When replacing the Bosch injector nozzles on a 617 turbo engine with new Monark nozzles, what is the appropriate pop pressure? Should the FSM specs for new Bosch nozzles be used or is there a different figure for the Monark nozzles?

If no one replies, contact member C Sean Watts; he rebuilt my 617 injectors 6 months ago. He did a fabulous job and the car runs a great deal better...

__________________
Regards,
Ian White

1995 E300 Diesel w124 OM606
2014 E550 w212 M278 biturbo

2001 BMW 740i E38 M62 (past)
1981 300SD w126 OM617 (past)

You are going to want them a the same pop pressure 135 bar. If you change it it's going to change injection timing.

__________________

Fuel pressure is supplied by the IP, so pop pressure is dictated by the original MB specs. Nozzle brand/type is irrelevant.

__________________
'98 E300 turbodiesel

+1

__________________
1987 300D (230,000 mi on a #14 head-watching the temp gauge and keeping the ghost in the machine)
Raleigh NC - Home of deep fried sushi!

For your engine, 135 is the MINIMUM for new nozzles. BUT over all, follow your FSM specs.

__________________
1987 300D (230,000 mi on a #14 head-watching the temp gauge and keeping the ghost in the machine)
Raleigh NC - Home of deep fried sushi!

Are you aware that the FSM calls for 135-143 bar for a new Bosch nozzle?

Any idea of what the bar-to-degree translation looks like? The FSM allows for 23 bar range of acceptable pressures (143 bar max for a new nozzle; 120 bar minimum for a used nozzle). That suggests to me that the affect on timing is not terribly significant.

Okay, thanks. I suppose that I will split the difference and shoot for 139 bar.

What FSM are you using? No offense intended but those numbers are off.

__________________
1987 300D (230,000 mi on a #14 head-watching the temp gauge and keeping the ghost in the machine)
Raleigh NC - Home of deep fried sushi!

Nozzles are a spray pattern thing, pressure is determined by shims, I think.

__________________
83 SD

84 CD

The nozzle bodies say 135bar on them. And as far as I know and heard, that is the standard for a 617 Turbo. The amount that they are off isn't gong to change things much, unless they are way off. To a certain point they will work when they are way too low or way to high, but you aren't going to get the best performance out of them. You are going to get rough idle/running and/or smoke. If you wanna bump the pressure up a few bar its not going to hurt anything. Just make sure they are all the same.

The VO guys often bump up the pop in their injectors to help atomize the VO.

__________________

The Mercedes Benz 617.95 Engine Manual.

Specifically, the book calls for injectors with new nozzles to be set to 135-143 bar and specifies 120 bar as the minimum acceptable pressure for used nozzles.

The pressure might be adjusted by shims, but it is certainly affected by the nozzle. Installing new nozzles increased my pop pressure by around 10 bar. Four of the five are still below 135 bar, however.

Is it actually published by Mercedes? My book (German) have 135-145 with 130 as the minimum, "used nozzle." That's the range, the balance 'window' is 3 bar. This is yet another difference in the English and German versions...

The important part, no so much for smoother idle but reducing stress on the crankshaft, is balancing the set.

__________________
1987 300D (230,000 mi on a #14 head-watching the temp gauge and keeping the ghost in the machine)
Raleigh NC - Home of deep fried sushi!