Diesel Doctor

[firstthumper]

I have a '93 6.5T in my 1ton, and have owned for many years. I reciently had minor trouble with one cylinder chugging white smoke on start. I was told to change glow plugs. After changing glow plugs their was no change to symptom. I was advise that since the injectors were original and 175K miles on motor that most likely a injector was leaking down causing the problem. I then ordered new marine injectors from a reputable 6.5 parts supplier. Following change of injectors the problem has become much worse. Now can block out the house with white smoke in the morning and engine does not smooth out for couple of minutes. When warmed up the truck runs great with very good and improved power.

Low compression maybe?
Bad wiring to one or more glow plugs?
Bad mechanical injector pump?

What do I check first? Anyone?

[JohnC]

Hard to say from a distance. The glow plug wiring is easy enough to check. What type of glow plugs did you install? Why do you say it was only one cylinder?

Marine injectors? They may be part of the problem. Depends on what the supplier calls "marine" injectors.

The fact that the problem got worse immediately after installing the injectors points toward the injection pump not being able to produce enough pressure to get good atomization of the fuel. However, this problem usually doesn't get better as the engine warms, but then the fuel is easier to burn when the engine temps are up... Any problems with hot starting? At 175K miles the injection pump is due.

Any problems with coolant being forced out of the overflow? You could have a bad head gasket. Try this: Release the pressure from the cooling system when the engine is cold. Replace the cap and start the engine. If the upper radiator hose gets hard before the engine warms up then you may have a bad head gasket.

[firstthumper]

Thanks John,
The cooling system check is a neat trick, I will give it a try tonight. Engine hot start is instant but it has been using a small amount of coolent, so you may be right about the head gasket. I will give that a try tonight. The good thing is this engine has never been overheated, I have gotten it to 220 a couple of times but not for long. I have pyro and trans temp plus boost guages on for last 100k or so. It still makes a nice 7-8lbs of boost and has never seen over 900 on the pyro. I installed exaust, K&N, cooling system upgrades when I bought the truck at 65k (high flow water pump, aluminum radiator) added duramax cluch and fan last year with lower thermostat to match the clutchfan. Oil change every 3K without fail. If it is the head gaskets maybe I could get lucky and not need to overhaul but will not know until the heads are off.

Watch for my next post.