Injector pop pressure ok?

[IanCC]

Hi,
Pop pressure 145 kilosomethings, should be 175 give or take 5.
Spray good, no leaks.

Knackered or chuck 'em back in?

Thanks in advance.

 

[DownWest]

Needs the spring adjusting. They give specs for a reason. If old, might as well replace the nozzle.

 

[IanCC]

Needs the spring adjusting. They give specs for a reason. If old, might as well replace the nozzle.

Yes, it's not an inconsiderable expense though. £250 ish for three.

 

[DownWest]

Yes, it's not an inconsiderable expense though. £250 ish for three.

A mere drop in the boating ocean..

 

[ChromeDome]

Yes, it's not an inconsiderable expense though. £250 ish for three.

Be happy! Common rail injectors (piezo) would be several times more.

 

[DownWest]

Be happy! Common rail injectors (piezo) would be several times more.

And, by the time it is taken apart to tighten the spring, not so much more.

 

[B27]

Yes, it's not an inconsiderable expense though. £250 ish for three.

Possibly the key thing is how well the three are matched?

 

[pandos]

Yes, it's not an inconsiderable expense though. £250 ish for three.

Have you tried non marine suppliers for nozzles... Can be much cheaper for new parts. (Key is to find the correct alternative part numbers)

 

[BobnLesley]

Yes, it's not an inconsiderable expense though. £250 ish for three.

A few years ago when we over-wintered in Marmaris I took two injectors (Volvo/Bosch) to the injector-man on the local industrial estate who fitted a complete new nozzle/tip on one, cleaned and replaced springs on them both and reset/adjusted the breakout pressures; job done while I waited/watched and a total cost for the lot was about £18. By the end of the following week there must've been two dozen boats who'd pulled their injectors and trotted around to see him on the 'at that price why wouldn't you' principal.

 

[IanCC]

Possibly the key thing is how well the three are matched?

It terms of pop pressure?

 

[IanCC]

A mere drop in the boating ocean..

But still dear if not needed. That's a big expense on my boat.

 

[B27]

It terms of pop pressure?

It's above my pay grade in diesels, but generally you want all the cylinders to behave the same, so they want the same amount of fuel at the same timing point, pop pressure will be a parameter which influences this.

Also I wonder whether the way you measure it might matter, so a different rig will give a different answer?
If all the injectors give the same reading, maybe the injectors are right and the rig is wrong?

 

[B27]

Also, make sure you're using the correct units!

 

[IanCC]

Also, make sure you're using the correct units!

Thanks, good points and agreed.

But pop pressure measurement is local specialist injector shop, so i think it will be right.

 

[ChromeDome]

I really support the idea of having all done.

The effort it the same - get 'em out, checked, fixed, adjusted and back in.

You won't regret it!

 

[Amlov]

The question must surely be ‘why did you have them tested’. If you had a problem with them and have now found something out of spec, then the next stage would be to get it fixed.

If you pulled the injectors for fun and the engine runs fine, then just put them back. But without knowing the answer to the question it is difficult to offer sensible advice.

 

[IanCC]

The question must surely be ‘why did you have them tested’. If you had a problem with them and have now found something out of spec, then the next stage would be to get it fixed.

If you pulled the injectors for fun and the engine runs fine, then just put them back. But without knowing the answer to the question it is difficult to offer sensible advice.

Fair point.

1999 3gm30f. Unknown hours. Not perfect starting, not perfect running. Acquired 3 injectors second hand for not much.
Trying to way up which way to play it.

 

[black mercury]

Unless you have the second hand ones tested they could be worse than what you have. It's normal for an injector to loose pressure as it ages, it's normal wear. If the spray pattern is good and they aren't dribbling then all they need is reshimmed to bring the opening pressure back in spec and maybe a polish. You might get a slight decrease in smoke and a decrease in fuel consumption, but in a boat you will hardly notice the latter.

 

[spudnukem]

If the spray pattern is good and you can shim the springs after a dam good clean in a cheap jewelry ultrasonic cleaner - as long as you have the right pop pressure everything will be fine.

 

[ChromeDome]

By experience from a 2gm the feed pump can be the culprit re. (cold-)starting issues.

In this case it actually was a not very old OEM pump!