18:1 compression and smoking on start up

[Jim P]

When I rebuilt my engine this past summer, I was shooting for 18:1 compression. Actually I think I ended up with it a little lower than that. Even in the summer, I had to use my manual glow plug button to after glow to keep the engine from smoking on start up.

Since the cold weather has arrived, the smoking is now much worse. I have new high pop injectors and I just put in new quick heat glow plugs. This morning with the truck plugged in, it didn't smoke as bad with the new glow plugs but when I was ready to come home from work, it still did its usual smoke job. It smokes so bad that My cousin drove by one day just after I had started it and he thought our shop was on fire. It even smells like raw fuel inside the shop with all the doors closed. It smokes for about 5 minutes before it finally clears up.

I use my manual glow plug button to give extra glow time and the truck starts instantly but you can tell when the glow plugs start to cool off because the engine begins to run rougher and the smoke really starts to bellow. If I hit the glow plugs again, the engines begins to smooth out and the smoke starts to tame down. It takes about 3 minutes of on and off on the glow plugs to completely eliminate the smoke.

I still have never got my tdc offset reset and it is at -.75. Does anyone think that getting this timing set would help with the smoke? Also does anyone else have this problem with their 18:1 motor? I forgot to add that the temp was about 10*F today.

Once it warms up, the engine runs great, it stills roasts off the tires even in 4-wheel drive. The smoke really don't bother me, its the other guys that have a problem with it. If they go out to start their vehicle right after I start mine, they can't even see theirs.

[More Power]

Generally, an 18:1 engine needs 4-5 more seconds of initial cold glow time to allow the engine to produce normal (like 21.3:1 compression) starts.

If you have a manual glow controller on your electronic 6.5, glow the plugs for 10 seconds manually, then turn the ignition switch to run, to allow the computer to cycle the plugs for its normal glow cycle. The combination of these two glow cycles should produce typical cold starts down to zero at least.

If your compression is lower than 18:1, I don't know.

Advancing the injection timing with a more negative TDC-Offset should help, as would a cetane improving fuel treatment.

MP

[Jim P]

I do use the manual to get about an extra 10 seconds of glow time. This makes it start great but it does not help the smoke problem. The only thing that helps the smoke is after glowing but like I said, it takes about 3 minutes of on and off after glowing to eliminate the smoke.

I am running power service fuel additive but it doesn't help any.

[Tough Guy]

My 18:1 truck is a little smokey after a cold start too for approx. 30 seconds, you need what I will be adding soon....an intake heater! All a guy needs is a switch, relay, and intake heater just like the one in the Dmax.

Cheers

[Jim P]

With my new vertical 4" exhaust the smoke doesn't bother everybody at work so bad. Now the smoke seems to rise and not fill everybody elses vehicle.

Here is a picture of the truck just after I started it on a 3*F morning without being plugged in. It smokes like this for about 5 minutes and then the smoke is completely gone.

http://my.netzero.net/s/ch?ch=photos

The truck starts great, even on these cold mornings. I give it an extra 10 seconds glow time with my manual switch and it only turns over about 1 1/2 times and it is running.

[britannic]

Originally posted by Jim P:
With my new vertical 4" exhaust the smoke doesn't bother everybody at work so bad. Now the smoke seems to rise and not fill everybody elses vehicle.

Here is a picture of the truck just after I started it on a 3*F morning without being plugged in. It smokes like this for about 5 minutes and then the smoke is completely gone.

http://my.netzero.net/s/ch?ch=photos

The truck starts great, even on these cold mornings. I give it an extra 10 seconds glow time with my manual switch and it only turns over about 1 1/2 times and it is running. The link doesn't take us to your photos, just the home page for "My NetZero" photos.

[Jim P]

Sorry about the picture. I am trying to switch internet providers but I have not got it all figured out yet.

Here is the picture at my old internet provider. I hope it works. It is the second pic in the album.

http://myweb.core.com/photos/jpfarmer@raex.com/chevy2500/

[rjschoolcraft]

I find this discussion interesting. As I've mentioned elsewhere, my dad's 4020 John Deere Diesel runs with 16.5:1 compression. It smokes a little, but not anything like the picutre of your 18:1 engine. Lately my stock compression 6.5 smokes more than the John Deere. The Deere has no glow plugs or intake heater, just an adapter on the dash to inject ether as your cranking. Is this a fuel system design difference? Any thoughts?

I can start it at 32F with no ether. Anything lower than that needs some ether. Even with temps in the 30's and 40's and no ether, it doesn't smoke very much.

[Jim P]

Ronniejoe,

A 4020 has direct injection, where the fuel injector injects right onto the top of the piston. A 6.5 has indirect injection, where the injector injects the fuel into a precombustion chamber. They say that the direct injection is harder on the engine but it does make it start better. I assume that gm used the indirect injection because the 6.5 is not near as heavy duty as other diesel engines such as your 4020. Those things were built like tanks.

[Kidd]

Think GM used indirect injection so the engine would run quieter, you get a longer burn time.
The direct injection engines have a crisper bark to them. You should hear my 5.9 Cummins power unit on a cold morning. That said, it doesn't need ether down to freezing point, and it fires right up. Think I would prefer direct injection.
K.D.

[rjschoolcraft]

That's a good point that I had neglected to factor in. Thanks.