal further the injector (the vacuum in effect "pulls" on the injector, seating it further against the o-ring and sleeve).

The neat things about these cars is that nothing was done without a purpose- it is not always obvious what the purpose is (or was), but once you figure it out it helps to make operating them and maintaining them a good deal clearer, and then being able to approach modifications more informed and intelligently.

Hope that helps...

[DaddyGlenn]

Originally Posted by mhoffman

{snip}...To answer your base question though of if they should be tight, the o-ring just provides a seating surface for the injector- it is not designed to be airtight with a differential pressure. The CIS Primer has a good discussion of it. The injector is "upstream" of the combustion chamber and is only exposed to a vacuum as the intake valve is open during the fuel injection and air intake stroke, which tends to seal further the injector (the vacuum in effect "pulls" on the injector, seating it further against the o-ring and sleeve). ....{snip}

Very enlightening and it makes perfect sense. Thanks.

+1 on the sleeves, too.

[FL911]

Perfect, those are the answers I was looking for.....an easy and inexpensive repair!!!
1 for 23 is not too bad.

Thanks Gents