Fuel Injectors

[Mal CSL 3.0]

Hi Guys,

For those with fuel injection, how often do the O-rings at the base of the injectors give out and need replacing? I find that my injector cylinder 1 leaks a little fuel even though my FI system was fully rebuilt 5 years ago. (Leaks worse on start up)

All 5 other injectors don’t leak.

Should I urgently get this one O-ring replaced? Worried a leaking injector could cause an engine fire?

Do BMW or Bosch still stock this part? Or can any generic Injector O-ring be substituted?

Thanks!

 

[merdad]

Hi Guys,

For those with fuel injection, how often do the O-rings at the base of the injectors give out and need replacing? I find that my injector cylinder 1 leaks a little fuel even though my FI system was fully rebuilt 5 years ago. (Leaks worse on start up)

All 5 other injectors don’t leak.

Should I urgently get this one O-ring replaced? Worried a leaking injector could cause an engine fire?

Do BMW or Bosch still stock this part? Or can any generic Injector O-ring be substituted?

Thanks!

View attachment 87981

W&N has both seals

 

[merdad]

W&N has both seals

 

[Honolulu]

I'd imagine that if you knew the correct sizes (realoem.com?) you can get the seals at just about any bearing shop. Maybe there's a cross reference for other BMWs, which would make getting the seals at your friendly local BMW dealer, or FLAP, even easier. W&N are a long way to go for just those o-rings.

 

[Mal CSL 3.0]

I'd imagine that if you knew the correct sizes (realoem.com?) you can get the seals at just about any bearing shop. Maybe there's a cross reference for other BMWs, which would make getting the seals at your friendly local BMW dealer, or FLAP, even easier. W&N are a long way to go for just those o-rings.

Thanks. Yes I spoke to a local FI specialist shop and they have a selection of O-rings and said they will find one that fits hopefully.

Is it a big job pulling the plenem, manifold and throttle body etc off to replace just one injector O-ring? The guy I spoke to at the FI specialist said it is a very time consuming job on an old BMW? = expensive. Is that the case?

 

[HB Chris]

I just pulled the throttle body, plenum, runners and stub manifolds on my e12, it should have taken two hours, but the nuts under the manifold were a bear to remove.

 

[Sven]

Also, note that this should be a square profile O-ring.

 

[Simufly]

Also, note that this should be a square profile O-ring.

Not on two rebuilds I have done with genuine BMW o rings

 

[Drew20]

Having just been in there on my csl, the seals were old and pretty solid. Last documented engine rebuild was in the late 80s, which seems about right. Anyway, mine weren't leaking fuel or air, despite their antiquity
Are you sure the fuel is coming from that seal? With the engine running the injector squirts straight down in a tight cone onto the valve head, and it's all under a vacuum, so fuel should not be being forced past this seal under pressure. The fuel under pressure is inside the injector and the hoses.
The chap who rebuilt my injectors said they can leak internally from between the metal body and plastic top.
One possible: if the injector is not squirting cleanly it might be soaking that seal, and fuel is then weeping out??

I have loads of these seals, original NOS ones, (both for with or without fitted pintle caps) if you need them. In the uk though.

 

[Mal CSL 3.0]

Having just been in there on my csl, the seals were old and pretty solid. Last documented engine rebuild was in the late 80s, which seems about right. Anyway, mine weren't leaking fuel or air, despite their antiquity
Are you sure the fuel is coming from that seal? With the engine running the injector squirts straight down in a tight cone onto the valve head, and it's all under a vacuum, so fuel should not be being forced past this seal under pressure. The fuel under pressure is inside the injector and the hoses.
The chap who rebuilt my injectors said they can leak internally from between the metal body and plastic top.
One possible: if the injector is not squirting cleanly it might be soaking that seal, and fuel is then weeping out??

I have loads of these seals, original NOS ones, (both for with or without fitted pintle caps) if you need them. In the uk though.

I think you are correct Drew! Just had another look and the whole injector from the top is wet with fuel. Could be leaking out of where the green plastic meets the metal - or where the fuel line comes in, although I tightened the fuel line clamp and it didn’t seem to stop the leak.

I’ll be taking it in to get fixed next week. My mechanic seems to be knowledgable on the Bosch D-Jet FI system which is good.

 

[Simufly]

If you need some new injectors I have a NIB set left over from a rebuild.

 

[Mal CSL 3.0]

If you need some new injectors I have a NIB set left over from a rebuild.

Awesome, thanks for letting me know, I will reach out if I need any. Many thanks.
Cheers

 

[Stefan]

The lower hose clamp in photo are the type that could be a bit rough on small diameters and soft rubber. My suggestion would be to replace those hose clamps to the type that are the original ones (My first simple thought what causes your leak). I find it very unlike that the injector should leak between internal parts. It's a more or less bullet proof part in a low pressure environment.

 

[HB Chris]

Here are the square shouldered o-rings, currently replacing on my e12.