White smoke from exhaust during prolonged downhill engine braking on HDJ81 (1 Viewer)

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We took our 1991 HDJ81 (5spd) along the Alpine Loop in Colorado (elevation 8,000 ft to 13,000 ft) a couple weeks ago. Due to some of the steep, rocky sections coming down from both Engineer Pass (elev. 12,800 ft) and Cinnamon Pass (elev. 12,640 ft) I was in 1st or 2nd gear in 4Lo for awhile (20 minutes or more) to avoid riding the brakes. I noticed that while I was descending I was pushing out a fair amount of white exhaust smoke. The white smoke was embarrassing coming down. On flat or uphill sections where the engine was under load it took awhile for the white smoke to disappear. The white smoke finally disappeared after 10-15 minutes of driving under load.

With the high(er) elevations our 1HDT had a harder time and definitely generated more diesel exhaust (i.e. sooty) than normal, which is to be expected. We were careful not to push it too hard however. The truck has always had some blow-by and oil consumption has stayed fairly consistent, with less than 1L of oil consumed per 5,000 km to 7,000 km between oil changes.

Any idea what is going on? Should I be concerned?

On my research it seems that this white smoke is unburned diesel. I'm wondering if the higher elevations, combined with prolonged engine compression braking was causing unburned diesel to exit the exhaust. Thoughts?
 
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Grande Prairie, Alberta
It seems like something isn't right then. I would expect that white smoke to smell like diesel, rather than engine oil or coolant.

You may want to start with measuring compression in each cylinder, and you could do a leak down test after that.

I would assume your fuel injection system is as-is, and you aren't running on recently rebuilt injection pump and rebuilt injectors.

You may be able to reproduce the fault by trailering.
 
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San Diego
That is due to worn valve seals, what happens is under engine braking a vacuum is created in the intake, bad seals allow oil from the crank case to be sucked into the intake and upon resuming positive pressure i.e under load the sucked in oil is in then pushed into the combustion, so the white smoke you are seeing is the burning of oil, until its gone. The degree of the deterioration in the seals will dictate the amount of smoke, mine was only happening upon resuming acceleration, but if they are bad enough it will happen even before load is applied. Sounds like your engine is fairly tired, and this is another symptom of that. Does not mean anything is wrong beyond what you already know. Top end rebuild will take care of it.
 
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Thanks @wapitimud and @Loober , it may be worn valve seals. Right now our HDJ81 doesn't blow any white or blue smoke on startup (besides a puff of normal smoke at startup), so I think I will keep it as it is. It looks like at some point I will need to deal with the worn valve seals in the long run (which would probably explain the blow-by and moderate oil consumption), but for now I think I'm ok. Still on the fence though.

I was just surprised at the effect of the prolonged engine braking combined with the higher elevations. We've done some engine braking here at ~2,000 ft. elevation on some trails in the National Forest, but didn't get any of the white smoke...

Thanks!!
 
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Its not abnormal for these engines to smoke/smell more at higher elevations, remember they are not computer controlled, as the air gets thinner, nothing is telling the pump to back off on fuel or adjust timing accordingly, so at elevation you are over fueling the engine, especially at low boost levels, once the turbo catches up it usually clears up. Obviously its nothing to worry about if you don;t live at elevation, and just traveling through. But if you do spend prolonged time in those conditions then you should adjust your timing/fuel. So the smoke you are getting is combination of that plus what I said earlier.
 

hj 60

JT1W0HJ6000960839
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I have this with 2H downhill (max altitude 1700 meters ,= 5500 feet, The distance d in feet (ft) is equal to the distance d in meters (m) divided by 0.304 ) with boat trailer pushing, after a few minutes also white smoke but not really alarming, did some 23% slopes with all gear is about 4000 kilogram (8818 lbs ) oil consumption is when I reach oil change interval (5000km) So I need to add oil as it goes to low oil mark on dipstick or replace it. (engine has 325k kilometers)
 

GTSSportCoupe

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Victoria, BC, Canada
We took our 1991 HDJ81 (5spd) along the Alpine Loop in Colorado (elevation 8,000 ft to 13,000 ft) a couple weeks ago. Due to some of the steep, rocky sections coming down from both Engineer Pass (elev. 12,800 ft) and Cinnamon Pass (elev. 12,640 ft) I was in 1st or 2nd gear in 4Lo for awhile (20 minutes or more) to avoid riding the brakes. I noticed that while I was descending I was pushing out a fair amount of white exhaust smoke. The white smoke was embarrassing coming down. On flat or uphill sections where the engine was under load it took awhile for the white smoke to disappear. The white smoke finally disappeared after 10-15 minutes of driving under load.

With the high(er) elevations our 1HDT had a harder time and definitely generated more diesel exhaust (i.e. sooty) than normal, which is to be expected. We were careful not to push it too hard however. The truck has always had some blow-by and oil consumption has stayed fairly consistent, with less than 1L of oil consumed per 5,000 km to 7,000 km between oil changes.

Any idea what is going on? Should I be concerned?

On my research it seems that this white smoke is unburned diesel. I'm wondering if the higher elevations, combined with prolonged engine compression braking was causing unburned diesel to exit the exhaust. Thoughts?

One other thing you may want to check. Pull the dump pipe off your turbo and look for oil in it. You can get white smoke from oil leaking out the turbo seal into the hot turbine housing and dump pipe. Usually it's worst after high load however...so not sure if it would be the case for your down-hill situation.

Oil from exhaust valve seals could do the same thing as well as it enters the hot exhaust manifold.... Pulling the turbo manifold would show you if this is a problem. You'd find oil in the exhaust ports from the cylinder head.
 
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Grande Prairie, Alberta
I don't think these are problems you want to put off until later. The cost of a cylinder head rebuild at a local machine shop, with new guides and valves should be reasonable, especially if you get the head off yourself.

Major failure is possible if you drop a valve here, and you won't know what else is wrong until you take it apart. The service manual details all the steps, but start with your compression test.
 
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Perth Western Australia
White smoke is from combustion that is too cool and going down steep descents makes the engine run cool. The volume of fuel going into the engine is not warming the combustion chambers enough.
If it starts instantly and runs smooth with minimal smoke on a cold start, its hard to say you have a problem.

How many klms has it done and when were the injectors last tested?
 
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@roscoFJ73 , our HDJ81 starts instantly and runs smoothly with minimal smoke on a cold start (i.e. the engine is cold...not necessarily the ambient air temperature). I have removed the ACSD on the IP so I have to nudge the idle up a bit for the first minute or two when it is cold out (i.e. ambient air temperature is cool). The engine has 245k kms on it and the injectors were replaced (with brand new DENSO's) back in 2017 at about 140k kms. The injection pump (IP) was replaced (refurbished core exchange) a year or so after the injectors were replaced. Our fuel mileage has been excellent...our recent trip to Colorado we averaged about 16 MPG (US Gallon) with plenty of gear, winch, roof rack, etc...
 
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I had an issue where I had white smoke when crawling and not boosting the turbo. In my case, discovered that my water separator was letting a little air into the fuel system. When I fixed that, it got a lot better. My rig still has a little smoke when crawling but not like before. I wonder if cool combustion temps or valve guides are the culprit.

For reference,

You can see the smoke before in this video

Here's the smoke level now

 
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Arkansas
Thanks @Lumpskie ! A couple pictures are worth two thousand words at least :) I switched out my fuel filter back at the beginning of 2018, so I've got a new one (OEM Toyota) ready to go...I may go ahead and just replace the manual primer pump at the same time, as I've heard of other folks having air leaks at that point. My 1991 is nearing the 30 year mark...I don't mind replacing some rubber seals once in awhile :)

So far @roscoFJ73 explanation seems the most likely culprit in my case. The part I don't understand is that I would think that ALL HDJ81's (or all Toyota 1-HDTs without electronically controlled IPs) would exhibit this if it was just due to cooler combustion when at higher elevations and engine braking. It makes sense to me that the non-electronically controlled IP (Injection Pump) could provide too much fuel given that the air is that much thinner at such elevations (8,000 ft to 13,000 ft) and engine braking. Or...it could be worn valve seals and perhaps the "white" smoke that I was seeing had some blue to it? I could have sworn it was white smoke...not blueish smoke.
 
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When an engine is tired, the first signs are nearly always poor starting when cold. Yours is doing everything perfectly
We dont have grades anything like you have on other continents, but the steepest long hill near me can lower the coolant temperature on a 1HZ from 85c to about 50c in 7-8 mins of downhill.

The white smoke finally disappeared after 10-15 minutes of driving under load.

I thought it would have gone away almost straight away.
 
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Me too @roscoFJ73 ... I was very surprised it took so long to get rid of the white smoke. When we were coming down those steep grades and then would get to a flat spot (or even a slight uphill) and the engine was put under load (with turbo engaging) it didn't necessarily get rid of the white smoke after a few minutes.
 
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I'm going to disagree with above posts suggesting issues. I've had three separate diesel cruisers in that area and all had that same issue on decel. One of these was a 12k mile 1hz and the other a freshly rebuilt 12ht. The third was a 3b with a recent head rebuild so none of those engines had worn seals. I attribute it to unburned fuel because of the elevation.
 
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Thank you @roma042987 for sharing ... with that many Toyota diesel engines exhibiting the same white smoke on engine compression braking at higher elevations, it makes me think it is not as isolated as I thought it was. I'm not going to fret over it...but it is good to know. It is not like we're up at 8,000 ft. + elevation every day...only once in awhile for a vacation :)
 
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Tulalip, WA
100% percent agree with @roscoFJ73 's and @roma042987 diagnosis. I have seen ,in very cool, high elevation ,downhill, engine overev situations an alarming amount of white smoke billowing out of an otherwise healthy engine. It's just not hot enough to burn the addl fuel the overrev from engine braking is introducing.
1 of my Land Rover 300TDis would do it so bad you could see it drifting through the trees if you started downhill right after the first start of the day.
I admit it is alarming to look in your mirror and see what amounts to a steam engine running behind you. But, if no other symptoms present, wouldn't worry about it.
 

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