BJ40 Exhaust smoke

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Jan 23, 2019
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Arvada, CO
Howdy! First time posting...

I have a 78 BJ40 that I’ve been rebuilding, and when firing it up for the first time, exhaust smoke was excessive, sometimes grey, sometimes darker and would calm to almost normal when bringing RPMs up. Attached are a few photos illustrating the changes as I start it (smoke!), start to drive w low RPMs (smoke still), drive (limit smoke), engage clutch (smoke returns) and then put in neutral before reversing back into driveway (darker smoke)

I am about to use a block test to confirm the the fluid isn’t coolant. Head was rebuilt by AMS, head gasket replaced and everything torqued to spec after cleaning up the block some too.

The smoke has no sweet smell at all and the oil dipstick also lacks a sweet smell.

Hoping it’s just a fuel pump adjustment but any input is helpful, I’ll answer any other questions as best I can and will post any photos requested (of the vehicle )

Thanks in advance!

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AussieHJCruza

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What does the smoke smell like? Is it oil or diesel? If it's diesel first thing I would check is the timing. If it's very retarded it may not be burning properly.
How does it start?
How old is the diesel and do you know if the injectors or fuel pump have ever been serviced/rebiilt?
 
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important to note that he is at like 5,500 feet or so in Arvada. I think that will be import for the experts to know as they help diagnose.

How warm was the engine when you were driving in the pics? At a bit over 6,500ft all of our N/A diesels smoke until warm.
 
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That was a lot of smoke but I have to agree with the winter altitude combo. Not enough heat in the air and not much air period! Does smoke go away with glow? Tuff to tell if you don't have a manual glow button. What's your timing set like? Do you run a cetane additive? Block heater by chance?
 

cbmontgo

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I had my diesel HJ47 in Colorado for a few months and it never smoked like that once it was warmed up. I'd suggest something other than altitude as the cause.
 
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Have to agree with @cbmontgo. I’ve had my 3B all over Colorado and Utah this winter and it smokes very little, even at 9k+ feet in negative temps.

Based on that last pic I’d definitely try turning down the fuel and see if it improves.
 
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Thanks for the fast response!

What would oil smell like vs diesel?

The injectors were just rebuilt. The smoke calms down as fuel is used or if I reduce fuel going to engine. I’m just skeptical about it only being fuel and curious about tuning it properly if it’s the pump.
 
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Thanks, House is at 6100 for elevation too... It was over the summer when started and engine definitely warmed up a good bit and it was still smoking
 
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I am inclined to agree and very happy no one is overly suspicious of a cracked block! I will try to adjust fuel next time I start it and then use the test kit! Will follow up w the results!

Thanks man
 

AussieHJCruza

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White smoke isn't overfuel on a diesel, that would be black and as @-MaTTi- says, would not manifest at idle.
Regarding how to tell the difference between oil and diesel smoke, I'm not sure how to describe this. Can @Memphisau79 give us a description of maybe what the smoke smells similar to? Also, what is the truck like to start?

My thoughts are
1) if the timing is that far off, surely the engine would be hard to start?

And

2) if she's burning that much oil, and not so down on compression that the engine won't run, is it valve stem seals?
 

YoYoHo

BJZ43 for Me !
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Have you checked that the fuel pump’s leather diaphragm is not cracked?
2230347010 Genuine Toyota DIAPHRAGM SUB-ASSY, GOVERNOR 22303-47010 | eBay
This is by far the most common issue that causes the issues you are having and is common.

I would replace it and see what happens.

As others have said if you are asking the questions I would strongly recommend against just turning screws on ya pump. They are a tractor and all but you can kill them if you lean it out .
 
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No no, it’s not overfuel, it would be completely black smoke and ok when idling.
Ok ok, I should have looked at the photos more closely.

You have to know what you are doing, not just turning screws and see what happens
You can most certainly turn screws and see what happens, as long as you only turn it down. :flipoff2:

They are a tractor and all but you can kill them if you lean it out .
How? A diesel is always lean by definition - not enough fuel and it just won’t run.
 
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The smoke smells like exhaust but I have a rookie sense of smell in this, nothing was super horrible or sweet smelling though. It was partially rebuilt before starting that day, so it struggled some to start but later that evening started fairly quick. The engine has new valves and seals too to address that.

If the diaphragm is from 1978 and has that rubber seal, I feel I should replace it for good measure regardless so I will order that and if it still produces smoke then, try adjusting fuel down some. I forgot to mention, I could get the smoke to clear up quite a bit (and loss of driving power) as I slightly pulled the fuel kill switch on dash out as I drove... does that help with finding an answer?

Thanks to all for everything so far and will continue to update when I get a day off work to work on her.
 

YoYoHo

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How? A diesel is always lean by definition - not enough fuel and it just won’t run.
lol let me be a bit more specific .. when I said you will kill it I was referring to killing the power not the actual engine. Yes I am aware a diesel is a Lean Burn Engine by design and due to their design they are "lean" .

If he over fuels it he will run more chance of getting it hot and doing mechanical damage as opposed to lose of power but being a B series without a Turbo it isn't hyper sensitive like a more modern engine.

Sorry for any confusion, replace ya diaphragm
 
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Ordered the diaphragm just now, thanks for the post on how to replace! You guys are awesome.

It does feel/sound like it idles high and the fuel kill switch connects w a wire directly to object the accelerator pedal’s wire attaches to, forgive my lack of knowledge of the nomenclature.

Diaphragm should be here in a few days, will follow up with the details, thanks again guys
 
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