Attention: TDR Forum Junkies 
HI Guys,
My work truck, a 1997 Freightliner MT 45 (step van....5.9 cummins engine, 4 speed Allison ...19K gvw, 285K miles) is running VERY rough.....BY running very rough I mean it'll barely pull 15-25 MPH on the road at nearly full throttle up seemingly minor grades....all the while laying down a clout of whitish / bluish smoke (the truck does not burn or leak oil).
Yesterday it ran so badly I thought It would die out in the middle of the road but luckily it never did....I managed to limp it home....
The truck used to run pretty powerfully (able to climb one hill in particular at 55 MPH but seemingly over time performance has slowly deteriorated to the point that it only does about 45 in a lower gear if I really push it up the same hill).
Anyways, one thing I will mention is that the truck had for awhile a "ticking sound" .....I feared that it was an exhaust manifold leak (i.e. hard to fix because of rusty bolts) but it was later discovered that one of the injectors had a leaky seal and an injector seal kit made the noise go away.
Around the same time as the injector "fix" (a few months ago while it was warm out), the truck seemed to develop a slight "miss" if you push the throttle hard around 55 MPH to maintain speed on grades (in all fairness the truck used to have a slight "miss" and whitish smoke screen during colder weather but it ususlly when away after about a half mile or so....just seemingly never at high speeds).....backing off the throttle made the miss go away but of course you lose speed doing so...It sometimes makes me think that all the return lines we had to take off to fix the one injector may have caused something to get messed up somewhere (i.e. fuel leak BUT everything is dry so I assume no leaks).
An interesting side note is this....historically, the missing and cold weather rough running combined with the smoke screen seemingly only happened when it was cold out (like fall / winter)....warm weather and I never laid a smoke screen down and seemingly never had a "miss"....Also the "miss" and rough running used to only be when the engine was cold or low temp. / low temp out and typically a half mile or so of driving and the truck was good for the rest of the day ...when the engine warmed up it was more or less fine....now the engine can be at full operating temp and miss / stumble and lay down whitish smoke.
A friend of mine suggested I change the fuel filter....I did that and to my horror this is what I found (see pic)....I have no idea what the "gunk" on the edges blocking the small holes along the filter rim is but it covered all but one and a half of the small holes.
FWIW, the pleats inside the filter as viewed from the big threaded center hole appeared to be clean.
I did put in 40 OZ approximately of diesel fuel treatment (I think it was power service in the gray bottle from Wal Mart)....I only put this in on the last trip where the truck was more or less unusable.
I did check for fuel leaks but no real drips / wet spots were seen.
Thanks in advance for any and all help.
Andrew
My work truck, a 1997 Freightliner MT 45 (step van....5.9 cummins engine, 4 speed Allison ...19K gvw, 285K miles) is running VERY rough.....BY running very rough I mean it'll barely pull 15-25 MPH on the road at nearly full throttle up seemingly minor grades....all the while laying down a clout of whitish / bluish smoke (the truck does not burn or leak oil).
Yesterday it ran so badly I thought It would die out in the middle of the road but luckily it never did....I managed to limp it home....
The truck used to run pretty powerfully (able to climb one hill in particular at 55 MPH but seemingly over time performance has slowly deteriorated to the point that it only does about 45 in a lower gear if I really push it up the same hill).
Anyways, one thing I will mention is that the truck had for awhile a "ticking sound" .....I feared that it was an exhaust manifold leak (i.e. hard to fix because of rusty bolts) but it was later discovered that one of the injectors had a leaky seal and an injector seal kit made the noise go away.
Around the same time as the injector "fix" (a few months ago while it was warm out), the truck seemed to develop a slight "miss" if you push the throttle hard around 55 MPH to maintain speed on grades (in all fairness the truck used to have a slight "miss" and whitish smoke screen during colder weather but it ususlly when away after about a half mile or so....just seemingly never at high speeds).....backing off the throttle made the miss go away but of course you lose speed doing so...It sometimes makes me think that all the return lines we had to take off to fix the one injector may have caused something to get messed up somewhere (i.e. fuel leak BUT everything is dry so I assume no leaks).
An interesting side note is this....historically, the missing and cold weather rough running combined with the smoke screen seemingly only happened when it was cold out (like fall / winter)....warm weather and I never laid a smoke screen down and seemingly never had a "miss"....Also the "miss" and rough running used to only be when the engine was cold or low temp. / low temp out and typically a half mile or so of driving and the truck was good for the rest of the day ...when the engine warmed up it was more or less fine....now the engine can be at full operating temp and miss / stumble and lay down whitish smoke.
A friend of mine suggested I change the fuel filter....I did that and to my horror this is what I found (see pic)....I have no idea what the "gunk" on the edges blocking the small holes along the filter rim is but it covered all but one and a half of the small holes.
FWIW, the pleats inside the filter as viewed from the big threaded center hole appeared to be clean.
I did put in 40 OZ approximately of diesel fuel treatment (I think it was power service in the gray bottle from Wal Mart)....I only put this in on the last trip where the truck was more or less unusable.
I did check for fuel leaks but no real drips / wet spots were seen.
Thanks in advance for any and all help.
Andrew
