Hey guys I have a Series 60 with DDEC 2 and is a non EGR engine. It smokes black at low manifold pressure. Not alot but enough to make me cringe at the dollars going out my pipe. It also has all the other symptoms of leaking o rings at the injectors. loses prime and ya have to crank the crap out of it to start. lopes and hunts for idle rpm And my tank and fuel get black from combustion soot. When the manifold pressure does come up it is good and strong at 25-30 psi. I know for a fact I have injector o-ring leaks and will need to be dealt with. Took it to the local Detroit shop here and they did a cylinder cut out test. They said #5 and #6 injectors are bad or weak. Ok so here is the big question. If the leaking o-ring is cylinder #4 what are the chances that exhaust gases are causing bubbling in the fuel and basically fowling out injector 5 and 6? I am thinking the black smoke is caused by the computer over fueling the good 4 injectors to compensate for what the other two injectors and cylinders are not putting out. Is this correct in my thinking? I am wondering if i should just replace the o-rings, run the overhead and see if that helps anything. If I still have the black smoke issue I can then pretty well bet that injector 5 and 6 need replacing. If this was an old school Cummins it would not be a question to have a fuel system rebuild as you used to be able to have a complete system rebuilt for the cost of two of these Detroit injectors. I very much hate to just throw injectors at it needlessly. The economy has improved but it just not that much better. Does anyone know if there is a independent rebuilder for these injectors? Also is there a way to have the injectors tested other than cut out test. I mean physically tested. Bad cut out test could be bad solenoid and injector itself fine right? I do all my own wrenching so labor is not a factor in the repair cost. Just the parts lol. I am very skilled mechanic and have more time than money. Thanks in advance.
Use a infrared gun on the exhaust manifold right after start up and run for fifteen minutes you will probably see three cold cylinders. Now one problem the 60 has is the harness for the injectors going bad. It's just always been a problem on the 60's. But if it's hard starting it also has injectors bleeding off. And high mileage 60's can do that, even low mileage too. As far as economy priced injectors-you will probably be sorry for buying them. As far as testing the injector it's mainly just a cut out test. Most Detroit shops don't have the ability or bench equipment to test out of engine. Truck Shop
Black smoke may be an injector with a bad needle valve or tip and it's dribbling fuel. That also could be the path for soot and combustion gases entering the fuel passages. Dribblers do not show on a cutout test. Like truckshop said, get a good thermal gun and check your exhaust port temps looking for a hot one on a cold start. The hard starting issue is probably junk in the check valve on the rear of the head that keeps fuel in the head.
Thats a great idea on the temp gun. I have used that trick before on the old two strokes to diagnose dead injectors when i used to wrench proffesionally. I guess now I finally have a reason to buy one for myself. One other thing I forgot to mention. I get black smoke when the jake is on. Its about the same level of smoke as when manifold pressure is low and throttle is applied. I suppose this could fit with a dribbling injector. I never thought of exhaust gas getting in a dribling injector
Also what about my thinking bubbles in fuel from compression geting in fuel rail and fowling out 5 and 6 injector on cut out test? Is this possible and have you ever seen this? I will get temp gun and post my results.
That's entirely possible. I have seen that in 3406E Cats with hi miles but it was an eroded injector cup allowing compression up through the O-rings. It did mess with the downstream cylinders but only under a heavy load, ran great the rest of the time. We put a clear hose in the return and as soon as it hit max torque you would see bubbles in the fuel. New cups and 0-rings fixed it. I personally think your number 4 is the culprit. Black smoke with the Jake on is a dribbler. Once you do the cold start heat check... You'll know.
On the old two strokes you used to be able to loosen the exhaust manifold and see which port was a smoker. Gotta love progress and technology LOL!
With engine warmed up you should see 325* to 350* temps at idle speed for a normal range. Truck Shop
Truck Shop I think your right on the economy injectors. Thats why I would really like to know which ones are bad and only replace just those. I cannot afford to just throw a set of injectors at it. I picked up a temp gun at HF. I will see if it was worth the money. If I do not work tomorrow I should have some data
I got some time this morning to take some temperatures. I took temps at 5 min intervals up to 20 min after start up. The results are as follows. #1 #2 #3 #4 #5 #6 5min 137 110 129 150 159 135 10min 144 135 144 170 153 150 15min 180 126 165 175 157 151 20 min 181 135 166 177 152 153 From what it looks like to me #2 is definitely suspect. Although whatever its doing is not enough to fowl injector 3,4,5,6. as the temps on injector 3,4 are fairly close to #1. #5 and 6 look to be a little low and could it be they are being fowled by air in fuel rail from injector#4? One thing to note it was not loping or hunting for idle during this test. It does not always do that. I think I may have more than one issue going on. Wish I could afford the $2,400 for a full set of injectors LOL.
And you took those temps right at exhaust port on manifold. Those readings are on the cold side for twenty minutes. Take it down the road and back, and recheck temps. Truck Shop
Yes it is. about an inch out from the head on the manifold. I figured it was the best spot as if you took it on the outside of the manifold you could get a false reading from that port as other ports t in and flow through that point on some ports. This was from a cold start up at about 70 degrees ambient temperature. Should I do it at full operating temperature?
You bet run it up to full operating temp recheck manifold temps plus check coolant temp at the top hose off thermostat housing. Truck Shop
workshoprat92 There is a line that goes from under the intake manifold to supply air to the air compressor. I have seen this line rupture and cause low boost and black smoke. For some reason it usually splits on the side facing the engine so the failure is not obvious. Make sure the line is good before spending a bunch of cash on the engine. Terry