When is it time for replacement Nozzles - PeachParts Mercedes-Benz Forum

bpjenks · #1 05-31-2009, 12:28 PM

My 300D has 190K on the clock and I'd like to know when it's time for injectors or nozzles? I think that it may be.

http://www.youtube.com/watch?v=i6kWYtA-NIA

http://www.youtube.com/watch?v=0eqon6T8q18&feature=related

Take a look.

Diesel911 · #2 05-31-2009, 12:56 PM

If after the following is done
Valves are adjusted
You know you Camshaft Timing is Ok
Your IP has been re-timed correcty
Ruled out the other causes of hard starting and Nailing

You have ruled out othe causes of excessive smoke and are still experiencing excessivs smoke or Nailing I would say it is time to pull the Injectors.

The choice is to have them tested before being rebuilt or simply have them rebuilt or get exchange set.
The other option would be to see of a Diesel Purge would help. However, while a Diesel Purge might clean the Spray Nozzles it will not change the Opening/Pop pressures if they are too low or no longer within the specs of Opening Pressures being balanced to each other.

If your 300D was made before 1986 and has the stock Bosch type Injector Spray nozzles; nearly all of the high mileage Injectors I have pulled out of my own car and at the Junk yard have had the Central Hole in the Spray Nozzle Pintel plugged (#14 and #15 in the above diagram) with Carbon (see the pic, this one appears to be OK).
Also the metal not covered by the heat shield (the black area in the pic)
gets burned/eroded away which by itself can be a reason to replace the spray Nozzles.

dannym · #3 06-01-2009, 08:39 AM

The manual has a section on testing injectors. That's the procedure you follow to determine if they need repalcement.

If they pop test OK & don't leak under pressure is the first test.
Then you dissasemble and check for visual wear but the real test is you remove the pintle about 3/4 and release it, it should draw back into the housing. If it passes these tests then it's OK.

lutzTD · #4 06-01-2009, 10:05 AM

if someone wanted to replace nozzles, what is a normal cost for parts and is it something that a medium level mechanic type could do on their own? Mine has 240K and I seriously doubt these have ever been changed.

Oracle12345 · #5 06-01-2009, 10:19 AM

from the cold start video sounds like your nozzles need replacing

#6 06-01-2009, 10:49 AM

Lutz I would not even say its at a medium lvl for any mechanic it is very simple really. And I spent around $120 for new nozzles including shipping from C. Sean Watts....or I belive Bgkast is still in the injector rebuilding business (he is very reasonable and has had nothing but good reveiws). Hope that helps.

lutzTD · #7 06-01-2009, 10:54 AM

mine takes longer than that to cold start when it needs the valves adjusted. after adjustment it is about the same as yours. doesnt seem like an unreasonable amount of start time, but I am only experienced with my 2 diesels of which my coupe is the better of the two.

lutzTD · #8 06-01-2009, 10:56 AM

Quote:

Originally Posted by helpplease

Lutz I would not even say its at a medium lvl for any mechanic it is very simple really. And I spent around $120 for new nozzles including shipping from C. Sean Watts....or I belive Bgkast is still in the injector rebuilding business (he is very reasonable and has had nothing but good reveiws). Hope that helps.

thanx, maybe for peace of mind I will get a set for the shelf

#9 06-01-2009, 10:59 AM

First thing I do when I get a new to me diesel is valve adjustment and a new set of Monark injectors (along with all the other stuff).....they can make a huge difference....or not but still I sleep good at night.

Diesel911 · #10 06-01-2009, 11:09 AM

Quote:

Originally Posted by lutzTD

if someone wanted to replace nozzles, what is a normal cost for parts and is it something that a medium level mechanic type could do on their own? Mine has 240K and I seriously doubt these have ever been changed.

This is what would be done by someone rebuilding the injectors.
They would be put on a Nozzle/Pop Tester (a hand operated hydraulic pump with a Gauge) to get some Idea of the condition of the Old Spray Nozzles and the Opening /Pop Pressure (the Spray Nozzles act as a spring loaded valve and they are not supposed to open and let the fuel inject until a specified pressure is met or the fuel will not atomize well).

Each Injector in taken apart in cleaned; if the Tech is smart he keeps all the parts for each Injector segregated from the others so that after the New Spray Nozzle is installed it will be easier to adjust the Opening/Pop Pressure.

The 3 precision surfaces inside of the Injector are lapped on a Lapping Plate to. This can be done by hand or with a Lapping Machine. It is extremely impotent to clean off all of the Lapping Compound. (filtered Compressed Air and an Air Gun are best for this.)

During Assembly all of the parts are dipped in clean Diesel Fuel just before assembly an blow off with Air and assembled with the proper Torque.
The Rebuilt Injector goes back on the Nozzle/Pop Tester to set the Opening /Pop Pressure. If the pressure is not correct the Injector is taken apart and the shim/s that are on top of the Pressure Spring are changed; the Injector is assembled again until the Opening/Pop Pressure are within the min-max specified pressure and all of the Injector Opening/Pop Pressures are within 5 bar of each other (1bar x 14.5 = psi) to balance.
A good experienced tech with good equipment can do the whole rebuild job in about 10-15 minutes per Injector with an occasional one taking longer as it can sometime be a problem to get them balanced; especially if you do not have an assortment of different sized shims.

The equipment you need to do the job right is: access to a Nozzle/Pop Tester, a Torque wrench, and a Lapping Plate with Lapping Compound.

We have 1 Member (C Sean Watts) that sells Monark Spray Nozzles (and other Companies also) and last year when I bought some were with the shipping added around $23 for the new Spray Nozzle itself. He will also rebuild your Injectors for I believe it was $10 each labor (you need to contact him as that was last years price).

Another member bgkast has a similar labor rate for rebuilding your Injectors.

With both unless you live near them you will need to pay shipping both ways.
Here is another opinion on how Injectors are rebuilt.
http://vincewaldon.com/index.php?option=com_content&task=view&id=20&Itemid=28

lutzTD · #11 06-01-2009, 11:48 AM

Quote:

Originally Posted by Diesel911

This is what would be done by someone rebuilding the injectors.
They would be put on a Nozzle/Pop Tester (a hand operated hydraulic pump with a Gauge) to get some Idea of the condition of the Old Spray Nozzles and the Opening /Pop Pressure (the Spray Nozzles act as a spring loaded valve and they are not supposed to open and let the fuel inject until a specified pressure is met or the fuel will not atomize well).

Each Injector in taken apart in cleaned; if the Tech is smart he keeps all the parts for each Injector segregated from the others so that after the New Spray Nozzle is installed it will be easier to adjust the Opening/Pop Pressure.

The 3 precision surfaces inside of the Injector are lapped on a Lapping Plate to. This can be done by hand or with a Lapping Machine. It is extremely impotent to clean off all of the Lapping Compound. (filtered Compressed Air and an Air Gun are best for this.)

During Assembly all of the parts are dipped in clean Diesel Fuel just before assembly an blow off with Air and assembled with the proper Torque.
The Rebuilt Injector goes back on the Nozzle/Pop Tester to set the Opening /Pop Pressure. If the pressure is not correct the Injector is taken apart and the shim/s that are on top of the Pressure Spring are changed; the Injector is assembled again until the Opening/Pop Pressure are within the min-max specified pressure and all of the Injector Opening/Pop Pressures are within 5 bar of each other (1bar x 14.5 = psi) to balance.
A good experienced tech with good equipment can do the whole rebuild job in about 10-15 minutes per Injector with an occasional one taking longer as it can sometime be a problem to get them balanced; especially if you do not have an assortment of different sized shims.

The equipment you need to do the job right is: access to a Nozzle/Pop Tester, a Torque wrench, and a Lapping Plate with Lapping Compound.

We have 1 Member (C Sean Watts) that sells Monark Spray Nozzles (and other Companies also) and last year when I bought some were with the shipping added around $23 for the new Spray Nozzle itself. He will also rebuild your Injectors for I believe it was $10 each labor (you need to contact him as that was last years price).

Another member Bkfast has a similar labor rate for rebuilding your Injectors.

With both unless you live near them you will need to pay shipping both ways.
Here is another opinion on how Injectors are rebuilt.
http://vincewaldon.com/index.php?option=com_content&task=view&id=20&Itemid=28

wow thanks, one other thing. Is it best to keep original injectors or would PNP injectors be a simple trade out swap. this way I could get the PNP injectors rebuilt and no down time as this is my daily driver. sorry if this is a thread hijack

oldsinner111 · #12 06-01-2009, 11:50 AM

I read somewhere a 240D got piston melted from leaky injector.So I'd think 200,000 is the most to run them.Half that if running wvo.More miles maybe 250,000 on biodiesel.

bgkast · #13 06-01-2009, 06:20 PM

The nozzles are not hard to replace, you just have to have a pop tester and some shims to adjust them...if you can adjust your valves you can rebuild your injectors.

If you do not want to do it your self I am still rebuilding them for $32 each, I use a new nozzle, pop test and shim them to the correct pressure and include a new heat shield for that price.

Hit Man X · #14 06-01-2009, 07:13 PM

Quote:

Originally Posted by bgkast

The nozzles are not hard to replace, you just have to have a pop tester and some shims to adjust them...if you can adjust your valves you can rebuild your injectors.

If you do not want to do it your self I am still rebuilding them for $32 each, I use a new nozzle, pop test and shim them to the correct pressure and include a new heat shield for that price.

Mine are still in a box, need to go to you as soon as I get to post office.

Diesel911 · #15 06-01-2009, 08:29 PM

Quote:

Originally Posted by bgkast

The nozzles are not hard to replace, you just have to have a pop tester and some shims to adjust them...if you can adjust your valves you can rebuild your injectors.

If you do not want to do it your self I am still rebuilding them for $32 each, I use a new nozzle, pop test and shim them to the correct pressure and include a new heat shield for that price.

I went back and corrected my misspelling of you Member Name.