Black smoke interrogations (1 Viewer)

[tohox]

Hi,

Just completed a 4000km run over the last 7 days with my 1991 PZJ77. Mostly on highways and at speeds varying between 95 and 110km/h. I have an RTT and cargo carrier + 3 passengers.

All was well until today when we encountered warmer temperatures (A/C full on) and started climbing slightly as we approached the Rockies. I noticed engine temp was up slightly from the usual <1/3 and started seeing a faint stream of black smoke behind me in the rearview mirror. I could modulate the smoke density by playing with the gas pedal. It disappeared when we returned to flat sections and returned in inclines if I tried to maintain speed.

When I started driving again after lunch with a cold engine I got the impression there was no smoke anymore but it returned later once the engine had reached its normal temp.

We will be going through the Rockies during the next week and I'd like to know if I should worry, just go easy on the throttle or seek help... I've never seen black smoke coming out of this truck's exhaust before but this is the first time I've stressed it like this over long periods.

I've had to add a little less than 1/2 pint of oil to maintain the same level I had when I left home last week. Not sure this is related but I've also had a slight leak at the injection pump since I got the truck two years ago. I planned to service the injectors, injection pump, change timing belt, water pump etc after this trip (odo at 285000 km).

Thanks!

 

[pithicus]

I thought black smoke was normal under heavy acceleration? Black is better than blue! Definitely keep an eye on the temp gauge though.

 

[roscoFJ73]

I thought black smoke was normal under heavy acceleration?

On older diesels it was, the 1PZ 1HZ were a new breed that make hardly any smoke when serviced correctly

We will be going through the Rockies during the next week and I'd like to know if I should worry, just go easy on the throttle or seek help

I wouldnt be too worried. The injectors probably need a service. Just take it easy, back off when you see a lot of smoke. At higher speeds 1PZ and 1HZ will use a bit of oil as they age. See if there is any oil in the air intake tube.

 

[coldtaco]

High altitude =less air =black smoke. Some engines came with the high altitude compensator to try and minimize this. Do a search on here, been discussed a lot.

 

[tohox]

High altitude =less air =black smoke. Some engines came with the high altitude compensator to try and minimize this. Do a search on here, been discussed a lot.

Yes I have read about those HAC here on the forum and I don't think my IP has one. I've also read one could adjust the fuel mix slightly to compensate for this.

We only gained 1000m altitude when the smoke appeared though. Not sure if this alone is enough to explain the smoke.

I'm tempted trying to find the fuel mix adjustment and see if backing it off a bit changes things. Any comments on that idea are welcome!

Thanks!

 

[Rigster]

Completely normal under load to see black smoke @tohox , especially with higher mileage, tired injectors.

And when it is warmer, AC on, and you are working it.... temps will rise. If it gets bad, just turn off the AC until you get past the hills...

For an engine with that many km's, if you don't know if the injectors have been serviced/rebuilt yet, I would start there before looking into the fuel pump. You are dumping fuel into the motor that is not getting properly atomized and you are losing efficiency. All adjusting the fuel will do is make it have less power. You WILL be successful in getting rid of the smoke, but at the expense of less go go...

Stop in and say hi while you are in the Okanagan!