Why Fuel Injectors leak - failed O-ring replacement?

An experienced Acura repair shop told me to replace the Injectors knowing there is leak.

We (a friend) tried changing the O-rings etc, bought from Acura but no luck - it worked for a very short time. Actually only one seems to be leaking somewhat more than what it used to be. My friend is an expert - he is very meticulous - so the repair must have been good.

I am thinking of replacing all 4 injectors with re-manufactured ones - but wondering why they leak in the first place - O-rings - if so it can leak again with the re-manufactured ones too?

Any one deeply familiar with these? Any tips?

Why not trust the judgement of your friend about new or reconditioned .

O rings usually leak 1) because they got nicked in the installation or 2) The cavity they are in is too large or cut/nicked/damaged or 3) the part that holds the O-ring is too small or cut/nicked/damaged. There is a 4th, a bad O-ring brand new out of the box. It happens. Not much else goes wrong. Careful installation should be all you need. I don’t doubt your friend’s expertise.

I am doubting whether the O-ring is actually at fault. Is it possible that the fuel is leaking internally through the injector? There are a number of parts inside the injector and there are seals for those parts and crimps that hold it all together. That may be your leak.

@Mustangman - thanks - pls see below:

  1. The four reasons that you gave point to O-ring
  2. I was relentlessly searching for answer and found a forum that pointed to
    That guy said dirty injector causes the leak
    Called again and spoke with another person - he says since I can see the Fuel, it is coming from the Railing - he suggest re-seat it. He says O-ring leak would be internal to the engine and I won’t see it
  3. Another Craigslist guy thought another poss. is the railing.
    The leaked Fuel rest on the bottom of the area and I can see it

There were three rings per FI (O, Seal and Cushion ring) - for all four injectors, it costed me over $65 from Acura - I am back to square one. I also found reman FI on eBay just over $40 for all four of them. A lot of time too.

I just want to get it right next time - it is ok to err on the side of part but want to ensure that its done.

The shop I like to go to is closed down. My fiend is the expert than the shops that I know.

Not exactly where I would look for help.

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There are several O-rings on each injector and also a very large rubber spacer that could be called an O-ring but isn’t always included in a set of injector specific O-rings and that large spacer has been the most common leak in my experience.

Injector O-rings eventually fail for the same reasons as any other elastomer under constant load. Cold-flow and release of components of the material (deterioration of the rubber).

The first, cold flow, is a process by which materials under constant load begin to flow, change shape, to take on the shape of the cavity in which they’re contained. It’s most obvious in valve cover gaskets, where they actually change shape to where they lose their preload and begin to allow the cavity pressure created in the crankcase to push oil that lubricates camshafts past them. When a weeping gasket is compared to a new gasket, the dimensions are visibly different. Cold flow affects injector gaskets too. And suspension spring pads. And every other rubber component that’s always under load.

The second, deterioration of the elastomer, is so well known and commonplace that I’ll skip the dissertation.

Were the injector O-rings lubed before installation?

I find petroleum jelly works best.


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Yes with synthetic engine oil -

The only O-rings I’ve ever replaced for injectors (had that problem w/my VW Rabbit) is the one that seals the injector where it seats. That one prevents air from leaking past the injector and into the engine, causing a sort of vacuum leak condition. That o-ring isn’t what prevents the injector from leaking gas when it is turned off, only to prevent air leaks into the engine. Are you replacing O-rings on the injector’s pintle-operating parts then OP?

This not even six months
Car would have done 1000 miles

O, Seal and Cushion ring: Seal ring?

We changed all of them on the FI -
They are called O, Seal and Cushion ring -

What it is that’s leaking? Fuel into the cylinder? Or air into the cylinder?

I saw Fluid/Gas - my friend said it is mixed with oil
When the heater is turned on and fan at speed 2, I smell gas, gas, gas - strong smell.

New O-rings on leaky injectors? Seems pointless.

If the first shop said the leaky injectors should be replaced, I suspect the leak is from the body of the injector.

If the fuel rail/injector O-rings were leaking they should have said the injector seals must be replaced. I think you need new injectors.

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I do not think it was ever diagnosed - not leaky FI but FI that was leaking

You would really trust $10 injectors off flea bay? Good luck with that.

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