Testing Cat 3116 injectors

[BKubu]

I have a 1998 M1078 with a Cat 3116. I think I have an injector that is bad. The truck smokes a bit (for about 15-20 seconds) from unburnt diesel fuel, but only when it is cold. Someone told me that I might have a bad injector. I have called around to quite a few diesel shops that specialize in injector work, but no one can test these injectors because they are mechanical. Any ideas of how to get them tested? Does anyone know of a company that could test them if I sent the injectors to them?

 

[NDT]

Did you try any snake oil like Lucas Fuel additives?

 

[BKubu]

Did you try any snake oil like Lucas Fuel additives?

I have not. I have the engine apart right now. I'd like to test the injectors. If I can't, I'll try something like Lucas. Thank you for the suggestion.

 

[Ronmar]

Yea because these are both injector pump and injector, it takes a pretty special rig to hold and feed fuel, as well as manipulate the rack, compress the mechanism repeatedly and monitor output pattern and volume… if you find a place it will probably be overseas(south America, Europe or Asia…

This may also simply be a adjustment/synchronization issue. Pay close attention to injector height/timing when you adjust the valves. when you get it back together measure individual exhaust temps(IR thermometer as close to the top of each ex manifold port as possible) looking for temp differences.

 

[aw113sgte]

I mean, it's a diesel...smoke when cold is expected. I'd be careful listening to "someone" and going down a rabbit hole.
My C7 smokes when cold and clears up eventually, typically starts around freezing and gets worse the colder it is.

 

[GeneralDisorder]

Agreed. 15-20 seconds is nothing. My 2008 C7 will roll coal under load when cold. The 370 HP map might have a little to do with it, but yeah - when REALLY cold they will smoke on startup.

Remember these are non-emissions engines so there's no DPF, and on your 3116 there's no catalytic converter, etc. You WILL see exhaust.

 

[Ronmar]

Yea a little smoke when cold is perfectly normal on a 3116…

 

[BKubu]

I understand about diesels smoking in cold weather. I've had all kinds of trucks with many different diesel engines. This is NOT typical diesel smoke in cold weather. While it only smokes for 15-20 seconds, the cloud of smoke is quite impressive afterwards. The truck runs very well overall, but I'm interested in getting rid of this condition if it is possible without just replacing all of the injectors. I appreciate all of the responses.

By the way, the "someone" who told me that it could be a bad injector is on this list and is a very reputable member who knows his stuff. He knows more than most and much more than I do.

 

[KN6KXR]

When I worked on ships we called this type of injector a "unit injector" because it has the jerk pump and nozzle holder all in one unit. We had test stands that were bought or built by the crew and fixed in place near the machine at a station or in the shop dedicated for service. Most folks don't have this kind of bandwidth in their home shop. As far as I get at home is rebuilding multifuel injectors but those are stupid easy and the tools are cheap.

I suggest you talk to some commercial bus and/or RV folks. A couple years ago I had to swap the injectors on a Detroit 12V-71 powering a generator. Those guys were the only guys that knew what I had and even had refurbed units to sell me at a decent price. They knew what they were talking about as well when I asked for the measurements to set the racks they had the numbers for me straight away.

When you find the folks that can help please post it up. I own one of these I might need the info some day.

 

[aw113sgte]

When I worked on ships we called this type of injector a "unit injector" because it has the jerk pump and nozzle holder all in one unit. We had test stands that were bought or built by the crew and fixed in place near the machine at a station or in the shop dedicated for service. Most folks don't have this kind of bandwidth in their home shop. As far as I get at home is rebuilding multifuel injectors but those are stupid easy and the tools are cheap.

I suggest you talk to some commercial bus and/or RV folks. A couple years ago I had to swap the injectors on a Detroit 12V-71 powering a generator. Those guys were the only guys that knew what I had and even had refurbed units to sell me at a decent price. They knew what they were talking about as well when I asked for the measurements to set the racks they had the numbers for me straight away.

When you find the folks that can help please post it up. I own one of these I might need the info some day.

C12 uses what's called "unit injectors" and are cam driven. Do you know if those work the same way? C12s do have an electrical plug though

 

[BKubu]

When I worked on ships we called this type of injector a "unit injector" because it has the jerk pump and nozzle holder all in one unit. We had test stands that were bought or built by the crew and fixed in place near the machine at a station or in the shop dedicated for service. Most folks don't have this kind of bandwidth in their home shop. As far as I get at home is rebuilding multifuel injectors but those are stupid easy and the tools are cheap.

I suggest you talk to some commercial bus and/or RV folks. A couple years ago I had to swap the injectors on a Detroit 12V-71 powering a generator. Those guys were the only guys that knew what I had and even had refurbed units to sell me at a decent price. They knew what they were talking about as well when I asked for the measurements to set the racks they had the numbers for me straight away.

When you find the folks that can help please post it up. I own one of these I might need the info some day.

This is very helpful. If I find anything out that would help others, I'll be sure to post about it.

 

[BKubu]

C12 uses what's called "unit injectors" and are cam driven. Do you know if those work the same way? C12s do have an electrical plug though

Yes, they are cam driven.