Author Topic: Ways to prevent or cure coked injectors???????????  (Read 28997 times)

Excalibur

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Re: Ways to prevent or cure coked injectors???????????
« Reply #15 on: November 07, 2013, 06:25:50 PM »
Great. Good set of tests to help narrow down the coking. Perhaps record the SG as a reference marker.

Jhanananda

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Re: Ways to prevent or cure coked injectors
« Reply #16 on: November 07, 2013, 06:53:16 PM »
Recording the SG of my fuel is a good idea, because just adding gasoline at 20% does not mean my SG is going to be the same all of the time.

Yes, recording my injectors as an indicator only just occurred to me.  Yes, I have lots of injector photos, but I have not simply run x-miles on y-blend and photoed the injectors afterwards.  So, this series should work out to be pretty informative. 

Moving toward greater gasoline in the blend will work out for other reasons, because it is getting colder here as winter is approaching.  So, I should have the series up to 30% gasoline, or more, before spring arrives.
I have run various blends of waste oils and unleaded gasoline since Feb, 2007 in a 1983 Chevy G-20 van with a 6.2L diesel V-8 engine, with a Stanadyne Rotary DB2 IP. I have started the engine with no difficulty on an 80/20 (WVO/gas) blend down to 3F (-16c).  I now run 60/20/20 (WVO/diesel/gas)

Jhanananda

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Re: Ways to prevent or cure coked injectors???????????
« Reply #17 on: November 09, 2013, 07:44:29 AM »
These coked injectors were posted by Turbovanman on another forum.  He is running almost the same engine that I am running, but it has a turbocharger. They look like mine running WMO, except that the coke is very grey, so that means it is more ash than carbon.  It looks like they were coked, then the coke burned off.  I suspect it was just the WMO that he was running.  He also runs WATF blended with Jet-A. 
I have run various blends of waste oils and unleaded gasoline since Feb, 2007 in a 1983 Chevy G-20 van with a 6.2L diesel V-8 engine, with a Stanadyne Rotary DB2 IP. I have started the engine with no difficulty on an 80/20 (WVO/gas) blend down to 3F (-16c).  I now run 60/20/20 (WVO/diesel/gas)

Jhanananda

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Re: Ways to prevent or cure coked injectors???????????
« Reply #18 on: November 10, 2013, 07:12:09 AM »
I just swapped my injectors out, then loaded a WVO 80/20 blend, then drove 300 highway miles.  The engine ran much better.  I plan to pull the injectors when I get back after driving about 600 highway miles; and I expect to find that my injectors will look a lot better.  I then plan to run a WVO 75/25 blend for about 1000 miles, then pull my injectors, and so on up to 30% gasoline.

I expect to find that there will be decreasing coking as I increase the gasoline content of my blends, which should disprove the hypothesis that gasoline causes coking, and support my hypothesis that increasing gasoline content in waste oil blends reduces coking.
I have run various blends of waste oils and unleaded gasoline since Feb, 2007 in a 1983 Chevy G-20 van with a 6.2L diesel V-8 engine, with a Stanadyne Rotary DB2 IP. I have started the engine with no difficulty on an 80/20 (WVO/gas) blend down to 3F (-16c).  I now run 60/20/20 (WVO/diesel/gas)

Jhanananda

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Re: Ways to prevent or cure coked injectors???????????
« Reply #19 on: November 11, 2013, 07:52:30 AM »

I had a case of fouled injector nozzles. Possibly it was the lingering effects from my trip away last month and it never fully recovered with the homemade injector cleaner. I noticed some diesel knock occuring and had reports of smoke plus awful smelling exhaust.
These injectors haven't been out for maybe 2 years or more. There'd been no need.


This pic is the injector port with injector removed. Note how the port is carboned over with a tiny hole for fuel to squirt through.


This pic is of the nozzle immediately after removal. It's quite good, virtually no carbon stuck to it.


This shot shows the port once I broke through the slug of carbon. I'm guessing at a build up of about 3-5mm thickness.
I decided to quote message from his thread to this thread, so that his photos can help us work through the causes and conditions that produce coking, so that we can understand how to prevent it.

After doing more Google searches I realize now that the Chevy IDI diesel injector modification being discussed, and experimented with here, is removing an integrated heat shield that is built into the lower injector body of early diesels made in the USA.  German diesels had the heat shield separate, see photos below.



I have run various blends of waste oils and unleaded gasoline since Feb, 2007 in a 1983 Chevy G-20 van with a 6.2L diesel V-8 engine, with a Stanadyne Rotary DB2 IP. I have started the engine with no difficulty on an 80/20 (WVO/gas) blend down to 3F (-16c).  I now run 60/20/20 (WVO/diesel/gas)

Jhanananda

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Re: Ways to prevent or cure coked injectors
« Reply #20 on: January 01, 2014, 06:36:34 AM »
Early November I modified one 6.2L diesel injector and replaced just one of my diesel injectors with it to see how it would perform.  I ahve not pulled it yet, but this is what it looks like

Modified 6.2L diesel injector

This is a similarly modified 6.2L diesel injector modified by someone else and run on a blend of WATF and Jet-A

The process of "modifying" a 6.2L diesel injector to reduce coking, which supposedly helps in burning WMO is simply hacking off the heat shield and exposing the injector nozzle.
I have run various blends of waste oils and unleaded gasoline since Feb, 2007 in a 1983 Chevy G-20 van with a 6.2L diesel V-8 engine, with a Stanadyne Rotary DB2 IP. I have started the engine with no difficulty on an 80/20 (WVO/gas) blend down to 3F (-16c).  I now run 60/20/20 (WVO/diesel/gas)

Jhanananda

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Re: Ways to prevent or cure coked injectors???????????
« Reply #21 on: January 07, 2014, 08:46:09 AM »
I was just reflecting upon the fact that some coked diesel injectors are coked with a yellow crust, not a black crust.  Black would be common coke, which is a combination of carbon and ash (which is mostly silica).  A yellow on a coked injector has to be something other than carbon, or it would be black.  I believe that yellow crust would be sulfur and ash (which is mostly silica).   Here are some photos of coked injectors with a yellow crust.

vic_v8 WMO at 3,000 miles, roughly 10-15% WMO, 1% gas, the rest Diesel on a 6.2l

turbovanman's coked injector from running WMO+Jet-A on a 6.2l turbo

My 6.2L N/A injector running translucent WMO blends

I did a Google search for sulfur in motor oil and found this
Quote
Elisa
posted Fri October 22 2004 03:54 PM
Gotta reply to this one even though the thread is a bit old. Sulfated ash measures the metal content of the oil. The sulfur here comes from the sulfuric acid used during the sulfated ash analysis - not from the oil.

Most sulfur in an oil comes from the ZDP, some comes from the oil itself, and some comes from the detergent or other components. In general, the higher the ZDP level, the higher the sulfur.

That said, the ballpark range for %S is ~0.3 to 0.8%.
http://forums.noria.com/eve/forums/a/tpc/f/616604995/m/425101204

If, the range of sulfur content in motor oils is only %S is ~0.3 to 0.8%, and the yellow crust that is appearing on some coked diesel injectors is indeed sulfur, then there has to be something at work that is allowing sulfur to collect at the end of the diesel injector.  So, I Googled sulfur and extracted the Wiki
Quote from: Wiki
Sulfur or sulphur (see spelling below) is a chemical element with the symbol S and atomic number 16. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow crystalline solid when at room temperature. Chemically, sulfur can react as either an oxidant or reducing agent. It oxidizes most metals and several nonmetals, including carbon, which leads to its negative charge in most organosulfur compounds, but it reduces several strong oxidants, such as oxygen and fluorine.

Sulfur occurs naturally as the pure element (native sulfur) and as sulfide and sulfate minerals. Elemental sulfur crystals are commonly sought after by mineral collectors for their distinct, brightly colored polyhedron shapes. Being abundant in native form, sulfur was known in ancient times, mentioned for its uses in ancient India, ancient Greece, China and Egypt.

Today, almost all elemental sulfur is produced as a byproduct of removing sulfur-containing contaminants from natural gas and petroleum.

Melting point    388.36 K, 115.21 C, 239.38 F
Boiling point    717.8 K, 444.6 C, 832.3 F

Sulfur's Boiling point = 717.8 K, 444.6 C, 832.3 F suggests that it could easily form in cooler parts of the cylinder of diesel engines.  That cooler place might just be the heat shield of a diesel injector inside a pre-chamber, especially in a diesel engine that does not have a turbo, which would mean the cylinder would be cooler than the cylinder of a turbocharged diesel engine.
« Last Edit: January 07, 2014, 08:48:46 AM by Jhanananda »
I have run various blends of waste oils and unleaded gasoline since Feb, 2007 in a 1983 Chevy G-20 van with a 6.2L diesel V-8 engine, with a Stanadyne Rotary DB2 IP. I have started the engine with no difficulty on an 80/20 (WVO/gas) blend down to 3F (-16c).  I now run 60/20/20 (WVO/diesel/gas)

Jhanananda

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Re: Ways to prevent or cure coked injectors???????????
« Reply #22 on: June 21, 2015, 03:58:17 PM »
Some people have speculated that the reason why my injectors get coked on 80/20 blends, is due to the 20% gasoline.  They are completely ignoring that it is most probably the 80% WVO that is causing the coking.  So, for the last 1.5 years I have been running 70/30 blends, and so far had not had a diesel injector failure.  However, I did have a diesel injector pump failure for various reasons, which have been documented elsewhere.  In the process of trouble shooting my recent starting problem I started with the injectors, which in the past had been the primary problem, but not this time.

The above is an unmodified Bosch diesel injector from a naturally aspirated 6.2L diesel engine.  While the injector is pretty well coked, it still worked fine, and probably would have made it another year or so before failure.

The above is a modified Bosch diesel injector from a naturally aspirated 6.2L diesel engine.  While the injector is pretty well coked, it still worked fine, and probably would have made it another year or so before failure.  It was; however, more coked than the unmodified Bosch diesel injector. 

Conclusions:
1] The injector modifications were useless.

2] Adding more gasoline reduced the rate of coking considerably, proving that gasoline in the blend is not the cause of injector coking.  It is either too much WVO, or not enough gasoline.  So, I plan to blend at 60% WVO to 40% gasoline.  After elastomer testing shows too much alcohol in the blend, then I will reduce the alcohol in the blend by adding diesel fuel at up to 20%.  This will also bring the WVO down to 40-50%.
« Last Edit: June 21, 2015, 04:25:14 PM by Jhanananda »
I have run various blends of waste oils and unleaded gasoline since Feb, 2007 in a 1983 Chevy G-20 van with a 6.2L diesel V-8 engine, with a Stanadyne Rotary DB2 IP. I have started the engine with no difficulty on an 80/20 (WVO/gas) blend down to 3F (-16c).  I now run 60/20/20 (WVO/diesel/gas)

Class_8

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Re: Ways to prevent or cure coked injectors???????????
« Reply #23 on: December 07, 2015, 10:44:16 PM »
I only read the first post/not the thread, buuuuut as soon as I saw the bit about 'HHO generation' it made me want to chime in - I would think if hydrogen works, so would propane or CNG just as well.  I've studied and read other reports that adding just 5% CNG fuel (by total btu content) improved power, economy, and emissions substantially in even already efficient diesels because it made the existing fuel burn much cleaner like with 97% efficiency.  (if I can ever dig up the article again i'll share but don't hold your breath, it's from an old notefile)

I see no reason propane shouldn't work the same, and people have made DIY propane injection systems for diesels remarkably simply, as simple as a bleed screw instead of a gas-carburetor since the turbocharger mixes things anyway, because for what I understand it can't touch off until the diesel fires anyways/ignition temperature high enough that it SHOULD be safe.  (though obviously i'd ask some other experts first)

Jhanananda

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Re: Ways to prevent or cure coked injectors???????????
« Reply #24 on: December 08, 2015, 06:36:16 AM »
Well, I agree that partially CNG aspiration on a diesel engine might have somewhat of the same effect that HHO does; however, HHO does not just improve combustion, it also very efficiently scavenges free carbon.
I have run various blends of waste oils and unleaded gasoline since Feb, 2007 in a 1983 Chevy G-20 van with a 6.2L diesel V-8 engine, with a Stanadyne Rotary DB2 IP. I have started the engine with no difficulty on an 80/20 (WVO/gas) blend down to 3F (-16c).  I now run 60/20/20 (WVO/diesel/gas)

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Re: Ways to prevent or cure coked injectors???????????
« Reply #25 on: December 08, 2015, 10:27:45 PM »
Just to be sure everyone sees this if subscribed here and not the other...  something I dug up from older notes I took on the subject.  A supposed "miracle formula" for clearing out coked injectors - 1/2 gallon pump diesel, 1 can seafoam, 6 ounces Diesel Kleen.  Mix in a 1 gallon container and disconnect your fuel lines/run direct to pull the mix from this container.  Idle through the mix then reconnect to your normal fuel mixture.

I have not tried this (do not currently have a waste oil vehicle) but i'd love to hear how this mix works for anyone else here.  Instead of throwing stuff in the tank you hit it with one gallon super concentrated mix to break crap loose basically.

Jhanananda

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Re: Ways to prevent or cure coked injectors???????????
« Reply #26 on: December 09, 2015, 06:16:42 AM »
I am not too much into secret engine cleaning formulas, because, in most cases, when we examine the MSDS on them, we find that they are just a blend of gasoline and oil; which is what we are doing anyway.  Also, out turns out direct injected turbo-charged diesel engines generally do not coke on waste oil-based fuels, so we should just stay way from the N/A IDI diesel engines.
I have run various blends of waste oils and unleaded gasoline since Feb, 2007 in a 1983 Chevy G-20 van with a 6.2L diesel V-8 engine, with a Stanadyne Rotary DB2 IP. I have started the engine with no difficulty on an 80/20 (WVO/gas) blend down to 3F (-16c).  I now run 60/20/20 (WVO/diesel/gas)

Excalibur

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Re: Ways to prevent or cure coked injectors???????????
« Reply #27 on: December 09, 2015, 01:59:13 PM »
Just to be sure everyone sees this if subscribed here and not the other...  something I dug up from older notes I took on the subject.  A supposed "miracle formula" for clearing out coked injectors - 1/2 gallon pump diesel, 1 can seafoam, 6 ounces Diesel Kleen.  Mix in a 1 gallon container and disconnect your fuel lines/run direct to pull the mix from this container.  Idle through the mix then reconnect to your normal fuel mixture.

I have not tried this (do not currently have a waste oil vehicle) but i'd love to hear how this mix works for anyone else here.  Instead of throwing stuff in the tank you hit it with one gallon super concentrated mix to break crap loose basically.
Many/most diesel vehicles have a return fuel line that routes diesel back to the tank. The object was to automatically eliminate trapped air plus it lost heat to the returning fuel thereby cooling the IP. So should you try the remedy, you'd have to run the return line to your gallon container else most of the miracle formula will end up in the tank. More fuel gets returned than the motor uses, especially at idle.
Seafoam and Diesel Kleen are not available in my part of world and if they were, they'd be s-t-o-o-p-i-d money. That's money I'd be better off buying diesel with which would do the same thing plus get the benefit of the miles it gave.
Aim to make diesel that maintains itself.