misfire and smoking

[ABeveridge]

I'm a new 1st gen owner. Found a '92 350D, 4x4, Auto, Flatbed w/liftgate with 160k on the ticker. The engine seems to idle fine but misfires and smokes(white w/ light blue) when rev'd a bit over idle when in "Park". As the truck warms up things get better, but the skipping is still there. In "Drive" the smoke disappears, but the truck seems to lag up hills. When I come to a stop (in gear) the cab sounds like a vibrating steel bucket filled with marbles. Because I fell in love at first sight, I have most likely done everything backwards so here is what I have done to date with little improvement: Valves adjusted, injectors removed and tested, Inj. Pump reworked and tested, filters(Air, Fuel & Oil) and fluids changed... From reading around maybe next items should be to advance timing, check boost pump pressure and then tank feed line if necessary... I look forward to any ideas and suggestions. By the way, I still love the truck just as she is.

 

[1stgen4evr]

this and that

If it is 4x4 it is a W not a D. Or you may be using the d to indicate diesel but that is not important here cause all we talk about is diesel.



The most significant indicator you can check is the blow by at the breather pipe down the side of the engine, near the starter. There should be near zero blow by. If that is in order, you can correct whatever else is deficient. If there is blow by, that is not good as it indicates a problem which requires $eriou$ attention.



You have changed the fuel filter so you know the fuel supply isn't restricted but maybe you should put a fuel pressure guage to know that the injection pump is getting correct primary pressure from the lift pump. Pump timing isn't going to make the problem you experience unless it is waaaay off.



Are your grid heaters working correctly? How cold is it where you are. Really, really cold will make the engine balky for a few minutes.



Have you owned a cummins before? They do make a bit of noise that is music to the afficianado.



You might possibily have a blown head gasket if it just won't clear up after it gets warm. Can you identify which cylinders are not fireing when this is going on?



Give more info and someone will probably jump in with more help.



Hang in there. If you love it now, wait till you get everything in order and you will really love it.



James

 

[ABeveridge]

James,



Thanks for the input.



The breather pipe is fine and as stated shows near zero blow by.



Grid heater(s) (?) seem to work, as the truck starts OK in the cold (20-30 degrees) I have not used the truck much in the sub Zero temps we have had lately because the cab heater has trouble keeping up. I opt for the warmth of my 2003.



I have owned a 2001 2500SLT 4x4 Auto and then traded for a 2003 3500SLT, 5 Speed, 4x4. And yes, even the 2001 Engine was music to me.



I will be checking the lift pump pressure next and advise.



Then if all is well, what is the easiest way for me to check for head gasket failure?



Thanks again.



Arnie

 

[phillips5]

Insuficient heat could be a givaway of headgasket trouble. my 93 ext cooks me out of it. I have a lot of head gasket trouble experiance with these trucks.

 

[1stgen4evr]

checking the head gasket

"Then if all is well, what is the easiest way for me to check for head gasket failure?"



Hummm, Not so sure there is an easy way to convince yourself to pull the head. Definitely a last resort, but these engines do exhibit head gasket problems. In fact, a Cummins company man stated that the head gasket is THE weak link on the 6b engines and intimated that this was intentional as a fail safe to keep other parts from failing.



Generally but not always, there will be loss of water and or bubbles in the radiator. If you are very confident of the entire injection system as well as the timing, it leaves little else. There are methods to pressurize each cylinder through the injector ports and determine if there is a leak.



Don't even want to think about it but you could have a cracked head.



Hopefully, someone will jump in here with a better answer.



James

 

[ABeveridge]

I guess its time for a repair manual and then a pressure test.



Thanks,



Arnie

 

[cojhl2]

Isn't there a way to do a compression check on these engines?



I maintained Isuzu and VW diesels in the past when my kids drove them while they were in college. I had all the adapters to check compression, time the pumps, and do other simple work on these engines. Cant believe this isn't available for the Cummins.



Havent had to worry about this on my farm PU yet.

 

[phillips5]

cummins does not have gloe plugs to screw out to make a easy place to screw in a compression tester. You have to remove the injector and stuf in a compression adapter. Most direct injection engines are that way.

 

[cojhl2]

phillips5



Even tho you have to remove and reinstall an injector,, isnt that easier than going thru all this speculation?



I ask this not to be a sharpshooter but I am sincerely interested in knowing this.

 

[1stgen4evr]

"isnt that easier than going thru all this speculation?"



Yes it is, but if you have not pulled a head, you may not be aware that it is a pita and is cause for procrastination if not speculation just trying to talk yourself into the hate and discontent of a head job. But I would absolutely do a presssure test before I pulled the head off if there were no other clear reason to do so.



And pulling the injectors usually isn't that big of a deal. I have on occasion had to use a snatch hammer to pull one. And by the way, if anyone doesn't know, DO NOT bend the injection lines.



You can't use a compression tester built for gas engines. It must be capable of the diesel system pressures.



James

 

[bgilbert]

Pressure test is good. A HG check can be with engine cold and radiator cap off, start the truck and look for bubbles inside the radiator. Oil sample and analysis will show if any coolant is in the oil, do you have any oil in the radiator or overflow resevoir? Coolant will appear milky on the oil dipstick and under the oil fill tube cap.

 

[TKingsbury]

If you suspect a combustion leak into the cooling system, you can get a block tester. It is a cylinder deal that you put test liquid in and attach to the radiator where the cap goes. You then use the little pump bulb to draw air out of the system to see if the air changes the test liquid color. A color change indicates a combustion leak in the cooling system. After that you need to decide where it is coming from.

Travis. .