6 new Monark nozzles, spray angles inconsistent with each other

[zebellis]

I replaced my 6 injector nozzles with new Monarks in my 87 300TD. I'll jump straight to my most important question before I get into the details of my other concerns. The numbers stamped on the side of the new nozzle holders are all identical (525 MDN, 39 305 128, and 0SD 265), but 3 of the nozzles have a wider spray angle than the others. One of them is quite a bit wider. I would say the angles range from 5-20° (this is just a guess, and 20° might be a stretch). I had this observation confirmed by a local injector shop. The atomization is all pretty uniform and the pop pressures are all between 2000-2075 psi. My question is whether or not the spray angle makes that much of a difference in efficiency of burn? Does the prechamber ball pin allow for some variance in the angle? Is the pop pressure (thus timing) and atomization more important for efficiency of burn than the spray angle?

I pop tested all 6 injectors before attempting to clean and rebuild them, and made notes of any oddities (#6 was a good 150 psi under the rest, and #5 was frequently streaming or "peeing" before the pop). I took them all apart and soaked everything very carefully in carb cleaner (from a can, not the spray kind). Everything cleaned up well. I followed all the precautions I read about here about keeping the parts separate and being as surgically clean as possible. I lapped the mating surfaces with 2000 grit sandpaper on a pane of glass. I blew the internal parts dry with air, lubricated in clean diesel before reassembling, etc. (I'm skipping some repetitive cleaning steps here for brevity). When it came time to install the new nozzles, I slid them directly out of the container they came in, directly into the lower injector half. I never handled the new nozzle holders and needles…

However, after everything was back together, I was having issues with 2 of the new nozzles streaming before the pop pressure was reached. It was intermittent, and sometimes I couldn't get them to do it, but with enough pops it would happen again. So I swapped those 2 nozzles into different injectors that seemed to be spraying fine and the problem repeated itself. This confirmed that the nozzles were bad and I was able to get replacements. However, I was also very rarely getting some streaming from some of the other injectors. It was very infrequent, and if I stopped testing for the day and tried again on another day, I wouldn't get the problem at all. I have opened the injectors back up and noticed that some of the nozzle needles don’t move smoothly in the nozzle holders - it feels like there was some invisible grit in there, even though the needle had not previously been separated from the holder. The only way grit could be introduced would be from the inside of the bench tester, or possibly if the filter I used for the diesel fuel wasn’t fine enough. I think my next step is to clean any rough feeling needles. Any tips on how to best do this? Diesel? WD40? Carb cleaner?

Any tips and insights are, as always, greatly appreciated!

[jt20]

From my limited experience rebuilding these with Bosio and Monark:

There often seems to be a bit of a 'fan' on many injectors, old and new.

Rotate your point of view, you may see a wider spread.


Personally, I think atomization is way (like way, way) more important. - Don't forget, all that spray is being shot into a little tiny canister where it will begin to ignite then spread out.


Also, new nozzles will certainly break in. Manufacturing can only get so close to perfection (consider alignment and contact at the nozzle tip in the nozzle body) - impossible to get a perfect contact seat.

[Clemson88]

From my limited experience I'v come to know a couple of things about new injectors for fact.

If you deliver the popping pressure slowly most injectors will pee. This worried the hound out of me until I read it here. The discovery that the problem was with my pumping and fooling around with pressure delivery satisfied me though two or three of my injectors peed. I put them on the pop tester again and brought them immediately to 1975 psi with a firm movement of the machine handle and was satisfied.

Spray patterns are corrupted by the tiniest of contaminates. I didn't buy the BS Diesel Giant was selling about boiling the injectors to remove the carbon. He's a great MB mechanic but he probably a better salesman who was working to sell his kit which did not include a solvent to clean injectors.

I got small glass bowls with lids and put Berryman carb cleaner in each then soaked each disassembled injector in a separate bowl. I doubt mixing up the springs, shims or even the body haves would matter but I kept them separate anyway. A 24 hour soak is the only way to go.

I moved the injectors from the Berryman bath using clean SS hemostats to a filtered diesel dip to dilute the strong solvent . Then I scrubbed each of the parts with a small brass brush while dipping them over and over in the diesel. As I finished with each part I moved them to another small bowl of filtered diesel. I held the outsides of the bodies with my hands and used a hemostats for the small internal parts.

As I lapped the injector bodies I'd dip them in the 'dirty,' bowl then the clean bowl before assembly. The new nozzles got their dual baths in lacquers thinner then filtered diesel. I held the nozzles with the hemostats and lifted the little needle valves by the stem with another pair of hemostats for the half distance drop. Never did the nozzle tips or needle valves touch anything but each other until I set the on the injector half for assembly. Of course they lay on the bottom of the glass bowls sometimes.

Each sprayed identical patterns which delighted me. I can not say why your injectors are spraying a variety of patterns I can only give you my limited experience with only one set of five 135 bar 617 injectors and hope you may narrow down whether it's defective nozzles, damage to the needle valves or contaminates between the nozzle bodies and the needle valves.

[zebellis]

Originally Posted by jt20

There often seems to be a bit of a 'fan' on many injectors, old and new.

Rotate your point of view, you may see a wider spread.


Personally, I think atomization is way (like way, way) more important. - Don't forget, all that spray is being shot into a little tiny canister where it will begin to ignite then spread out.


Also, new nozzles will certainly break in.

Rotating my point of view had crossed my mind, and I did try to view them from different angles. Still, when I was looking from the POV showing the spray angle at it's widest, there were inconsistencies from one nozzle to the next.

The point about atomization is my thinking as well. I pulled my prechambers too and cleaned them up so I could inspect the ball pin. Each one looked smooth. I'm not sure exactly how far the ball pin is from the tip of the injector nozzle (15-20mm?) but at that length, the difference between a 5° and 20° spray angle isn't enough to overshoot the ball - meaning that the fuel should still reflect outwards into the upper prechamber as intended (I'm guessing). This is all based on gross assumptions. It would be interesting to use some actual numbers to understand this better.

Originally Posted by Clemson88

From my limited experience I'v come to know a couple of things about new injectors for fact.

If you deliver the popping pressure slowly most injectors will pee. This worried the hound out of me until I read it here. The discovery that the problem was with my pumping and fooling around with pressure delivery satisfied me though two or three of my injectors peed. I put them on the pop tester again and brought them immediately to 1975 psi with a firm movement of the machine handle and was satisfied.

That's good to know. Thanks for that input!

Originally Posted by Clemson88

I got small glass bowls with lids and put Berryman carb cleaner in each then soaked each disassembled injector in a separate bowl. I doubt mixing up the springs, shims or even the body haves would matter but I kept them separate anyway. A 24 hour soak is the only way to go.

...

The new nozzles got their dual baths in lacquers thinner then filtered diesel. I held the nozzles with the hemostats and lifted the little needle valves by the stem with another pair of hemostats for the half distance drop. Never did the nozzle tips or needle valves touch anything but each other until I set the on the injector half for assembly. Of course they lay on the bottom of the glass bowls sometimes.

I think I ended up soaking all the parts for 3-4 days (the prechambers seemed to benefit the most from the extra time because you can't really get at the inside). At this point, I'm thinking I will dip the nozzle holders and needles to rinse them of any contaminates and carefully reassemble everything. Is there a reason you used lacquer thinner before the diesel, and what should I use to filter the diesel? Would using compressed air to blow out the nozzle holder from the bottom to free up anything, or do you think multiple dippings should do the trick?

[Clemson88]

Originally Posted by zebellis

Rotating my point of view had crossed my mind, and I did try to view them from different angles. Still, when I was looking from the POV showing the spray angle at it's widest, there were inconsistencies from one nozzle to the next.

The point about atomization is my thinking as well. I pulled my prechambers too and cleaned them up so I could inspect the ball pin. Each one looked smooth. I'm not sure exactly how far the ball pin is from the tip of the injector nozzle (15-20mm?) but at that length, the difference between a 5° and 20° spray angle isn't enough to overshoot the ball - meaning that the fuel should still reflect outwards into the upper prechamber as intended (I'm guessing). This is all based on gross assumptions. It would be interesting to use some actual numbers to understand this better.





That's good to know. Thanks for that input!



I think I ended up soaking all the parts for 3-4 days (the prechambers seemed to benefit the most from the extra time because you can't really get at the inside). At this point, I'm thinking I will dip the nozzle holders and needles to rinse them of any contaminates and carefully reassemble everything. Is there a reason you used lacquer thinner before the diesel, and what should I use to filter the diesel? Would using compressed air to blow out the nozzle holder from the bottom to free up anything, or do you think multiple dippings should do the trick?

Lacquer thinner is a little stronger solvent than diesel. I used it to remove the shipping oil which the nozzles were coated with when they arrived.

I used a Mithvac to suck diesel through a primary filter. I know it isn't as clean as that which the secondary filter produces but it turned out to be fine. If there's a better filter for diesel I hope someone comments with the information. Clear hose of the correct size is fairly cheap at Ace Hardware stores.

The main thing is that you make sure the needle valves will drop half their length under their own weight inside the nozzle body. On some of them I had to give them a little help during the first trial but found that after the diesel was somewhat purged/pushed out of the nozzle they all dropped just fine. This will ensure that they are free of contaminates.

Don't play with the pressure when you pop them. Go straight to popping pressure and make sure it's correct to your wants and the specifications then let it bleed down and apply enough pressure to bring them just under popping pressure and hold that buy pushing on the pump handle slowly. This checks the injector bodies for leaks.

Some of the steps and procedures I took seemed like outrageous overkill but it was my first trial at this activity and I didn't want to learn trial and error. I'm sure someone who does this regularly could have spent much less time but they all popped at exactly 1975 psi and have operated trouble free so far. I lapped the body seat before I gave them a first pop test then again to fine tune the popping pressure after making shim additions to just under my pop pressure goal. Ridiculous.



At what pressure did you get the injectors to pop?

[BillGrissom]

Most of your questions are at the engineering research level. I used to work in spray research long ago. You could review the ILASS and ICLASS seminar papers in a university library for detailed info. I will relate just a few things. In-cylinder high-speed video showed that the spray cloud from ~1990's diesel injectors (pop style) would impact the far cylinder wall. That was thought to be a big cause incomplete combustion, thus soot. This was in big truck engines, w/o a pre-chamber.

The current "common rail" systems raised injection pressures from ~2000 psig to >10,000 psig. I understand that was mostly developed by Fiat, and I recall many Italian researchers at conferences then. The result is much finer atomization and spray presumably not impacting the cylinder walls as much. You rarely see trucks smoking today (plus exhaust traps) and they are more efficient. In car diesels, that allowed tapering the initial injection to minimize pinging and thus get rid of the pre-chamber, greatly increasing efficiency. Thus, atomization is most critical.

The spray in your engine at >400 psig will likely look different than in the atmosphere, since the gas density is much higher. But, what you see in the air is still good for comparisons between injectors. My experience is similar to others. To get an injector to chatter with the machine-gun sound, requires fast motion of the hand lever. When an injector streams continuously instead of chatters, it is usually more due to your stroking technique. Try again and you can usually get it to chatter. I see fairly narrow spray cones (~20 deg included angle), at least as best I can see thru the cloud of droplets. It is quite forceful and will knock a container over. I put screen in the bottom to avoid splash-back. To quantify the spray cone, one would need a video setup, probably w/ 2 cameras at 90 deg.

BTW, anybody wanting to buy a pop tester, I just saw several new ones on ebay ~$80 (current bid). From India, but I recall free shipping.

[scottmcphee]

..and everybody knows to keep body parts and fingers the hell away from the spray coming out of the tip, right?! Not getting any ideas about "feeling the spray".

Would pass right through your thin glove, skin.. right to blood poisoning.

Always worth mentioning, if noobies are following along.

[97 SL320]

Originally Posted by BillGrissom

Most of your questions are at the engineering research level. I used to work in spray research long ago. You could review the ILASS and ICLASS seminar papers in a university library for detailed info. I will relate just a few things. In-cylinder high-speed video showed that the spray cloud from ~1990's diesel injectors (pop style) would impact the far cylinder wall. That was thought to be a big cause incomplete combustion, thus soot. This was in big truck engines, w/o a pre-chamber.

My Deutz diesel guy says a poor pattern in a DI engine can burn piston tops due to too much fuel being concentrated in one area.

Originally Posted by BillGrissom

The current "common rail" systems raised injection pressures from ~2000 psig to >10,000 psig. I understand that was mostly developed by Fiat, and I recall many Italian researchers at conferences then. The result is much finer atomization and spray presumably not impacting the cylinder walls as much. You rarely see trucks smoking today (plus exhaust traps) and they are more efficient. In car diesels, that allowed tapering the initial injection to minimize pinging and thus get rid of the pre-chamber, greatly increasing efficiency. Thus, atomization is most critical.

I think Ford was the first with super high pressure in the US, might have been developed by Bosch. I was researching a 2014 Ford 6.7 diesel and it claims 29,000 PSI.

Also says that the injector ( Piezo ) can give up to 6 injection events per cycle with the first to get things burning. Electronic injectors can also generate engine braking by injecting a bit of fuel way before TDC.

[Clemson88]

I think it's possible to find a bad new Monarch injector nozzle but the probability that two of six is bad must be astronomical. Three of six? Nah, my guess is that the OP just contaminated the nozzles or deformed the needle valve tips with a much higher probability on contaminates.

[vstech]

Originally Posted by BillGrissom

BTW, anybody wanting to buy a pop tester, I just saw several new ones on ebay ~$80 (current bid). From India, but I recall free shipping.

! 67.00 free shipping. Buy it Now... awesome

[jt20]

I admit, much against the wisdom of this board, I was not impressed with Monark's pattern right out of the box. I really wouldnt waste any sleep over these issues.

Bosio, perhaps more consistent in direction and fanning etc... , but they had their own 'imperfections' for sure.

I brought my Monark rebuilds to a diesel shop to verify (Bosch certified pump / injector center) and they said they didnt like the patterns either. - in fact, they said they weren't that impressed with Monarks in general. (but they don't sell Monark, soooo....)

They have run great though. Really quiet and smooth. I think its easy to imagine that a perfect spray pattern should be achieved from a set of new nozzles. But in the real world, it probably makes very little difference once you get good atomization directed into the correct general region.

And if the other option is Bosch India (which I have tested).... I'll pass. These 2 manufacturers are quite acceptable.

[jt20]

Originally Posted by zebellis

The point about atomization is my thinking as well. I pulled my prechambers too and cleaned them up so I could inspect the ball pin. Each one looked smooth. I'm not sure exactly how far the ball pin is from the tip of the injector nozzle (15-20mm?) but at that length, the difference between a 5° and 20° spray angle isn't enough to overshoot the ball - meaning that the fuel should still reflect outwards into the upper prechamber as intended (I'm guessing). This is all based on gross assumptions. It would be interesting to use some actual numbers to understand this better.

To better understand some of 'this' better: do some searching on this forum for 'prechamber modifications flame front'

I forget the actual threads and users involved, and much of it should be taken with a cautious attitude, but an interesting investigation with lots of great data to say the least. - a good starting point for further research if you are so inclined.

[PARSHOOT1]

Zebellis you need to PM Pelican member Greazzer, he's thr resident injector expert.

[Clemson88]

Originally Posted by jt20

I admit, much against the wisdom of this board, I was not impressed with Monark's pattern right out of the box. I really wouldnt waste any sleep over these issues.

Bosio, perhaps more consistent in direction and fanning etc... , but they had their own 'imperfections' for sure.

I brought my Monark rebuilds to a diesel shop to verify (Bosch certified pump / injector center) and they said they didnt like the patterns either. - in fact, they said they weren't that impressed with Monarks in general. (but they don't sell Monark, soooo....)

They have run great though. Really quiet and smooth. I think its easy to imagine that a perfect spray pattern should be achieved from a set of new nozzles. But in the real world, it probably makes very little difference once you get good atomization directed into the correct general region.

And if the other option is Bosch India (which I have tested).... I'll pass. These 2 manufacturers are quite acceptable.

Diesel Giant was all about Bosio nozzles until he got the contract to sell Monarch. Now he's all about Monarchs. I went with the German made injector nozzles because, well German.

I have no experience with Bosios but the Monarch had exactly the spray patter which was depicted in the FMS. As far as how they perform, I have no idea how a new 1984 300SD performs and the improvement from what is probably original injectors with 300+ thousand miles is not fair.

My car runs like a bat out of hades. My sons freaked when I pinned them back against the seats. I viewed the exhaust by following the car and it's slight compared to every other diesel I've seen. If you didn't know it was diesel you wouldn't know it's a diesel from the smoke.

[Diesel911]

Originally Posted by zebellis

I replaced my 6 injector nozzles with new Monarks in my 87 300TD. I'll jump straight to my most important question before I get into the details of my other concerns. The numbers stamped on the side of the new nozzle holders are all identical (525 MDN, 39 305 128, and 0SD 265), but 3 of the nozzles have a wider spray angle than the others. One of them is quite a bit wider. I would say the angles range from 5-20° (this is just a guess, and 20° might be a stretch). I had this observation confirmed by a local injector shop. The atomization is all pretty uniform and the pop pressures are all between 2000-2075 psi. My question is whether or not the spray angle makes that much of a difference in efficiency of burn? Does the prechamber ball pin allow for some variance in the angle? Is the pop pressure (thus timing) and atomization more important for efficiency of burn than the spray angle?

I pop tested all 6 injectors before attempting to clean and rebuild them, and made notes of any oddities (#6 was a good 150 psi under the rest, and #5 was frequently streaming or "peeing" before the pop). I took them all apart and soaked everything very carefully in carb cleaner (from a can, not the spray kind). Everything cleaned up well. I followed all the precautions I read about here about keeping the parts separate and being as surgically clean as possible. I lapped the mating surfaces with 2000 grit sandpaper on a pane of glass. I blew the internal parts dry with air, lubricated in clean diesel before reassembling, etc. (I'm skipping some repetitive cleaning steps here for brevity). When it came time to install the new nozzles, I slid them directly out of the container they came in, directly into the lower injector half. I never handled the new nozzle holders and needles…

However, after everything was back together, I was having issues with 2 of the new nozzles streaming before the pop pressure was reached. It was intermittent, and sometimes I couldn't get them to do it, but with enough pops it would happen again. So I swapped those 2 nozzles into different injectors that seemed to be spraying fine and the problem repeated itself. This confirmed that the nozzles were bad and I was able to get replacements. However, I was also very rarely getting some streaming from some of the other injectors. It was very infrequent, and if I stopped testing for the day and tried again on another day, I wouldn't get the problem at all. I have opened the injectors back up and noticed that some of the nozzle needles don’t move smoothly in the nozzle holders - it feels like there was some invisible grit in there, even though the needle had not previously been separated from the holder. The only way grit could be introduced would be from the inside of the bench tester, or possibly if the filter I used for the diesel fuel wasn’t fine enough. I think my next step is to clean any rough feeling needles. Any tips on how to best do this? Diesel? WD40? Carb cleaner?

Any tips and insights are, as always, greatly appreciated!

I am curious why the Fuel Injection Shop did not say if they thought the spray patteren usable or not?

Back something like 5 years ago there was a period where the Monak Nozzle quality took a plung and for close to a year no Nozzles were being sold here.
When the nozzles returned that problem was apparently fixed.

I bought about 40 nozzles totaled and had one that was extremely bad and it projected a figur 8 type pattern.

Each 2 parts of the Injector Nozzles are a mated assembly. If you mixed parts between the Nozzles you can get the situation that you have.

If any grit got into the Injector Nozzle that can damge the seating area of the nozzle.

Both of the items I mentioned above can cause the Injector Nozzle to pee out before reaching the opening pressure and or effect the spray pattern.

The test for the nozzle seating areas is to find out the opening pressure of a particular injector and set it correctly if not so. Then you slowly bring up the pressure till it is 200 psi before the opening pressure you recorded. At that point you are allowed x amount of drips per x amount of time (I don't remember specifics).

A really excellent Injector Nozzle will not drip all they way up to the opening pressure and then open and spray suddenly.