Diagnosing white smoke

[Gunner_1]

Hello, trying to get my 1991.5 Cummins truck running good, I have been replacing lots of parts over the last 4 years trying to make the truck a solid dependable daily driver / long trip capable truck. The truck has smoked white at idle, after it warms up, and while driving the truck since I got it 4 years ago. The only modifications over stock are the ones I have made in the last 4 years.
-7.3 mishimoto intercooler

• 4 core aluminum radiator
• big air filter
• 4” straight exhaust
• thd high volume lift pump
• 1/8” timing advance rotating the injection pump towards the head
• ratman fuel pin, 3200 gov spring, brass tip fuel shutoff plunger pin
• dynamite diesel 5x12 injectors
• new oem holset hx35 with new oil drain tube

The last 2 were recommended as a possible cause of the white smoke, nothing has lessened the white smoke and with the exception of the fuel pin, gov spring, and plunger pin the injection pump has not been adjusted anyway.
It doesn’t leak coolant, and I don’t have to add any so I don’t think it’s the head gasket

 

[BigPapa]

White smoke usually means a timing issue.

 

[Gunner_1]

White smoke usually means a timing issue.

I advanced the timing rotating the pump to the head 1/8” I was told that can’t cause white smoke. The timing gear tooth is on “E” what else can I look for as far as timing issue?

 

[BigPapa]

what else can I look for as far as timing issue?

Sorry, I'm not familiar enough with the VE Pump to help you. Maybe others will chime in and help you out. Someone like @NIsaacs , @RWherley , @RedD250 , @Bluebird

 

[Grumpy8811]

you ever check the compression in the engine?

 

[BigPapa]

@NIsaacs , @RWherley , @RedD250 , @Bluebird

None of you guys have any ideas?

 

[Gunner_1]

I have rotated the pump back to the stock setting, no change in smoke. I loosened each injector line while running, fuel came out and the idle changed for each. Once the truck warmed up, I took heat readings on the manifold and head for each cylinder showing compression of each cylinder. I removed the valve covers and watched each cylinder working each valve spring and pushrod correctly. I’m going to replace the fuel filter again today and fill it up with hotshots diesel extreme today. Like I mentioned earlier the truck runs great, just chasing this white smoke , any other ideas?

 

[STeichert]

I bought a first gen years ago that did this, and it ended up being the thermostat was stuck open. The temp gauge would move very little so that was my best clue for the thermostat. The white smoke went away after changing it. It sounds like yours gets to operating temps just fine, so my thoughts would be fuel related, but you have already addressed the injectors. I see you said that the fuel pump has not been adjusted. Is the tamper proof cap still on the full fuel screw? if not, maybe a previous owner adjusted it and turning it down may help. Just a thought!

 

[Gunner_1]

I bought a first gen years ago that did this, and it ended up being the thermostat was stuck open. The temp gauge would move very little so that was my best clue for the thermostat. The white smoke went away after changing it. It sounds like yours gets to operating temps just fine, so my thoughts would be fuel related, but you have already addressed the injectors. I see you said that the fuel pump has not been adjusted. Is the tamper proof cap still on the full fuel screw? if not, maybe a previous owner adjusted it and turning it down may help. Just a thought!

I have replaced the thermostat with a new Cummins one with no change. I have removed the tamper proof caps on the injection pump myself when adding the fuel pin, gov spring but haven’t adjusted anything on the pump.

 

[NIsaacs]

This might be a possibility. I have not ever needed to but....timing spacer.

It has been awhile but if I recall correctly, there is a screen in the fuel return near/on the pump. Maybe plugged? Or plugged down stream?

https://video.search.yahoo.com/vide...60&w=480&l=314&age=1612389299&fr=yfp-t-s&tt=b

 

[BigPapa]

Have the injectors been changed? You can get hazing if they don’t have the proper spray angle and they’re spraying outside the bowl.

 

[Gunner_1]

Have the injectors been changed? You can get hazing if they don’t have the proper spray angle and they’re spraying outside the bowl.

Yes I just put in new 5x12’s and it’s still smoking white

 

[Gunner_1]

I pulled the injection pump shaft nut off, to add a lock washer and I was curious if the key way was there I couldn’t see down there but I have a small mirror and flashlight, it looks like the key way is missing

 

[Bromiley99]

This is from Oregon Fuel Injection, they have other diagnostic info to look at but I had this problem once before.


The KSB unit on the injection pump uses a temperature sensor in the intake manifold to advance the pump timing when the engine is cold, which reduces blue/white smoke.

1. 89 to early 91 used a wax motor style KSB unit that voltage is applied to, via the cold start switch, once the intake air temperature is above 160 degrees.
2. 91.5 – 93 used a solenoid style KSB. The intake air temperature sensor applies 12 volts to the KSB solenoid until intake air temperature is above 90 degrees.

 

[Gunner_1]

This is from Oregon Fuel Injection, they have other diagnostic info to look at but I had this problem once before.


The KSB unit on the injection pump uses a temperature sensor in the intake manifold to advance the pump timing when the engine is cold, which reduces blue/white smoke.

1. 89 to early 91 used a wax motor style KSB unit that voltage is applied to, via the cold start switch, once the intake air temperature is above 160 degrees.
2. 91.5 – 93 used a solenoid style KSB. The intake air temperature sensor applies 12 volts to the KSB solenoid until intake air temperature is above 90 degrees.

What problem did you have with the ksb? Also my truck smokes white all the time, even after warming up

 

[Gunner_1]

I pulled the injection pump shaft nut off, to add a lock washer and I was curious if the key way was there I couldn’t see down there but I have a small mirror and flashlight, it looks like the key way is missing

well maybe it’s in there I’ll post a pic
I read this top part of the article and thought maybe you hat was my problem:
https://rotordesign.com/1993cummins/category/bosch-ve-pump/page/2/

 

[Topzide]

I looks to me like the key is gone, or sheared. Could just be the camera angle. You should see a lot more of it in the slot. Hopefully others will chime in with more hands on experience.

 

[STeichert]

That Key does look like it's missing. Can you run a piece of wire through the hole to see if it's gone completely or just sheared off?

 

[Gunner_1]

I have been told the keyway doesn’t stick up much, I ordered a new keyway and that makes sense after seeing how short the new keyway is. It looks like it may be in there still when I shine a light on a small mirror down there. I’m not certain though, so I might pull the timing cover again to check. I have been told I can use a steering wheel puller to remove the timing gear from the front and check this way? If I do this I will go ahead and jump a tooth and line the notch up with c, instead of e at this time

 

[NIsaacs]

I have been told the keyway doesn’t stick up much, I ordered a new keyway and that makes sense after seeing how short the new keyway is. It looks like it may be in there still when I shine a light on a small mirror down there. I’m not certain though, so I might pull the timing cover again to check. I have been told I can use a steering wheel puller to remove the timing gear from the front and check this way? If I do this I will go ahead and jump a tooth and line the notch up with c, instead of e at this time

Yes, you can pull the gear with a small puller. You can't change a tooth without pulling the whole front cover, that's a big job. So is pulling the pump to change keys. I would leave it alone, if you can confirm the key it there.