Engine/Transmission (1994 - 1998) Decelerating and cold start smoke

[JoelAbq]

Hey guys,



Great forum, tons of information. I've been lurking and searching around for months and have found lots of good stuff here. I thought I would post to get a little more specific advise.



First, I have noticed that when the temps are just above the Grid heater threshold (say 60F or a little higher), I get white smoke for a few minutes. Likewise, in the winter at 30F and below, I have to cycle the grid heater 2-3 times to keep the smoke minimal unless I have the block heater plugged in for a few hours before startup.



Second, I noticed while descending a trail road in Colorado this weekend in 4low and first gear that I was leaving white smoke. This happened again while descending US550 in 3rd gear locked at 55mph or so. Pyro said 200-250F, and I was off the gas. If I goosed it I let out a larger puff of white, if I hit OD on and hit the fuel it blackend up right almost immediately.



Truck runs pretty well, when I bought the truck in March of 06 it didn't run quite as nice towing as it does now. I bought gauges (Pyro, Trans, Boost) and moved the stock plate an 1/8” forward. When I bought the truck it would barely move past 2200rpm, so I did a home-made 3k GSK and now it runs up to 2600-2700 (although it doesn’t have as much power up there). EGTs on a hellish climbs max out at 1250F usually, but I refuse to sustain that and downshift if it heads up there in temps. I have a lockup switch as well. I tow a 7500 dry Fifth wheel (loaded I’m sure I’m at 8500-9000, but since I just bought it a month ago I haven’t hit the scales yet). I haven’t adjusted timing (nor do I have access to the tools at this time), and KDP is killed. Is this a simple matter of timing, or something else? I don’t really want to leave trails of white smoke on decal down steep hills, and I don’t like smoking out the camping neighbors when I startup my truck in the mountains at 50-65F and 8000+ alt.



Any ideas?



Thanks!



Joel

 

[Vaughn MacKenzie]

Hi Joel, your smoke definitely doesn't sound normal unless you got big injectors or running a thicker head gasket (lower compression). If your timing has slipped or is too retarded then you would get a ratty miss/bark with a lot of white smoke if you blip the throttle within the first minute or so after starting up, especially if it's cool or cold weather.

I am thinking more like you're sucking air in somewhere, it would be good to service your prefilter unit and replace the gaskets, and make sure the heater is OK. When you take it out check to see if the electrical connection has any oily buildup from leaking fuel- when these fail they leak around the electrical pins.

Another place for leaks is the short 90-degree rubber hose, make sure it's not cracked or the clamps are weak. And finally there is a little rubber O-ring on the hard line entering the prefilter unit that gets hard and starts letting air in. Here is a thread talking about that and it's item #3 in the picture https://www.turbodieselregister.com...l-heater-input-seal-replacement-question.html

Here is a thread on NW Bombers I posted about the issues with 12 valve fuel systems: 12 Valve Fuel System - BOMBER Board

Another good link Fuel Pre-Filter Cleaning on Ram/Cummins

Once you give it a good going over hopefully it'll clear your smoke. If it doesn't I'd pull the injectors and clean the tips then have a shop check popoff pressures. When I pulled the stock injectors out of both my 12-valves they looked horrible. . . tons of deposits on the tips. I think anytime injectors haven't been pulled in 100k miles it's good to jerk 'em out of there and at least clean off the deposits.

Let us know how it goes.

 

[Coalsmoke]

Something interesting I have noticed is that when you start up an older big rig engine when its cold, it will blow white / light grey for a while. When its cold here and I start my 5. 9, I get some light grey for the first minute of warm-up and then medium grey for the next 5 or so minutes, but not white like the big diesel blocks do. I'm not sure why they do, just something I have observed.

 

[JoelAbq]

Hi Joel, your smoke definitely doesn't sound normal unless you got big injectors or running a thicker head gasket (lower compression). If your timing has slipped or is too retarded then you would get a ratty miss/bark with a lot of white smoke if you blip the throttle within the first minute or so after starting up, especially if it's cool or cold weather.

When I first start it, I don't ever blip the throttle when it's cold, but I'll usually let the oil pressure come up and then rev it slowly to 1k for a few seconds. It sounds like it's missing 2 cylinders during this time, but that clears up within the first 60-90 seconds.

I am thinking more like you're sucking air in somewhere, it would be good to service your prefilter unit and replace the gaskets, and make sure the heater is OK. When you take it out check to see if the electrical connection has any oily buildup from leaking fuel- when these fail they leak around the electrical pins.



Once you give it a good going over hopefully it'll clear your smoke. If it doesn't I'd pull the injectors and clean the tips then have a shop check popoff pressures. When I pulled the stock injectors out of both my 12-valves they looked horrible. . . tons of deposits on the tips. I think anytime injectors haven't been pulled in 100k miles it's good to jerk 'em out of there and at least clean off the deposits.



Let us know how it goes.

I will check these items soon and report back. Thanks!



Joel